Rice Dreg Protein as an Alternative to Soy Protein Isolate: Comparison of Nutritional Properties

Rice dreg protein could be a valuable source of plant-based proteins, as an alternative to soy proteins in some food products. Here, nutritional properties of rice dreg protein were compared with those of soy protein isolate. The protein content of rice dreg protein was approximately 62.6 g/100 g sample, with large amounts of fat, carbohydrate, and ash. The denaturation temperatures of rice protein isolate from rice dreg protein were 47.4 and 97.2°C, respectively. This indicated that these proteins could be denatured during rice syrup processing to form aggregates, but were relatively more stable than rice endosperm protein and soy protein isolate. The main amino acids in rice dreg protein and rice protein isolate were Glu, Pro, Arg, Asp, and Leu, with Lys as the lowest content. Most of essential amino acids and nutritional parameters of rice protein isolate and rice dreg protein met the suggested nutritional requirements for a child according to FAO/WHO, and were relatively higher than those of soy protein isolate. In addition, rice protein isolate showed better digestibility than soy protein isolate during four hours sequential pepsin and pancreatin digestions. The final digestibility value was 96.66% for rice protein isolate compared to 91.41% for soy protein isolate. Thus rice dreg protein could potentially replace soy proteins as a good source of value-added protein for human nutrition in response to the increasing demand for plant proteins.     

Functional and Edible Uses of Soy Protein Products

ABSTRACT: Consumers are becoming increasingly interested in healthful foods and are open to soy protein ingredients. Soybeans as food are very versatile and a rich source of essential nutrients. They are also an excellent source of good‐quality protein, comparable to other protein foods, and suitable for all ages. Adverse nutritional and other undesirable effects followed by the consumption of raw soybean meal have been attributed to the presence of endogenous inhibitors of digestive enzymes and lectins, as well as poor digestibility. To improve the nutritional quality of soy foods, inhibitors and lectins are generally inactivated by heat or eliminated by fractionation during food processing. Soybeans provide an alternative source of protein for people who are allergic to milk protein. Soy protein is highly digestible (92% to 100%) and contains all essential amino acids. Although relatively low in methionine, it is a good source of lysine. Soy‐protein products contain a high concentration of isoflavones, up to 1 g/kg. Increased acceptance of soy proteins is due to unmatched qualities like good functional properties in food applications, high nutritional quality, abundance, availability, and low cost. At present the various forms of soy proteins are primarily utilized for their functional effects rather than their nutritional properties. This article summarizes the integrated overview of the widely available, scattered information about the nutritional and functional uses of the soy proteins when applied in food systems and intends to present the most current knowledge with an interest to stimulate further research to optimize their beneficial effects.     

Effect of processing parameters on the properties of transglutaminase-treated soy protein isolate films

The effects of processing parameters, including the applied amount of microbial transglutaminase (MTGase), the pH of film-forming solution, air-drying temperature, as well as the additional pre-incubation, on the properties of MTGase-treated soy protein isolate (SPI) films were investigated. The treatment with low concentration of MTGase (4–10 units per gram of SPI, U g^− 1) significantly increased the tensile strength (TS) values of SPI films, while high concentration of MTGase (over 20 U g^− 1) resulted in significant decrease in the TS values (P ≤ 0.05). The elongation at break (EB) values of corresponding films gradually decreased, and the contact angle values persistently increased with the enzyme concentration. At alkaline pH range, the TS and EB values of MTGase-treated SPI films were significantly higher than that at pH 7.0 (P ≤ 0.05). Meanwhile, the contact angle values significantly decreased with increasing pH from 7.0 to 10.0 (P ≤ 0.05). The TS, EB and contact angle values of MTGase-treated films gradually but insignificantly decreased with increasing the air-drying temperature from 18 to 50 °C (P > 0.05). The properties of MTGase-treated films were also affected by the additional pre-incubation of film-forming solutions with MTGase before casting. Furthermore, the aggregation of SPI or its components induced by MTGase has been proved to mainly account for the influence of processing parameters on the properties of SPI films (MTGase-treated). Thus, low concentration of enzyme, alkaline pH range and low air-drying temperature, at which conditions the MTGase-induced aggregation of SPI in film-forming solutions could be in some extent inhibited or delayed, might facilitate the improvement of the properties of SPI films by MTGase, especially the mechanical and surface hydrophobic properties.Industrial relevanceThe development of biodegradable protein film has attracted a lot of attention worldwide. The enzymatic cross-linking induced by transglutaminase has been confirmed to improve mechanical and surface hydrophobic properties of cast films from most of food proteins, including soy proteins. Results of this study show that, the improvement of properties of cast films of soy proteins by transglutaminase treatment is largely dependent upon many processing parameters, e.g., enzyme concentration, the pH of film-forming solution and temperature.     

