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.     

Tepary Bean Flour, Albumin and Globulin Fractions Functional Properties Compared with Soy Protein Isolate

The solubilities of teparies albumin (TA) and globulin (TG) compared to soy protein isolate (SPI) were higher at pH 1–4 but similar at pH 8–12. Although SPI developed significantly higher viscosity than the tepary bean proteins, the flour (TF) and TA had significantly higher heat coagulability and foaming properties. TG did not coagulate upon heating (100°C). Also, TG formed a weaker and less stable foam and had significantly lower emulsion capacity than TF, TA, and SPI. Tepary bean proteins absorbed significantly higher amounts of fat (corn oil) than SPI.     

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).     

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。     

Isolation and Characterization of Adzuki Bean (Vigna angularis cv Takara) Proteins

Protein extract (P-I), isolate (P-II), albumin (PA), and globulin (PC) were isolated from Minnesota-grown adzuki beans. Total extractable protein and water- and salt-soluble fractions accounted for 21.6, 15.8, and 2.3% (d.b.), respectively. Fractions were compared with a commercial soy protein (PS) for chemical and functional properties. Proteins in P-I, PA, PG, P-II, and PS were 78.8, 69.4, 89.2, 91.3, and 89.9% (d.b.), respectively. P-I, PA, and PG were superior to PS in essential amino acid contents; P-II was comparable to it. Adzuki bean proteins, except for PA, showed high solubility at acidic and alkaline pH. Compared to PS, the adzuki bean protein fractions (except P-II) showed greater fat absorption and water adsorption, greater foaming (except PG), and lower emulsifying capacities (except P-II) and stabilities. P-I and PA showed lower, and P-II higher, least gelation concentrations than PS.     

大豆分离蛋白的凝胶稳定性的研究进展

大豆分离蛋白因其蛋白质含量高,具有凝胶性等多种功能特性,在食品工业中得到广泛应用。但大豆分离蛋白在贮藏过程中,其凝胶的稳定性往往下降,严重地影响了产品的质量。国内外研究发现,在贮藏过程中蛋白组成成分、蛋白浓度、温度、pH 值和离子强度等的变化对凝胶形成具有一定影响,通过各种改性方法可以提高大豆蛋白的凝胶稳定性。     

Functional Properties of Raw and Heat Processed Winged Bean (Psophocarpus tetragonolobus) Flour

Nitrogen solubility, emulsification capacity, foam capacity, fat and water absorption capacity of raw and heat-processed winged bean flour were compared with those of raw soy flour, both as a function of pH and NaCl concentration. Nitrogen solubility vs pH profile showed only one minimum, at pH 4.5. Heat processing of winged bean flour lowered nitrogen solubility. Water and fat absorption capacity of winged bean flour were 2.1 g/g and 1.4 g/g, respectively; those of raw soy flour were 3.1 g/g and 1.2 g/g. Heat processing increased water and fat absorption capacity of winged bean flour by 38% and 57%, respectively. Emulsification capacity of raw winged bean flour was higher than that of raw soy flour by about 30–60% depending on the pH. Heat processing diminished emulsification and foam capacity of winged bean flour by about 35% and 18%, respectively. Incorporation of NaCl up to 0.4M improved emulsification capacity of winged bean flour and foam capacity up to 0.2 M.     

Isolation and characterization of proteins from soymilk residue (okara)

Protein was extracted from okara at pH 9.0 and 80 °C for 30 min, giving a recovery of 53% protein. The extracted protein was isolated by isoelectric precipitation at pH 4.5, and the dried, defatted protein isolates (prepared at 25 and 80 °C) had over 80% protein.

The okara protein isolates have essential amino acid profiles similar to the FAO scoring pattern, and high in vitro protein digestibility, with methionine and cysteine as the limiting amino acids. Polyacrylamide gel electrophoresis in sodium dodecyl sulfate showed that okara protein isolates had a large quantity of high molecular weight components suggesting protein aggregation. Differential scanning calorimetry and hydrophobicity data suggested extensive protein unfolding in the okara products.

Okara protein isolates had lower solubility than a commercial soy protein isolate at both acidic and alkaline pH, probably due to protein aggregation. Other functional properties, including emulsifying, water and fat binding, and foaming properties, were found to be comparable to the commercial soy isolate.     

