STABILITY OF OIL-IN-WATER EMULSIONS. 2. Effects of Oil Phase Volume, Stability Test, Viscosity, Type of Oil and Protein Additive

SUMMARY –Stability of oil-in-water emulsions stabilized in sodium caseinate, gelatin and soy sodium proteinate was found to be increased by either an increase in the aqueous phase protein concentration (0.5–2.5%) or oil phase volume (20–50%). Both factors were significantly interrelated. Emulsions stabilized by soy sodium proteinate were generally higher in stability as compared to those stabilized by gelatin or sodium caseinate. With emulsions containing gelatin, greater stability occurred when the stability testing temperature was increased from 37–70°C and when the time interval was decreased from 24 hr to 90 min. Maximum relative viscosities of emulsions stabilized by gelatin and sodium caseinate were 2.0 and 2.5, respectively. Emulsions stabilized by soy sodium proteinate were quite viscous, with relative viscosity from 1.5–30 depending on both protein concentration and oil phase volume. Interchanging the emulsified oil among corn, soybean, safflower and peanut oils did not alter emulsion stability when examined at three concentrations of soy sodium proteinate. Changing the oil to olive oil significantly increased emulsion stability at each soy sodium proteinate level with oil phase volumes of 30, 40 and 50%.     

INFLUENCE OF EGG YOLK LIPOPROTEINS ON THE RHEOLOGY AND STABILITY OF O/W EMULSIONS AND MAYONNAISE 1. VISCOELASTICITY OF GROUNDNUT OIL-IN-WATER EMULSIONS AND MAYONNAISE

Viscoelastic properties of groundnut oil-in-water emulsions stabilized by egg yolk and of mayonnaise have been deduced from their creep compliance-time response to a constant low shear stress. The viscoelastic parameter values, emulsion stability and initial mean drop size were influenced by pH and NaCl, due to disruption of the egg yolk components. When carboxymethylcellulose was incorporated in the continuous phase of the O/W emulsions an egg yolk-carboxymethylcellulose complex was formed and this affected the rheological properties of the emulsions and also their stability. Mayonnaises exhibited more pronounced viscoelasticity and greater stability than the O/W emulsions. At elevated temperature the micelles adsorbed around oil drops degrade. Their lipoprotein structure unfolds so that more segments on adjacent drops are then available for interlinking and network formation.     

SOY AND MEAT PROTEINS AS FOOD EMULSION STABILIZERS 1. VISCOELASTIC PROPERTIES OF CORN OIL-IN-WATER EMULSIONS INCORPORATING SOY OR MEAT PROTEINS

The creep compliance-time response of 50% (wt/wt) corn oil-in-water emulsions has been studied at a constant stress of 47.8 dyne cm⁻² over the pH range 2.5–7.5. The emulsions were stabilised by acid precipitated (APSP), 7S(7SPRF) or 11S(11SPRF) soy protein fractions, water soluble (WSMP) or salt soluble (SSMP) meat protein fractions. All the emulsions exhibited viscoelasticity. WSMP emulsions exhibited the highest initial viscoelasticity parameter values and this was attributed to the strong interlinking of WSMP loops adsorbed on the surfaces of adjacent oil drops. The parameter values of all the emulsions increased during the first 5–7 days storage and then they decreased. At any selected pH the 7SPRF emulsions exhibited the largest relative increase in parameter values. The changes in viscoelasticity during storage were explained on the basis of the relative effects of further protein loop interlinkage and drop coalescence.     

Surface Tension and Foaming of Protein Solutions

The relationship between surface tension and foamability of protein solutions was examined. Proteins including egg albumin, soybean protein, casein, milk whey protein and gelatin were used. Foamability was expressed as “foaming power” which corresponded to the ratio of gas volume to the liquid volume in the foam. The absolute surface tensions of protein solutions were not correlated to foamability, but the rate constant of surface tension decay of protein solutions was significantly correlated to foamability of protein solution.     

