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IFT Annual Meetings - Abstracts of Posters & Presentations that Used the TA.XT2 or TA.XTPlus Texture Analysers
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| This list is of publicly available abstracts of research that we have identified that uses SMS' family of texture analysers. The referenced work remains the property of the authors, their institutions and the IFT. Requests for reprints of the posters and should be directed to the authors, their institutions and to the IFT. The abstracts are presented here for the educational purpose of quickly allowing researchers to determine which research has been done using this class of instrumentation. | |||||
| We strongly recommend membership in the Institute of Food Technologists for everyone interested in food science and technology; as well as for their publications Food Technology and The Journal of Food Science. Please learn more about the IFT at their web site: http://www.ift.org | |||||
| If you have research that used our instrument and was presented at the 2005 IFT and it is not listed then please e-mail us and we will be pleased to incorporate the abstract on this list. The abstracts with titles in red text are likely to have also used our instruments in the research because of our understanding of the authors' research and their laboratory equipment, but the instrument attribution on the poster was unclear. | |||||
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18A-23
Effects of gluten, starch tailing and water soluble constituents on dough rheology and biscuit quality
P. Fustier1, A. R. TAHERIAN1,
Flour fractionation-reconstitution procedures were used to study the influence of gluten, starch tailing and water soluble constituents on dough rheology and dimensional as well as textural characteristics of a commercial soft wheat flour. A semi-sweet biscuit recipe (flour, sugar, fat:water of 100:30:8:36 on 14 wt% moisture basis) was used to assess the influence of the 3 constituents isolated from a patent and clear flour grades on dough consistency, hardness, half relaxation time (Tla) and biscuits volume, density, firmness and dimensions. Increasing the gluten content from 9.5 to 13.5 wt% (d.w.b of flour) incorporated into the commercial flour increased dough consistency, hardness and Tla by 3.2, 2.8, and 1.6 times of the original or control flour. In parallel, the biscuit's density and firmness rose by approximately 14.2 and 56.1%, while the dimensional parameters decreased slightly along with increasing gluten. The clear gluten yielded similar trends than the patent flour, but to a lower extend. Starch tailing of the patent and clear added at level of 3, 6, and 9 wt% induced more substantial increment of consistency and hardness to the dough than gluten ,that is,~4.7 and 6.2 times, respectively, versus the control flour. However, it decreased the dough elasticity due to the water binding capacity of this pentosan-rich fraction. The starch tailing rose significantly the biscuit's density and firmness, but decreased its volume. The flour water soluble constituents added at 1, 2.5, and 5 wt% had a negligible effect on the dough and cookie characteristics. However, it contributes to severe dough stickiness. The results of this study suggested that both the rheological properties of the dough and biscuit's characteristics made with commercial soft wheat flour could be modified by the incorporation of the endogenous flour constituents rather than the composition in fat, sugar and water of the recipe..
18A-27
Extended storage stability of wheat flour tortillas with alpha amylase and soy proteins
F. P. BEJOSANO1, J. N. Alviola2, and R. D. Waniska2. (1) Dept. of Soil and Crop Sciences, Texas A&M Univ., 370 Olsen Blvd., Heep Ctr., 2474 TAMU, College Station, TX 77843-2474, (2) Dept. of Soil & Crop Sciences, Texas A&M Univ., 370 Olsen Blvd., Heep Ctr., 2474 TAMU, College Station, TX 77843-2474
Commercially-produced wheat flour tortillas are made with anti-molding additives thus, they are generally shelf-stable in terms of microbial quality. However, loss in textural quality rapidly occurs during storage which limits the storage stability of tortillas. Such occurrence, often referred to as staling is believed to be caused by starch retrogradation and/or loss of flexibility of the protein matrix. This study was conducted to find ways of preserving the textural quality of wheat flour tortillas during storage. The effect of alpha amylase on reducing tortilla staling due to starch retrogradation was studied. The addition of soy proteins to help improve the stability of the protein matrix in tortillas was also investigated. Alpha amylase and soy proteins were added into a standard tortilla formulation. The tortillas were evaluated for their sensory properties, opacity, diameter and specific volume. Texture measurements were done using the two-dimensional extensibility test with the TA-XT2i texture analyzer and the subjective rollability test. Tortillas with alpha amylase had larger diameter than the control. Most of the soy proteins resulted in softer tortillas although some protein isolates reduced tortilla diameter. Marked improvement in the retention of textural quality during storage was noted in tortillas with alpha amylase alone, and in combination with soy proteins. Control tortillas lost flexibility after 14 d. of storage while those with alpha amylase (with or without soy proteins) remain flexible through 28 d. Thus, with the use of these additives, tortillas with extended storage stability can be produced which benefits both the tortilla manufacturers and the consumers.
18D-18
Effect of heat resistant lactic acid bacteria on pork batter shelf life
N. L. RAMÍREZ-CHAVARIN1, E. Ponce-Alquicira1, I. Guerrero-Legarreta2, M. C. Wacher-Rodarte3, A. Totosaus-Sánchez4, and M. L. Pérez-Chabela2. (1) Dept. de Biotecnología, Univ. Autónoma Metropolitana, Iztapalapa, Apartado Postal 55-535, Mexico D.F., 09340, Mexico, (2) Dept. de Biotecnología, Univ. Autónoma Metropolitana, Iztapalapa, Apartado Postal 55-535, Mexico D.F., 09340, Mexico, (3) Departamento de Alimentos, Facultad de Química, Univ. Nacional Autónoma de México, Ciudad Univ., Mexico D.F., Mexico, (4) Tecnológico de Estudios Superiores de Ecatepec, Subdirección de Investigación., Av. Valle del Mayo esquina Av. Hank González. Colonia Valle de Anáhuac, Ecatepec,
Lactic acid bacteria in foods include cocci of genus Lactococcus, Streptococcus, Pediococcus and Leuconostoc, and bacilli of genus Lactobacillus and Carnobacterium. These bacteria metabolize sugars into organic acids promoting pH decrease. However, they also produce a variety of low molecular weight antimicrobial compounds such as organic acids, bacteriocins, diacetyl, hydrogen peroxide and reuterin. When lactic acid bacteria are subjected to temperatures above the optimum growth range, physiological and morphological changes occur resulting in enzyme activity reduction. The objective of this work was to study the effect of heat resistant lactic acid bacteria on increasing shelf life of pork batters. Strains isolated from meat and meat products, previously identified as heat resistant, were inoculated in uncooked pork batters (5% w:w). Once cooked, the product was divided into three batches for microbial, sensory and physicochemical analysis. Samples were vacuum-packed and stored at 4oC for 15 days. Fifty untrained panelists carried out sensory evaluation at day 2 of storage; the analyzed variables were color, overall acceptability, tenderness and flavor. Enterobacteria counts as well as instrumental color (Hunter Lab) and texture (compression) were also analyzed. The control was uninoculated pork batters. Enterobacteria count decreased one log cycle during the first 8 days of storage, constant values were observed from then up to the end of storage; the highest count was 105 cfu/g, below the legal limit accepted by the Mexican legislation for this type of products. Overall acceptability and flavor of inoculated samples were significantly different to control samples, in agreement with other authors who reported improved sensory attributes of cooked meat products previously inoculated with lactic acid bacteria in addition of a decrease of L. monocytogenes and E. coli counts. No significant difference was observed with respect to texture. Conversely, significant differences were observed in color coordinates (Lab) as compared to the control, which showed higher paleness. Inoculation of lactic acid bacteria to uncooked batters would be a means to increase cooked sausage shelf life, decreasing enterobacteria counts without considerably affecting sensory characteristics.
18E-4
Physical and chemical properties of structured lipids synthesized by chemical interesterification of chicken fat and medium chain triacylglycerols
M. C. CHIU, Faculty of Pharmaceutical Sciences, São Paulo Univ., Av. Prof. Lineu Prestes, 580 B.16, São Paulo, 05508-900, Brazil, L. A. Gioielli, Faculty of Pharmaceutical Sciences, Univ. of São Paulo, Av. Prof. Lineu Prestes, 580, B16, CEP 05508-900, São Paulo, Brazil, and R. Grimaldi, Faculty of Food Engineering, Campinas State Univ., Rua Bertrand Russel,s/n, esquina com Josué de Castro, Campinas, 13083-970, Brazil.
MonoUnsaturated Fatty Acids (MUFA) are known to reduce blood cholesterol levels. It has been recommended that MUFA intake be as high as half of the total recommended dietary intake of calories from fat, as a way to reduce the risk of heart diseases. Chicken Fat (CF) can be considered a source of MUFA since they constitute 45 to 50% of chicken fat. Medium-Chain Triacylglycerols (MCT) are mainly composed of octanoic and decanoic acids. They are metabolized more easily and provide less calories than saturated Long Chain Triacylglycerols (LCT). Our objective was to produce Structured Lipids (SL) with better nutri-tive or pharmaceutical characteristics and evaluate them in terms of physical and chemical properties. CF and MCT were blended in ten different proportions and interester-ified. The fatty acid composition of SLs was determined by gas chromatography. Softening and melting points were determined by AOCS official methods and a constant speed texture analyser was used to evaluate consistency of the samples. Solid Fat Content (SFC) was performed by NMR. Melting behaviour was determined by differential scanning calorimetry. The results showed that the interesterified blends presented 12.3 to 60.9% medium chain fatty acids (MCFA), 14.5 to 34.9% saturated fatty acids (SFA), 18.1 to 42.1% MUFA and 6.6 to 15.1% polyunsatured fatty acids (PUFA). Softening and melting points values ranged from -2.1 to 43.1ºC and –2.1 to 46.3ºC, respectively. Consistency was determined at 10°C to 25ºC. SL had a SFC of 22.5% at 10°C, which progressed downward until no solid fat was present (45°C). Chicken fat and SL showed distintct DSC thermograms. The SL with defined character-istics can be used to combine the beneficial dietary effects of the MUFA and MCFA with desirable physical and chemical properties. They can provide specific metabolic effects for application in food products.
