EFFECT OF PARTICLE SIZE AND HEAT ON ABSORPTIVE PROPERTIES OF SOY HULLS1,2

Given the potential contribution of soy hulls to the human diet, a methodology was developed to determine their moisture and lipid absorptive properties under conditions simulating those within a restructured pork product during thermal processing. Laboratory procedures were developed to determine the interactive effects of particle size, heat (25, 50, 75, and 95°C), and varying levels of available water, pork lipids, and water/pork lipids emulsion upon absorption abilities. Absorption of all media was influenced by particle size; as particle size increased, media absorption generally increased. Higher temperatures tended to increase water and water/pork lipid emulsion absorption, but had no effect on pork lipid absorption. Water was found to be preferentially absorbed over lipids. These results can be used by food processors in developing a restructured pork/soy hull product for human consumption.     

全脂大豆蛋白对面条品质影响的探讨

通过在面粉中添加不同比例的全脂大豆蛋白，探讨了其对蛋白质品质、面团流变学特性、面条色泽、断条率、咀嚼感、爽口感及面条蒸煮品质和感官品质的影响。结果表明，在面粉中加入8％的全脂大豆蛋白可显著提高面粉的蛋白含量和湿面筋含量，改善了面团的流变学特性及面条的韧性和口感，既增加了面条营养价值，又提高了面条的质量和加工性能。     

不同制粉工艺对面粉粉质特性和糊化特性的影响

脱皮制粉工艺先除去小麦部分皮层,再入磨,使后序的皮磨以及清粉系统大大简化.本试验利用两种工艺加工面粉后,用RVA测定和分析了面粉粉质特性和糊化特性的变化.结果表明,脱皮工艺下面粉的损伤淀粉含量减少、淀粉平均粒度变大、α-淀粉酶含量减少;降落数值和平均粒度分布分别与低谷粘度呈显著正相关（r=0.581,p＜0.05;r=0.603,p＜0.05）,衰减度和平均粒度呈显著的负相关（r=0.605,p＜0.05）;制粉工艺对中筋的南阳白麦和高筋的8901二等粉的影响最为显著,脱皮工艺下这两种面粉的峰值粘度和最终粘度明显增加,并且其衰减度较大;脱皮工艺的低谷粘度均高于传统工艺的同等面粉,但回生值较低.     

DYNAMIC VISCOELASTIC PROPERTIES OF SOY ISOLATE DOUGHS

The linear viscoelastic properties of soy isolate doughs have been determined as a function of flour concentration and temperature using a Rheometrics Mechanical Spectrometer. The material of lowest concentration (15%) which is classified as a dispersion rather than a dough exhibited values of storage (G') and loss moduli (G") which increased with increasing temperature above 50°C. On the other hand, values of G' and G" for 20% and 25% doughs showed only a slight increase with increasing temperature. The shape of the G' and G" versus frequency (ω) curves is suggestive of solid-like behavior for the doughs. The shape of these curves does not change with temperature which indicates there is very little change in the ability of the protein molecules to undergo configurational rearrangements as the result of heating. The phenomenon of gelation does not arise in the doughs but only in the dispersion of lower concentration. The data indicate that the bonds between protein molecules are noncovalent in nature and that the process of cooking soy dough does not involve the formation of crosslinks.     

EFFECT OF EXTRUDER RETENTION TIME ON CAPILLARY FLOW OF SOY DOUGH1

Soy dough (defatted soy flakes), at 120° C and 30% moisture, was extruded through a series of dies of differing length (L) and radius (R). Rlots of pressure (P) were linear with the length to radius ratios (L/R) of the dies at constant output rate (Q) and R. The intercepts of the P versus (L/R) plots on the P = O axis give the end corrections (e) for capillary flow at each output rate. For soy dough, these end corrections were surprisingly large at low output rates and generally decreased rapidly with increasing output rate. This is contrary to the normal behavior of viscoelastic fluids, such as thermoplastics, where the end correction increases with increasing output rate. Both the end correction, which is a measure of the elastic properties of the soy dough, and the viscosity of the soy dough depended on the output rate as expected and also on the retention time of the material in the system.     

