Isolates from faba bean and soybean with lowered content of phytic acid and activity of the trypsin inhibitors

For obtaining protein isolates, water, whey, and waste effluents from a potato processing plant were used as extraction solvents. Isolates obtained on laboratory conditions were subjected to chemical and organoleptic tests. It was shown that proper steering of the processing allowed for obtaining isolates with lower phytic acid content and decreased activity of the trypsin inhibitors, although the efficiency of the process decreased also. Modified processing was more efficient for elimination of the phytic acid from soybean isolates compared to faba bean. It was also shown that isolate neutralization considerably improved their solubility and decreased the activity of trypsin inhibitors.     

Chemical characteristics and physico-chemical properties of faba bean starch isolated from the by-product after protein extraction

Studies were made on the effect of protein extraction from faba bean flour, using water, whey and waste effluents from potato processing on chemical composition of starch and its physico-chemical properties. The results showed that the chemical composition of starch obtained from the by-product was different compared to native starch. The range of gelatinization temperature and maximal viscosity at 95 °C were also noticeably changed compared to native starch.     

SOYBEAN WHEY PROTEINS-RECOVERY AND AMINO ACID ANALYSIS

SUMMARY– About 14 million Ib of soybean whey protein of high biological value is disposed of as waste based on estimated production figures for soybean concentrates and isolates. An estimated 5–7% annual increase in consumption poses serious waste disposal problems and alternates should be sought. By simulated commercial procedures, yield and protein content of soybean whey were determined. Whey solids account for 2–28% of original nitrogen in dehulled, defatted flakes. Whole whey protein was prepared by dialysis, and whey was also fractionated by heating into heat-coagulable and supernatant proteins. Whole whey protein has a good balance of essential amino acids when compared with a system followed by the Food and Agricultural Organization of United Nations based on hen's egg protein. Heat-coagulable and supernatant proteins varied greatly: heat-coagulable fractions had 42% of the sulfur amino acid content but 181% of the tryptophan content of hen's egg protein; supernatant protein had 142% of the sulfur amino acid content but only about 60% of the isolevcine, valine, leucine and tryptophan content of hen's egg protein. All three whey protein fractions would be suitable for addition to feeds.     

Compositional and structural properties of whey proteins of sweet,acid and salty whey concentrates and their respective spray dried powders

The influence of physiochemical characteristics of whey concentrates obtained by ultrafiltration of acid and salty whey streams on the surface composition, particle organisation, secondary structures and protein interactions of the respective spray dried whey powders was investigated. Their properties were compared with those of native and sweet whey. Acid whey concentrate demonstrated characteristically low surface charge, high surface hydrophobicity, high average particle size and high thiol activity compared with sweet and native whey concentrates. Salty whey concentrate was characterised by low surface hydrophobicity, high thiol activity and low average particle size. Surface characterisation of whey powders revealed protein-rich surfaces for all whey powders while those in salty whey were highly hydrophobic. Protein characteristics of native and sweet whey powders largely followed those of concentrates. In contrast, protein characteristics of the acid and salty whey powders largely changed from those of the concentrates.     

The effect of coagulum washing on the quality of soybean and faba bean isolates

Protein isolates of faba bean and soybean, obtained using waste effluents of potato as protein extrahent, and water or 86% ethanol or 2% ascorbic acid for washing coagulum, were investigated. Both the use of 86% ethanol and 2% ascorbic acid lowered the solubility of isolates (approx. 1.7–11.9%), stronger protein denaturation being caused by ethanol. Although the use of waste effluents of potato increased trypsin inhibitors activity compared with the use of water, applying ethanol or ascorbic acid washing considerably lowered this activity. The use of 86% ethanol also caused an elimination of approx. 60% phytates from soybean isolates and a little less from faba bean ones. Ascorbic acid eliminated these undesirable compounds only to a small extent. In the case of 86% ethanol the organoleptic properties of isolates were found to have been improved. The isolates were of lighter colour and they were completely devoid of the leguminous taste.     

