转谷氨酰胺酶聚合改性大豆分离蛋白的功能特性研究

研究了转谷氨酰胺酶(MTGase)聚合改性大豆分离蛋白的持水性、吸油性、溶解性、乳化性、发泡性及凝胶强度等功能特性。结果显示,与大豆分离蛋白相比,MTGase改性的大豆分离蛋白(MSPI)具有更高的凝胶性和乳化稳定性,但其溶解性、持水性、吸油性、起泡性与泡沫稳定性和乳化性明显减弱。     

物理改性对棉籽分离蛋白功能特性影响

采用水浴加热、超声波和微波辐射三种方法对棉籽分离蛋白进行改性处理,研究不同方法对蛋白的溶解性、持水性、吸油性、乳化性、乳化稳定性和起泡性等影响。实验结果表明,不同处理方法对棉籽分离蛋白功能特性均有一定改善,其中加热方法对蛋白起泡性影响较大,提高53.2%;微波辐射方法对蛋白溶解性、持水性、吸油性、乳化性有明显改善,分别提高5.0%、70.3%、6.5%、35.8%;超声波方法对蛋白乳化稳定性及起泡稳定性有一定改善,乳化稳定性提高51.6%;三种方法以微波辐射改性方法效果最优。     

南瓜籽蛋白的提取分离及性质研究

南瓜籽粕经醇洗、盐提酸沉后制得南瓜籽分离蛋白,对其溶解性、吸水性、吸油性、乳化性和起泡性进行了研究,并与大豆分离蛋白进行比较。发现南瓜籽分离蛋白的吸水性、吸油性稍低于大豆分离蛋白,而起泡性和起泡稳定性都高于大豆分离蛋白,乳化活力和乳化稳定性稍稍高于大豆分离蛋白。南瓜籽分离蛋白SDS-PAGE显示南瓜籽分离蛋白由9条主带组成。     

红小豆分离蛋白功能特性研究

研究红小豆分离蛋白的溶解性、吸水性、吸油性、乳化性和乳化稳定性、起泡性和起泡稳定性,并与大豆分离蛋白进行对比。结果表明:红小豆分离蛋白在较低的pH值下具有更好的溶解性,吸油性、乳化性和起泡性与大豆分离蛋白相当,但比大豆分离蛋白具有更好的乳化稳定性和起泡稳定性。     

冷冻温度和时间对大豆分离蛋白功能特性的影响

研究不同冷冻温度下大豆分离蛋白吸油性、乳化性、黏度和溶解性等功能特性随时间的变化。结果表明:大豆分离蛋白的吸油性在-30℃条件下波动相对较小,性质相对较稳定;大豆分离蛋白的乳化性在25 d之内,波动范围不大,25 d时乳化性最低,30~35 d时乳化性上升并保持稳定。大豆分离蛋白的黏度整体呈下降趋势,30~35 d时,黏度有一定程度的上升,但是均未达到初始状态最大值;大豆分离蛋白的溶解性在0℃的储存条件下较稳定,波动较小,但超过30 d溶解性下降。     

辐照对大豆中蛋白质品质的影响

以大豆为原料,利用食品辐照技术对大豆进行了加工处理,研究了不同辐照剂量和储存时间对大豆中菌落数、粗蛋白含量以及浓缩蛋白功能特性(氮溶指数、吸水性、吸油性、乳化性和乳化稳定性)的影响.研究结果表明,10kGy的辐照可以有效减少大豆中的霉菌数,提高粗蛋白干基含量,同时可以改善大豆浓缩蛋白的功能特性20kGy的辐照与10kGy的辐照剂量相比,虽然也能达到杀菌的效果,但是却会导致蛋白功能特性的降低.     