Influence of sucrose on cold gelation of heat‐denatured whey protein isolate

A solution of heat‐denatured whey proteins was prepared by heating 100 g kg⁻¹ whey protein isolate (WPI) at pH 7.0 to 75 °C for 15 min in the absence of salt. Heat treatment caused the globular protein molecules to unfold, but electrostatic repulsion opposed strong protein–protein aggregation and so prevented gel formation. When the heat‐denatured whey protein solution was cooled to room temperature and mixed with 15 mM CaCl₂, it formed a gel. We investigated the influence of the presence of sucrose in the protein solutions prior to CaCl₂ addition on the gelation rate. At relatively low concentrations (0–100 g kg⁻¹), sucrose decreased the gelation rate, presumably because sucrose increased the aqueous phase viscosity. At higher concentrations (100–300 g kg⁻¹), sucrose decreased the gelation rate, probably because sugar competes for the water of hydration and therefore increases the attraction between proteins. These data have important implications for the application of cold‐setting WPI ingredients in sweetened food products such as desserts. © 2000 Society of Chemical Industry     

Enzymatic modification as a tool to improve the functional properties of heat‐processed soy flour

BACKGROUND: There are a number of antinutritional factors present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are protease inhibitors and lectins. Protease inhibitors show antinutritional effect and moreover the digestibility of the protein is limited by the presence of these antinutrients. The aims of the present study are (1) to study the effect of autoclaving on the trypsin inhibitor inactivation, nitrogen solubility and protein digestibility of defatted soy flour and (2) to study the effect of enzymatic modification on the functional properties of autoclaved soy flour. RESULTS: The solubility of the soy flour decreased with increase in autoclaving time. Partial hydrolysis of the autoclaved soy flour increased its acid solubility (pH 4.5) from 17% to 56% over a control value of 24% without affecting its functional properties. Inactivation of trypsin inhibitors improved the protein digestibility of soy flour from 25% to 95%. Particle size analysis of the autoclaved flour indicated the formation of soy protein aggregates, which resulted in poor solubility. The enzymatic modification of autoclaved soy flour resulted in its property as a good emulsifying agent with an emulsion capacity of 118 ± 4 mL. CONCLUSION: Enzymatic modification of the heat‐processed soy flour increased its solubility and other functional attributes. The increased acid solubility would be advantageous in the utilization of soy proteins in acidic foods. Thus the autoclaved and partially modified soy flour is a potential source for specific functional foods. Copyright © 2007 Society of Chemical Industry     