Influence of skimmed milk concentrate replacement by dry dairy products in a low fat set‐type yoghurt model system. I: Use of whey protein concentrates,milk protein concentrates and skimmed milk powder

Ten commercial samples of dry dairy products used for protein fortification in a low fat yoghurt model system at industrial scale were studied. The products employed were whey protein concentratres, milk protein concentrates, skimmed milk concentrates and skimmed milk powder which originated from different countries. The gross chemical composition of these dried products were determined, including polyacrylamide gel electrophoresis (SDS‐PAGE) and isoelectric focusing of the proteins, and minerals such as Na, Ca, K and Mg. Yoghurts were formulated using a skim milk concentrated as a milk base enriched with different dry dairy products up to a 43 g kg⁻¹ protein content. Replacement percentage of skim milk concentrated by dry dairy products in the mix was between 1.49 and 3.77%. Yoghurts enriched with milk protein concentrates did not show significantly different viscosity (35.12 Pa s) and syneresis index (591.4 g kg⁻¹) than the two control yoghurts obtained only from skimmed milk concentrates (35.6 Pa s and 565.7 g kg⁻¹) and skimmed milk powder (32.77 Pa s and 551.5 g kg⁻¹), respectively. Yoghurt fortified with the whey protein concentrates, however, was less firm (22.59 Pa s) and had less syneresis index (216 g kg⁻¹) than control yoghurts. Therefore, whey protein concentrates may be useful for drinking yoghurt production. © 1999 Society of Chemical Industry     

Compositional Factors That Affect the Emulsifying and Foaming Properties of Whey Protein Concentrates

An emulsion containing 30% fat was used to study emulsifying and foaming properties of commercial whey protein concentrates. Residual lipids, both total and phospholipids, inhibited foaming of dilute aqueous solutions of whey protein concentrates, whereas in aerated emulsions residual lipids were positively correlated with foaming. Under both test conditions the ash content was positively correlated with good and moderate foaming properties. Among the compositional factors which best predicted foaming of emulsions were sulfhydryls. Emulsions which contained insoluble whey proteins were highly stable but air incorporation was poor. When soluble whey proteins were utilized to stabilize emulsions, serum separation occurred more readily but did not correlate with good foaming properties.     

Characterization of the Composition, Physicochemical and Functional Properties of Acid Whey Protein Concentrates

Membrane-processed acid whey protein concentrates were studied for their foaming and emulsifying properties in dilute whey protein solutions and in a 30% fat emulsion. Among the compositional factors and physicochemical characters which significantly correlated with foaming and emulsifying properties were protein hydrophobicity, solubility, free-sulfhydryl content, phosphorus and β-lactoglobulin concentration. Heptane binding was negatively correlated with foam overrun and foam stability of whey protein solutions, whereas, exposed hydrophobicity was positively correlated with overrun in the whipped topping.     

Properties of casein concentrates containing various levels of beta‐casein

Microfiltration (MF) of milk was used to produce casein (CN) concentrates (80% protein) with reduced whey protein levels. By varying temperature of MF, we altered the proportion of β‐CN to αs‐CN in CN concentrates and compared them to milk protein concentrate (MPC). Casein content as a % of protein was approximately 90% for CN concentrates and approximately 80% for MPC. Smaller micelles and weaker rennet gels were observed for CN concentrates with low β‐CN level. Foam stability and yield stress values were higher for CN concentrates with a high β‐CN level. Modified CN concentrates can be produced by altering the proportions of individual CNs.     

Hydration of Whey Powders as Determined by Different Methods

Four methods for evaluating water hydration of 15 whey derivative powders were compared, and results are discussed with respect to the chemical composition of the powders. Hydration capacities between 0.21 and 4.64 mL water/g of powder were obtained, depending on the method used. The filtration/centrifugation method gave the highest hydration capacity, whereas the paste-water retention method gave the lowest. The Baumann test and the paste-water retention method were well correlated with protein and lactose content of the powders, enabling differentiation between hydration capacities of whey protein concentrates (35% proteins) and electrodialyzed whey powders (12% proteins). Reliable characterization of hydration required a combination of methods.     