蛋白质溶液表面张力及其与功能性质的关系

为了探讨蛋白质溶液表面张力的变化规律，本文利用表面张力计和食品流变学方法系统地研究了蛋白质溶液表面张力随液滴停留时间的变化及其与功能性质的关系。结果表明：高浓度时，液滴停留时间与表面张力的变化遵循下列一次方程In[（θt-θe）/（θw-θe）]=-kt。对同一蛋白质来说，k值随浓度的增加而增大。蛋白质起泡力与k值呈极显著的线性关系，泡沫稳定性与k值呈正相关。蛋白质的乳化性低浓度时与表面张力呈正相关；高浓度时，乳化性与k值呈正相关。     

Physicochemical Effects of the Lipid Phase and Protein Level on Meat Emulsion Stability,Texture, and Microstructure

ABSTRACT: The effects of beef fat (25%) substitution with rendered beef fat, canola oil, palm oil, or hydrogenated palm oil at varying meat protein levels (8%, 11%, and 14%) were studied in emulsified beef meat batters. There was no significant difference in fat loss among meat batters made with beef fat, rendered beef fat, or palm oil. Hydrogenated palm oil provided the most stable batters at all protein levels. Increasing meat protein to 14% resulted in high fat loss in batters prepared with canola oil, which did not occur in the other formulations. This indicates that the physicochemical characteristics of fat/oil affect emulsion stability. Cooked batter hardness was higher (P < 0.05) when protein level was raised; highest in hydrogenated palm oil batters when compared at similar protein levels. As protein level was raised springiness values were increased in all the meat treatments. Springiness was higher in the canola oil treatments. Light microscopy revealed fat globule coalescence in canola oil meat batters prepared with 14% protein, as well as the development of fat channels and more protein aggregation; both seem to result in lower emulsion stability. Hydrogenated palm oil batters showed fat particles with sharp edges as opposed to the round ones seen in all other treatments.     

Surface Tension and Foamability of Protein and Surfactant Solutions

Decay of surface tension of protein solutions obeyed an empirical equation for first-order decay during the first 10 to 60 min after formation of a new surface. First-order rate constants (k) for surface tension decay of protein solutions, calculated at various protein concentrations, were closely correlated with “foaming power” (foamability) of the solutions. A similar correlation between “foaming power” and k values was also observed for low molecular weight surfactant solutions. The k values for low molecular weight surfactant solutions were lower than those for protein solutions with similar “foaming power” to surfactant solutions. Equilibrium surface tensions of low molecular weight surfactant solutions were closely correlated with their “foaming power,” though such correlation was not found in the case of protein solutions.     

SOY AND MEAT PROTEINS AS FOOD EMULSION STABILIZERS 2. INFLUENCE OF EMULSIFICATION TEMPERATURE, NaCl AND METHANOL ON THE VISCOELASTIC PROPERTIES OF CORN OIL-IN-WATER EMULSIONS INCORPORATING ACID PRECIPITATED SOY PROTEIN

The rheological properties of concentrated corn oil-in-water emulsions stabilised by acid precipitated soy protein have been studied as a function of emulsification temperature, methanol and salt concentration. Viscoelasticity parameters were derived from the creep compliance-time response of the emulsions at a constant stress of 47.8 dyne cm⁻². All of the emulsions exhibited higher parameter values, both immediately after preparation and during storage, than comparable emulsions prepared at ambient temperature in the absence of methanol or NaCl. This was attributed to the increased unfolding of adsorbed protein molecules which permits greater interlinking, by hydrophobic bonds, of molecular segments projecting from the surfaces of adjacent oil drops.     

蛋白质浓度、pH、离子强度对鲢鱼肌原纤维蛋白粘度的影响

利用二次回归正交旋转试验设计 ,研究了蛋白质浓度、pH、离子强度对鲢鱼肌原纤维蛋白粘度的影响 ,建立相应的回归方程 ,分析比较了它们间的相互作用关系 ,确定了取得最优粘度时 ,各因素的组合     

Studies on Pasteurized and Commercially Sterilized Poultry Meat Bologna. Effects of Chopping Condition and Type of Meat

Poultry meat bologna has been studied under two systems of heat processing, pasteurizing and commercial sterilizing in cans. Mechanically deboned turkey meat was chopped (1) from the tempered state, (2) after thawing, refreezing and tempering, (3) after thawing. Treatments 1 and 2 resulted in reduction in cooking loss, while treatment 1 gave a firmer textured product, as measured by shear value but not by taste panel. Turkey meat was compared with spent Leghorn laying fowl meat, and mechanically deboned meat with manually deboned meat. Bologna made from mechanically deboned laying fowl had the highest cooking loss. Laying fowl bologna was firmer textured than turkey bologna, and manually deboned meat bologna was firmer than MDM bologna by both shear value and taste panel measuremnts.     