脱脂油棕谷蛋白-2的 营养价值与功能特性

为促进油棕蛋白在食品中的应用,本试验对油棕谷蛋白-2的营养价值和功能特性展开研究。首先采用逐步提取法从脱脂油棕中提取谷蛋白-2,测定其氨基酸组成、体外消化吸收率、生物价、乳化性和黏度。结果表明,脱脂油棕谷蛋白-2中必需氨基酸总含量(48.65 g/100 g)显著(P<0.05)高于FAO/WHO的推荐值(12.7 g/100 g),其含硫氨基酸(半胱氨酸+甲硫氨酸)、支链氨基酸(亮氨酸、异亮氨酸)和天冬酰胺的含量也较高。此外,脱脂油棕谷蛋白-2的生物价为63.03,体外消化吸收率为70.02 g/100 g,因此其营养价值较高。Bigelow参数分析表明,脱脂油棕谷蛋白-2中极性氨基酸与非极性氨基酸的比值为2.18,表面疏水性为37.29。SDS-PAGE分析表明,脱脂油棕谷蛋白-2的分子量为22.1~133.5 kDa,主要由5个亚基组成,且亚基之间有二硫键。功能特性分析表明,脱脂油棕谷蛋白-2的乳化性(251.58±5.28) m²/g和乳化稳定性(84.40%)很高,显著(P<0.05)高于大豆分离蛋白(32.57 m²/g);其泡沫稳定性(17.61%)和黏度(21.33 cP)与大豆分离蛋白接近。本试验结果表明脱脂油棕谷蛋白-2的营养价值较高、功能特性较好,具有开发为营养强化剂、乳化剂、增稠剂等产品的潜力。     

大豆分离蛋白在成膜后的营养特性变化

采用胃蛋白酶和2，4，6-三硝基苯磺酸分别测定大豆分离蛋白膜的消化率和赖氨酸有效性。结果表明，蛋白质的消化率和赖氨酸有效性随成膜溶液的pH升高而下降，并因一些增加蛋白交联的物质如单宁、阿魏酸和过氧化氢的添加而降低。蛋白膜的机械性与膜蛋白消化率和赖氨酸有效性存在一定负相关，即机械性能较强的膜，其消化率和赖氨酸有效性较低。不过，玉米淀粉似乎是个例外，它在改善机械特性的同时，也保持了大豆蛋白膜的营养。由于大豆分离蛋白制备成膜后，其消化率和赖氨酸有效性下降，因此将大豆蛋白膜称为生物可降解膜似乎比称作可食性膜更科学。     

Solubility and Foaming Properties of Phytate-Reduced Soy Protein Isolate

A pilot scale ion exchange process was developed to produce a 75 - 77% phytate-reduced soy protein isolate. The solubility and foaming properties of this isolate were compared to those of control and commercial soy protein isolates as a function of protein concentration (5 and 10%, w/v), pH (3, 6 and 9) and preheat temperature (25, 60 and 80°C). Phytate-reduced soy protein extract exhibited minimum solubility at pH 4.8 - 5.0, compared to 4.2 - 4.5 for control soy extract. Phytate-reduced soy protein isolate was most soluble and functional at pH values below its isoelectric point (pH 3), whereas control and commercial soy isolates were generally most soluble and functional at pH values above their isoelectric point (pH 6 and 9).     

湿法糖基化改性对大豆分离蛋白功能性质的影响

大豆分离蛋白与葡萄糖按质量比4∶1溶解在重蒸水中配制成蛋白质质量浓度为8 g/100 mL的混合液,分别在70、80、90 ℃条件下反应0、1、2、3、4、5、6 h,得到不同反应温度和时间的糖基化产物。通过测定各糖基化产物的pH值、溶解性、乳化性和凝胶性质,研究糖基化对大豆分离蛋白功能性质的影响。结果表明：随着加热时间的延长,不同温度反应体系的颜色加深,pH值逐渐降低,溶解性、乳化活性和乳化稳定性显著提高,凝胶的弹性和硬度呈先上升后下降的趋势。其中90 ℃反应体系糖基化大豆分离蛋白的功能性质提高最为明显,从0 h到6 h,溶解性和乳化活性分别从17.37%、0.168提高到了38.7%、0.574,且效果显著（P＜0.05）;加热4 h制得的糖基化样品的乳化稳定性最强,其乳化稳定性为39.6;并且糖基化样品凝胶的硬度和弹性在反应3 h时最大,其硬度和弹性分别为81.3g和0.936。因此,糖基化修饰可有效提高大豆分离蛋白的功能性质。     