Composition and properties of whey protein concentrates from ultrafiltration

Chemical and nutrient composition and functional properties of whey protein concentrates from ultrafiltration of sweet and acid wheys were studied for potential food uses. Vitamins passed readily through the membrane; thus, vitamin content was slightly higher than in whey. Amino acid values were considerably higher, increasing in direct proportion to increases in protein. Lysine availability was not significantly affected by fractionation or by subsequent beat treatment. Since this process results in substantial removal of minerals along with the permeate, the protein to ash ratio of the protein concentrate increased. Unlike most other methods of recovering protein from whey, solubility was not adversely affected by ultrafiltration. However, protein concentrates were susceptible to heat; normal pasteurization temperatures resulted in approximately 20% denaturation. Whey protein exhibited excellent water retention. Addition of 1.5% protein to skim milk followed by heating formed a custard-like gel with sufficient body to stand alone without leakage. Approximately twice as much egg albumin was required to achieve comparable results. Whipping properties were very good when butterfat content was less than 2%. Excellent stable whips could be produced by a combination of heat and pH adjustment.     

蛋白含量对牦牛乳清蛋白浓缩物功能特性的影响

通过不同截留分子质量的再生纤维素膜过滤纯化牦牛原乳清液和牦牛甜乳清液,分别制取牦牛原乳清蛋白浓缩物（native whey protein concentrate,NWPC）和牦牛甜乳清蛋白浓缩物（sweet whey protein concentrate,SWPC）,研究蛋白含量不同的乳清蛋白浓缩物（whey protein concentrate,WPC）主要成分（乳糖含量、pH值和总蛋白质含量）和功能特性（溶解性、持水性、持油性、起泡性、乳化性及热稳定性）的特征。结果表明：10 000 Da再生纤维素膜透析得到的牦牛WPC中总蛋白含量达到80%以上,不含乳糖,功能特性（溶解性、持水性、持油性、起泡性、乳化性及热稳定性）均显著高于经3 500 Da卷式膜、5 000 Da再生纤维素膜透析得牦牛WPC,WPC蛋白含量越高,其功能特性越好;不同蛋白含量的牦牛SWPC起泡能力、泡沫稳定性、乳化活性和乳化稳定性均显著（P＜0.05）高于牦牛NWPC。牦牛乳WPC最不稳定温度为85 ℃,高于荷斯坦牛乳WPC的80 ℃,热处理会适当改善牦牛WPC的起泡性能、乳化性能和热稳定性。通过膜牦牛处理获取的高蛋白含量的WPC,功能特性较好,应用广泛,对解决牦牛乳清资源的利用问题、保护环境、提高企业的经济效益起到关键性作用。     

Effect of partial whey protein depletion during membrane filtration on thermal stability of milk concentrates

Membrane filtration technologies are widespread unit operations in the dairy industry, often employed to obtain ingredients with tailored processing functionalities. The objective of this work was to better understand the effect of partial removal of whey proteins by microfiltration (MF) on the heat stability of the fresh concentrates. The micellar casein concentrates were compared with control concentrates obtained using ultrafiltration (UF). Pasteurized milk was microfiltered (80 kDa polysulfone membrane) or ultrafiltered (30 kDa cellulose membrane) without diafiltration (i.e., no addition of water) to 2× and 4× concentration, based on volume reduction. The final concentrates showed no differences in pH, casein micelle size, or mineral concentration in the serum phase. The micellar casein retentates (obtained by MF) showed a 20 and 40% decrease in whey protein concentration compared with the corresponding UF milk protein concentrates for 2× and 4× concentration, respectively. The heat coagulation time decreased with increasing protein concentration, regardless of the treatment; however, MF retentates showed a higher thermal stability than the corresponding UF controls. The average diameter for casein micelles increased after heating in UF but not MF concentrates. The turbidity (measured by light scattering) increased after heating, but to a higher extent for UF retentates than for MF retentates at the same protein concentration. It was concluded that the reduced amount of whey protein in the MF retentates caused a significant increase in the heat stability compared with the corresponding UF retentates. This difference was not due to ionic composition differences or pH, but to the type and amount of complexes formed in the serum phase.     

