TEXTURAL PROPERTIES OF RESTRUCTURED BEEF PRODUCTS WITH FIVE BINDERS AT FOUR ISOTHERMAL TEMPERATURES1

Texture profile analysis (TPA) and shear force of restructured beef products with one of five binders (isolated soy protein, sodium caseinate, waxy modified corn starch, carrageenan, and oat flour) were analyzed at 35, 45, 55 and 65 C. Hardness, cohesiveness, springiness, gumminess, and chewiness were significantly affected (p<0.05) by binders, temperatures and their interactions. Hardness and gumminess showed no significant (p<0.05) differences among binders and temperatures below 45C, but each increased between 45 – 65C. Isolated soy protein gave the highest hardness and gumminess values; oat flour, the lowest at 55 and 65C. Except for oat flour, cohesiveness, springiness and chewiness decreased from the raw state until 45C, and then increased. Oat flour gave the highest values for cohesiveness, springiness and chewiness < 45C; the lowest at 55 and 65C. Oat flour gave the lowest shear force (N) values at 55 and 65C. Conclusions were reached that the influence of these binders on the textural parameters of restructured beef products was temperature-dependent.     

EVALUATION OF THE TEXTURAL PROPERTIES OF JAPANESE PEAR

The texture of Japanese pear (Pyrus serotina Rehder var. culta 'Housui') during fruit enlargement and ripening was evaluated. From the plate compression test, only the deformation ratio, modulus of elasticity, and relaxation were the interpretable textural indices for the Japanese pear. From the puncture test, interpretable textural indices were the rupture force, deformation at the rupture point, toughness, average firmness, initial firmness, apparent modulus of elasticity, bioyield force, penetrating force and penetrating energy in the flesh. The skin of the Japanese pear contributed 70–80% of the firmness of the fruit. As the fruits enlarged, the strain decreased, the elasticity increased, the fruit skin was more prone to mechanical damage, the fruit flesh became softer, and firmness and rigidity of the whole fruit was reduced.     

TEXTURAL CHARACTERIZATION OF SOY-BASED YOGURT BY THE VANE METHOD

The vane method was applied to evaluate failure characteristics of soy-based yogurts prepared from five soybean varieties at Brix values of 6, 8, and 10°. Yield stress, yield strain, and water-holding capacity were compared. Yield stress values ranging from 133 to 420 Pa at 2.5% protein and 498 to 1171 Pa at 4.0% protein were dependent on soybean variety and increased with increasing protein concentration. The average yield strain of samples was not affected by protein or variety. Compared to commercial dairy yogurt, soy yogurt had 132 to 445% higher yield stress at similar protein content, and was less deformable based on yield strain measurements. Water-holding capacity of soy yogurts was variety dependent, although this dependence was less pronounced at higher protein concentrations. The vane method may be effectively used as a rapid and inexpensive technique for detecting textural differences of soy-based yogurts.     

TEXTURAL CHARACTERIZATION OF TEMPERATURE SENSITIVE FOODS

The instrumental texture profile method is extended to include the temperature variant. Using dessert gel systems and whipped toppings as examples of thermally sensitive foods, advantages are demonstrated of performing instrumental measurements at a series of ascending temperatures covering the range that would be encountered during sensory evaluation. Plotting instrumental values against temperature yields curves which, for different samples within a product system, cross each other at different points and exhibit different rates of change. Advantages are also demonstrated of using several complementary instruments to obtain a more complete characterization. The Texturometer, the Gel Characterization Apparatus and the Brookfield Viscometer were used with the gel systems. In addition, the Texture Test System fitted with an orifice attachment and the Cenco Calorimeter were used with whipped toppings. Correlations with sensory evaluations using the texture profiling system are reported.     

ANALYTICAL CHARACTERIZATION OF THE PRODUCTS OF NONENZYMATIC GLYCOSYLATION OF LYSOZYME

The quantitative analysis of the reaction products of the water activity dependent nonenzymatic glycosylation of lysozyme was not straightforward. Difficulties arose in the determination of the number of bound glucose molecules because glycosylation leads to glucose mediated protein aggregation, and the likely presence of a mixture of relatively labile Schiff-base intermediates, and the more stable ketoamine products generated by Amadori rearrangement. Polyacrylamide gel electrophoresis was used to monitor protein aggregation; periodate oxidation, nuclear magnetic resonance (NMR), and oxalic acid hydrolysis combined with HPLC, emerged as the most promising methods to quantitate the degree of glycosylation. Possible interpretations are advanced to explain the apparent discrepancies in degree of glycosylation suggested by the different analytical methods evaluated.     