玉米醇溶蛋白提取工艺及功能性质研究

阐述了玉米醇溶蛋白的提取工艺，并对玉米醇溶蛋白的吸水性、持水力、湿润性、吸油性、乳化性、乳化稳定性、凝胶性和粘度等功能特性进行了测定，并与大豆分离蛋白和酪蛋白的相关性质进行比较，结果表明：玉米醇溶蛋白的吸水性低于大豆分离蛋白，但高于酪蛋白；玉米醇溶蛋白具有较好湿润性、吸油性、凝胶性，较弱的持水力和乳化性，一定的乳化稳定性．粘度随时间增加而增大。     

蚕豆分离蛋白的制备及其功能性质研究

研究了蚕豆分离蛋白的制备工艺，确定了蚕豆蛋白浸提的最佳工艺参数，并对蚕豆分离蛋白的溶解性、吸水性、吸油性、乳化性及乳化稳定性、起泡性、凝胶性等功能性质进行了研究。研究结果表明：蚕豆蛋白浸提的最佳工艺条件为pH值8．0、提取时间20min、提取温度50℃、料水比1：15；蚕豆分离蛋白的吸油性、乳化稳定性和起泡性优于大豆分离蛋白，吸水性、乳化性较差。     

甜杏仁蛋白的功能和结构的研究

溶解度测定表明,甜杏仁蛋白的等电点为4.5.对甜杏仁蛋白功能性质的测定表明,甜杏仁蛋白的吸水和吸油能力均优于大豆分离蛋白;当乳化温度由20℃上升至50℃时,其乳化能力逐渐上升,60℃后乳化能力逐渐下降.乳化稳定性在40℃后显著下降;其起泡性不如大豆分离蛋白,而泡沫稳定性与大豆分离蛋白相似.对甜杏仁蛋白的氨基酸组成分析表明,其氨基酸种类齐全,尤其谷氨酸含量丰富.组成分析结果表明,甜杏仁蛋白包含四种不同组分,其中77%左右为清蛋白,其余三种蛋白含量较低.     

微波处理对醇法大豆浓缩蛋白功能性的影响

利用微波处理对醇法生产的大豆浓缩蛋白进行改性,通过单因素试验和正交试验研究微波改性对大豆浓缩蛋白的乳化性、吸油性和吸水性的影响。试验结果表明:微波处理能够提高醇法大豆浓缩蛋白的乳化性、吸油性和吸水性,改性的最佳工艺条件为pH11、改性时间80s、功率630W、料液比1∶8。最佳改性条件下改性的大豆浓缩蛋白的乳化性、吸油性和吸水性为0.227OD、1.543g/g和5.669g/g,分别比对照提高了56.55%、17.7%和50.53%。     

Comparative studies on the functional properties of various protein concentrate preparations of peanut protein

The effect of different preparations on the functional properties of peanut protein concentrates was studied. Peanut protein concentrates were isolated from defatted peanut flour by isoelectric precipitation, alcohol precipitation, isoelectric precipitation combined with alcohol precipitation, alkali solution with isoelectric precipitation and their functional properties (protein solubility, water holding/oil binding capacity, emulsifying capacity and stability, foaming capacity and rheology) were evaluated. The results showed that the protein solubility, foaming capacity and stability of protein prepared by alkali solution with isoelectric precipitation were the best of all the peanut protein products. But the protein prepared by alcohol precipitation had better water holding/oil binding capacity, which was significantly different from other protein products. The emulsifying stability of protein concentrate prepared by different methods was significantly lower than that of defatted protein flour. The protein prepared by isoelectric precipitation and isoelectric precipitation combined with alcohol precipitation had better gel properties which indicated that they were a potential food ingredient.     

Effect of extraction and isolation on physicochemical and functional properties of an underutilized seed protein: Gingerbread plum (Neocarya macrophylla)