Minimizing variations in functionality of whey protein concentrates from different sources

Enhancement in processing technology has improved the nutritional and functional properties of whey protein concentrates by increasing the content and quality of the protein, leading to their increased use in different food products. The extent of heat treatment affects the quality of the whey protein concentrate, and wide variation in product quality exists due to the various means of manufacture and from the whey product history from farm to factory. The study was carried out with 6 commercial whey protein concentrates with 80% protein (WPC80) to determine variations in physical properties, particle size and density, and functional properties--solubility, gel strength, foam volume, and stability. Significant differences were observed among all the products for every property compared. Particulate size was the most important determinant of functional characteristics. Larger particulate WPC80 had significantly higher fat content and were less soluble with poor foam stability; but narrowing the particle size distribution through sieving, minimized variations. We determined that sieving all products within the particle size distribution range of 100 to 150 microns minimized variation in physical composition, making functionality uniform. WPC80 from different manufacturers can be made to perform uniformly within a narrow functionality range by reducing the particle size distribution through sieving.     

Effects of polymerized goat milk whey protein on physicochemical properties and microstructure of recombined goat milk yogurt

Goat milk whey protein concentrates were manufactured by microfiltration (MF) and ultrafiltration (UF). When MF retentate blended with cream, which could be used as a starting material in yogurt making. The objective of this study was to prepare goat milk whey protein concentrates by membrane separation technology and to investigate the effects of polymerized goat milk whey protein (PGWP) on the physicochemical properties and microstructure of recombined goat milk yogurt. A 3-stage MF study was conducted to separate whey protein from casein in skim milk with 0.1-µm ceramic membrane. The MF permeate was ultrafiltered using a 10 kDa cut-off membrane to 10-fold, followed by 3 step diafiltration. The ultrafiltration-diafiltration-treated whey was electrodialyzed to remove 85% of salt, and to obtain goat milk whey protein concentrates with 80.99% protein content (wt/wt, dry basis). Recombined goat milk yogurt was prepared by mixing cream and MF retentate, and PGWP was used as main thickening agent. Compared with the recombined goat milk yogurt without PGWP, the yogurt with 0.50% PGWP had desirable viscosity and low level of syneresis. There was no significant difference in chemical composition and pH between the recombined goat milk yogurt with PGWP and control (without PGWP). Viscosity of all the yogurt samples decreased during the study. There was a slight but not significant decrease in pH during storage. Bifidobacterium and Lactobacillus acidophilus in yogurt samples remained above 10⁶ cfu/g during 8-wk storage. Scanning electron microscopy of the recombined goat milk yogurt with PGWP displayed a compact protein network. Results indicated that PGWP prepared directly from raw milk may be a novel protein-based thickening agent for authentic goat milk yogurt making.     

乳清蛋白及其水解物对马铃薯淀粉体外消化性和理化性质的影响

本文通过构建乳清蛋白及乳清蛋白水解物与马铃薯淀粉的共糊化体系来探究乳清蛋白及其水解物对马铃薯淀粉体外消化性和理化性质的影响。结果表明,经过胃蛋白酶和胰酶水解处理的乳清蛋白水解物对淀粉的消化率抑制效果最为明显。其中,天然马铃薯淀粉中快消化淀粉（RDS）含量最高（94.54%）,抗性淀粉（RS）含量最低（3.10%）。而经过胃蛋白酶处理后经胰酶处理120 min的样品中的RDS含量最低（67.51%）,RS含量最高（12.69%）。乳清蛋白水解物对马铃薯淀粉的溶胀和糊化的抑制作用均强于乳清蛋白。这说明乳清蛋白水解物的分子量对马铃薯淀粉的理化特性和消化性均有较大影响。此外,乳清蛋白及其水解物增强了体系中的氢键作用并提高了淀粉结构的有序程度,表明乳清蛋白及其水解物与马铃薯淀粉之间的相互作用会降低淀粉的消化性。     

