Gelation Enhancement of Soy Protein Isolate using the Maillard Reaction and High Temperatures

Soy protein isolate gels prepared by autoclaving solutions in the presence of xylose of glucono-δ-lactone (GDL), were compared. In both cases, the pH decreased from neutral to pH 5.5 during gel formation. In the xylose systems, this pH decrease was a consequence of the Maillard reaction. The Maillard gels showed less syneresis, had a higher breaking force and were more elastic, as determined by stress relaxation, then the GDL gels. The differences were attributed to formation of additional covalent crosslinks due to the Maillard reaction, as evidenced by greatly reduced solubility in sodium dodecyl sulfate +β-mercaptoethanol.     

凝固剂及凝固条件对大豆蛋白胶凝性质的影响

以大豆蛋白的凝胶强度、持水性、凝固速率这3个胶凝特性为主要指标,测定了包括蛋白浓度、热处理温度和时间、凝固剂种类和添加量、pH值、离子强度在内的这些因素对上述胶凝性质的影响,并确定了最优凝固工艺条件:质量浓度60g/L的SPI溶液经95℃热处理15min后,分别以质量分数0.4%熟石膏(CaSO4·1/2H2O)和质量分数0.28%葡萄糖酸内酯(GDL)作为凝固剂,保温30min后,冷却至室温;最佳离子强度为0.01mol/L(NaCl)。     

盐浓度对商用大豆分离蛋白凝胶的胶凝过程及动态粘弹性的影响

通过动态振荡测量检讨了NaCl和CaCl2对商用大豆分离蛋白(SPI)热诱导凝胶的胶凝过程及动态粘弹性的影响。添加一定浓度的NaCl延缓了商用SPI的起始凝胶点,然而却显著地增强了其凝胶性能。对于经超声处理的商用SPI分散液,情形则相反,添加NaCl加快了起始凝胶点,然而却降低了最终形成的凝胶的粘弹性。添加CaCl2也可使经超声处理的SPI样品的起始凝胶点大大提前,而且增强了最终形成的凝胶的粘弹性。上述结果说明,超声处理可改变商用SPI的凝胶性能,凝胶的形成几乎不需添加NaCl,而且似乎可以通过添加CaCl2调控经超声处理的SPI分散液直接形成凝胶,从而显示出超声处理在食品工业中的应用前景。     

蛋白质凝胶机理的研究进展

凝胶特性是食品蛋白质的重要功能特性,蛋白质的凝胶行为及其流变性质是形成某些食品独特的质构、感官和风味的决定性因素。长期以来,人们对蛋白质的凝胶行为进行了广泛深入的研究,但对蛋白质凝胶的机理和凝胶动力学还没有完全了解。本文对当前有关蛋白质凝胶的类型、凝胶过程中蛋白质分子构象的变化、形成蛋白质凝胶的主要作用力和凝胶动力学过程的研究进展作了综述。随着现代分析研究技术的进步,对蛋白质凝胶行为的认识也逐渐深入。     

商用大豆分离蛋白可溶絮凝物的制备及其性能研究

本文报道了超声处理制备可溶的商用大豆分离蛋白(SPI)絮凝物。经SDS-PAGE及SE-HPLC分析确认,超声处理可使不溶的SPI组份形成一种可溶的絮凝物,后者包含了原先不溶的大豆球蛋白的碱性亚基及大部分的β-伴大豆球蛋白。与未经超声处理的SPI分散液相比,经超声处理的分散液具有更高的热稳定性及凝胶性能。该研究结果可为商用SPI在食品中的应用提供一定的指导。     

肌原纤维蛋白与大豆分离蛋白复合体系乳化性的研究

本研究选择95℃加热90min的大豆分离蛋白构建肌原纤维蛋白与大豆分离蛋白复合乳化体系。在单因素实验基础上,选取蛋白比例、氯化钠浓度和均质时间3个因素对肌原纤维蛋白与大豆分离蛋白复合体系的乳化性进行响应曲面分析,建立复合蛋白乳化活性2次多项数学模型。在分析各因素的显著性和交互作用后,确定提高肌原纤维蛋白与大豆分离蛋白复合体系乳化性的方法为:蛋白比例1∶4.4,Na Cl浓度0.46mol/L,均质时间70s,该条件下肌原纤维蛋白与大豆分离蛋白复合体系乳化活性为22.42m2/g。      

