Effect of processing methods and protein content of the concentrate on the properties of milk protein concentrate with 80% protein

In recent years, a large increase in the production of milk protein concentrates (MPC) has occurred. However, compared with other types of milk powders, few studies exist on the effect of key processing parameters on powder properties. In particular, it is important to understand if key processing parameters contribute to the poor solubility observed during storage of high-protein MPC powders. Ultrafiltration (UF) and diafiltration (DF) are processing steps needed to reduce the lactose content of concentrates in the preparation of MPC with a protein content of 80% (MPC80). Evaporation is sometimes used to increase the TS content of concentrates before spray drying, and some indications exist that inclusion of this processing step may affect protein properties. In this study, MPC80 powders were manufactured by 2 types of concentration methods: membrane filtration with and without the inclusion of an evaporation step. Different concentration methods could affect the mineral content of MPC powders, as soluble salts can permeate the UF membrane, whereas no mineral loss occurs during evaporation, although a shift in calcium equilibrium toward insoluble forms may occur at high protein concentration levels. It is more desirable from an energy efficiency perspective to use higher total solids in concentrates before drying, but concerns exist about whether a higher protein content would negatively affect powder functionality. Thus, MPC80 powders were also manufactured from concentrates that had 3 different final protein concentrations (19, 21, and 23%; made from 1 UF retentate using batch recirculation evaporation, a similar concentration method). After manufacture, powders were stored for 6 mo at 30°C to help understand changes in MPC80 properties that might occur during shelf-life. Solubility and foaming properties were determined at various time points during high-temperature powder storage. Inclusion of an evaporation step, as a concentration method, resulted in MPC80 that had higher ash, total calcium, and bound calcium (of rehydrated powder) contents compared to concentration with only membrane filtration. Concentration method did not significantly affect the bulk (tapped) density, solubility, or foaming properties of the MPC powders. Powder produced from concentrate with 23% protein content exhibited a higher bulk density and powder particle size than powder produced from concentrate that had 19% protein. The solubility of MPC80 powder was not influenced by the protein content of the concentrate. The solubility of all powders significantly decreased during storage at 30°C. Higher protein concentrations in concentrates resulted in rehydrated powders that had higher viscosities (even when tested at a constant protein concentration). The protein content of the concentrate did not significantly affect foaming properties. Significant changes in the mineral content are used commercially to improve MPC80 solubility. However, although the concentration method did produce a small change in the total calcium content of experimental MPC80 samples, this modification was not sufficiently large enough (<7%) to influence powder solubility.     

Utilisation of chitosan flocculation of residual lipids and microfiltration for the production of low fat,clear WPC80

Annato coloured cheese whey was adjusted to pH 4.5 and treated with 0.01% (w/w) chitosan to selectively precipitate residual lipids, which were removed by gravity settling and microfiltration (MF). MF permeate was concentrated by ultrafiltration/diafiltration (UF/DF) to produce whey protein concentrate with 80% protein (WPC80‐Chitosan). WPC80 samples were also produced by UF/DF only (Control), and by MF without chitosan treatment (MF). Both WPC80‐Chitosan and WPC80‐MF samples had lower fat, lower turbidity, higher foam overrun/stability and lower quantities of volatile compounds than WPC80‐Control before and after storage. WPC80‐Chitosan samples have an additional advantage of annatto removal (excellent clarity).     

Chemical Pretreatment and Microfiltration for Making Delipidized Whey Protein Concentrate

Chemical pretreatment, microfiltration (MF) and ultrafiltration (UF) were applied to produce delipidized whey protein concentrates (WPC). Processes including both chemical pretreatment and MF resulted in WPC with <0.5% lipids. Low-pH UF and isoelectric point (PI) precipitation were more effective for lipid removal than chemical pretreatment by thermocalcic aggregation. Protein permeation ratios in MF processes were improved by UF preconcentration of whey. Protein permeation and flux were different between the two MF membranes used. Isoelectric point precipitation increased β-Lg contents, but not α-La, in the resulting WPC (B). Minor proteins exhibited lower concentrations in WPC B and MF WPC products.     