EFFECT OF SPRAY-DRIED OR REDUCED-CHOLESTEROL YOLK AND TEMPERATURE ON THE LINEAR VISCOELASTIC PROPERTIES OF MAYONNAISE

The dynamic viscoelastic properties of five mayonnaise products were evaluated at 5–30C and 0,031-31,4 s⁻¹. The composition of the products was held constant, while the type of egg product was varied. Two egg yolks (native and spraydried) and three whole egg products (native, dried-yolk containing and low-in-cholesterol-yolk containing) were used as the emulsifiers. Temperature generally produces a decrease in the viscoelastic functions. A replacement of yolk (native or not) by egg white reduces the viscoelastic properties of mayonnaise. Processed yolk gives rise to greater viscoelastic parameters than native yolk. This effect loses significance when yolk is diluted by native egg white. The low-cholesterol mayonnaise has similar viscoelastic properties when compared to commercial mayonnaise.     

EFFECT OF ACETIC ACID AND CMC ON RHEOLOGICAL AND BAKING PROPERTIES OF FLOUR

The effects of addition of acetic acid (0.05, 0.1, 0.2 and 0.4%) and carboxymethyl cellulose (0.25, 0.5, 1.0, 2.0%) on rheological, gas release and bread making properties of flour were examined. Water absorption, dough stability, dough development time, loaf volume and overall acceptability scores decreased, while degree of softening and bread firmness increased with an increase in acetic acid concentration. Addition of CMC showed similar effects on dough stability, dough development time and degree of softening. Maximum dough height (H_m), maximum height of CO₂ production (H,_m), gas formation and retention decreased with the increase in acetic acid and CMC levels. Addition of 0.05% of acetic acid in combination with 0.25% CMC was most effective in improving dough characteristics, and overall acceptability scores.     

THE EFFECT OF PROTEIN FORTIFICATION ON THE ACCEPTABILITY AND RHEOLOGICAL PROPERTIES OF COOKIE DOUGH AND ITS FINAL PRODUCT1

All-purpose wheat flour and all-purpose wheat flour fortified with 6% soy flour; 2, 4 and 6% single cell protein (SCP) were used. Protein quantity was increased significantly in both flour and cookies. Sensory panel evaluations were conducted for flavor, texture and overall acceptability of cookies, and objective evaluation of rheological properties were made with the farinograph and shear-press on doughs, and shear-press on cookies. Fortification with SCP at all levels altered all the sensory parameters significantly, but fortification with soy flour altered only cookie texture. Fortification with both SCP and soy flour significantly decreased the “spread factor” quality. Correlations between panel texture scores and texture parameters from the farinograph or the shear-press were not significant. However “Consistency” and “Elasticity” obtained from farinograms were significantly increased due to the high level of fortification by SCP and soy flour, and the same results were found in “Viscoelasticity” obtained from the shear-press. Also, the determinations from both instruments showed that the tolerance to kneading was significantly reduced as a result of the fortification. Adhesive properties of dough as obtained from texturegrams were significantly increased due to the 5% SCP and soy flour fortifications. The variations of textural characteristics were highly predictable from texture parameters of doughs as obtained from both instruments. Thus the coefficient of determination (R²) of crispness and hardness as measured by the shear-press were 0.987 and 0.999 when farinogram parameters were used, and 0.999 and 0.997 when texturegram parameters were used as independent variables.     