大豆分离蛋白制备过程中热处理及干燥方式对其热聚集行为和凝胶性能的影响

该研究以低温脱脂豆粕为原料,采用“碱溶酸沉”法收集大豆蛋白沉淀,对其进行分散、热处理和喷雾干燥或冷冻干燥制备获得大豆分离蛋白（SPI）。通过观察该产品的热聚集行为及其所成热致凝胶机械性能,考察热处理和干燥方式对所得产品凝胶性能的影响。结果表明,热处理使制得大豆分离蛋白多以聚集体的形式存在,导致其溶解性（pH值7.0）分别从79.9%和69.8%下降至35.2%和42.0%。相对于经过热处理制得的大豆分离蛋白,未经过热处理制得的大豆分离蛋白其差示扫描量热仪分析图存在78℃和98℃吸热峰;其分散液再次经历热处理后,分散液中蛋白的体积分数约从30%下降至20%,展现出进一步聚集并形成有序结构的趋势;对于质量分数为16%的喷雾干燥大豆分离蛋白（SD-SPI）和冷冻干燥大豆分离蛋白（FD-SPI）样品分散液所制备的凝胶,其断裂应力分别为10.80 kPa和12.50 kPa,显著高于对应HSD-SPI（经热处理）凝胶的3.69 kPa和HFD-SPI（经热处理）的4.36 kPa,但后两者硬度高于前两者。另一方面,干燥方式没有对所得大豆分离蛋白的凝胶性质产生显著的影响。可见,大豆分离蛋白制备过程...     

Covalent chemical modification of myofibrillar proteins to improve their gelation properties: A systematic review

To improve the quality of meat products is a constant focus for both the meat industry and scientists. As major components in meat protein, the gelation properties of myofibrillar proteins (MPs) predominantly determine the sensory quality and product yield of the final product. Naturally or artificially occurring covalent modifications are known to largely affect MP functionality by changing the protein structure and forming aggregates, leading to both favorable and unfavorable outcomes. The review aims to summarize the mechanisms associated with several covalent modifications and the recent developments in enhancing MP gelation properties. Various extrinsic and intrinsic parameters controlling oxidation, phenolic–protein interactions, enzyme catalysis, glycation, and isoelectric solubilization/precipitation, and their effects on the characteristics of heat-induced MP gels are discussed. This article provides an improved understanding of the covalent modifications that occur mainly in the MP system and how they can be utilized to promote its gelation properties. Covalent modifications exhibited dose-dependent and dual-role manners for MP gelation properties. Mild oxidation, enzyme catalysis, and isoelectric solubilization/precipitation treatment would be beneficial to form more aligned and cross-linked three-dimensional networks for MP gels because of moderate protein aggregation. However, an excessive aggregate impedes the MP gelation behavior, leading to reduced gelation quality. Glycation effectively increased hydrophilicity of MPs and phenolic conjugation provides MPs with novel bioactivity. A proper utilization of such a process or even a rational combination of them allowed us to enhance the gelation properties of MP with assorted appreciated functionalities and further improve the quality of meat products.     

Production of safflower protein isolates: Composition,yield and protein quality

The use of laboratory- and commercially-prepared safflower meal for the production of protein isolates is described. The isolates were obtained by micellisation and isoelectric precipitation techniques, the latter being the most efficient procedure. Previous treatments received by the meal, for example heating, influenced the protein recovery. In general, isolates produced by micellisation were more soluble than samples obtained by isoelectric precipitation. The colour of the protein isolates depended on the isolation technique and type of safflower meal utilised. All isolates had a similar amino acid composition and levels of in-vitro protein digestibility.     

Effects of oxidative modification on thermal aggregation and gel properties of soy protein by peroxyl radicals

Effects of protein oxidation on thermal aggregation and gel properties of soy protein by 2,2′‐azobis (2‐amidinopropane) dihydrochloride (AAPH)‐derived peroxyl radicals were investigated in this article. Incubation of soy protein to increase concentration of AAPH resulted in a decrease in particle size and content of thermal aggregates during thermal‐induced denaturation. Protein oxidation resulted in a decrease in water‐holding capacity (WHC), gel hardness and gel strength of soy protein gel. An increase in coarseness and interstice of the gel network was accompanied by uneven distribution of interstice as extent of oxidation of soy protein increased. A decrease in disulphide content and formation of oxidation aggregates in the process of oxidative modification were contributed to the decline of particle size and content of thermal aggregates during thermal‐induced denaturation, leading to a decrease in WHC, gel hardness and gel strength of soy protein gel.     