Functional properties of proteins isolated from phorbol ester-free physic nut (Jatropha curcas L.) seed cake

Phorbol ester-free physic nut (Jatropha curcas L.) seed cake is a nutritious protein source. Functional properties of the protein isolates obtained from various protein precipitation methods were investigated. Proteins isolated from the seed cake by ammonium sulfate gave the highest yield. The solubility of all proteins increased with increasing pH with their maximum and minimum solubility at pH of 12.0 and 4.0, respectively. The protein prepared by ethanol provided the maximum water holding capacity (3.34 mL water/g protein). The oil binding capacities of all proteins were 1.96–2.03 mL oil/g protein. The protein precipitated by ethanol showed higher emulsion activity and stability than that precipitated by acetone and ammonium sulfate. The protein obtained from ammonium sulfate gave the highest foam capacity, while the protein from acetone had the highest foam stability. Different functional properties of the proteins were achieved by various protein precipitation methods. The protein isolate obtained from each method could serve as a food ingredient applied to food products requiring a specific functional property.     

An enzyme-based extraction process for the purification and enrichment of vegetable proteins to be applied in bakery products

In the current study an efficient aqueous extraction procedure using glucoamylase was developed to produce food grade protein extracts from lentils and white beans. The extracts contained 50.3 ± 0.6 and 49.2 ± 0.05 g protein per 100 g dry extract, respectively. The nutritional value of lentil and white bean protein extracts proved to be satisfying according to the amino acid composition, where methionine was the limiting amino acid. The produced extracts were tested for their technological properties. Both lentil and white bean protein extracts showed similar or even better technological properties regarding foaming and emulsifying capacities, heat stability and gelling properties compared to soy and pea protein extracts. Food application tests in white bread, pound cake and sponge cake proved lentil and white bean protein extracts to be potential alternatives to soy protein in replacing proteins from animal origin.     

Protein Isolates from Bambara Groundnut (Voandzeia Subterranean L.): Chemical Characterization and Functional Properties

The physicochemical, functional, and thermal properties of protein isolates obtained from two varieties of Bambara groundnut were evaluated. Proteins were isolated using alkaline extraction (isoelectric precipitation [IEP]) and micellisation techniques. IEP recorded a higher protein yield (56.3–58.2 g/100 g) than the micellised protein (MP) (14.2 – 15.6 g/100 g). A similar trend was observed for the protein content of the isolates. The isolates contained a high level of lysine, arginine, and glutamic acid compared to soy protein. Minimum solubility of the flours of the two varieties occured at pH 5. MP isolates exhibited higher solubility than the corresponding isoelectric (IEP) isolates over all pH values. The micellised protein recorded superior functional characteristics than the isoelectric isolates. The micellised isolates also showed a significantly higher (P < 0.05) foam capacity and stability, oil and water absorption properties than the isoelectric isolate. The MP of both varieties also recorded significantly higher emulsifying properties-+ than their isoelectric protein isolates. The micellised protein also had better gelation properties than the isoelectric isolate. Micellised and isoelectric isolates did not reveal major differences in the electrophoretic patterns; both isolates had three major bands at 35.0, 43.0, and 112.0 kDa. The bands in the isoelectric protein isolate however, were well defined compared with the micellised isolate. All Bambara isolates were not dissociated by 1,4-Dithiothreitol (DTT) suggesting that they do not contain subunits linked by a disulphide bond. This suggests that 7S vicilin may be the major storage protein in Bambara groundnut isolates. Differential scanning calorimetry studies (DSC) of the two varieties of bambara groundnut proteins indicated that the thermograms of the micellised isolates have a higher denaturation temperature Td (97.9–108.4°C) than their corresponding isoelectric isolates (89.5–90.6°C).     