18F-2
Analyzing processing procedure by response surface methodology for black rice cookie
J. H. LEE1, G. H. Kim2, and Y. S. Kim2. (1) Dept. of Food Science and Engineering, Daegu Univ., 15 Naeri Jillyang, Gyeongsan, 712-714, South Korea, (2) Division of Food, Biological and Chemical Engineering, Daegu Univ., 15 Naeri Jillyang, Gyeongsan, 712-714, South Korea
Black rice (Oryza sativa L. Indica type) contains high amounts of protein, phytofats, cellulose, minerals, vitamins, and niacin. Anthocyanin pigments in the black rice have been reported to be highly effective in reducing cholesterol levels in humans. Attempts were made to produce a snack having a chocolate image and, at the same time, taking advantage of functional properties of black rice including carcinogenic, mutagenic, and antioxidative activities. Our objective was to investigate the effects of processing variables (sugar type, amount of black rice added, and baking time) on the cookie-making properties using response surface methodology. The cookie dough was aged for 30 min in a refrigerator, and then sheeted to a thickness of 0.4 cm with the help of a rolling pin. The cookies were baked at 180° C for 10 to 14 min in an oven, then cooled to room temperature and packed in airtight bags. Physico-chemical and sensory properties of sample were determined according to central composite design. The pH, specific volume, moisture content, and spread factor of the cookies were influenced by black rice content and type of sugar used. The pH of both dough and cookie increased as the black rice content increased. Specific volume was significantly increased after baking. Lightness significantly decreased as the black rice content increased in both dough and cookie. Redness increased significantly as the amount of black rice increased in both dough and cookie. Hardness was distinctively affected by type of sugar used. The results provided valuable information on developing new cookies with black rice. The models can be used to describe the effect of sugar, baking time, and black rice on dough and cookie characteristics that are very important for new product development.
18F-7
Development and evaluation (physical and microstructural) of dough and bread fortified with F20 fiber
N. GUEMES VERA1, M. I. Reyes Santamarìa2, N. Maldonado-Hernandez2, and S. Soto-Simental3. (1) Instituto de Ciencias Agropecuarias- CICYTA, Univ. Autonoma del Estado de Hidalgo, Av. Universidad s/n C.P., Tulancingo Hidalgo, 43600, Mexico, (2) Instituto de Ciencias Agropecuarias-CICYTA, Univ. Autonoma del Estado de Hidalgo, Av. Universidad s/n C.P., Tulancingo Hidalgo, 43600, Mexico, (3) Centro de Investigación en Ciencia y Tecnología de Alimentos, ICAp, Univ. Autónoma del Estado de Hidalgo, Av. Universidad Km. 1, Rancho Universitario, Tulancingo, 43600, Mexico
Dietary fiber has been shown to aid in cardiovascular and gastrointestinal health, cancer prevention, and weight management. The average population ingests only 3 to 4 g of soluble fiber/day, which is below the recommended daily intake of 5 to 10 g. The aim of this work was to examine different levels of fiber fortification in wheat dough, preserving those functional properties required to obtain Mexican bread products with acceptable quality attributes while having an improved fiber content and texture. Different formulations were prepared containing fiber (F20) as the main component at four different levels (5, 10, 15, and 20%). The structure of dough samples was examined with a light microscope. Chemical (proximate and dietary fiber content) and physical properties (texture, weight, and volume) were evaluated in samples of Mexican-style bread fortified with the fiber. The micrographs of dough samples showed interconnections within the structure, which are probably due to the presence of the fiber. The chemical analysis also demonstrated an increase in fiber content. On the other hand, texture profile was improved as a result of the new formulation, and the bread volume increased from 100 to 110 cm3 as compared to the blank. This study shows that F20 fiber can be used as a novel ingredient in baked products since it has the potential to improve the physical and sensory properties of wheat bread.
18F-13
Effects of processing conditions on the physical properties of Job's tears cake
B. D. SHIN1, F. Hsieh2, E.-H. Kim1, and J.-B. Eun1. (1) Dept. of Food Science and Technology, Chonnam National Univ., Gwangju, 500-757, South Korea, (2) Dept. of Biological Engineering, Univ. of Missouri-Columbia, 1406 E. Rollins St., 254 Agricultural Engineering Bldg., Columbia, MO 65211-5200
More consumers are demanding for natural and/or functional foods. Rice cakes containing functional cereals such as buckwheat and black rice are receiving increased interest. Job's tears (Coix lacryma-jobi var. ma-yuen) have higher protein and fat contents than other cereals. In addition, it has a bioactive compound, coixol, which has anti-inflammatory, anticonvulsant, and muscle relaxant effects. These functional properties create the opportunity of developing a new puffed snack product using a rice cake machine. The objective of this study was to investigate the effects of various cake puffing conditions on the physical properties of the Job's tears cakes. Independent variables were tempering moisture (14%, 15%, 16%), heating temperature (238, 243, 248° C), and heating time (4, 5, 6 sec). The specific volume and color of the Job's tears cakes were measured by the rapeseed replacement method and a Hunter colorimeter, respectively. The breaking strength and integrity of cakes were determined using a Texture Analyzer and a tumbling device. At higher tempering moistures, specific volume of cakes increased with the increase of either heating temperature or heating time. Higher breaking strength was observed when heating at 238° C for 6 sec. The breaking strength increased as heating time and temperature increased, but decreased with increasing moisture contents. The integrity decreased more when tempering moisture increased from 15 to 16% than from 14 to 15%. The integrity decreased with increasing heating temperature and heating time. The lightness of Job's tears cakes decreased with increasing either heating temperature or heating time, but yellowness and redness showed the opposite trend. Tempering moisture, heating temperature, and heating time significantly influenced physical properties of Job's tears cakes such as specific volume, color, breaking strength, and integrity.
18F-21
Increasing the marketability and consumption of soybeans and their components through the development of soy-based food products
M. KATAYAMA and L. A. Wilson. Dept. of Food Science and Human Nutrition, Iowa State Univ., 2312 Food Sciences Building, Ames, IA 50011
In October 1999, the FDA approved a front-label health claim for products high in soy protein, indicating that these foods may help lower heart disease risk. While high-protein soy foods are entering mainstream consumer consciousness and purchase behavior, beany flavors contribute to low consumption of many soy products. The utilization of entire soybean components, including byproducts from soymilk production, can improve human health, soy marketability, and reduce environmental wastes. Our objective was to use Textured Soy Proteins (TSP) and byproducts (okara) from soymilk production to develop, transfer, and commercialize soybean-based food products and technology to benefit the public. Four different TSPs and flavors, with either frying or baking, were used to find the best formulation for a new TSP food product. Two different dried okara powders were used to find the best formulation for a new soy-based snack product. For both studies, a trained descriptive analysis panel evaluated the intensity of aroma, flavor, texture, and color attributes of the products. A focus group was used during the early formulations to define desirable characteristics in products. A consumer preference test was performed for the flavored TSP products. Instrumental and chemical analyses were performed to evaluate color, texture, and nutritional value of ingredients and finished products. The deep-fried, small-sized TSP with chicken-like flavor was the most acceptable product for consumers (less oiliness and more enjoyable crispiness). The okara snack product made from triple-null soybeans gave the best product (less beany flavor and best texture). These results show that the chicken-flavored TSP and an okara-based snack food can be formulated for both Japanese and American markets; however, improvements in surface appearance of the okara product are needed. These products will give a new high-protein product rich in fiber for soy food industries and consumers.
18F-29
Puffing of okara/rice blends using a rice cake machine
M. XIE, H. E. Huff, F.-H. Hsieh, and A. Mustapha. Dept. of Food Science, Univ. of Missouri, 256 William C. Stringer Wing, Eckles Hall, Columbia, MO 65211-5160
The insoluble byproduct of soymilk and tofu manufacture, called okara, is a nutritious, cheap, and rich source of protein (22%) and dietary fiber (15%). The objective of this study was to develop a novel puffed soy rice cake product with blends of okara pellets and parboiled rice. Okara pellets were prepared by extruding a mixture of dried okara and rice flour at a ratio of 3:2 (w/w) with a twin-screw extruder. The experiment was a 3 x 2 x 3 x 3 x 2 factorial design with two replications. Okara pellets and rice were blended in three ratios: 90/10, 70/30, and 40/60 (w/w) and tempered to two moisture contents: 14 and 17%. The blends were puffed at three heating temperatures (221, 232, 243o C) and times (4, 5, 6 sec). The soy-rice cakes were evaluated for specific volume (SPV), texture, color, and percent weight loss after tumbling. All the processing factors had significant effects (P < 0.05) on the quality of the soy-rice cakes, with the exception of two to four interactions. Increases in heating temperature, time, and moisture led to greater SPV, higher hardness, lighter color, and decreased redness and yellowness values. Higher okara content led to lower SPV, higher hardness, darker color, and increased redness and yellowness values. The SPV for the okara pellet percentages of 0, 40, 70, and 90% were 9.80, 5.35, 4.26, and 3.81 mL/g, respectively, while the corresponding hardness values were 1.38, 1.50, 1.47, and 1.56 g, respectively. Respectively, lightness (L) values were 81.5, 70.6, 69.9, and 68.4, redness (a) values were 1.39, 4.65, 5.61, and 6.93, and yellowness (b) values were 14.9, 19.0, 21.6, and 25.5. This study has demonstrated that soy-rice cakes could successfully be manufactured, using a rice cake machine, making it a novel approach to using okara as human food.
18F-32
Total and partial replacement of whole egg with soy-, wheat-, and whey-based egg substitutes in egg noodles
T. J. Herald, H. A. Khouryieh, and F. M. ARAMOUNI. Food Science Institute, Kansas State Univ., Call Hall,
Eggs possess multifunctional properties that enhance food quality. Conversely, consumers and processors find drawbacks in this ingredient. Consumers are concerned over cholesterol and food safety, whereas processors are concerned over the high cost of eggs. Processors are inquisitive as to whether or not egg substitutes can fully or partially replace eggs without significant loss in product quality, while reducing cholesterol and food safety issues. The objective of this study was to determine if whole egg may be totally or partially replaced with soy, wheat, and whey protein-based egg substitutes and still maintain product quality in egg noodles. Egg noodles were prepared by mixing semolina flour with whole egg and/or egg substitutes. Eggs were replaced at either 50 or 100% with soy protein- (46%), wheat protein- (85%), or whey protein- (60, 90, and 95%) based egg substitutes. Water content and mixing times varied depending on the egg substitute used in the formulation. The dough was folded and sheeted twice. The egg noodles were stored at 4 °C for 0, 15, and 30 days. Physical measurements (thickness, texture, color) and cooking parameters (cooking loss, weight gain) were measured at each time interval. Egg noodle (control) had lower cooking loss, firmer texture, higher L* and b* values among days compared to soy- or wheat-based egg substitutes at 100%. Whey-based (95%) egg substitute exhibited the lowest cooking loss and water uptake, firmer texture, and higher L* and b* values among egg substitutes at 50% replacement. Firmness, L* and b* were higher for soy- and wheat-based egg substitutes at 50%, compared to 100% substitution. Whole egg could not be totally replaced with any of the egg substitutes studied in the egg noodles without some loss of quality. However, partial replacement of eggs was competitive in regard to the physical properties evaluated.