膜技术分离纯化金银花绿原酸提取液工艺研究

研究膜技术分离纯化绿原酸提取液的过程。以金银花为原料,以平均通量、膜截留率、绿原酸透过率为指标,比较3 种微滤膜MF1、MF2 和MF3,4 种超滤膜UF1、UF2、UF3 和UF4,及两种反渗透膜RO1 和RO2 对绿原酸提取液的过滤特性,并研究浓缩液的洗滤对绿原酸截留率的影响。结果表明：MF1、UF1 和RO2膜的过滤性能明显优于其他同类型膜,使用MF1-UF1-RO2 膜组合处理效果最佳,其绿原酸回收率可达67.75%,产品纯度可达13.21% 以上;同时,洗滤可进一步提高处理效果,经间歇洗滤后,MF1 膜的绿原酸截留率可由9.54% 降低到1.17%,UF2 膜的绿原酸截留率可由32.36% 降低到20.11%。     

A microfiltration process to maximize removal of serum proteins from skim milk before cheese making

Microfiltration (MF) is a membrane process that can separate casein micelles from milk serum proteins (SP), mainly beta-lactoglobulin and alpha-lactalbumin. Our objective was to develop a multistage MF process to remove a high percentage of SP from skim milk while producing a low concentration factor retentate from microfiltration (RMF) with concentrations of soluble minerals, nonprotein nitrogen (NPN), and lactose similar to the original skim milk. The RMF could be blended with cream to standardize milk for traditional Cheddar cheese making. Permeate from ultrafiltration (PUF) obtained from the ultrafiltration (UF) of permeate from MF (PMF) of skim milk was successfully used as a diafiltrant to remove SP from skim milk before cheese making, while maintaining the concentration of lactose, NPN, and nonmicellar calcium. About 95% of the SP originally in skim milk was removed by combining one 3 x MF stage and two 3 x PUF diafiltration stages. The final 3 x RMF can be diluted with PUF to the desired concentration of casein for traditional cheese making. The PMF from the skim milk was concentrated in a UF system to yield an SP concentrate with protein content similar to a whey protein concentrate, but without residuals from cheese making (i.e., rennet, culture, color, and lactic acid) that can produce undesirable functional and sensory characteristics in whey products. Additional processing steps to this 3-stage MF process for SP removal are discussed to produce an MF skim retentate for a continuous cottage cheese manufacturing process.     

The ultrafiltration molecular weight cut-off has a limited effect on the concentration and protein profile during preparation of human milk protein concentrates

Optimizing protein intake for very low birth weight (<1,500 g) infants is fundamental to prevent faltering postnatal growth with the potential association of impaired neurodevelopment. The protein content of human milk is not sufficient to support the growth of very low birth weight infants. To meet their elevated protein requirements, human milk is currently fortified using typically bovine milk-based protein isolates (>85% on a dry basis). However, these products have several limitations for use in this vulnerable population. To overcome the shortcomings of bovine milk-based protein supplement, a human milk protein concentrate (HMPC) was developed. In preliminary attempts using 10 kDa ultrafiltration (UF) membranes, it was not possible to reach the protein content of commercial protein isolates, presumably due to the retention of human milk oligosaccharides (HMO). Consequently, it was hypothesized that the use of a UF membrane with a higher molecular weight cut-off (50 kDa rather than 10 kDa) could improve the transmission of carbohydrates, including HMO, in the permeate, thus increasing the protein purity of the subsequent HMPC. The results showed that permeate fluxes during the concentration step were similar to either UF molecular weight cut-off, but the 50-kDa membrane had a higher permeate flux during the diafiltration sequence. However, it was not sufficient to increase the protein purity of the human milk retentate, as both membranes generated HMPC with similar protein contents of 48.8% (10 kDa) and 50% (50 kDa) on a dry basis. This result was related to the high retention of HMO, mainly during the concentration step, although the diafiltration step was efficient to decrease their content in the HMPC. As the major bioactive proteins (lactoferrin, lysozyme, bile salt stimulated lipase, and α1-antitrypsin) in human milk were detected in both HMPC, the 50-kDa membrane seems the most appropriate to the preparation of HMPC in terms of permeation flux values. However, improving the separation of HMO from proteins is essential to increase the protein purity of HMPC.     

Efficiency of removal of whey protein from sweet whey using polymeric microfiltration membranes