磷酸盐-大豆分离蛋白联合处理对草鱼肌原纤维蛋白凝胶化的影响

为探讨磷酸盐(三聚磷酸钠、六偏磷酸钠、焦磷酸钠(tetrasodium pyrophosphate,TSPP))和大豆分离蛋白(soy protein isolate,SPI)对草鱼肌原纤维蛋白凝胶化的影响,采用热处理方法,将不同质量浓度的磷酸盐、SPI与草鱼肌原纤维蛋白混合制成凝胶.用黏度、嫩度、持水性、显微结构和粗...     

Foaming Characteristics of Commercial Soy Protein Isolate as Influenced by Heat-Induced Aggregation

The foaming properties of commercial soy protein isolate subjected to different temperatures (20–90°C) were assessed. The results revealed that the solubility and surface hydrophobicity of a 5% (w/v) commercial soy protein isolate suspension increased with increasing temperature, which increased foaming capacity and reduced foaming stability. Commercial soy protein isolate supernatant (i.e., soluble fraction) had higher foaming capacity at low temperatures (20–50°C). A high content of commercial soy protein isolate soluble fraction increased foaming capacity but decreased foaming stability. The SDS-PAGE patterns and molecular weight distribution of commercial soy protein isolate revealed that there were soluble, large molecular weight aggregates (>400 kDa) formed mainly from A and B-11S polypeptides of commercial soy protein isolate via disulfide bonds. Additionally, some aggregates also dissociated into small polypeptides and subunits after heat treatment. Commercial soy protein isolate precipitate (i.e., insoluble fraction) had a high content of proline and cysteine, which probably contributed to the foaming stability of commercial soy protein isolate.     

Enzymatic hydrolysis of blue whiting (Micromesistius poutassou); functional and bioactive properties

Functional and biochemical properties of fish protein hydrolysates (FPH) from blue whiting (BW) were studied. FPH (2.5%, 5%, 10%, and 15% degree of hydrolysis [DH]) were made from isolated proteins from headed and gutted BW with Alcalase 2.4 L. The properties of dried BW mince and protein isolate compared to 4 reference proteins (soy and milk protein) were studied: color, solubility, water-holding capacity (WHC), oil-binding capacity (OBC), emulsion capacity (EC), and emulsion stability (ES). The angiotensin I-converting enzyme (ACE) inhibitory activities of the soluble fraction of BW powders were also investigated. Furthermore, the products were characterized by analyzing their chemical composition. Chemical composition, solubility, OBC, and EC of the BW powders was significantly (P < 0.05) different with different DH, while color, ES, and WHC were not significantly (P > 0.05) different. Salt content of the FPH was high (4% to 19%) and increased with increased DH. Protein solubility varied from 10% to 70% and increased with increased DH. WHC of the FPH was around 97% and was higher than that of all the reference proteins tested. OBC decreased with increased DH (from 3.5 to 2.1 g oil/g protein) and was higher than OBC of the soy and milk proteins (1.6 to 1.9 g oil/g protein). EC of FPH was similar or lower than the reference proteins. ES of FPH (60% to 90%) was similar to or lower than soy and whey proteins (60% to 98%) but higher than casein (20%). ACE inhibition activity increased as DH was increased. Practical Application: The results from this study demonstrate that a functional bioactive hydrolysate can be produced from BW, which is an underutilized fish species, and may aid the industry in better utilizing this raw material. The novelty of this research was the use of BW as a raw material where the protein has been isolated with the pH shift method. Furthermore, it was novel that bioactivity and functionality was measured in the same samples.     

Physicochemical and Functional Properties of Winged Bean Flour and Isolate Compared with Soy Isolate

The proximate composition, amino acid profile and functional properties of isolated winged bean proteins were determined and compared with soy protein isolate. Winged bean protein extracted at pH 10 and pH 12 had protein contents of about 90% and 80%, respectively. Alkali extraction of winged bean proteins at pH 10 and pH 12 did not affect the amino acid distribution of the isolated proteins. Oil and water absorption, emulsion, and foaming properties of winged bean isolated compared favorably with soy isolate. Least gelation concentration for winged bean isolate was 18% compared to 14% for soy isolate. Thus, winged bean protein isolate with its high protein content, high lysine and other essential amino acid content and good functionality has a good potential as an ingredient in food products.     