36D-6
Development of instrumental methods and data analysis tools for objective textural characterization of extruded food products
L. SAMUEL, H. Dogan, and J. L. Kokini. Dept. of Food Science, Rutgers, The
Textural characterization of foods is a critical aspect of new product development and quality control in the food industry. Texture analysis procedures are generally empirical in nature. For a specific product, the effect of test parameters on the relevance of the data generated must be clearly understood. Variation in test parameters must be minimized for maximum accuracy of results. Objectives of this study included identification of quantitative measures for textural properties of extruded foods through instrumental analysis, and to develop operator independent decision-making tools for reliable and robust interpretation of the experimental data. A wide range of extruded food products were analyzed with the texture analyzer by uniaxial compression and puncture tests (with conical and cylindrical probes). Test parameters studied were probe speed (1-3 mm/sec) and strain level (70-90%). All measurements were done in 20 replicates. Force-deformation curves were analyzed for fracture force, fracture area, gradient, total work, number of peaks and ratio of linear distances. The deformation behavior of the samples under different probes affected the textural information obtained by the different methods. Force-deformation curves from uniaxial compression gave maximum information about the above parameters. Test speed of 1mm/sec and 80% strain level gave most reproducible results. Equations were introduced into the macro to calculate threshold values for the identification of fracture force, fracture area, gradient and peak number. This made the macro operator independent as compared to thresholds based on arbitrary, user defined numerical values. Gradient calculations are also done automatically within the macro. Macros developed in this study proved to be compatible in a wide range of extruded products with different composition, shape and mechanical properties that disintegrate in a similar manner.
36D-7
Textural analysis method development for two-phase food products
L. SAMUEL, H. Dogan, and J. L. Kokini. Dept. of Food Science, Rutgers, The
The composition and morphology of food products influence the quantitative measures of textural properties derived during their mechanical deformation. The focus of textural analysis of two-phase dry food products like cream or fruit-filled snack bites, is to differentiate between the textural properties of each phase (crust and filler). Our objective was to identify test methods and conditions which can objectively differentiate between the textural characteristics of the different phases of such two-phase products. Compression and penetration tests were done to evaluate the extent of textural information that can be obtained for the crust and filler phases. Test parameters studied were probe speed (1-3 mm/sec) and probe diameter (0.5-100 mm). A robust and operator independent macro was developed to analyze the force-deformation curves for various texture parameters. Uniaxial compression failed to deconvolute the properties of the shell and filler phases. During compression, the sealed edges of the crust collapsed, preventing a reliable measurement. The shape of the conical probe resulted in breakage of the sample before penetration. Moreover, as the samples break instantaneously when the probe tip contacts the surface, the results were point specific and did not describe the mechanical properties of the sample as a whole or of the phases themselves. The punch probe was able to differentiate between the resistances to mechanical deformation offered by the two phases. The developed macro identified differences between the mechanical properties of the two phases which was then used to generate useful, reliable information related to their textural properties. Mechanical measurements with different probes showed the importance of selection of appropriate test methods and conditions for textural analyses of two phased products. The introduction of operator independent decision-making tools in the macro made the analysis robust and reliable.
36D-14
Rheological properties of soy protein hydrolysates
B. P. LAMSAL1,
Targeted enzymatic modification of proteins could result in ingredients with functionality tailored to specific food applications. For soy proteins, stronger gelation and high viscosity are preferable in applications for comminuted meat products, soups and gravies. At the same time, baby food applications, yogurts, and soups need less viscous product mix and weaker gelation. We hypothesize that minimal enzyme treatment of soy proteins retains thermo-rheological properties that could have use in target food applications. Our objective was to investigate the effect of minimal protease treatment of soy protein products on such rheological properties as gelation and viscosity. Limited enzymatic hydrolysis (2 and 4% degree of hydrolysis, DH) of soy protein isolate, concentrate, extruder-expelled (EE) flour, and hexane-extracted soy flour was carried out at pH 7, 50° C with endoprotease bromelain in a 250-mL glass reactor and monitored with a pH-STAT. Rheological properties of freeze-dried hydrolysates (10% w/w protein dispersion) was evaluated with RS 150 Haake rheometer. Dynamic shear (1% oscillatory strain, 0.1 Hz) was monitored in a temperature sweep (25 to 90° C, cooled to 25° C), while apparent viscosity was followed through the shear rate of 10 to 500 s-1.The non-treated protein isolate produced strongest gel followed by concentrate, EE meal and flour. Our results showed that soy protein hydrolysates retained their gelling ability even after protease hydrolysis at 2 and 4 % DH. Hydrolysis up to 4% DH caused dramatic loss of gelling ability for all substrates ranging between 8 to 40 fold. Storage modulus (G') increased during cooling after heating to 90° C. G' values at 25° C were in the order: Control > DH2% > DH4%. Power law model provided excellent fit to hydrolysate dispersions showing shear-thinning behavior (n<1). Hydrolysis increased flow index and decreased consistency coefficient resulting in less viscous dispersions. The results suggest that limited protease hydrolysis of different soy protein substrates at low DH results in weaker gels and thinner dispersions. They could be useful in applications utilizing such properties like baby foods, yogurts, and soups.
36D-17
Effects of internal temperature changes and sodium tripolyphosphates on cook losses and textural properties of meats
S. B. UNAL, F. Erdogdu, and H. I. Ekiz. Dept. of Food Engineering,
Polyphosphates, especially sodium tripolyphosphates (STP) are important functional additives used in meat and meat products. Textural properties and cook losses of meats are significantly affected by internal temperature changes and STPs. The STPs reduce cook losses and improve textural properties especially by increasing water holding capacity of the meat proteins. However, the increase in internal temperature enhances meat proteins denaturation and decreases their water holding capacity. Therefore, it is important to determine these changes and effects of internal temperature and STPs on these properties. The objective of this research was to determine the effects of internal temperature, STP concentration and STP dipping time on cook losses and textural properties of meats. The meat samples (2×2×2 cm in size) were dipped in different concentrations of STP solutions (2, 4 and 6%) for different times (0, 10, 20, 30 minutes) and cooked in boiling water for 0, 5, 10, 15 minutes. Internal temperature changes were determined using analytical solutions. Thermal properties of meats were determined based on their moisture content via the equations found in the literature. Cook losses were calculated from weight changes, and textural properties were determined using texture profile analysis in Texture Analyzer TA-XT2i (Stable Micro Systems). STPs decreased cook losses and hardness in meats while the increase in STP concentration increased springeness and cohesiveness values. Increases in internal temperature resulted in higher hardness, gumminess, chewiness and cook loss values. In addition to these, cook losses and hardness values were the highest in meats that were not treated with STPs before cooking. The results showed that the STP concentration and the internal temperature changes affected the textural properties and the cook losses in a great manner. These results may be used for a further meat processing optimization studies when they are correlated with sensory data.
36D-18
Development of capillary extrusion viscometer for the viscosity measurement of fish protein paste
J. W. PARK, Dept. of Food Science & Technology, Oregon State Univ., OSU Seafood Research Lab., 2001 Marine Dr., Rm. 253, Astoria, OR 97103 and B.-Y. Kim, Dept. of Food Science & Technology, Kyung Hee Univ., Seochun 1, Yongin, South Korea.
Viscosity often determines the flow of products and controls the productivity. However, due to the nature of fish muscle proteins (surimi) that easily entangle upon setting or heating, the viscosity is not properly measured using an ordinary Brookfield viscometer. In addition, the dilution factor of surimi paste without salt does not show a linear relationship with a viscosity value. As a result the quality control to oversee the production flow is not easily maintained. Consequently, there is a significant need for a quick and easy method to determine viscosity of fish muscle proteins. Objectives were to develop a capillary extrusion viscometer and equations for measuring the viscosity of fish protein paste. We further wanted to estimate the quality of gel texture using the viscosity values. A capillary extrusion viscometer with a plunger (tube length: 3 and 1 cm, tube diameter: 6 mm) was developed. This viscometer was attached to a TA Plus texture analyzer (Stable Micro System). The viscosity of surimi paste was measured as a function of moisture content(75-80%), salt content (2-4%), and egg white content (2-4%). Each value was also compared with fundamental dynamic values measured using Bohlin CS50 dynamic shear rheometer. As moisture, salt, and egg white contents increased, viscosity gradually decreased. These viscosity values, obtained using our new capillary extrusion viscometer, were well correlated to those values measured using dynamic shear rheometer. The viscosity values showed a reversible relationship with gel failure properties of surimi gel, especially shear stress from the torsion test. This easy viscosity measurement can effectively facilitate production control of comminuted muscle food, including surimi paste. Based on simple linear equations, the viscosity values could be used to quickly and easily to predict final gel quality.
36D-22
Structure-property relationships in amorphous starch matrices
L. Castro, P. Bouchon, and J. M. AGUILERA. Dept. of Chemical and Bioprocess Engineering, Pontificia Univ. Católica de Chile,
Although most engineering properties of foods depend on their structure no clear relationships are usually derived, as is the case of textural properties and microstructure of dry cereal products. The objective of this work was to relate microstructural features of a simple dry starch model to mechanical parameters and fracture mechanism as a function of water activity and drying temperature. A pregelatinized potato starch suspension (23% w/w) was dried into strips at temperatures between 65-105ºC to induce different microstructures. Probes were equilibrated to water activities (aw) in the range of 0.00 to 0.75 and analyzed for mechanical properties and glass transition temperature. From the force-deformation curves two textural parameters were calculated: Maximum Force at Breakage (MFB) and Work to Fracture (WF). Images were obtained by light and scanning electron microscopy, and main features (e.g., bubble size, thickness) quantified by image analysis. Probes dried at high temperature were thicker and less dense than those dried at low temperatures, and contained several bubbles of increasing mean size. Mechanical parameters for all samples were similar and low at aw below 0.44-0.65, but increased drastically above this range and depended strongly on the drying temperature. For example, WF and MFB decreased 12 and 5 times, respectively, as drying temperature increased from 65º to 105º C. The fracture behavior changed from brittle to ductile in the mentioned aw interval, as studied in real time by coupling videomicroscopy to the mechanical assay. Glass transition temperatures of samples at the same water activity were similar. It is concluded that: 1) several microstructures, hence, different mechanical behaviors may be induced by drying the starch model; 2) water activity has a dramatic effect on mechanical properties and observed fracture mechanism, and; 3) the glass transition temperature itself is not a good predictor of the mechanical properties of the system.