FACTORS AFFECTING MACADAMIA NUT STABILITY. 3. Effects of Roasting Oil Quality and Antioxidants

SUMMARY– Chemical and physical changes in roasting oil from a commercial processing plant and the relationship of these changes to quality and shelf-life of roasted macadamia kernels were investigated. Oil was sampled initially and after 2, 4 and 13 weeks of roasting. Generally, free fatty acid, color (absorbance at 550 nm), refractive index and viscosity of the roasting oil increased with use. Changes in iodine number and fatty acid composition indicated there was considerable oil exchange between roasting oil and macadamia kernels. Antioxidant loss in the roasting oil was rapid. No flavor differences were observed in kernels immediately after roasting in the various oil samples, and shelf-life was not appreciably affected by continuous use of the oil for as long as 13 weeks. A second study investigated the effects of vacuum-packing (0, 15 and 24 in.) and direct antioxidant application (approximately 76 ppm butylated hydroxyanisole and butylated hydroxy-toluene) on the stability of dry-roasted macadamia kernels. Stability of antioxidant-treated kernels was greater than that of untreated kernels, regardless of vacuum level. Vacuum packing had no effect on antioxidant-treated kernels, but showed some benefit for untreated kernels.     

Effect of Gradual Heating and Fat/Oil Type on Fat Stability,Texture, Color,and Microstructure of Meat Batters

The effects of endpoint cooking temperature (40, 50, 60, 70, 80, and 90 °C) on emulsion stability, texture, color, and microstructure of meat batters prepared with different fats/oils were studied. Canola oil treatments showed the highest cooking loss whereas hydrogenated palm oil provided the most stable meat batters. Rendered beef fat was less stable than regular beef fat. Increasing endpoint cooking temperatures resulted in a progressive reduction of water holding capacity in all treatments. As temperature was raised, meat batters showed higher hardness and cohesiveness values, but no appreciable changes in cohesiveness above 60 °C. Canola and hydrogenated palm oil treatments showed the highest hardness and chewiness values. Lightness (L^*) values of all meat batters increased significantly with increasing temperature from 40 to 60 or 70 °C; no major changes observed above 70 °C. Light microscopy revealed no substantial changes in the microstructure of all the stable meat batters cooked to between 50 and 70 °C. Heating to 90 °C changed the microstructure in all meat batters except the hydrogenated palm oil treatments, which still showed nonround fat particles and a less aggregated protein matrix.     

蛋白氧化对肉品品质影响及其控制方法研究进展

近年来,肉品中的蛋白氧化越来越受到关注。氧化作用会改变肉蛋白的结构和功能特性,也会影响肉品品质(包括持水性、嫩度、色泽、营养与可消化性)。本论文针对蛋白氧化机理、氧化对蛋白结构和凝胶性质的影响,对肉品品质的影响以及肉品中蛋白氧化的控制措施等方面进行了综述,以期为肉品工业的发展提供理论参考依据。     

Interrelationships of Protein, Fat and Moisture Content of broiler Meat

Nutrient composition data of broiler tissues were statistically evaluated for any significant relationships between and among the four major components, moisture (M), protein (P), fat (F) and ash (A). The ratios of M/P, F/M, and P/F were generally characterized by broiler part. Estimations of fat and protein from moisture content were applicable within each part of each reported data set. Multiple correlation coefficients among P, F and M were high regardless of part or cooking status. The total of these three major components accounted for approximately 99% of the tissue weight with slight variations between laboratories. The results support the method for estimating of P by subtracting the F and M from 99% or other values established by each laboratory.     

不同黏度多糖阿拉伯胶和瓜尔胶对肌原纤维蛋白乳化性质的影响

选取两种分子质量相近、黏度相差较大的天然高分子多糖阿拉伯胶（arabic gum,AG）和瓜尔胶（guar gum,GG）分别与肌原纤维蛋白（myofibrillarprotein,MP）进行复合,研究不同多糖添加量（0.1%～0.5%）对MP-多糖复合物乳液性质的影响规律。结果表明,AG和GG均可以显著改善MP的乳化性质,其中AG对乳化活性的改善效果较好,而GG更有利于乳液的稳定性。随着多糖质量分数增加,乳化活性指数和稳定性指数均呈先升高后降低趋势,AG和GG添加量分别为0.3%和0.2%时,乳化活性指数和稳定性指数达到最大值。界面蛋白含量测定结果显示,AG和GG均会导致界面蛋白含量下降,尤其是GG的作用更明显。随着AG和GG添加量增加,乳液粒径逐渐减小,且尺寸分布更加均一,添加量超过0.3%后,GG组乳液出现少量絮凝现象。同一添加量下,GG组乳液粒径明显小于AG组。流变学分析证实,所有乳液均为假塑性流体,表现出弱凝胶性质。AG添加量较少（≤0.3%）时会降低乳液黏度,并明显提高乳液的储能模量,而GG的添加使乳液表观黏度和储能模量均显著提高,与AG相比,高黏度GG制备的乳液拥有更高的...     

