TEXTURAL PROPERTIES OF STARCH GELS FILLED WITH COLLAGEN AND CHITIN

Chitin and collagen powders were added as fillers to various starches (potato, sweet potato, kudzu, corn, wheat, and mung bean), heated at 100C for 10 min with stirring to make a hot paste and allowed to gel quiescently at 5C for 2 h in order to investigate the effects of the filler particle on the texture of the gels. The parameters of hardness, cohesiveness and adhesiveness were determined instrumentally and compared. The filler particles of collagen and chitin were effective in increasing hardness of corn starch gels but had no effects on hardness of the potato, sweet potato, kudzu, wheat and mung bean starch gels except at the lower starch concentrations. Cohesiveness was increased slightly in all starch gels by addition of collagen whereas chitin addition only increased the cohesiveness of sweet potato and mung bean starch gels. Collagen and chitin addition increased adhesiveness all of starch gels, but the intensity of the effect was most remarkable for collagen. The observed differences in effects was apparently due to differences in the interactions between starches and filler particles arising from differences in the surface properties of the filler particles.     

A PUNCH AND DIE TEST CELL FOR DETERMINING THE TEXTURAL QUALITIES OF MEAT *

Abstract . A test ceil is described that measures the response of materials to a punch-shear deformation. The cell, designed as a punch and die unit, was used with the Instron Universal Testing Instrument to determine the textural characteristics of several food products. Data are presented for beef muscles from US Choice and US Commercial grade animals. Sensory evaluation using magnitude estimation techniques showed high correlation with instrumental measurements. When all combinations of three sensory attributes and three instrumental properties were considered, correlation coefficients ranged from 0.92 to 0.98. Sensory judgments showed that the differences between muscles were 2 to 3 times greater than those found using the test cell, but the large scatter in panel results reduced sensitivity below that of the instrument. The panel judged the psoas major and the semiten-dinosus from the US Commercial grade animal to be twice as tough as the same muscles from the US Choice grade animal. The biceps femoris was judged to be 4 times tougher in the Commercial than in the Choice grade animal.     

INFLUENCE OF PARBOILING ON RICE STARCH STRUCTURE AND COOKED-RICE TEXTURE

Four varieties of rice having very high (29.4%) to low (17.6%) amylose-equivalent (AE) were parboiled by steaming at atmospheric (PB-O) and at 3 kg/cm2 (PB-3) gauge pressure. The cooked rice texture of the raw, PB-0 and PB-3 rice was determined by Viscoelastographe. Gel permeation chromatography of rice flour starch on Sepharose CL-2B, in general, indicated thermal breakdown of starch. The extent of starch breakdown and the firmness values of cooked PB-0 and PB-3 rices were reasonably well correlated suggesting that starch breakdown during parboiling may have some role to play in varying the texture of rice by parboiling. The chain profile of rice starch remained unaltered after parboiling.     

CHARACTERIZATION OF THE TEXTURAL PROPERTIES OF SPREADABLE PEANUT BASED PRODUCTS 1

Textural characteristics of two peanut butter samples and one peanut paste sample were determined using three instrumental methods and a texture profile panel. In Method A, a penetrometer with a cone-shaped probe attachment was used. Method B involved the use of a plunger attached to the crosshead of the Instron Universal Testing Machine. Method C was a modified texture profile analysis (TPA). Instrumental measures show that peanut paste was the hardest, exhibited the greatest adhesive force but the least time to break the peanut column, and was the least cohesive. All instrumental methods were acceptable but TPA provided more information than the two other methods in describing texture. The panel rated the paste as firmest, least adhesive, spread least on the tongue, least smooth, most grainy, and most difficult to swallow. Significant correlations were found between several instrumental measures and sensory characteristics.     

MOLECULAR DEGRADATION OF STARCH DURING EXTRUSION COOKING OF RICE

ABSTRACT

Effect of barrel temperature (80°–100°C) and amylose content (28.6 gkg^?1, 22.3 gkg^?1 and 5.0 gkg^?1) of rice upon extrusion cooking on macromolecular profile of starch was studied by gel permeation chromatography (GPC) of the rice flour on Sepharose CL-2B. Starch in all rice samples was separated into two main fractions, viz. Fraction-I, a high molecular weight, was excluded by gel, amylopectin, and Fraction-II, a low molecular weight, that entered the gel, amylose. Extrusion cooking of rice led to the degradation of high molecular weight fraction of the starch, the extent of degradation increasing with increasing severity of extrusion conditions. The absorption maxima (λ _max) of iodine complex of the fraction-I showed an increase after extrusion cooking and this increase was more in the non-waxy variety of rice than in waxy.     

RS4型抗消化淀粉的结晶结构及消化性能研究

利用偏光显微、X射线衍射等现代分析技术，研究了酯化改性后淀粉颗粒形貌和结晶结构的变化。结果表明，与HylonV玉米淀粉相比，酯化改性后得到的RS4型抗消化淀粉的颗粒形貌和结晶结构都受到不同程度的破坏，尤其导致了结晶形态由B型向V型转变。由此引起淀粉的消化性能发生改变，经体外模拟试验表明，RS4型抗消化淀粉在人工胃液和人工小肠液中都有良好的抗消化性能，且随着抗消化淀粉含量的增加，抗消化性能越显著，显示了其良好的结肠靶向性。     