36D-32
A novel non-invasive method to measure viscoelastic properties of cereal grains during processing
D. C. GONZALEZ, B. Mert, O. H. Campanella, and M. R. Okos. Dept. of Agricultural & Biological Engineering, Purdue Univ., 1146 Agricultural & Biological Engineering Bldg., West Lafayette, IN 47907-1146
The palatability of cereal grain foods is often increased with the addition of sugars during the cooking process. However, the role of sugars and the mechanisms in which they influence the physical and rheological properties of cereal grains after cooking and upon further processing is not well understood. Therefore, the effect of sugars on starch reassociation (e.g. retrogradation) during further processing (e.g. tempering) was investigated. Tempering was chosen because it is a common processing step used in the production of cereals from grain and it is associated with starch retrogradation. The cooking process consisted of cooking cereal grains (wheat and corn) with an amount of water 1:1 by weight in a pressure cooker. Eight grams of sucrose were added per every 100 grams of cereal grain for the cooking process. Similarly, 8 grams of High Fructose Corn Syrup (HFCS) were added for every 100 grams of grains. The effect of a combination of sucrose and HFCS was also studied (4 grams of each sugar per 100 grams of grain). A control containing no sugar was also tested. The cooked cereal grains were dried to moistures of 20% and 15%. The tempering process consisted of packing the dried grains into sealed containers and holding them for equal amounts of time until moisture was equilibrated. The rheological changes occurring during the tempering process for the cereal grains were monitored by a broad band oscillatory squeezing flow method developed in our laboratory. The method is based on the measurement of the mechanical impedance of the sample. This mechanical impedance is closely related to the sample's viscoelastic properties. Both viscous damping and elastic stiffness values increased with increasing tempering times in all cases examined. Cereal grains cooked with sugars exhibited the greatest increases in hardness supporting the role of these ingredients in promoting retrogradation.
36D-36
Effect of moisture content at harvest of various kernel thickness fractions on rice instrumental texture properties
M. I. SALEH, J. -F. Meullenet, T. J. Siebenmorgen, and L. Wang. Dept. of Food Science,
Thickness rice fractions vary in their protein, lipid, crude fiber and starch contents. This variation in chemical composition is expected to lead to differences in functional properties of cooked rice. The objective of this study was to determine the effect of rice thickness fractions, harvested at different moisture contents, on rice texture properties. Wells and Francis rice cultivars from two locations and of high and intermediate Harvest Moisture Content (HMC) were fractionated using a Carter-Day-grader to small, medium, and large thickness fractions. Milled rice dimensions were measured using a Satake rice image-analyzer RIV-1A (
36E-23
Biochemical changes of stored soybeans and its effect on soymilk and tofu quality
J. Y. L. KUAN and L. A. Wilson. Dept. of Food Science and Human Nutrition, Iowa State Univ., 2312 Food Sciences Building, Ames, IA 50011
Post-harvest modification of soybeans is very pronounced in the summer months, especially during storage and transporting across continents. Over prolonged storage, soybean seed quality and quality of edible products made thereof decreases. The objective of this study was to observe the biochemical changes that occur during soybean storage and its effects on soy food quality, particularly soymilk and tofu. Three different soybean cultivars from two crop years were stored at different temperature (20, 30, 40o C) and humidity (75% RH, 32% RH) combinations for 0-12 months. Soybeans were analyzed for color (HunterLab), oxalates (enzymatic assay), antioxidants (PhotoChem), sugars (HPLC), and processed into soymilk and tofu (Japanese method). With increased storage time, temperature and humidity, soybeans had lower Hunter L values (darker), as browning of the soybean seed coat was observed. This in turn carried over into soymilk and tofu produced from these soybeans. At elevated temperatures and humidities, most proteins have degraded, confirmed by the soymilk not coagulating after 6-9 months of storage. Environmental factors and genotype accounted for the differences in oxalate concentration in the soybeans. Antioxidants in soybeans, when stored at a higher temperature and humidity, had an increased concentration, which could be attributed to the conversion of isoflavones (an antioxidant) from the malonyl to aglycone form. Soybean soluble sugars, although present in small amounts, are important, especially oligosaccharides and reducing sugars. Glucose was only found under high temperature and humidity storage conditions, which suggests complex oligosaccharide breakdown. Sucrose remained relatively stable at all storage conditions, indicating that sucrose was not consumed in Maillard browning reactions. Biochemical changes were also observed within each cultivar based on crop year and environmental factors. Based on these results, storing soybeans under low moisture and temperature conditions are recommended in order to have quality soy products with good functional properties and economic viability.
36E-30
Effects of a combination of £^-irradiation and 1% CaCl2 treatment on quality characteristics and microbiological shelf life of diced red bell peppers
W.-L. CHOU1, A. Prakash2, R. L. Pilling1, and D. M. Foley3. (1) Dept. of Physical Sciences, Chapman Univ., One University Drive, Orange, CA 92866, (2) Dept. of Food Science and Nutrition, Chapman Univ., 1 University Dr., Orange, CA 92866, (3) Dept. of Biological Sciences, Chapman Univ., 1 University Dr., Orange, CA 92866
Diced red bell peppers are becoming popular in retail and food service markets, however, their shelf-life is limited to a few days. Low-dose irradiation is known to improve microbiological quality of fresh produce but, in some products, irradiation can result in softening of the fruit and vegetable tissue. Calcium treatments have been shown to improve firmness by reducing solubilization of pectic substances. The objective was to determine the effects of combined irradiation and 1%CaCl2 treatment on the shelf life properties of diced red bell peppers. Diced red bell peppers were dipped in 1%CaCl2 for 1 minute and subjected to ?- irradiation at 1kGy from a Co60 source. The control, CaCl2 dipped, irradiated, and combination treated samples were stored at 4¢XC and analyzed for changes in texture (Kramer Shear), microbial loads (total aerobic count, and yeast & mold), headspace gas concentrations, polygalacturonase activity, pH and color. Calcium treatment alone increased the firmness of diced red bell peppers by 15%. However, calcium treatment was not effective in diminishing the loss of firmness due to irradiation. Irradiation alone as well as the combination treatment were highly effective in reducing microbial counts. Color was not affected by calcification, but increased in L, a, b values following irradiation. Headspace CO2 production was suppressed significantly (P<0.05) at day 1 in calcium treated samples, but not affected in both irradiated samples. Sensory evaluation is necessary to determine if the loss of firmness due to irradiation is acceptable to consumers. Also, a lower irradiation dose and/or the use of other firming agents that can mitigate the effects of irradiation should be tested to optimize the microbial quality and shelf-life of diced red bell peppers.
36E-31
Effects of calcium ascorbate, an antioxidant and antibrowning agent, on radiation resistance of L. monocytogenes and quality of “Gala” apple slices
X. FAN1, K. B. Sokorai1, C. H. Sommers1, B. A. Niemira1, and J. Mattheis2. (1) Food Safety Intervention Technologies Research Unit, USDA-ARS-Eastern Regional Research Center, 600 E. Mermaid Ln., Wyndmoor, PA 19038-8598, (2) Tree Fruit Research Lab, USDA, ARS, 1104 N. Western Ave, Wenatchee, WA 98801
Ionizing radiation exerts its effect mainly through the free radicals generated from radiolysis of water. Antioxidants may scavenge the radicals, negating or reducing the impact of irradiation on pathogen inactivation and on product quality. This study was conducted to evaluate the impact of calcium ascorbate (CaA, an antioxidant and antibrowning agent) on the radiation resistance of L. monocytogenes inoculated into CaA solutions and on apple slices, and to investigate the effects of irradiation and CaA on quality of ‘Gala' apple slices. The radiation resistance of L. monocytogenes artificially inoculated in 0, 3.5 and 7% CaA solutions and on apple slices that had been treated with the three levels of CaA were analyzed. Non-inoculated apple slices treated with 0, 3.5%, and 7.0% CaA were exposed to 1.6 kGy gamma radiation (a dose equivalent to at least 5-log reduction in L. monocytogenes). Quality was analyzed during 14 days of modified atmosphere storage at 4° C. Results showed that CaA significantly increased radiation resistance of the pathogen both in solution and on apple slices. CaA at levels of both 3.5 and 7.0% prevented the browning of the apple slices. The apple aroma intensity, however, decreased as the concentrations of CaA increased. Irradiation at 1.6 kGy did not significantly affect color, soluble solid content, titratable acidity, or apple aroma intensity. The only negative effect of irradiation on apple slices appeared to be a loss of firmness. However, firmness of irradiated samples treated with 3.5 or 7.0% CaA was always similar compared to the non-irradiated samples that were not treated with CaA. CaA protected L. monocytonenes from radiation both in solution and on apple slices, but radiation at doses sufficient to inactivate a 5-log of the bacterium did not have a significant influence on product quality attributes except the loss in firmness.
36E-33
Textural properties of malic acid incorporated carboxymethyl cellulose and soy protein isolate coatings on alfalfa and mung bean sprouts on storage at 4 oC
K. H. TRAN, N. S. Hettiarachchy, and
Texture plays an important role in fresh produce. A difference from the textural property norm could lead to consumers? rejection of the produce. Carboxymethyl cellulose (CMC) and soy protein isolate (SPI) have been used for years as an edible coating for fresh fruits and vegetables? protection. The incorporation of malic acid into the edible coating solutions is assumed to assist in the textural property?s preservation and extension of alfalfa and mung bean sprouts? shelf-life. Our objectives were to incorporate malic acid into the CMC and SP edible film coating solutions and coat the alfalfa sprouts and mung bean sprouts and to determine the textural property of sprouts. The edible film coating solutions were formed using CMC (for alfalfa) and SPI (for mung beans). The sprouts were dipped into the film coating solutions, dried at ambient temperature, and kept at 4 o C for a week in a plastic bag. The texture of the sprouts was determined using the TA-XT2i Texture Analyzer for puncture force and shear force. Our results showed that the malic acid incorporated edible film coating solutions had preserved the texture of the sprouts. The CMC (0.5 g) and SPI (2 g) coating solutions showed higher hardness force (N) (1.2 and 14.62, respectively) during storage compared to other concentrations of CMC (0.25 g and 0.75 g) and SPI (1g and 4 g) (0.52, 0.88 and 11.56, 14, respectively). These results indicate that the coated sprouts maintained their quality in texture at these concentration levels. The results suggest that malic acid incorporated with CMC and SPI film solution preserves the texture and extend the alfalfa and mung bean sprouts? shelf-life.
36E-62
Osmotic dehydration of guavas in sucrose and maltose solutions with calcium addition
L. M. Pereira1, R. L. Cunha, H. M. A. B. Cardello, M. D. Hubinger1, and M. CRISTIANINI1. (1) Dept. of Food Engineering, State
Sucrose solutions are commonly employed as osmotic agent in fruit dehydration process, however the use of others sugars, like maltose, has appeared as a good alternative due to its protective effect on the structural properties and color stability. Calcium salts are also been used in osmotic solution in order to preserve the processed tissues structure, resulting in products with better texture characteristics. The osmotic dehydration of guavas (var. Paluma) in sucrose and maltose solutions, with calcium lactate addition was studied to verify the effects of these two different disaccharides and of calcium ion on color (L*, a* and b*), texture (stress and strain at failure, relaxation time and residual stress) and sensory acceptance of dehydrated fruits. Three concentrations of the sugars (40, 50 and 60º Brix) and six concentrations of calcium lactate (0 to 1.5%) were employed and the osmotic process was carried out at 40º C during two hours. The sugar type was the more important variable in guavas characteristics, showing a strong influence on color and texture of fruits as well as on sensory acceptance. The guavas color was also influenced by sugar concentration and calcium lactate addition was determinant on guavas texture. The guavas osmotically dehydrated in sucrose solution had better sensory acceptance than the fruits treated with maltose solution independent on sugar concentration and on calcium addition, although all samples studied were accepted by the consumers.