pH值对罗非鱼蛋白-大豆蛋白混合热凝胶特性及体外消化性的影响

以罗非鱼和大豆为原料分别提取鱼分离蛋白(fish protein isolate,FPI)和大豆分离蛋白(soy protein isolate,SPI),制备罗非鱼蛋白-大豆蛋白(FPI:SPI=1:1,质量比)热诱导凝胶,探讨pH值(6.0、6.5、7.0、7.5)对混合蛋白热凝胶特性和体外消化性的影响.结果表明:...     

Peanut protein concentrate: Production and functional properties as affected by processing

Peanut protein concentrate (PPC) was isolated from fermented and unfermented defatted peanut flour by isoelectric precipitation and physical separation procedures. PPC was dried by spray or vacuum drying. PPC powders from each drying technique were evaluated for proximate composition and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity and viscosity) along with defatted peanut flour and soy protein isolate as references. PPC contained over 85% protein versus 50% protein in the defatted peanut flour used as raw material for PPC production. PPC had a solubility profile similar to that of peanut flour, with minimum solubility observed at pH 3.5–4.5 and maximum solubility at pH 10 and higher. Roasting of peanut reduced all functional properties of defatted peanut flour while fermentation had the reverse effect. The type of drying significantly affected the functional properties of PPC. Spray dried PPCs exhibited better functional properties, particularly emulsifying capacity and foaming capacity, than vacuum oven dried PPC. Spray dried PPCs also showed comparable oil binding and foaming capacity to commercially available soy protein isolate (SPC). At equivalent concentrations and room temperature, PPC suspension exhibited lower viscosity than soy protein isolate (SPI) suspensions. However, upon heating to 90 °C for 30 min, the viscosity of PPC suspension increased sharply. Results obtained from this study suggest that the PPC could be used in food formulations requiring high emulsifying capacity, but would not be suitable for applications requiring high water retention and foaming capacity. PPC could be a good source of protein fortification for a variety of food products for protein deficient consumers in developing countries as well as a functional ingredient for the peanut industry. The production of PPC could also add value to defatted peanut flour, a low value by-product of peanut oil production.     

小麦蛋白对TGase酶交联改性大豆蛋白凝胶特性的影响及机制

为探讨TGase酶对大豆与小麦混合蛋白凝胶性质的影响,本文研究了小麦蛋白的加入前后混合蛋白凝胶功能性质的变化规律。通过研究TGase酶添加量、反应温度、反应pH对混合蛋白凝胶特性的影响可知:蛋白浓度为11%（11 g/100 mL）保持不变,TGase酶添加量为30 U/g,反应温度为40℃,反应pH为7.0时,TGase酶对混合蛋白凝胶特性改善效果最强。对比小麦蛋白加入前后蛋白凝胶的性质,发现小麦蛋白的添加使得蛋白结构的β-折叠含量升高,游离巯基含量减少,凝胶弹性模量（G’）增强,形成了更为多空且紧密有序的三维网络结构,使得混合蛋白的凝胶性能显著增强（p<0.05）。      

WATER AND LIPID ABSORPTION PROPERTIES OF LIGNIN-REDUCED SOY HULLS1,2

Given the nutritional benefits of incorporating lignin-reduced soy hulls into human foods such as restructured pork products, their moisture and lipid absorptive properties were investigated. The effects of three particle sizes, heat, and level of media (water, pork lipid, and water/pork lipid emulsion) were investigated. As particle size increased, water and emulsion absorption generally increased. The fine particle size absorbed less lipids than either of the two larger sizes. An increase in temperature generally increased water absorption, had little effect on emulsion absorption, and no effect on lipid absorption. Water was preferentially absorbed over lipids. Differences in composition enabled lignin-reduced soy hulls to absorb up to 53% more water than unprocessed soy hulls. These results can be used to predict the functional properties of soy hulls when exposed to different media during product formulation.