STRUCTURE AND SOLUBILITY OF COLLAGEN AND GLYCOSAMINOGLYCANS IN TWO BOVINE MUSCLES WITH DIFFERENT TEXTURAL PROPERTIES

Meat samples were collected from two bovine muscles , psoas major and semitendinosus, exhibiting different textural properties as measured by Warner Bratzler Shear Force. The structure and composition of the intramuscular connective tissue was compared by transmission electron microscopy, fibril diameter measurements, statistical analysis, collagen and glycosaminoglycan solubility studies in acetic acid and acetic acid added pepsin. The mean fibril diameter was significantly larger in the tougher muscle and the fibrils were tightly bundled into fibers. The tender muscle exhibited mainly randomly oriented fibrils with more space in between. The biochemical study confirmed the microscopy, showing a higher hexuronic acid/hydroxyproline ratio in the tender muscle, mainly in pepsin digested samples. The content of hydroxyproline after defatting in acetone was 30% higher in ST. No major differences were seen in the proportion of acid labile or stable cross-links in the collagen of the tough and tender muscle.     

RELATIONSHIP BETWEEN STRUCTURE AND TEXTURE OF EXTRUDED SOY AND COTTONSEED FLOUR PRODUCTS

Textural properties of extruder cooked soybean and cottonseed flours were evaluated by a tasting panel and ultrastructure study. An attempt was made to correlate the findings of the tasting panel with chemical and physical parameters. The role of NSI in the flours and the size of the texturing machinery (X-5 vs X-25 or laboratory vs plant size) were evaluated as well. Water absorption and integrity tests values of the cottonseed products were lower than those of soybean. The free gossypol values of the cottonseed extruded products are relatively very low. Significant differences were found between the ultrastructure of the soybean and the cottonseed extrudates. Several stages of induced texturization of cottonseed protein were observed by the electron microscope while soy proteins had only one.     

A REVIEW OF TEXTURAL DEFECTS IN COOKED RECONSTITUTED LEGUMES —THE INFLUENCE OF STRUCTURE AND COMPOSITION

Legumes provide an important part of the world's protein requirements, as well as other nutrients, but they are underutilized as food. A major factor limiting expanded consumption is storage induced textural defects that prolong cooking time and demand correspondingly higher energy requirements for preparation. These defects, including the hard-to-cook phenomenon and hardshell, are initiated by structural and compositional factors but can be at least partially controlled by storage and processing conditions. Structural components implicated include seed coat, cell walls, middle lamella, starch granules and membranes while, compositionally, proteins, carbohydrates, phytate, polyphenols and lignin may also be important. Methods of texture measurement of legumes, including mechanical, physical and sensory properties are reviewed. The most commonly held hypothesis for the mechanism of the hard-to-cook defect states that beans fail to soften after exposure to high temperature and humidity storage because the increased water activity potentiates phytase which hydrolyzes phytate, rendering it no longer capable of chelating the Ca⁺⁺ and Mg⁺⁺ ions of the middle lamella and, hence, undissoluble. More recent evidence, however, provides potential roles for lignification, starch gelatinization and perhaps other mechanisms depending upon conditions. The possibility of a nonenzymatic as well as an enzymatic route is raised and thoughts presented on a course of action for future research.     

百合化学成分及其淀粉粒结构与一般特性

对百合基本成分、淀粉粒的表面与晶体结构以及其淀粉的一般特性进行了系统研究，结果显示：百合含有丰富的淀粉、蛋白质与果胶，脂肪含量低；百合淀粉粒具有多种形态，粒径范围宽（10μm-105μm），平均粒径为35μm。百合淀粉粒具有典型的晶体结构特征，晶型为B-型；百合淀粉溶解度和膨润力较马铃薯淀粉与玉米淀粉大；百合淀粉的抗冻稳定性较马铃薯淀粉与玉米淀粉差。     

TEXTURAL QUALITY OF GREEN AND WHITE ASPARAGUS

A textural comparison between green and white asparagus was conducted on three cultivars (‘Jersey Gem’, ‘Jersey General’, and ‘Jersey Giant’) harvested during spring and summer of 1990. Spears were analyzed for fibrousness and sensory characteristics at three different sections: tip, middle and base. Fibrousness of both green and white asparagus was greater in the spring. On the other hand, white spears were more fibrous than green ones. Sensory assessment of spear hardness revealed that tip and middle sections of white spears were harder than equivalent sections of green spears. Concurrently, sensory fibrousness was greater in white than in green spears and decreased from tip to base. No measurement of texture was affected by cultivar. Light microscopy did not reveal differences between green and white asparagus. However, regardless of type, the number of lignified tracheal elements within vascular bundles increased basipetally along the stem, explaining the difference among sections of spear.     

EFFECTS OF SESAME LIGNAN EXTRACT ON LINOLEIC ACID, LIPID OXIDATION, COLOR AND TEXTURAL PROPERTIES OF GROUND PORK, AND SAUSAGE PRODUCTS

Sesame lignan extract was prepared from roasted sesame oil and added at 0.02, 0.05, 0.10 and 0.20% (w/w) to linoleic acid and ground pork products. Cooked ground pork containing more than 0.02% of lignan extract showed TBA values lower than those containing butylated hydroxyanisole (BHA) during storage. Sausages containing 0.05% of lignan extract had lower thiobarbituric acid (TBA) values when stored at 4C for 14 days; they also showed higher CIE color values than the control meat sample (P < 0.05). There were no differences in textural properties such as hardness, cohesiveness and chewiness between the control and the sausages containing lignan extract when determined by Instron Testing Machine. Thus, lignan extract prepared from roasted sesame oils was highly antioxidative when used in cooked ground pork at > 0.02% or in sausages at > 0.05%.     

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.