The effect of extraction and isolation on the physicochemical and functional properties of gingerbread plum seed protein isolate was studied. Gingerbread plum seed protein isolate was extracted from defatted gingerbread plum seed flour (DGPSF) by alkali solution along with isoelectric precipitation. The protein isolate was subjected to freeze or vacuum drying process. Freeze dried gingerbread plum seed protein isolate (FGPSPI) and vacuum dried gingerbread plum seed protein isolate (VGPSPI) were evaluated for their physicochemical and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity). Among physicochemical parameters, the proximate composition, amino acid composition, minerals, differential scanning calorimetry (DSC), SDS-PAGE and color attributes were studied. Both FGPSPI and VGPSPI contained over 90% protein versus DGPSF (56.72%) used as raw material. The method of drying had significant effect (p < 0.05) on the physicochemical characteristics of FGPSPI and VGPSPI except for amino acids composition. The functional properties were variable among samples. DGPSF had higher emulsifying, water holding and oil binding capacities compared with FGPSPI and VGPSPI. FGPSPI exhibited better emulsifying capacity and water holding capacity than VGPSPI. FGPSPI also showed comparable oil binding capacity and bulk density to commercial soy protein isolate (SPI). The results indicated that FGPSPI and VGPSPI could be a good source of protein fortification for a variety of food products for protein deficient consumers as well as a potential food ingredient.     

Effect of Partial Proteolysis and Succinylation on Functionality of Corn Germ Protein Isolate

Corn germ protein isolate (CGPI) was partially hydrolyzed with trypsin and pepsin and succinylated at three levels. Various functional and electrophoretic properties of the native and modified protein were determined. Water absorption and foaming properties of CGPI were Improved by partial hydrolysis with trypsin; emulsifying capacity and nitrogen solubility were reduced; oil absorption was increased only slightly. CGPI pepsin hydrolyzate has decreased oil absorption, nitrogen solubility and emulsifying capacity but improved foaming properties; water absorption was unchanged. Treatment of CGPI with succinic anhydride improved water and oil absorption, nitrogen solubility and foaming capacity but decreased emulsifying capacity; foam stability was unchanged. Succinylation retarded electropohoretic mobility while hydrolysis altered band intensities.     

Functional properties of 8S globulin fractions from 15 mung bean (Vigna radiata (L.) Wilczek) cultivars

The functional properties including solubility, water absorption capacity, oil absorption capacity, foaming properties and emulsifying properties of 8S globulin fractions from 15 mung bean cultivars were investigated in this study. In addition, the effects of pH on solubility, foaming properties and emulsifying properties were studied. The functional properties of the 8S globulin fractions varied significantly among the different mung bean varieties and exhibited better performance in solubility and emulsion stability compared with soya bean 7S protein. A negative correlation was found between water absorption capacity and oil absorption capacity. Remarkable differences in polypeptides constituents were observed in 8S globulin fractions, and the ratio of 11S/8S globulins has a positive effect on water absorption capacity while a negative effect on oil absorption capacity. As a function of pH, the emulsifying activity indexes of the 8S globulin fractions were found to be distinctly dependent on the solubility, while no significant correlation was found between the emulsifying stability and solubility, nor between the foaming properties and solubility. The foaming capacity showed a strong correlation with foam stability.     

Enhancement of Functional Properties of Rice Bran Proteins by High Pressure Treatment and Their Correlation with Surface Hydrophobicity

Changes in functional properties of rice bran proteins as influenced by high-pressure (HP) treatment (100–500 MPa, 10 min) were studied. Properties evaluated were protein solubility, water absorption capacity, oil absorption capacity, foaming capacity, foam stability, emulsifying activity, emulsion stability, least gelation concentration, and surface hydrophobicity. HP treatment at 100 and 200 MPa significantly improved the solubility and oil absorption capacity, while water absorption and foaming capacities increased further reaching the maximum at 500 MPa. Compared with the untreated control sample, the emulsifying activity and foam stability of treated samples were significantly higher and least gelation concentration was lower, but none of them showed any specific trend with pressure level. Emulsion stability and surface hydrophobicity increased with the pressure level until 400 MPa and decreased slightly at 500 MPa. Pearson correlation coefficients clearly showed that surface hydrophobicity was positively correlated with water absorption capacity, foaming capacity, emulsifying activity index, and emulsion stability index, but negatively correlated with least gelation concentration. The pressure treated rice bran protein possessed good functional properties for use as a food ingredient in the formulations.     