Roles of soluble and insoluble aggregates induced by soy protein processing in the gelation of myofibrillar protein

The role of soluble and insoluble aggregates induced by soy protein isolate (SPI) processing in the gelling properties of myofibrillar protein (MP) was studied. Incorporating soluble SPI aggregate could greatly improve (P < 0.05) the elastic modulus (G’) and water‐holding capacity (WHC) of MP gel, but had no notable effect on MP gel strength. In contrast, incorporating the insoluble SPI aggregate significantly enhanced the G’, strength and WHC of MP gel, although the improvement in WHC was smaller than that produced by the soluble aggregate. The results of environmental scanning electron microscopy showed that the soluble SPI aggregate induced a less randomly composite gel structure, which may explain its notable enhancement of WHC. However, the insoluble SPI aggregate appeared to be granules embedded in the continuous MP gel matrix, which may be related to the reinforcement of gel strength. Hence, the results of this study suggest further means of processing commercial SPI for use in meat products.     

改性大豆分离蛋白与肌原纤维蛋白共混体系乳化性及凝胶性研究

采用热改性、碱改性、超声改性及辐照改性4种方法将大豆分离蛋白进行改性处理,并建立改性大豆分离蛋白与肌原纤维蛋白共混体系,对其乳化性及凝胶性进行研究。结果表明经热改性的大豆分离蛋白与肌原纤维蛋白共混体系的乳化性及凝胶性有显著提高,其中乳化活性提高了12.6 m2/g,硬度和弹性分别增加了18.58 g和0.16 mm,持水性增加了22.14%。经碱改性的SPI对混合体系的乳化性和凝胶性影响次之,而经超声和辐照改性的大豆分离蛋白,只对共混体系的持水性和乳化稳定性有影响,对质构性和乳化活性影响不显著。     

醇法大豆浓缩蛋白改性及在肉制品中的应用

采用醇法提取大豆浓缩蛋白具有明显优势,但此方法提取的大豆浓缩蛋白功能性不好,应用受限。本文介绍了通过物理、化学、酶法、基因工程等方法对醇法大豆浓缩蛋白进行改性,改性后醇法大豆浓缩蛋白的功能性明显提高。改性后的醇法大豆浓缩蛋白应用于肉制品中具有优良的持水持油性、乳化性以及凝胶性,可以提高肉制品的组织结构特性,并降低生产成本,且价格低廉,是一种性价比很高的大豆蛋白产品。     

Functional,amino acid composition and protein profiling of protein isolates from different pigmented,nonpigmented and improved rice varieties and their effects on starch thermal and dynamic rheological behaviour

The amino acids composition, protein profiling and functional properties of protein isolates from different pigmented rice (PR), nonpigmented rice (NPR) and improved rice (IR) varieties were determined and their effects of incorporation on starch thermal, and dynamic rheological were evaluated to know the possible interactions in food matrix. Protein isolates (PI) from PR and IR showed better foaming capacity and, foam stability than those from NPR. PI from both the PR and IR showed higher proportion of histidine, threonine, valine, methionine, phenylalanine and isoleucine. PI from IR showed higher accumulations of glutelins (31 and 33kDa, 21 and 22 kDa) and prolamins (15kDa, 16kDa, 17 kDa and 20kDa) than those from rice types. Starches from IR showed higher storage modulus (Gʹ) and loss modulus (Gʺ) than that from PR, and NPR, and decreased on addition of PI. PI from PB1121 IR was more suitable for protein enrichment due to more lightness value, and superior functionality (emulsification and foaming properties). Starch-protein interaction affects the functionality, and behaviour of matrix and, developing hypoallergenic infant formulations or other food products.     