THE EFFECT OF TEMPERATURE ON SOME RHEOLOGICAL PROPERTIES OF WHEAT FLOUR DOUGHS

Abstract. Doughs from three flours were sheared between a cone and plate at constant rates in the range 6 times 10^-4-2 times 10^-2 s^-1.
At temperatures between 25 and 40C, the apparent viscosity decreased with increasing temperature and with increasing rate of shear. The effects of the temperature and of the rate of shear were independent one of another, and can be described by an Arrhenius type equation and a power equation, respectively. At temperatures between 45 and 60C, the apparent viscosity increased rapidly with increasing temperature; this is ascribed to starch gelatinization. In this temperature range, the apparent viscosity decreased more rapidly with increasing rate of shear than at lower temperatures.
At temperatures between 25 and 45C, the shear modulus decreased with increasing temperature and slightly increased with increasing rate of shear. From the former fact it is concluded that the elasticity of dough has an origin different from rubber elasticity. In this temperature range, the shear modulus can be described by an equation similar to that for the apparent viscosity. At temperatures between 45 and 65C, the modulus increased with increasing temperature, though to a lesser extent than the apparent viscosity.
Changes in the rate of stress relaxation are in accordance with the effects of temperature and rate of shear on the apparent viscosity and the modulus.     

变性淀粉及谷朊粉对面团特性的影响研究

研究淀粉及变性淀粉、谷朊粉对面团特性的影响。结果显示：在面粉中，按4％的比例添加马铃薯变性淀粉，对面团的稳定时间、弱化度及抗张强度等均有显著的影响（P〈0．01）；添加6％木薯变性淀粉，面团抗张力增加26、6％；添加3％的谷朊粉，面团形成时间及稳定时间均有较大增加。木薯原淀粉及其变性淀粉等对面团的特性影响不大。     

THE INFLUENCE OF WORK SOFTENING ON THE VISCOELASTIC PROPERTIES OF BUTTER AND MARGARINE

Abstract Creep compliance-time studies at low stresses give more information about the structural changes in work softened butter and margarine than the Cone Penetrometer. They show that margarine undergoes a greater structural change than butter. Margarine loses most of its instantaneous elasticity in an unrecoverable manner. However, most of the Newtonian viscosity loss is recovered. Butter loses much less of its instantaneous elasticity, and most of what is lost is recovered during aging, but less of the Newtonian viscosity which is lost is recovered. Retardation spectra derived from creep compliance-time curves for both butter and margarine before work softening show a peak at ∼10⁴ sec. In contrast to margarine, butter does not lose this peak when work-softened. For margarine, the peak slowly redevelops during aging and occurs at ∼10² sec. Past interpretation of Cone Penetrometer data has been based on the simplified concept of primary irreversible bonds and secondary reversible bonds, and the changes in their relative proportions during work softening. The present approach avoids the allocation of bond strengths into these arbitrary categories, and is based on the realization that butter and margarine contain a wide range of bond strengths.     

FULL-FAT SOY FLOUR EXTRUSION COOKED: PROPERTIES AND FOOD USES

SUMMARY– Full-fat soy flours prepared by the extrusion process were shown to have good nutritive value, flavor, and stability. A flour cooked to a nitrogen solubility index (NSI) of 30 stored well, but the addition of tertiary butyl hydroquinone was necessary to prevent rancidity in flours cooked to 19 and 11 NSI values. The 30 NSI flour was more yellow than a commercial flour cooked to the same degree by a different process. When soy flours were compared in bread to 3 and 6% nonfat dry milk on an equivalent protein, fat, and reducing sugar basis, baking properties were similar. At 15 and 20% levels of soy flour, loaf volume decreased less with the extruded products than with nonextrusion-processed soy flour.     

EFFECT OF INDIVIDUAL MUSCLES AND CONNECTIVE TISSUE LEVELS ON THE SENSORY AND SHEAR PROPERTIES OF RESTRUCTURED BEEF STEAKS

Restructured steaks were made from slices of forequarter muscles known to be different in tenderness. Additional steaks were made from pieces that were sorted to contain either epimysium, intramuscular connective tissue sheets or no visible connective tissue. Texture panels and shear force values could discriminate between steaks from some of the different muscles. High correlations ( P < 0.05) existed between connective tissue amounts and the sensory evaluations of residual connective tissue toughness and instrumental shear force values.