RELATIONSHIPS OF INSTRUMENTAL TEXTURAL PROPERTIES AND MUSCLE FIBER TYPES TO THE SENSORY PROPERTIES OF BEEF

Longissimus muscle steaks from 94 cattle were used to determine the relationship between sensory tenderness ratings and instrumental textural properties of beef and to determine the role of muscle fiber type characteristics to sensory and instrumental textural properties. It was determined that ease of fragmentation, amount of detectable connective tissue, and tenderness ratings were all measurements of the same attribute. Peak load was found to be the best predicator of tenderness and the use of additional instrumental textural properties in regression equations did not substantially improve predictability. White muscle fiber characteristics were found to be positively correlated to sensory tenderness ratings.     

TEXTURAL QUALITIES AND MOLECULAR STRUCTURE OF STARCH PRODUCTS

This review deals with the physical properties of starch important in foods and with some of the factors which influence those properties. The major topics discussed are the molecular structure of the starch grain, the interaction of starch with water and with other compounds, the rheology of starch and starch products, and textural problems of starch in some representative foods.     

EVALUATION OF SOME TEXTURAL PROPERTIES OF FOODS WITH THE INSTRON UNIVERSAL TESTING MACHINE

Abstract. Analysis of published chewing force patterns indicates that the 'first bite' involves an approximately linear application of force. The Instron Universal Testing Machine also offers a linear pattern of force application making it possible to obtain information about textural properties identified during the 'first bite' from force-compression tests. However, the data obtained in such tests are influenced not only by the applied force but also by the rate at which it is applied. Both variables must be taken into account when analysing the data, since the applied force in chewing and also the rate of force application depend on the textural characteristics of the food being evaluated. Based on a correlation of sensory responses with instrumental force-compression-rate of force application data, a procedure is described for establishing the mechanical force conditions that should be used in Instron tests so that they simulate those associated with the sensory evaluation.     

花生水解蛋白的功能性质研究

对花生水解蛋白的溶解性和乳化性质进行了研究.结果表明,花生水解蛋白在碱性条件下溶解度较好;提高温度可增加花生水解蛋白乳化活性,在远离等电点时花生水解蛋白具有较好的乳化活性,而乳化稳定性随PH变化未呈现规律性变化.增加花生水解蛋白浓度或添加可溶性淀粉均可显著改善该蛋白质的乳化性能.     

INSTRUMENTAL AND SENSORY TEXTURAL PROPERTIES OF FURA

ABSTRACT

A uniaxial compression test and sensory textural analysis was conducted of fura samples made from millet flour. Significant differences (p<0.05) existed among the samples for hardness (the force to compress the sample between molar teeth), cohesiveness (extent to which sample falls apart during chewing) and gumminess (denseness and cohesion persisting during mastication). Correlations between sensory and instrumental tests revealed that a significant relationship exists between modulus of deformability and cohesiveness (r=?0.93, p<0.05); gradient and springiness (r=?0.90, p<0.05); deformation at failure and chewiness (r=0.98, p<0.05); energy per unit mass and gumminess (r=?0.95, p<0.05). A fura quality scale was established based on the peak force; soft and poor quality fura have a peak force of <19 kN; acceptable fura has a peak force of 19–24 kN; a firm and good quality fura, 24–25 kN; very hard and very poor quality fura have a peak force of >25 kN.     

EFFECTS OF CHITOOLIGOSACCHARIDE ON THE PHYSICOCHEMICAL, TEXTURAL AND SENSORY PROPERTIES OF TOFU

Chitinous polymers have been experimented with for the purpose of shelf-life extension of foods due to their antimicrobial activity. Food additives, however, may impair the taste, color or texture of foods. Therefore, it is necessary to evaluate the effect of a food additive on foods before it is used. In this study, we investigated how the physicochemical properties, microstructure, textural properties and sensory characteristics of tofu are affected by the addition of chitooligosaccharide during its preparation. The addition of chitooligosaccharide to tofu did not significantly affect its physicochemical properties including moisture content, yield, turbidity and color. The chitooligosaccharide tofu, however, had lower hardness and smaller protein aggregates than the control tofu. The chitooligosaccharide did not influence most sensory attributes of tofu except for imparting a bitter taste.     

EVALUATION BY INSTRUMENTAL METHODS OF THE TEXTURAL PROPERTIES OF SOME TROPICAL FRUITS1: (A REVIEW)

Published applications to tropical fruits of instrumental methods for texture evaluation are cited and tabulated. The comparability of the results is evaluated in light of the morphological characteristics of the fruits, the types of methods used and the test procedure employed.