食用碱对小麦淀粉特性及面条表面黏性变化的影响

为研究食用碱对小麦淀粉特性及面条表面黏性影响的变化规律,该研究采用低场核磁共振仪、快速粘度仪、质构仪等分别研究食用碱对淀粉糊化特性、凝胶特性以及面条表面黏性等的影响。研究表明随着食用碱添加量的增加,面团吸水率、强结合水含量呈升高趋势,淀粉糊化黏度值增大,衰减值、回生值减小。淀粉透明度、溶解度和膨润率不断提高,析水率逐渐降低。食用碱添加至0.4%时,淀粉的凝胶破裂强度降低至40.81%,凝胶破裂距离增加至17.99%,凝胶黏度增加至30.94%。食用碱的添加可显著降低面条的表面黏性。面条表面黏性与面团吸水率、强结合水含量、淀粉溶解度、凝胶破裂距离呈负相关,与淀粉冻融特性、回生值、衰减值呈正相关。食用碱提高了淀粉的糊化稳定性、凝胶弹性以及冻融稳定性,降低了面条的粘连程度。     

Evaluation of Rapid Fat, Moisture, and Protein Determination in Meats and Meat Products using an Automatic Meat Analyzer

The Hobart FMP-1 Automatic Meat Analyzer has been developed for rapid (approximately 5 min), simultaneous determination of the fat, moisture and protein content of meat and meat products. Results were compared with those using official AOAC methods for raw beef and pork and cooked sausage samples. Analyses of the data indicated that, except for determination of fat content of raw pork and protein content of raw beef, the Hobart FMP-1 was not significantly different from the official AOAC methods within the sampling parameters studied. From a practical meat operations standpoint, these differences were not considered to be of major concern as the machine can be calibrated to adjust for bias.     

Effects of Fiber Type and Level on Mineral Excretion, Transit Time, and Intestinal Histology

The effects of various fibers on transit time, jejunal histology, and fecal excretion of nitrogen and five trace elements were determined in rats. Cellulose, microcrystalline cellulose, pectin, soy fiber, and wheat bran were fed at l%, 5%, lo%, and 15% dietary levels based on neutral detergent fiber (NDF) analysis. Transit times varied significantly for both fiber type (P < 0.01) and level (P < 0.05). Jejunal histology showed that macrovilli surface area increased with longer exposure to the fiber and with a higher level fed. There was no effect of fiber level on mineral excretion and only a few general trends with regard to effects of fiber type. It is suggested that dietary fiber fractions other than those determined by NDF analysis influence cation exchange of minerals in the gut.     

Protein Concentration, pH and Ionic Strength Affect Apparent Viscosity of Actomyosin

Response surface methodology was used to compare effects of NaCl protein concentration, and pH on apparent viscosity (ζapp) of natural actomyosin from hake, pork and chicken muscle. Models for the three species had R² of 0.921, 0.915 and 0.814 (P<0.01) for chicken, pork and hake, respectively. Protein concentration and pH increased qapp, whereas higher ionic strength decreased it and had less influence. Interactions occurred between protein concentration and pH. Models did not reveal inter-species differences (P<0.05). However, analysis of variance of regression coefficients for each variable showed some differences due to pH.     

Salt, Phosphate and Oil Temperature Effects on Emulsion Capacity of Fresh or Frozen Meat and Sheep Tail Fat

The effects of K₂HP0₄, NaCl and oil temperature on emulsion capacity (EC) and microstructure of fresh and frozen Turkish beef was studied by utilizing a model system. EC of frozen meat was 6.4% higher than fresh meat. EC also increased with increasing phosphate levels increasing 8.5 and 10.4% over the control with 0.50 and 0.75% phosphate respectively. EC increased 1.6% for 3.0% salt over 2.5% salt. Microstructure photographs of the phosphate containing emulsions indicated the protein aggregates diminished and the emulsion was more homogeneous.