36E-64
1-MCP post-harvest effects on cantaloupes and watermelons harvested at different maturity stages.
J. E. VILLARREAL and L. Cisneros-Zevallos. Dept. of Horticultural Sciences, Texas A&M Univ., 202 Horticulture and Forestry Science Bldg., 2133 TAMU, College Station, TX 77843-2133
The use of 1-methylcyclopropane (1-MCP) treatments has shown to delay quality changes during storage on different horticultural products, including cantaloupes and watermelons. Some factors that may affect the response to treatments include the 1-MCP dose and the produce maturity stage. Selecting appropriate produce maturity stage is critical, since it will potentially allow to optimize the 1-MCP treatment benefits. The objective of this study was to determine the effect of physiological maturity of cantaloupes and watermelons on quality changes when treated with different doses of 1-MCP after harvest. Cantaloupes
36E-71
Extending shelf-life of fresh-cut apples by using whey protein coatings with ascorbic acid, citric acid, calcium chloride, and potassium sorbate
K. I. MATSOS, U. V. Lay, and J. D. Floros. Dept. of Food Science, The Pennsylvania State Univ., 111 Borland Lab, University Park, PA 16802-2504
The limited shelf-life of fresh-cut fruits is the main barrier of the wide commercialization of such products. Chemical treatments and the use of whey protein edible coatings have been shown to delay rapid quality deterioration of minimally processed fruits. However, the combined effect of different active compounds, carried by whey protein coatings, on fresh-cut product quality (color and texture) and microbial decay has not been studied in depth. Our objective was to study the effect of ascorbic acid (AA), citric acid (CA), calcium chloride (CaCl2), and potassium sorbate (PS) in whey protein coatings on the quality (color and texture) and microbial decay of fresh-cut apples. Apple slices (var. red delicious) were dipped in whey protein coating solutions of various AA, CA, CaCl2, and PS concentrations, according to a central composite experimental design. The slices were punctured and inoculated with Penicillium expansum. The samples were stored for 4 weeks in plastic bags at 5° C. The color, texture and microbial growth were evaluated over time. The presence of the coating reduced surface browning of apple slices. Addition of PS in the coating appeared to have a dramatic negative effect on both the color and texture of the product. The effect of PS on product quality was so severe that masked any possible positive effects from other compounds (e.g. AA). CA also appeared to have a negative effect on the color of the product. Regarding microbial growth, PS concentrations above 1.1% inhibited microbial growth for at least 21 days. The above results suggest that whey protein coatings delay color changes of fresh-cut apples. Addition of PS inhibits microbial growth on contaminated surfaces. However, due to its severe negative effect on product quality, PS should be replaced by another antimicrobial agent.
36E-73
Influence of osmotic dehydration, ripeness and frozen storage on physicochemical, optical mechanical and sensory properties of mango fruit
A. Rincon, Food Science and Technology, Univ. of Georgia, Food Science Building, ATHENS, GA 30605 and W. L. KERR, Dept. of Food Science and Technology, Univ. of Georgia, 122 Food Science Bldg., Athens, GA 30602-7610.
There is much demand for high-quality minimally processed fruits for food formulations. The flavor and texture of mango is difficult to maintain in normal drying or freezing operations. Partial osmotic dehydration prior to freezing is an effective way to reduce water content and thus minimize cellular damage incurred during freezing. The objectives of this study were first, to analyze the effect of initial ripeness, sucrose syrup concentration and frozen storage time on the physicochemical, optical and textural properties of mango slices; and second, to assess the sensory properties of treated mangoes by a trained panel. Mango fruit was classified into three categories of ripeness (cutting force 3kg <, 3-4.9 kg, 5kg >), cut into 1.5 cm slices and immersed in sucrose syrups (10-30° Brix) at 20° C for 4 hours. Treated samples were frozen in a blast freezer at –18° C. Moisture loss, soluble solids content, vitamin C, lightness (L*), and hardness were evaluated over 20 weeks of frozen storage. Descriptive sensory terms were developed and evaluated by a trained panel. Moisture loss and soluble solids increased with syrup concentration. Vitamin C, L* and hardness decreased with increasing ripeness, storage time and syrup concentration. Sensory analysis showed that treatment with 30° Brix syrups produced firm pieces with highest sensory scores for sweetness and mango-like flavor. These results suggest that partial osmotic drying with sucrose syrups can produce frozen mango pieces with more fresh-like attributes.
36E-76
Effect of minimally processing and 1 methylcyclopropene on respiration rate, color and texture of guava fruit (Psidium guajava L) cv Media China
G. R. ORTIZ-HERNÁNDEZ1, E. López-Enríquez2, C. Saucedo-Veloz3, and E. Mercado-Silva1. (1) Dept. de Investigación y Posgrado en Alimentos, Univ. Autónoma de Querétaro, Centro Universitario S/N, Querétaro, 76010, Mexico, (2) Dept. de Investigaciòn y Posgrado en Alimentos, Univ. Autónoma de Querétaro, Centro Universitario S/N, Querétaro, 76010, Mexico, (3) Colegio de Posgraduados, Montecillo, Estado de México, Texcoco, Mexico
Because of overproduction of guava in México, new markets are needed as well as developmental work to control the ripening process and allow for a longer distribution time. Our objectives were 1) to measure the physiological response in guava which is minimally processed and stored at different temperatures and 2) to analyze the effects of 1 Methylcyclopropene (1-MCP) on the ripening process of intact fruit. Guava ripe fruits were peeling (1 min in NaOH 2% at 85° C), washed and stored at different temperatures (0, to 15° C) under wet air flow. Every three days the respiration rate was measured by gas chromatography. In other experiment, mature green guava fruit were treated with an air flow with 1-MCP (0-1.2 ppm) for different times (0-5 h); after the fruit was stored at 10° C under an air flow wet during 30 days. Every 4 days the color (hue value) and penetration force (N) was measured using a texture analyzer. After seven days of storage, the respiration rate in all fruit minimally processed was three to eight times higher than respiration rate of intact fruit (50 mL CO2/ kg h) indicating high sensibility of this fruit to minimal processing; at 0° C the respiration rate reached 457 mL CO2/ kg h. The application of 0.6 ppm of 1-MCP during 3-5 h in mature green fruit and stored at 10° C for 30 days, delayed the color changes (hue value 84) and maintained high the penetration force (13N) in comparison with control fruit (hue value 79 and penetration force 4N). The minimal processing in guava fruit increased strongly the metabolism decreasing its potential use in this fruit. However, the application of 1-MCP showed possibilities to increase the shelf life of intact fruit and to facilitate their distribution
36E-82
Alginate coatings for the preservation of minimally processed Gala apples
G. I. OLIVAS1, D.
Edible coatings made from alginate were investigated for their ability to preserve the quality of minimally processed Gala apples. Apple wedges were immersed in a calcium chloride (CaCl2) solution and subsequently coated with one of three different coating formulations: alginate, alginate-acetylated monoglyceride-linoleic acid, and alginate-butter-linoleic acid. Apple wedges were stored at 5°C and 85% Relative Humidity (RH). Weight loss, color, texture, volatiles profile, microbial load, titratable acidity, and soluble solids were assessed over ~9 days of storage. Alginate coatings prolonged the refrigerated shelf life of cut apples. All studied coatings minimized weight loss during storage, however, apples with coatings containing acetylated monoglyceride remained the closest to their original weight. Hardness of coated apples remained practically constant during storage regardless of the type of coating, while control apples had a large decrease in hardness during storage. Browning of apple slices was retarded in coated apples. It was also demonstrated that the studied coatings did not cause anaerobic respiration. A higher production of some typical aroma volatiles 1-butanol, hexanal, trans-2-hexenal, and 1-hexanol, was observed on coated apples presumably due to the metabolization of fatty acids contained in the coatings. No effects from the applied treatments on microbial load, titratable acidity, or soluble solids were found. The use of alginate coatings for the preservation of minimally processed fruits is a promising technology that can improve the quality of fresh products and increase their shelf life and stability.
36E-84
Quality comparison of apple cubes blanched with infrared and steam heating
Y. ZHU, Dept. of Food Science and Technology, Univ. of California, Davis, Bainer Hall 1330D, One Shields Avenue, Davis, CA 95616 and Z. Pan, Processed Foods Research Unit, Western Regional Research Center, USDA, Agricultural Research Service, 800 Buchanan St., Albany, CA 94710.
The blanching process is widely used for inactivating enzymes that are responsible for causing quality deterioration of fruits and vegetables during storage. Typically, it is achieved by using hot water or steam. However, they are energy intensive processes and water and condensed steam can result in leaching of nutrients. It is important to seek alternative blanching technologies with high energy efficiency and without using water and steam. Using Infrared Dry Blanching (IDB) technology could inactivate enzymes with high energy efficiency and no leaching of solids and nutrients compared to hot water and steam blanching. The objective of this research was to study the quality characteristics of blanched apples with IDB and steam. A catalytic flameless gas-fired infrared emitter emitting medium and far infrared radiation energy was used to perform the dry-blanching. Each 12.7 mm apple cube was blanched with both infrared and steam at various temperatures and time lengths. The heating rates of the samples were measured under different treatments. The product quality indicators including color, texture, total phenols, and residual peroxidase activity were measured right after blanching. The blanched products were also frozen and stored at -18° C. Then, the quality indicators were measured again after the samples were thawed at ambient temperature. Our results showed that IDB could effectively inactivate enzymes of apple cubes with high energy efficiency. It took about 5.5 min to completely inactivate the peroxidase in the samples by using IDB. Samples treated by using IDB had brighter color and firmer texture than steam blanching. Since the IDB technology can satisfactorily inactivate the enzymes with high energy efficiency and product quality, it has a great potential as an alternative to replace current steam, water and/or microwave blanching methods.