FUNCTIONAL PROPERTIES AND NUTRITIONAL QUALITY OF ALKALI- AND HEAT-TREATED SOY PROTEIN ISOLATE

Alkali and heat are increasingly utilized in food processing. This study was conducted to evaluate specific functional and nutritional properties of alkali- and heat-treated soy protein isolate (AHSPI) and the relationship between these properties. High pH (12.0) and temperature (100C) increased protein solubility of the isolate from 47 to 99.5% and emulsifying activity index from 74 to 184 m²/g. The values for in vitro protein digestibility (IVPD), computed-protein efficiency ratio, and IVPD-corrected amino acid score of AHSPI were not significantly (P>0.05) affected at pH 8.0 or 10.0, but were reduced At pH 12.0. At pH 12.0, lysinoalanine content significantly (p<0.05) increased from 0.39 to 1.22 g/100g protein as temperature was increased from 40 to 100C. Improvements in functional properties of soy proteins can be obtained through combined alkali and heat treatments. However, very high pH and temperature should be avoided to maintain nutritional quality of the proteins.     

四棱豆油脂、脂肪酸、蛋白质、氨基酸的分析

以4 个四棱豆品种的种子为材料,采用索式提取法、毛细管柱测定总脂肪含量及分析各脂肪酸含量;利用凯氏定氮法、全自动氨基酸分析仪测定蛋白质总量及各蛋白氨基酸组成。结果表明,四棱豆种子中油脂总量在20%～22%,主要含有28 种脂肪酸,油酸占单不饱和脂肪酸的90.7%;多不饱和脂肪酸主要为亚油酸、α - 亚麻酸和EPA;饱和脂肪酸平均含量为25.76%,主要为棕榈酸和硬脂酸。蛋白质总量在38% 左右,必需氨基酸含量丰富。     

Extraction of nitrogenous material from winged bean [Psophocarpus tetragonolobus (L.) DC] flour and the preparation and properties of protein isolates

The extractability of nitrogenous material from the seeds of 12 winged bean accessions has been investigated. Little variation in nitrogen content and extractability in water or salt solution was obtained, although decortication considerably reduced the levels of extraction. The effect of three oil extraction procedures on the extractability of nitrogenous material at different pH values is reported. Protein isolates were prepared and simple laboratory tests were used to evaluate their functional properties. The prepared winged bean isolates possessed very low bulk densities and high fat absorption values and the relationship between these factors was investigated further. Winged bean isolates showed high (100%) nitrogen dispersibilities and were able to form heat-stable emulsions. They did not form gels under the conditions used except in the presence of CaCl₂. Isolates prepared from unheated winged bean flour formed stiff but unstable foams. The relationship between the oil extraction procedure and isolate yield, purity and functional properties is discussed.     

Comparative Analysis of the Physico-Chemical,Thermal, and Oxidative Properties of Winged Bean and Soybean Oils

To explore possible food applications, the oxidative stability, antioxidants contents (tocopherols and tocotrienols), thermal properties, and solid fat content of winged bean oil were investigated along with soybean oil for comparison. Results showed that winged bean oil was significantly (p < 0.05) resistant to oxidation (27 h) compared to soybean oil (9 h) heated at 110^oC for 32 h, due presumably to the presence of alpha tocotrienol and the high behemic acid content. The high content of tocopherols, 230 mg/100 g in soybean oil did not contribute much to its oxidation stability. At around 25^oC, winged bean oil contained about 15% solid fat content with <1% in soybean oil. Soybean oil, however, had better levels of the omega-3 and omega-6 fatty acids with a ratio of 7.6:1, falling within the range of 5:1 and 10:1 recommended by the Food and Agriculture Organization/World Health Organization, when compared to winged bean oil having a ratio of 34.4:1. The positional fatty acids esterified as stearoyl, palmitoyl, behemoyl or lignoceroyl triacylglycerides species, PSP, PPP, PLB, POB and SSlg+PBP overwhelmed the unsaturated FAs of winged bean oil for free radical reaction and also conferred it high thermal conductivity. The high oxidative stability, solid fat content, and thermal conductivity of winged bean oil coupled with its crystalization characteristics confirmed it to be good material for frying and for making zero-trans-fat margarines and spreads.     