Our objective was to measure whey protein removal percentage from separated sweet whey using spiral-wound (SW) polymeric microfiltration (MF) membranes using a 3-stage, 3× process at 50°C and to compare the performance of polymeric membranes with ceramic membranes. Pasteurized, separated Cheddar cheese whey (1,080 kg) was microfiltered using a polymeric 0.3-μm polyvinylidene (PVDF) fluoride SW membrane and a 3×, 3-stage MF process. Cheese making and whey processing were replicated 3 times. There was no detectable level of lactoferrin and no intact α- or β-casein detected in the MF permeate from the 0.3-μm SW PVDF membranes used in this study. We found BSA and IgG in both the retentate and permeate. The β-lactoglobulin (β-LG) and α-lactalbumin (α-LA) partitioned between retentate and permeate, but β-LG passage through the membrane was retarded more than α-LA because the ratio of β-LG to α-LA was higher in the MF retentate than either in the sweet whey feed or the MF permeate. About 69% of the crude protein present in the pasteurized separated sweet whey was removed using a 3×, 3-stage, 0.3-μm SW PVDF MF process at 50°C compared with 0.1-μm ceramic graded permeability MF that removed about 85% of crude protein from sweet whey. The polymeric SW membranes used in this study achieve approximately 20% lower yield of whey protein isolate (WPI) and a 50% higher yield of whey protein phospholipid concentrate (WPPC) under the same MF processing conditions as ceramic MF membranes used in the comparison study. Total gross revenue from the sale of WPI plus WPPC produced with polymeric versus ceramic membranes is influenced by both the absolute market price for each product and the ratio of market price of these 2 products. The combination of the market price of WPPC versus WPI and the influence of difference in yield of WPPC and WPI produced with polymeric versus ceramic membranes yielded a price ratio of WPPC versus WPI of 0.556 as the cross over point that determined which membrane type achieves higher total gross revenue return from production of these 2 products from separated sweet whey. A complete economic engineering study comparison of the WPI and WPPC manufacturing costs for polymeric versus ceramic MF membranes is needed to determine the effect of membrane material selection on long-term processing costs, which will affect net revenue and profit when the same quantity of sweet whey is processed under various market price conditions.     

Soy Protein Concentrates by Ultrafiltration

ABSTRACT: Soybean protein concentrates were produced by ultrafiltration with a commercial 4-in spiral wound module with a polyvinylidene difluoride membrane. With soy flour suspensions of 2% total solids (TS), protein content could be increased from 50% (dry basis) to 67% by ultrafiltration and/or diafiltration. Soluble sugars could be removed almost completely, but ash content of retentate solids did not decrease significantly. Higher protein contents would require removal of some of the fiber and/or manipulation of the feed environment to reduce solute-solute interactions. Protein yields were 90%. Flux decreased from 78 L/m²/h (LMH) with 2% TS soy flour suspension to 22 LMH at 17% TS.     

Impact of ultrafiltration/diafiltration sequence on the production of soy protein isolate by membrane technologies

In previous studies, the advantages of combining electrodialysis using a bipolar-cationic membranes configuration to acidify a soy protein extract to pH 6 with ultrafiltration/diafiltration (UF/DF) using a 100 kDa membrane to produce a soy protein isolate with low phytic acid content and improved solubility between pH 2 and 4 was demonstrated, when compared to the production of soy protein isolates by isoelectric precipitation and by UF/DF of a soy protein extract at pH 9. However, limited work was done to establish the impact of the UF/DF sequence for the purification of the pH 6 extract. Therefore, the purpose of this work was to study the impact of four different UF/DF sequences with a total permeate volume of 1.5–1.6 times the initial volume, on membrane fouling and permeate flux, as well as on the isolate protein, ash and phytic acid contents and solubility profile. Of the investigated UF/DF sequences, the VCR 5, VD 4 sequence was shown to be the one with the most severe fouling and consequently the most severe permeate flux decline. At the same time, it was also the VCR 5, VD 4 sequence which was the most efficient in terms of ash and phytic acid removal, followed by the VCR 5, re-VCR5 sequence, the VCR 2, VD 2 sequence and the VCR 2, (re-VCR 2)X 2 sequence, respectively. It was also observed that isolate with low phytic acid content resulted in narrower protein solubility profiles around the isoelectric point and higher protein solubility for the pH range of 2 to 4.Industrial relevancePlant proteins have made up a higher proportion of the human diet in recent years. Soybeans are the most important source of plant protein ingredients accounting for some 68% of global plant protein consumption in the world. Soy protein isolate is traditionally prepared by isoelectric precipitation process. This process has high productivity, however, it results in products with poor functional properties due to protein denaturation and to the presence of phytic acid (1–3% w/w) which alters the solubility of the isolates especially for the pH below the proteins' isoelectric point. In this work, we combined electrodialysis using a bipolar-cationic membranes configuration to acidify a soy protein extract to pH 6 with ultrafiltration/diafiltration (UF/DF) using a 100 kDa membrane to produce soy protein isolates with low phytic acid content. The impact of four different UF/DF sequences on membrane fouling, permeate flux, isolate composition and solubility profile was studied. Of the investigated UF/DF sequences, the VCR 5, VD 4 sequence was shown to be the one with the most severe fouling but at the same time the most efficient in terms of ash and phytic acid removal. It was also observed that the isolate produced by the VCR 5, VD 4 sequence shows narrower protein solubility profiles around the isoelectric point and higher protein solubility for the pH range of 2 to 4 than isolates produced by alternative UF/DF sequences. This isolate could be considered as a valuable ingredient for the formulation of fruit juice beverages or power juices, considering that the pH of these liquid food products is around 3.5.     