36E-86
Quality evaluation and shelf-life extension of hardy kiwifruit (Actinidia arguta ‘Ananasnaya’)
C. L. FISK1, A. M. Silver2, M. R. McDaniel1, B. C. Strik3, and Y. Zhao1. (1) Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331-6602, (2) Culinary Institute of America, 1356 Monte Vista Ave., Saint Helena, CA 94574, (3) Dept. of Horticulture, Oregon State Univ., 4017 Agricultural & Life Sciences Bldg., Corvallis, OR 97331-7304
Hardy kiwifruit (Actinidia arguta) have an edible skin and are smaller in size than fuzzy kiwifruit. They are picked when physiologically mature, with ripening triggered during storage. It is not known how ºBrix at harvest affects shelf-life and quality of ripened fruit. Hardy kiwifruit are very sensitive to dehydration during storage and transport. Variable fruit quality, dehydration, and short shelf-life have been identified as the major problems related to fresh marketing. The objectives of this study were to determine the effects of harvest Brix and storage conditions on the physicochemical and sensory qualities of hardy kiwifruit and to use edible coatings to extend the shelf-life of fresh fruit. Hardy kiwifruit were harvested at 6.0, 8.7, 9.1, and 15.1 ºBrix and packaged in either high- or low-vent clamshell packaging and stored under room (22±1ºC, 45% RH) or refrigeration (2°C, 88% RH) conditions until ripe. Physicochemical properties were measured using AOAC methods and ripened fruit were processed into purees for sensory evaluation by Free-Choice Profiling method. Fruit harvested at 9.1 ºBrix were coated using a commercial coating material, SemperfreshTM, and stored at 2°C and 88% RH for up to 10 weeks for shelf-life evaluation. Results show that the use of low-vent packaging and refrigeration reduced moisture loss and lengthened the shelf-life of fresh fruit. Edible coatings provided glossiness, reduced moisture loss, and slowed ripening and surface pitting. Fruit harvested at 6.0 ºBrix were higher in sourness, astringency, and vegetal character and lower in fruity character and soluble solids than fruit harvested at later ripeness levels. Results suggest that the shelf-life of hardy kiwifruit can be extended through the use of low-vent packaging, refrigeration, and edible coatings, and support industry observation that hardy kiwifruit harvested at the same stage as fuzzy kiwifruit do not develop adequate aroma and flavor profiles for fresh marketing.
36E-88
Effect of chitosan and water soluble chitosan coatings on quality of small fruits.
J. K. NOH1, J. R. Mount1,
Edible coating has been applied on the surface of fresh produce to extend shelf-life by suppressing respiration, transmission, and microbial growth. It can help to decrease weight loss and moisture loss. It may also offer a protective barrier against bacterial contamination and spoilage. Recent studies have indicated chitosan as an effective coating that can extend shelf-life by maintaining the quality of fruits. The objective of this study was to demonstrate the effectiveness of natural biodegradable chitosan coatings in extending shelf-life and quality of fresh small fruits, such as strawberries, blueberries, and grapes. Fruits were dipped for 30 seconds in 1% chitosan in 1% aqueous acetic acid, 1% water-soluble chitosan in water, 1% acetic acid solution or tap water. Non-treated fruits served as a control treatment. Samples were stored at 4±2° C and 80±10% RH up to 24 days. Quality analysis was performed every 3 days. The analysis included measurements of texture (TA.XT plus), color (Hunter), weight loss, and ethylene and CO2 production. Statistical analysis was conducted for all dip treatments and control fruit. Ethylene production (0.038ppm/hr to 0.194ppm/hr; p<0.01) and CO2 production (3.6% to 4.7%; p<0.05) decreased significantly for both chitosan treatments compared to control fruit. Firmness among the chitosan and control treatments was also significantly different (p<0.01). Hunter b-values (p<0.01) were significantly different but there were no significant changes in L or a-values (p>0.10) among treatments. There was no significant change in moisture loss (p>0.10) among the treatments. The results suggest that chitosan coatings have a potential to be used on small fruits to maintain quality and extend shelf-life by reducing respiration.
36E-101
Processing and properties of strawberry leathers
Fruit leathers are one of the popular snacks in American diet. Strawberries are high in vitamin C and fiber. Strawberry leathers found in cookbooks are usually mixed with other fruit ingredients. Fruit leathers with strawberries as the main ingredient have not been reported. The objectives were to investigate the effects of three added ingredients on certain properties and to compare strawberry leather prototypes with commercial products. The independent variables were corn syrup (20, 30, and 40%), pectin (1, 2, and 3%), and citric acid (0.5, 1.0, and 1.5%) based on weight of strawberry natural puree. All treatments were replicated. For each treatment, the blended mixture was dried in a hot air oven at 70° C for 4.5 h until leathery sheets were obtained with thickness of 1.20 – 1.45 mm. The blends were measured for viscosity and pH while the sheets were measured for pH, water activity (aw), moisture content, color, glass transition temperature (Tg), and textural properties. All independent variables significantly affected chemical and physical properties such as viscosity profile, texture profile, tensile strength, and glass transition temperature in the order of corn syrup, pectin, and citric acid. With an aw of 0.51 and a moisture content of 9.5%, strawberry leathers are regarded as low moisture foods. The prototypes had an appealing color with moderate redness and low yellowness. Many textural characteristics were similar to two commercial fruit leathers. The results showed that each ingredient had an impact on strawberry leathers' properties. In addition, certain properties such as Tg, aw, and textural parameters were correlated with each other. Hardness, chewiness, gumminess, and tensile strength were influenced by Tg. The development of fruit leathers has the potential of adding value to fruits that are over produced or are not suitable for direct consumption and contributes to a new healthy snack.
36G-2
Effect of different additives in quality characteristics of frozen bread
J. F. VÉLEZ-RUIZ1, D. Encinas-Banda2, H. González-Loo3, M. García3, and M. E. Sosa-Morales4. (1) Dept. of Chemical and Food Engineering, Univ. de las Américas -
Dough freezing is not a simple process because baking is a complex biochemical process involved in Food Processing. The resulting bread will depend on raw materials, process conditions, and employed additives. The objective of this study was to formulate dough for bread that will be submitted to the freezing process and to get a product similar to those recently baked. Four formulations were used: (A) increasing the yeast level to 4% and adding a mixture of soybean flour and enzymes, (B) adding a mixture of gums, enzymes and gluten, (C) adding an emulsifier—diacetil tartaric of mono- and diglicerides, and adding a crioprotector agent (D). Formulations B, C, and D also included a modified starch and maintained 1.5% of yeast level. Formulations were prepared, formed, and frozen up to -12° C in a tunnel freezer at -30° C. Frozen dough was stored at -18° C for six weeks. After storage, the dough was baked at 200° C for 15 min and some quality characteristics were determined. Dough moisture content was 33.5% without changes during frozen storage, while bread moisture was 23.7% (wet basis). The specific volume ranged between 4.16 and 4.80 g/cm3, without effect of the formulation (á=0.05); these values are comparable with those reported for baguettes (4.98 g/cm3) by Bonnardel and Maitre. For texture, a compression test was carried out. The softest formulation was D with a compression of 4.68 N, while the hardest formulation was B (7.63 N). Color was affected by the additives, being the luminosity the parameter with bigger changes. A sensory analysis was conducted with 22 nontrained judges, who gave higher qualification to the formulation D, but without significant differences with respect to formulations A and C (Α=0.05).
36G-7
Rheological and textural properties of foamed dairy and nondairy emulsions prepared with various commercial hydrocolloids
A. R. TAHERIAN, A. Bégin, and E.-A. Levesque. Food Research and Development Centre, Agriculture and Agri-Food Canada, Processed Plant Products, 3600 Casavant Blvd. W., Saint-Hyacinthe, QC J2S 8E3, Canada
Commercial hydrocolloids and their mixtures are used in frozen desserts to impart texture and palatability to the final product and to protect the whipped product against excessive drainage during storage. The mechanism of stabilization by hydrocolloids in foamed emulsions is not yet fully known, and a clear understanding of their role is needed to improve functionality and extend shelf life. Contributions of maltodextrin and arabic gum to flow and dynamic properties, glass transition, particle size and distribution, water-holding capacity, and texture of nondairy emulsions, in forms of mix and frozen foam, were investigated. The results were then compared to the properties driven from a commercial ice cream mix at both mix and frozen states. An identical procedure was used to prepare foamed emulsions, and all samples were stored for one week at -20°C prior to examinations. Rheological and textural characteristics of mix and frozen were determined using an AR-1000N Rheometer equipped with a 60mm cone of 2° C and a TA-XT2 Texture Analyzer attached with a 50mm circular probe. Glass transition temperatures were also measured using a Universal V2.5H TA Instruments differential scanning colorimetry. Examination of flow and dynamic properties of prepared mixes indicated a higher viscosity and flow behavior index for the mix prepared with maltodextrin. All mixes indicated pseudoplastic behavior and G' or elastic modulus at maximum frequency level (50 rad s-1), and apparent viscosity at minimum shear rate (0.1 s-1) of mixes and texture of frozen foams were related. Glass transition temperature of mix containing matodextrin, arabic gum, and commercial ice cream mix were found to be -27.54, -30.94, and -30.41° C, respectively. The results of this study could help to understand more about the functionality of hydrocolloids in frozen desserts.
47-6
Relating sensory and instrumental measurements of cheese texture
J.-F. C. MEULLENET, Dept. of Food Science, Univ. of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704-5585
Texture is very important to consumers' perception of cheese quality. Quality control methods, designed to evaluate texture quality, are often difficult to implement because of the challenges associated with correlating instrumental rheological measurements to perceived sensory attributes or acceptability. In addition, the texture of foods has long been recognized as a multidimensional sensory quality which manifests itself in many ways. As a result, instrumental tests should be able to predict multiple sensory characteristics to be successfully used as a quality control tool. Various aspects for developing successful and meaningful instrumental methods will be discussed, including selecting a geometry, optimizing test conditions, and utilizing novel statistical approaches. Methods such as uniaxial compression, cone penetrometry, and needle puncture will be discussed. Approaches for optimizing instrumental test conditions, including strain levels and rates, will be taken as examples and how multivariate statistical techniques can best be utilized to improve the prediction ability of rheological methods. Texture is difficult to assess from a perceptual standpoint because the physical properties of food cause complex sensations in the mouth. The selection of teeth; amount of saliva; tactile response perceived by the tongue, cheek, and lips; muscle activity; and the chewing phase are all parameters involved in the mastication of food. The lack of understanding of physiological processes has probably contributed to the inability to fully unravel texture perception. This presentation will also address some of the biomechanical aspects of texture perception. In particular, ways of incorporating learning from jaw movement studies of mastication and biting into the development of rheological methods will be explored. Finally, exploratory work in mathematical simulations of food deformation during biting and how it could be used in the future to study the effect of cheese formulation on the perception of texture will be discussed.
50-3
Multidisciplinary approaches for early determination of gelation properties of fish proteins
N. T. N. KOK1, J. D. Park, T. M. Lin, and J. W. Park. (1) Dept. of Food Science & Technology, Oregon State Univ., OSU Seafood Research Lab., 2001 Marine Dr., Rm. 253, Astoria, OR 97103-3420
Rheological properties are measured by instruments to determine product texture. Torsion, a fundamental test, and punch, an empirical test, are the most common rheological methods used to evaluate texture. For the torsion test, gel strength is represented by shear stress, whereas for the punch test, gel strength is represented by breaking force. Typically, the gels are first cooked in a 90° C water bath for 15 to 40 min and then stored overnight at 4° C. Results of the texture analysis are obtained 24 hr after sampling and usually after the product has been completed and/or shipped to market. It would therefore be beneficial to the industry to find more timely means of determining product textural quality. Our objectives were to determine the quality of fish proteins at an early stage of production using differential scanning calorimetry, oscillatory dynamic properties, and biochemical properties, and to establish a relationship between these three methods and fracture gel analysis. Strong correlation for deformation against ATPase activity was found with R2=0.74. Deformation increased with an increase in ATPase activity. A strong correlation between the storage moduli G'1 against deformation, with a correlation coefficient of (R2) 0.74, was established. The correlation coefficient of G'1 against breaking force was 0.55. The correlation coefficient of G' initial peak-G'2 against deformation was 0.63 and for breaking force 0.55. G'1 and G initial peak-G'2 decreased with increasing breaking force and deformation. Early determination of fish protein quality was determined by ATPase activity and the dynamic oscillatory method. These methods could be incorporated into industry to obtain timely and accurate results pertaining to the gel quality of the fish proteins being processed.