大豆分离蛋白-水溶性大豆多糖可食性复合膜的制备与性质

以大豆分离蛋白(soy protein isolates,SPI)和水溶性大豆多糖(soluble soybean polysaccharides,SSPS)为主要原料进行了可食性复合膜的制备与性质研究。综合考虑SPI与SSPS的比例、甘油、海藻酸钠添加量及钙离子浓度等影响因素,通过单因素与正交实验对成膜配方进行研究,得到了复合膜的最佳配比,并从水溶性、水蒸气透过性、抗拉伸强度、断裂延伸率等方面对膜的性质进行了综合评价。结果显示:在SPI∶SSPS质量比为1∶7,甘油添加量2%,海藻酸钠添加量4%,Ca2+浓度为1.0mol/L的条件下,复合膜的综合性能评分最高,为67.8。     

Physicochemical, thermal and functional characterisation of protein isolates from Kabuli and Desi chickpea (Cicer arietinum L.): a comparative study with soy (Glycine max) and pea (Pisum sativum L.)

BACKGROUND: Chickpea (Cicer arietinum L.) seeds are a good source of protein that has potential applications in new product formulation and fortification. The main objectives of this study were to analyse the physicochemical, thermal and functional properties of chickpea protein isolates (CPIs) and compare them with those of soy (SPI) and pea (PPI) protein isolates. RESULTS: Extracted CPIs had mean protein contents of 728–853 g kg^?1 (dry weight basis). Analysis of their deconvoluted Fourier transform infrared spectra gave secondary structure estimates of 25.6–32.7% α‐helices, 32.5–40.4% β‐sheets, 13.8–18.9% turns and 16.3–19.2% disordered structures. CPIs from CDC Xena, among Kabuli varieties, and Myles, among Desi varieties, as well as SPI had the highest water‐holding and oil absorption capacities. The emulsifying properties of Kabuli CPIs were superior to those of PPI and Desi CPIs and as good as those of SPI. The heat‐induced gelation properties of CPIs showed a minimum protein concentration required to form a gel structure ranging from 100 to 140 g L^?1. Denaturation temperatures and enthalpies of CPIs ranged from 89.0 to 92.0 °C and from 2.4 to 4.0 J g^?1 respectively. CONCLUSION: The results suggest that most physicochemical, thermal and functional properties of CPIs compare favourably with those of SPI and are better than those of PPI. Hence CPI may be suitable as a high‐quality substitute for SPI in food applications. Copyright © 2011 Society of Chemical Industry     

葡萄糖、氯化钠、磷酸盐及卡拉胶对大豆分离蛋白凝胶特性的影响

肉制品生产需要添加多种辅料成分,包括调味类、发色类、品质改良类、抗氧化类等等,辅料的作用并非单纯叠加,而是存在交互作用,共同影响制品状态。本文选择了肉制品中普遍添加的葡萄糖、氯化钠、复合磷酸盐、卡拉胶,以大豆分离蛋白凝胶特性和感官状态为指标,考察了四种成分对大豆分离蛋白的影响,为肉制品辅料的应用提供一些基础数据。      

Thermal denaturation and gelation of vicilin-rich protein isolates from three Phaseolus legumes: A comparative study

The thermal denaturation and gelation properties of vicilin-rich protein isolates from red bean, red kidney bean and mung beans (further denoted as RPI, KPI and MPI) were investigated by differential scanning calorimetry (DSC) and dynamic oscillatory measurements. The relation between the properties of these proteins to their free sulphydryl (SH)/disulfide bond (SS) contents was also evaluated. DSC analyses showed that many DSC characteristics of major endothermic peak (corresponding to vicilin component), including its denaturation temperature (T_d), enthalpy changes (ΔH) and width at half-peak height (ΔT_1/2), significantly varied with the type of protein isolates. Furthermore, the heat-induced gelation, including onset of gelation and the development of mechanical moduli, was also dependent on the type of protein isolates. The thermal denaturation of these proteins was nearly unaffected by the presence of reducing agent dithiothreitol (DTT), while the presence of DTT weakened the gel formation. The T_d of vicilin components and the mechanical moduli of corresponding formed gels were positively related to their SS contents. Additionally, the formed gels were thermo-irreversible, and heat pretreatment (carried out at temperatures higher than or close to the T_d of these vicilins) could improve the gel network formation. These results confirm that vicilin-rich protein isolates from various legumes show different patterns of thermal denaturation and gelation, and these properties are to a great extent related to their SH and/or SS contents.