膜技术分离纯化燕麦蛋白的工艺研究

根据酶法提取燕麦中的燕麦蛋白,将浸提液过滤后通过膜设备工作过程进行除杂浓缩。经过实验得出,微滤膜、超滤膜和纳滤膜分别选用MF1、UF2和NF1作为最佳膜设备。对燕麦提取液进行除杂浓缩,能够去除大部分的固形杂质,并将水提液浓缩11.88倍,将测定得到燕麦蛋白的含量达到92.76%。     

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.     

Production efficiency of micellar casein concentrate using polymeric spiral-wound microfiltration membranes

Most current research has focused on using ceramic microfiltration (MF) membranes for micellar casein concentrate production, but little research has focused on the use of polymeric spiral-wound (SW) MF membranes. A method for the production of a serum protein (SP)-reduced micellar casein concentrate using SW MF was compared with a ceramic MF membrane. Pasteurized (79°C, 18s) skim milk (1,100 kg) was microfiltered at 50°C [about 3 × concentration] using a 0.3-μm polyvinylidene fluoride spiral-wound membrane, bleed-and-feed, 3-stage process, using 2 diafiltration stages, where the retentate was diluted 1:2 with reverse osmosis water. Skim milk, permeate, and retentate were analyzed for SP content, and the reduction of SP from skim milk was determined. Theoretically, 68% of the SP content of skim milk can be removed using a single-stage 3× MF. If 2 subsequent water diafiltration stages are used, an additional 22% and 7% of the SP can be removed, respectively, giving a total SP removal of 97%. Removal of SP greater than 95% has been achieved using a 0.1-μm pore size ceramic uniform transmembrane pressure (UTP) MF membrane after a 3-stage MF with diafiltration process. One stage of MF plus 2 stages of diafiltration of 50°C skim milk using a polyvinylidene fluoride polymeric SW 0.3-μm membrane yielded a total SP reduction of only 70.3% (stages 1, 2, and 3: 38.6, 20.8, and 10.9%, respectively). The SP removal rate for the polymeric SW MF membrane was lower in all 3 stages of processing (stages 1, 2, and 3: 0.05, 0.04, and 0.03 kg/m² per hour, respectively) than that of the comparable ceramic UTP MF membrane (stages 1, 2, and 3: 0.30, 0.11, and 0.06 kg/m² per hour, respectively), indicating that SW MF is less efficient at removing SP from 50°C skim milk than the ceramic UTP system. To estimate the number of steps required for the SW system to reach 95% SP removal, the third-stage SP removal rate (27.4% of the starting material SP content) was used to extrapolate that an additional 5 water diafiltration stages would be necessary, for a total of 8 stages, to remove 95% of the SP from skim milk. The 8-plus stages necessary to remove >95% SP for the SW MF membrane would create more permeate and a lengthier process than required with ceramic membranes.     

Moisture sorption and thermodynamic properties of cassava starch and soy protein concentrate based edible films

Moisture sorption isotherms and thermodynamic properties of cassava starch and soy protein concentrate–based edible films were investigated. Equilibrium moisture content was determined at various temperatures (10, 20, 30 and 40 °C) and relative humidities (17–83%) using gravimetric method, and the results were analysed using four sorption isotherm models. The equilibrium moisture of edible films (both adsorption and desorption modes) decreased with soy protein concentrate addition and temperature at constant water activity. The monolayer moisture content values of cassava starch–soy protein concentrate edible films decreased with increase in temperature and soy protein level. GAB and Oswin models (%RMS ≤10) best described the isotherms of the biofilms with the monolayer moisture contents, isosteric enthalpy and entropy higher for adsorption with significant kinetic compensations. The moisture sorption and thermodynamic properties of cassava starch–soy protein concentrate edible films showed that they are suitable for packaging applications.     