50-12
Incorporation of minced trout (Oncorhynchus mykiss) in egg based noodles
D. SCOTT, Food Science and Human Nutrition, Washington State Univ.,
Improving recovery of muscle tissue increases utilization of aquatic food products. Development of novel, yet feasible applications, for minced fish recovered from fish frames is needed. Noodles products containing fish or shrimp muscle or flavorings are widely consumed, particularly in Asian markets. The objective of this study was to determine the feasibility of incorporating washed minced trout muscle into egg based noodles and evaluating functional, textural and sensory attributes. A conventional egg noodle recipe was modified to replace 10% or 20% of the flour with minced trout by weight. Fresh noodles were tested for color and moisture content, then either boiled or fried. Moisture, texture profile analysis (TPA) parameters, color, and yield were determined. A consumer panel evaluated acceptability and preference. Moisture content of the fresh noodles increased with increasing fish content. The color of fresh noodles containing fish was redder and more yellow than the control. There was no significant difference in cooking loss, cohesiveness and springiness among any of the treatments. There was a significant decrease in hardness, gumminess, and chewiness in the cooked noodles as the level of minced fish increased. For the fried noodles, there was no significant difference in texture, moisture content, and yellow color as a function of substitution level. However, the fish noodles were darker and redder than the controls. Panelists found the control and experimental products to be equally acceptable, except for those panelists who did not like fish. Preference was evenly divided between the control and experimental products. These findings indicate the feasibility of incorporating minced fish into egg noodle products. Developing new uses for minced fish will increase utilization and the saleable of currently low grade minced products.
52-3
Effect of structure and phase behavior on physical markers for crispness
H. DOGAN, L. Samuel, and J. L. Kokini. Dept. of Food Science, Rutgers, The
Crispness is a key textural attribute of expanded cereal products greatly affecting consumer acceptability. Structure-texture-sensory relationships are of immense value in designing new products of desired properties in the food industry. We attempted to identify appropriate sensory perception cues for crispness and to systematically study the effect of cellular structure, phase behavior and mechanical deformation of expanded products on crispness sensation. Corn extrudates of diverse structures were produced by extrusion at 120-140°C, 15-20% of feed moisture content and 200 rpm screw speed. Sodium bicarbonate was added at 0.5-2% levels to alter the cellularity and cell wall characteristics. Structural characterization of extrudates was done in terms of cell size and cell size distribution, cell wall thickness, solid density, bulk density and porosity. Mechanical properties were determined by uniaxial compression at 1 mm/sec and 80% strain level. The jaggedness of the resulting force deformation curves were evaluated by calculating the number of peaks, ratio of linear distance and fractal dimensions. The method of magnitude estimation was used for sensory evaluation of these products, for crispness and hardness. Addition of sodium bicarbonate increased cell density but decreased average cell size. Average number of peaks was found to be a good predictor for sensory crispness and also related well with the structural characteristics of extruded corn. Experimental data clearly showed the impact of structural properties on instrumental and sensory texture. Fractal dimension excessively compressed the jaggedness of the force deformation curve for sensory evaluation purposes. Both sensory and instrumental crispness were highest in the glassy state and decreased significantly as the samples underwent a phase transition to the rubbery state at higher water activities. Identification of the appropriate sensory perception cues is of critical importance to relate instrumental textural parameters to sensory properties.
53-4
Effect of crumb density, glycerol, and enzyme addition on bread staling
G. KALETUNÇ, Dept. of Food, Agricultural and Biological Engineering, The Ohio State Univ., 590 Woody Hayes Dr., 210 Agricultural Engineering Bldg., Columbus, OH 43210-1058 and A. H. Barrett, U.S. Army Natick Soldier Center, U.S. Army Research, Development and Engineering Command, Combat Feeding Innovative Science Team, Kansas St., Bldg. 36, Rm. E-108, Natick, MA 01760-5018.
Parameters that increase the shelf life of bread by slowing the staling process are beneficial to bread manufacturers. The analysis of the effect of baking protocols and formulation on staling must be characterized in order to determine and control the critical parameters, thereby improving textural shelf life of bread. The objective of this study was to determine the effect of increased crumb density of white pan bread on the rate of staling. The effects of glycerol, protease, and amylase enzymes, and a modified bake process were studied. A method restricting the rise of the bread to increase the crumb density was developed. Densities of control bread crumb and high-density bread crumb were 0.29 to 0.34 and 0.36 to 0.41 g/cm3, respectively. Loaves of both high-density and control bread were vacuum-packaged and held for ten wk in an incubator at 23° C. The effect of formulation and the baking protocol on starch crystallization and texture of bread were monitored through DSC and texture analysis. DSC was used to monitor melting endotherms of recrystallized starch, while compression studies were employed to quantify the elastic modulus at 0, 1, 2, 4, 8, and 10 wk. Water activity for the breads with and without glycerol was 0.83 to 0.88 and 0.90, respectively. DSC analysis showed three irreversible endotherms occuring at approximately 66° C, 99° C, and 138° C. The endotherms at 99° C and 138° C were interpreted as melting of amylose-lipid complex and uncooked starch, respectively. The 66° C endotherm was attributed to be the melting of amylopectin recrystallized during storage and increased during storage. Bread firmness was evaluated in terms of the elastic modulus increased with crumb density without apparent relation to starch crystallization. The modified bake process that was used to create higher-density bread may have decreased crystal formation and crumb firming, thereby improving the textural characteristics and shelf life of bread.
53-8
Physical properties of muffins as affected by peanut flour and dried plum powder
M. J. HINDS, Dept. of Nutritional Sciences, Oklahoma State Univ., 309 HES Bldg., Stillwater, OK 74078-6141, T. J. Bowser, Biosystems and Ag Engineering, Oklahoma State Univ., and S. S. Reilly, Oklahoma Food and Agricultural Products Research and Technology Ctr., Oklahoma State Univ., 105 FAPC, Stillwater, OK 74078-6055.
Peanuts and dried plums contain components that can improve cardiovascular and bone health, respectively. Muffins can serve as convenient deliverers of these functional ingredients. The objective of this study was to evaluate the physical properties of muffins as affected by peanut flour (12% fat, PF), dried plum powder (PLMP), and appropriate additives. Response surface methodology was used with a Box-Behnken 3-level fractional factorial design in a standard muffin formulation. The four independent variables were: PF (50, 75, 100% wheat flour replacement); PLMP (6, 15, 24% dry ingredients wt); calcium-stearoyl lactylate (CSL, 1.5, 2.0, 2.5% dry ingredients wt); and glycerol monostearate (GMS, 0.5, 1.0, 1.5% dry ingredients wt). Their effects on texture profile (TA.XT2i Texture Analyzer), water activity, and crumb structure by computer microtomography (Scanco Micro-CT 40) were evaluated. PLMP affected all physical properties, but PF did not affect water activity of the muffins, which decreased with increased PLMP. CSL and GMS both affected muffin resilience, but CSL only affected hardness and chewiness, whereas GMS had significant effect on crumb cohesiveness. PF and PLMP had a synergistic effect on hardness, which peaked in formulations containing 100% PF and 24% PLMP for all levels of CSL. When formulations contained 1% GMS and 1.5% CSL, chewiness and gumminess increased with increased PF only, but for all other combinations of GMS and CSL, chewiness and gumminess increased with increased PF and PLMP. Springiness decreased with increased PLMP for all levels of GMS and CSL, but increased with high levels of PF when CSL was > 2% and GMS was > 1%. Generally, cohesiveness and resilience increased with higher PF and decreased with higher PLMP. Crumb cells were larger and more uniform with decreased PLMP and with increased CSL. Muffins containing 75 to 85% PF, 18 to 24% PLMP, 1.5% CSL, and 0.5 to 1.0% GMS would have optimum physical properties.
53-11
Utilization of mushroom sclerotium in traditional Chinese plain noodles
K. M. MA, Dept. of Biology, The Chinese Univ. of Hong Kong, Room 381, Science Center South Block, Shatin, New Territories, Hong Kong, China and P. C. K. Cheung, Food and Nutritional Sciences Programme, The Chinese Univ. of Hong Kong, Shatin, New Territories, Hong Kong, China.
Sclerotium is the dormant state of mushrooms, which contains over 80% dry weight of nondigestible carbohydrates. It could be a potential source to fortify the dietary fiber content in various kinds of functional foods. The objective of this project was to evaluate the nutritional and sensory attributes by incorporating three different kinds of mushroom sclerotia into the traditional Chinese plain noodles. Three edible mushroom sclerotium powders produced from Poria cocos (PC), Polyporous rhinoceros (PR), and Pleurotus tuberregium (PTR) were characterized for their functional properties. They were used to substitute for high-gluten flour at three levels (3, 6, and 10% w/w) based on the original Chinese plain noodle recipe. TA-TX2 texture analyzer was used to analyze the noodle texture. The sensory attributes of the noodles with 10% (w/w) sclerotium were evaluated in comparison with the control noodles using hedonic scale for color, surface smoothness, flavor, aftertaste, stickiness, springiness, and total acceptance. Sclerotium of PTR had a significantly lower water-holding capacity (P < 0.05) than PC and PR sclerotia. This resulted in a significantly greater cooking loss in the PTR-substituted noodles when compared to the PC- and PR-incorporated noodles at all levels of substitution. The hardness, stickiness, and firmness of the noodles differed with increasing levels of various sclerotium substitutions. The total dietary fiber content in 10% sclerotial PC-, PR-, and PTR-substituted noodles are 8.09% ± 0.65, 8.64% ± 0.82, and 6.60% ± 0.46, respectively. There were no significant differences in starch, protein, fat, and ash content among 10% sclerotium-containing noodles (P > 0.05). Sensory panelists did not show any significant difference in the preference to any of the noodles. However, the PC- and PR-containing noodles have a significantly higher total acceptance than the PTR-containing noodles. Mushroom sclerotia from Poria cocos and Polyporous rhinoceros are potential ingredients to be incorporated into fiber-rich food.