Isolation and study of the functional properties of pea proteins.

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying--and foaming properties, water--and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.     

响应面优化提高大豆分离蛋白中蛋白干基得率的工艺研究

为获得更高含量大豆分离蛋白干基,采用物理沉降法,控制酸沉pH梯度变化,添加氯化钠调整溶液离子强度,逐级分离沉降11S大豆蛋白和7S大豆蛋白,以提高大豆分离蛋白质干基含量。分别在料液比、温度、NaCl加入量的单因素试验基础上,进行响应面优化设计分析。结果表明最佳工艺条件为料液比1:11．35、萃取温度48．63℃、NaCl加入量0．126mol/L,获得蛋白质干基含量96．04%,同比市售较好水平产品93．31%的蛋白质干基含量提高了2．67%。     

Isolation and study of the functional properties of pea proteins

Proteins of pea seeds were isolated after defatting with hexane using alkaline (0.1 M sodium hydroxide) extraction and acid (HCl) precipitation. Concentrates were also prepared by hexane extraction and ethanolic extraction (pH = 5). Gross chemical composition amino acid content and functional properties (solubility profile, emulsifying – and foaming properties, water – and oil absorption) were studied. The results were compared with the same parameters of soy and lupin protein products. Although the majority of functional characteristics of isolates were lower in comparison to soy isolates, pea protein concentrate and isolate could be successfully used in bakery products for enrichment in protein and improvement of biological value. Their utilization as meat protein substitute in some Frankfurter type sausages is also possibly.     

κ-卡拉胶对大豆分离蛋白乳浊凝胶特性的影响

研究了κ 卡拉胶在不同pH的条件下对大豆分离蛋白乳浊凝胶质构特性和流变特性的影响。研究结果表明 ,pH 7 3条件下的乳浊体系比 pH 6 8的体系更易形成凝胶。卡拉胶质量分数为 0 0 5 %时 ,因与大豆分离蛋白发生静电吸引相互作用形成连接型凝胶而显著提高了凝胶的质构特性和流变特性。 0 2 %时则形成相分离型凝胶 ,降低了凝胶的弹性和内聚性。     

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.     

大豆分离蛋白-脂质涂层对冷却牛肉品质的影响

研究脂质(硬脂酸、棕榈酸、巴西棕榈蜡和三乙酸甘油脂)与大豆分离蛋白制成的可食性涂层对冷却牛肉品质的影响。考察冷却牛肉在4℃下贮藏108h过程中失重率、颜色、pH值、硫代巴比妥酸值和感官特性的变化。结果表明冷却牛肉在4℃贮藏时的货架期小于108h,而且在4℃贮藏84h后,不同大豆分离蛋白-脂质涂层的优点不同。其中,三乙酸甘油酯蛋白涂层不仅延缓冷却牛肉的氧化,而且有效维持其感官特性,对维持冷却牛肉品质和延长期货架期效果最佳。     

聚磷酸钠对大豆分离蛋白的修饰研究

采用多聚磷酸钠对大豆分离蛋白进行磷酸化修饰,研究磷酸化反应的工艺条件及改性后大豆分离蛋白几种功能特性的变化。结果表明:当大豆分离蛋白4%、三聚磷酸钠9%、反应初始pH9、反应时间3h时,磷酸化程度最大;磷酸化后的大豆分离蛋白的溶解性、乳化性以及粘度都有不同程度的改善。     

Amino acid profile of the seed and other parts of the winged bean

The chemical composition of the seeds and other parts of the winged bean shows some variation in their nutrient content. The protein content in the seeds is similar to that in soybean while the roots have a protein level higher than that of any known tropical root crop. The amino acid composition of the different parts of the winged bean indicates high amounts of lysine and threonine with total essential amino acids similar—or even superior—to that of soybean seeds. All the parts studied except the roots, the unripe pods and the entire plant contain less total S-amino acids than soybean seeds. In terms of their percentage of FAO values adjusted for digestibility, all the different parts show good quality protein which can be utilised in supplementing cereal-based diets.