A NONLINEAR PROGRAMMING TECHNIQUE TO DEVELOP LEAST COST FORMULATIONS OF SURIMI PRODUCTS

Optimization programming techniques were applied to develop the least cost formulations for Pacific whiting surimi-based seafood (PWSBS). To develop the quality constraint functions, texture and color of whiting surimi gels were determined by torsion test and colorimeter, respectively. Whiting surimi gels were produced by heating at 90C for 15 min with 2% NaCl, five final moisture contents (74, 76, 78, 80, 82%), and various combinations of beef plasma protein (0–2%), potato starch (0–8%), and two whey protein concentrates (0–8%). Due to the nonlinear constraint functions describing texture and color, a nonlinear programming search technique was required to solve the least cost model for PWSBS. Results for representative target quality constraints are reported in this study and show that whey protein concentrate both increases the texture properties and remains economically competitive with other ingredients which similarly influence functionality in PWSBS.     

Physical properties of yogurt fortified with various commercial whey protein concentrates

The effects of whey protein concentrates on physical and rheological properties of yogurt were studied. Five commercial whey protein concentrates (340 g kg^?1 protein nominal) were used to fortify milk to 45 g protein kg^?1. Fermentation was performed with two different starters (ropy and non‐ropy). Resulting yogurts were compared with a control yogurt enriched with skim milk powder. The water‐holding capacity of the yogurt fortified with skim milk powder was 500 g kg^?1 and ranged from 600 to 638 g kg^?1 when fortified with whey protein concentrates. Significant rheological differences have been noticed between the yogurts fortified with different whey protein concentrates, independent of the starter used. Three whey protein concentrates generated yogurts with a behavior similar to the control. The two others produced yogurt with lower firmness (15 g compared with 17 g), lower Brookfield viscosity (6 Pa s compared with 9 Pa s), lower yield stress (2 Pa compared with 4 Pa), lower complex viscosity (13 Pa s compared with 26 Pa s), and lower apparent viscosity (0.4 Pa s compared with 1 Pa s) than the control, respectively. The yogurts with the lowest firmness and viscosity were produced with concentrates which contained the highest amount of non‐protein nitrogen fraction (160 g kg^?1 versus 126 g kg^?1 of the total nitrogen), and the highest amount of denaturation of the whey protein (262 versus 200 g kg^?1 of the total nitrogen). Copyright © 2004 Society of Chemical Industry     

Variation of Total and Available Lysine in Dehydrated Products from Cheese Wheys by Different Processes

Excessive or prolonged exposure to heat during manufacture of dehydrated products from cheese whey and cheese whey protein concentrates is chiefly responsible for decreasing the lysine content of these products. With ion exchange chromatography of acid hydrolysates to determine total lysine, and 2,4,6,-trinitrobenzene sulfonic acid reagent to determine available lysine with its epsilon amino group free for chemical reaction, both total and available lysine were higher in spray-dried whey powders than in roller-dried whey powders. Of the lysine originally available in the protein of cottage cheese whey, 88% remained available in an experimental dehydrated high-protein isolate prepared by ultrafiltration, followed by gel permeation followed by pasteurization, vacuum evaporation, and shelf drying of the protein concentrate. Unfractionated foam spray-dried cottage cheese whey powder retained 96% of the original available lysine.     

Assessment of Added Protein/Starch on the Functional Properties of Surimi Gels Manufactured from Atlantic Whiting

ABSTRACT: The functional properties (hardness, cohesiveness, color, and whiteness) of 5 food ingredients (2 whey protein concentrates [WPC 45 and WPC 76], whey protein isolate [WPI], egg white [EW], and potato starch [PS]) added to surimi gels were evaluated using 2 different thermal regimes. Hardness and cohesiveness of whiting surimi gels prepared using a rapid cook treatment (90°C for 15 min) did not significantly change on the addition of test ingredients. Hardness and cohesiveness of whiting surimi with added ingredients prepared using a suwari set treatment (0° to 4 °C for 12 h followed by 90°C for 15 min) were increased ( P < 0.05) on addition of additives with the exception of WPC 76, which decreased ( P < 0.05) surimi hardness and cohesiveness. Results showed that starch was more effective in improving the functional properties of surimi when compared with all other protein additives assessed.