54C-2
Gel formation and characteristics of flaxseed gum
Flaxseed gum is one of hydrocolloids. Recent studies suggest that the flaxseed gum displays weak-gel properties that can be used to replace most of the non-gelling gum for food and non-food system applications. However the weak-gel properties of flaxseed gum have not been studied in detail. The aim of this work was to study the mechanism of gel formation and examine the effect of different factors, including dissolution temperature, concentration, pH level and different valent cations, on the gel strength. Both of Dynamic Rheological Measurement and Differential Scanning Calorimetry were used to determine gelling and melting point of flaxseed gum. The gel-formation mechanism of flaxseed gum was described using Atomic Force Microscopy and chemical methods. The gel strength and microstructure were measured with Texture Analyzer, Scanning Electron Microscopy and Zeta Potential Measurement. The results showed that both gelling and melting point increased with increase in dissolution temperature. But the gelling point was lower than its melting point at the same dissolution temperature due to extra energy for transition from order to disorder. The proposed mechanism of gelation was that the hydrogen bonds between hydroxyl groups of flaxseed gum molecules played a primary role. The maximum gel strength was obtained at pH 6 to 8, the gel strength decreased with lowering pH values at pH 2 to 6 or raising pH values above pH 8. Addition of Na+ lowered the Zeta potential, thus decreasing the gel strength. Addition of divalent cation Ca2+ had an unusual effect on the gel strength. Low concentration of CaCl2 (<0.3%w/w) increased the gel strength with facilitating the formation of three-dimensional networks due to Ca2+ cross-linking; but high concentration of CaCl2 (>0.3% w/w) decreased gel strength with decreasing Zeta potential. The flaxseed gum could form thermoreversible cold set gel, therefore it can be widely applied in meat and pasta products.
54D-6
Water vapor permeability and mechanical properties of whey protein based films
O. ERDOHAN and K. N. Turhan. Department of Food Engineering,
The edible films and coatings improve food quality, extend shelf life, append to foods some functional properties and reduce using of synthetic packaging materials. Some ingredients such as many proteins, polysaccharides, and lipids have good film forming properties. It is possible to improve film characteristics for specific application by incorporating these film forming ingredients. The objective of this study was to investigate the effect of different combinations of whey protein powders and methylcellulose (MC) on film formation and physical properties of films. Films were prepared from 5 % (w/v) whey protein isolate or concentrate, MC (30, 40, 60, 65, 70, 80 %, MC/whey protein powder), and glycerol as a plasticizer (50 %, glycerol/total polymer, w/w). ASTM E96-80 was used to determine gravimetrically water vapor permeability of the films. A texture analyzer was used to determine mechanical properties of whey protein based films according to ASTM D638M-93. Addition of MC to whey protein based film caused a decrease on water vapor permeability (WVP) of films. The lowest WVP values were obtained with 80 % MC/whey protein powder films. Tensile strength and elongation increased as MC amount in film forming solution increased. There is the potential to improve the physical properties of whey protein films by incorporating MC into the film system. Future work in this area should be improve permeability and mechanical properties of whey protein powder-MC films using different lipids and plasticizers.
54D-11
Development of cranberry pomace based edible films
Cranberry pomaces, byproduct from fruit juice and concentrate processing, are rich in natural pigments, phenolic antioxidants, organic acids, proteins, cellulose and pectin. Unfortunately, this useful resource hasn't been well utilized. The cellulose, pectin, and natural pigment in cranberry pomace are important components for making edible films. The development of fruit pomace based films would add significant value to the fruit processing industry. The objectives of this study were to examine the feasibility of using cranberry pomace extract to make edible films containing natural cranberry pigments and flavor, and to evaluate the mechanical and barrier properties of the films. Frozen cranberry pomace was grinded and mixed with water at ratio of 1 to 5. Hot water extraction was performed at 75 oC for 30 min. Pectin, protein, fat, ash, and moisture contents of grinded cranberry pomace and water extracts were analyzed. Low methoxyl pectin (LMP) or high methoxyl pectin (HMP) at concentration of 0.25% to 0.75% was added into the extracts for making films. Sorbitol or glycerol (0.25%) was used as a plasticizer. The pH and Brixo of film forming solutions and barrier and mechanical properties of dried films were analyzed. About 1.25% solids were obtained from cranberry pomace water extracts. Dried films contained bright red color and natural cranberry flavor. The type and concentration of pectins and plasticizers affected film properties. Tensile strength of the films increased with pectin addition. Generally, LMP added films showed higher tensile strength and lower water vapor permeability than those HMP added films. This study demonstrated the potential of developing cranberry pomace based edible films that have natural color and flavor. Such colorful films may be used as a stand alone films or edible coatings for various food products.
54D-17
Antimicrobial films as a potential technology to increase pathogen radiation sensitivity
J. HAN, M. E. Castell-Perez, and R. G. Moreira. Dept. of Biological & Agricultural Engineering, Texas A&M Univ.,
Electron beam irradiation is becoming a well-established decontamination technology. However, it is limited by undesirable changes in product quality at the required radiation doses. Thus, if we can increase the radiation sensitivity of the pathogens, we may successfully reduce these quality changes. One approach is to use packaging materials with self-sterilizing ability that may reduce the needed irradiation dose. Our first goal was to establish whether low-dose irradiation treatments affected the properties of antimicrobial films. FDA-approved sorbic acid, carvacrol, cinnamaldehyde, thymol and rosemary oleoresin, were added to a polyamide solution (1% of final solution weight). The coatings were applied to one side of low-density polyethylene (LDPE) films, dried at 20° C for 12hr, irradiated (1-3kGy) using a 10MeV linear electron accelerator, and stored in a desiccator until analyzed. We evaluated the antimicrobial effectiveness of the films against L. innocua ATCC 33090, and E. coli ATCC 11229 and ATCC 884 using agar diffusion and liquid culture tests. The films mechanical and barrier properties were measured using standard methods. All films showed inhibition zones in agar diffusion test against L. innocua and E. coli ATCC 884. However, films with carvacrol, cinnamaldehyde, and thymol extract did not show inhibition zone against E. coli ATCC 11229. In the liquid culture test, the active compounds significantly reduced the specific growth rate and final cell concentration of L. innocua. Irradiation dose did not affect the antimicrobial activity of the compounds. Neither the presence of active compound nor irradiation dose affected the mechanical (percent elongation, toughness, tensile strength) and barrier (water vapor, oxygen permeability) properties of the films. Polyamide coating, however, significantly reduced their tensile strength. Film surface properties will be investigated. These results are an encouraging first step to the development of self-sterile active packaging systems for food safety applications.
54E-11
Flavor and texture characterization of Mexican Fresco cheese by sensory evaluation and instrumental analysis
B. VALLEJO-CORDOBA1, M. D. J. Torres-Llánez2, A. F. González-Córdova2, and M. D. C. Estrada-Montoya2. (1) Dept. de Tecnología de Alimentos de Origen Animal, Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Carretera a La Victoria Km 0.6, Apartado 1735, Hermosillo, Sonora, 83000, Mexico, (2) Mexico
Fresco cheese or Queso Fresco made from pasteurized milk as required by the Mexican regulations, results in a uniform product of good sanitary quality; however, pasteurization adversely affects cheese flavor and texture. The indigenous microflora in the raw milk are partly responsible for the development of the typical flavor and texture of the traditional artisanal cheese preferred by the consumer. Thus, to restore flavor and texture, nonspecific starters isolated from artisanal cheese made from raw milk were developed to improve these attributes. Although these cheeses were found to have acceptable sensory attributes, their flavor and texture were not fully characterized. Thus, the objectives of this work were to fully characterize the flavor and texture of Queso Fresco by using sensory evaluation and instrumental analysis and to monitor proteolysis and lipolysis during refrigerated storage. Three batches of Queso Fresco were prepared. Cheeses were made by pasteurizing milk and using five different specific starters. Flavor and texture attributes were evaluated by sensory analysis and instrumental analysis. Volatiles were determined by gas chromatography, and texture was evaluated by a texture analyzer. Proteolysis was monitored by determining the nitrogen content of fractions that are soluble in water (WSN), trichloroacetic acid (TCA), and phosphotungstic acid (PTA). Lipolysis was monitored by determining the acid degree value (ADV). Sensory analysis and nonprotein nitrogen indicated that Queso Fresco made with one of the specific starter cultures was not significantly different (P > 0.01) from the traditional artisanal cheese (control). However, ADV values, gas chromatographic profiles and firmness for this cheese were signficantly different (P < 0.01) from the control. The flavor and texture characterization of Fresco cheese presented in this work provides the basic information needed to establish standards of identity required by the Mexican regulations.
54E-24
Textural attribute of yogurt manufactured from milk treated with microbial transglutaminase
M. G. Vera-Vite, Departamento de Tecnología de Alimentos de Origen Animal, Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD), Carretera a la Victoria Km 0.6, Apartado 1735, Hermosillo, Sonora., 83000, Mexico, A. F. GONZÁLEZ-CÓRDOVA, Centro de Investigación en Alimentación y Desarrollo (CIAD), Mexico, and B. Vallejo-Cordoba, Mexico.
The texture of yogurt is highly dependent on the amount and functionality of the individual components comprising yogurt gel, and on the interaction between the components as well as on the technological steps in the production process. Milk composition and process influence yogurt stability (wheying-off) and rheological properties such as firmness, consistency, adhesiveness, and cohesiveness. To improve texture and prevent syneresis, stabilizers and polysacharide-producing cultures have been used. As an alternative method to improve texture, chemically induced acid gels were produced after milk enzymatic modification with microbial transglutaminase (MTGase). MTGase is an enzyme that catalyzes the cross-linking of proteins through the formation of covalent bonds. The two amino acids that it uses to cross-link are glutamine and lysine. The objective was to evaluate the texture of yogurt made from MTGase-treated milk and to compare it to the yogurt made from untreated milk. Milk was batch-pasteurized at 85 °C for 30 min, cooled to 50 ºC, and treated with varying amounts of MTGase (0.03, 0.09, and 0.15%). Then it was inoculated using a yogurt starter culture (S. thermophilus and L. delbrueckii sbs. bulgaricus). After inoculation, samples were incubated at 43 ºC until a pH of 4.4 was reached. Additionally, yogurt was made from milk supplemented with 3% nonfat dry milk (NFDM). Wheying-off, pH, firmness, consistency, adhesiveness, and cohesiveness were monitored after 24 hr of refrigerated storage. Yogurt made from milk treated with MTGase (0.15%) developed less wheying-off, higher firmness, consistency, adhesiveness, and cohesiveness than the control made from untreated milk or yogurt made from milk supplemented with 3% NFDM (P < 0.05). Milk treatment with MTGase proved to be a good alternative method to improve yogurt texture and may reduce or eliminate the use of stabilizers or the fortification with NFDM.
54F-21
Effect of electron beam irradiation on quality of blueberries (Vaccinium corymbosum L)
M. A. MORENO, C. Gomes, P. C. F. Da Silva, M. E. Ca