Functional properties of plant proteins. Part 2. Selected physicochemical properties of native and denatured protein isolates from faba beans,soybeans, and sunflower seed

Functional properties — as solubility, water and oil adsorption, emulsifying capacity, emulsion activity and stability — of protein isolates from faba beans, soybeans and sunflower seed depending on the isolation process were determined. Proteins isolated under mild conditions, it means by precipitation using dialysis or dilution of salt extracts with water, show the highest solubility, characterized by a sharp minimum of solubility at a rather narrow range of pH. An incubation of the precipitated proteins at low pH (pH 2) results in a decrease of the solubility on the alcaline and acidic part of the solubility profile. On the contrary to the decreased solubility, the proteins denatured by acid show an increased water adsorption capacity. Depending on the kind of protein and the conditions of preparation these values can reach the manifold ones of the control. Smaller increases of oil adsorption in acid-denatured proteins were found, too. The emulsion activity and stability were not or only slightly influenced, but the emulsifying capacity was strongly decreased by the denaturation procedure. The emulsifying capacity was influenced by the solubility of the protein, but a strong correlation does not exist. The high water adsorption of Promine D can be reached by the other plant proteins after denaturation. The sunflower protein showed the highest emulsifying capacity. Increasing the pH from the isoelectric range to 7 improves all studied functional properties.     

Preparation of spent brewer's yeast β-glucans for potential applications in the food industry

A preparation of β‐glucan, obtained from spent brewer's yeast, was evaluated for potential food applications. This material was autolysed and the cell walls that were obtained were homogenized, extracted firstly with alkali, then with acid, and then spray dried. Effects of the homogenization on the chemical composition, rheological properties and functional properties of β‐glucan were investigated. Homogenized cell walls exhibited higher β‐glucan content and apparent viscosity than those which had not been homogenized because of fragmentation of the cell walls. When compared with commercial β‐glucan from baker's yeast, it was found that the β‐glucan obtained from this study had higher apparent viscosity, water‐holding capacity and emulsion stabilizing capacity, but very similar oil‐binding capacity. These findings suggest that β‐glucan obtained from brewer's yeast can be used in food products as a thickening, water‐holding, or oil‐binding agent and emulsifying stabilizer.     

棉籽分离蛋白功能性质的研究

考察了棉籽各分离蛋白,包括清蛋白、球蛋白、醇溶谷蛋白及谷蛋白在棉籽蛋白中所占的比例,研究了各蛋白的功能性质,包括吸水性、吸油性、乳化性和乳化稳定性、起泡性与泡沫稳定性以及各蛋白的抗氧化活性。结果表明,谷蛋白为棉籽蛋白中的主要分离蛋白,棉籽清蛋白具有较高的吸水性、乳化性、乳化稳定性以及起泡性,吸油性相对较差,适用性相对较好,但在棉籽蛋白中含量较少,而谷蛋白的吸水性、乳化性、起泡性很差,具有一定的吸油性,适用性较差,但在棉籽蛋白中含量丰富,在抗氧化活性方面,各分离蛋白的抗氧化活性能力都较差,需要进行改性处理。     

减压等离子体处理对大豆分离蛋白功能性质的影响

运用减压等离子体处理大豆分离蛋白(soybean protein isolate,SPI),研究处理时间对SPI溶解性、乳化活性、触变性、热稳定性及表面粗糙度等功能性质的影响。结果表明:经100 W的减压等离子体处理150 s后,SPI的溶解度、乳化活性指数和吸水性均达到最大,分别为572.83μg/mL、0.584 m2/g和12.675 g/g,比对照分别增加约35%、15%和48%;吸油性随着处理时间的延长呈现先降低后上升的趋势,当处理时间为300 s时达到最大值2.071 mL/g,比对照增加了12%;流变学研究表明减压等离子体处理使SPI的黏度有所降低,但未影响其触变性及剪切变稀行为;差示扫描量热分析表明减压等离子体处理略微降低了SPI的热稳定性,扫描电子显微镜观察结果则表明减压等离子体处理增加了SPI颗粒的表面粗糙度。上述研究表明,减压等离子体处理可以改善SPI的溶解性、乳化性、吸水性、吸油性,因此在SPI的改性中具有潜在的应用价值。     

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.