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。     

Pre-treatment methods of Edam cheese milk. Effect on the whey composition

Edam cheese milk was subjected to high-heat treatment (HH), ultrafiltration (UF) and microfiltration (MF). The effect on the recovery yield and the composition of whey was studied. Traditional Edam process was used as a reference. HH reduced the whey protein concentration of milk and whey, but the recovery from milk to whey was not affected. Reduction of whey proteins was the highest (28%) with MF treatment, during which 15% was lost in the MF permeate and 13% was co-precipitated with the cheese curd. Co-precipitation of the whey proteins was the highest (84%) with ultrafiltered milk. MF and UF treatments produced 22% less whey with increased whey protein concentration. Elevation of the cheese milk protein concentration by microfiltration or ultrafiltration decreased the recovery of fat in whey. None of the treatments decreased the residual casein concentration in whey. The protein composition was altered by UF and MF treatments, which significantly increased the caseinomacropeptide content of total protein in whey. The whey was processed into whey protein concentrate powders. The amino acid composition of the whey protein concentrate produced from microfiltration process was significantly different from the others.     

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.     

木瓜蛋白酶提高醇法大豆浓缩蛋白乳化性的研究

制取低成本、高蛋白含量的大豆浓缩蛋白时,乙醇产生变性作用,从而降低了大豆浓缩蛋白的功能特性,因此本研究采用木瓜蛋白酶对醇法大豆浓缩蛋白进行改性。通过对酶浓度、底物浓度、改性时间与改性温度的单因素实验,针对乳化性进行研究,然后进行正交试验,最终得出木瓜蛋白酶提高醇法大豆浓缩蛋白乳化性最佳工艺条件:酶用量(E/S)为3%、底物浓度为(W/V)8%、改性时间为2h、改性温度为50℃,改性中pH值为6.0,可提高乳化能力3.8倍,乳化稳定性3.9倍。     

Composition,Nutrition, and Utilization of Okara (Soybean Residue)

Okara is a by-product generated during tofu or soymilk production processes. It contains about 50% dietary fiber, 25% protein, 10% lipid, and other nutrients. The huge quantities of okara produced annually pose a significant disposal problem. Extensive studies have been done on the chemical composition, nutritional values, and biological activities of okara and on its potential utilization. Due to its high fiber content and low production costs, okara is a good raw material and rich source for preparing fiber and could also be used as a dietary supplement to prevent diabetes, obesity, and hyperlipidemia. Chemical or enzymatic treatment, fermentation, extrusion, high pressure, and micronization can increase the content of soluble fiber of okara, which improves its nutritional quality and processing properties. Fresh okara putrefies quickly due to its high moisture content, so it should be dried as early as possible. This review focuses on the application of okara in the food industry as partial replacement for wheat or soy flour to increase fiber and protein contents of foods. Okara can also be used as a fermentation substrate to produce a variety of products (natto, fibrinolytic enzymes, α-glucosidase inhibitor, β-fructofuranosidase, edible fungi, iturin A, chitosan, alcohol, etc.) for human consumption and nonfood production. In addition, the application of okara in feed and environmentally friendly material has also been documented.     

Characterization of Isoflavones in Membrane-processed Soy Protein Concentrate

ABSTRACT: Aqueous soy flour solutions (5% w/w) were treated for 3 h at 45 to 50 °C with Crystalzyme®, without enzyme at 45 to 50 °C, or blanched at 80 °C. Solutions were ultra‐ and dia‐filtered to produce membrane soy concentrates (MSC). Total isoflavones of MSCs were 3.02 mg/g, 3.12 mg/g, or 3.42 mg/g, respectively, on a dry weight basis. Membrane processing contributed to approximately 18, 15, or 8% decreases, respectively, in total isoflavones of MSCs compared with soy flour (3.71mg/g). This represents at least an 82% recovery. There was no significant difference in total isoflavone content in any MSC, however the profile of isoflavones as glucosides or aglycones changed with treatment conditions.     

Characterization of Soy Protein Concentrate Produced by Membrane Ultrafiltration

The functionality of membrane processed soy concentrate was very similar to soy flour in terms of solubility and water hydration capacity. The high emulsifying activity index of soy flour is believed to be reflective of its higher solubility, while surface hydrophobicity is believed to be responsible for an equally high emulsifying activity index in acid precipitated soy isolate. The proteins of soy flour and membrane soy concentrate seem to have most of their hydrophobic residues buried in the interior, while they are exposed in acid precipitated soy isolate. Heating resulted in a decrease in solubility but improved the hydration capacity and emulsifying activity of both soy flour and membrane soy concentrate. The essential amino acid profile of concentrate was comparable to current commercial isolates manufactured by acid precipitation. The majority of the polypeptides present in soy flour were observed to be present in the concentrate. The membrane soy concentrate was determined to have the least soybean aroma when compared to both soy flour and acid precipitated soy isolate.