改性大豆分离蛋白可降解材料抗水性的研究

利用环氧氯丙烷对大豆分离蛋白进行改性制取可降解材料,探讨各种影响因素对大豆分离蛋白可降解材料吸水性能的影响。结果表明,邻苯二甲酸酐对催化环氧氯丙烷交联改性大豆分离蛋白制取可降解材料的抗水性能有显著影响。     

大豆分离蛋白可降解材料抗水性的红外光谱法研究

利用环氧氯丙烷对大豆分离蛋白进行改性制取可降解材料,借助红外光谱测试技术探讨大豆分离蛋白可降解材料内部基团的变化与其抗水性能的关系。结果表明,邻苯二甲酸酐对催化环氧氯丙烷交联改性大豆分离蛋白制取可降解材料的抗水性能有显著地影响。     

环氧氯丙烷-己内酰胺改性对大豆分离蛋白可降解材料伸长率影响的研究

研究了大豆分离蛋白经过己内酰胺化学改性,丙酸增塑之后伸长率的变化,比较了不同体系下大豆分离蛋白材料的伸长率,同时分析指出了环氧氯丙烷-己内酰胺体系对材料机械性能的影响,为今后以大豆分离蛋白为原料制取可降解材料的研究奠定了基础。     

己内酰胺改性对大豆分离蛋白可降解材料性能影响的研究

研究大豆分离蛋白经过环氧氯丙烷和己内酰胺化学改性,丙酸增塑之后来制取可生物降解材料.以材料的拉伸强度、伸长率以及吸水率作为考察指标,测得了最佳结果为伸长率216%、吸水率33%、拉伸强度9 MPa.比较了不同改性体系下大豆分离蛋白可降解材料的性能,分析指出了环氧氯丙烷-己内酰胺体系对材料性能的影响,为今后的研究奠定了基础.     

脂类乳化剂对大豆分离蛋白塑料性能的影响

研究了脂类乳化剂对20%甘油增塑的大豆分离蛋白塑料性能的影响,结果表明:添加乳化剂能有效降低甘油增塑塑料的拉伸应变,但也降低了塑料的抗拉强度;单甘酯和硬脂酰乳酸钠都增加了塑料的吸水率;而较高添加量的硬脂酰乳酸钙降低了塑料的吸水率。添加8%的乳化剂都降低了大豆分离蛋白的变性温度,有利于塑料的塑化。研究表明,硬脂酰乳酸钙作为制备刚性大豆分离蛋白塑料的填充剂具有一定的应用价值。     

谷氨酰胺转氨酶对大豆分离蛋白塑料拉伸性能的影响

研究了微生物谷氨酰氨转胺酶对大豆分离蛋白塑料拉伸性能的影响,发现在50℃时转氨酶对大豆分离蛋白催化聚合反应60 min,形成的高分子聚合物使大豆分离蛋白的抗拉强度和杨氏模量分别由未经处理时的9.2 MPa和265.4 MPa增加到14.7 MPa和390.1 MPa,同时增加了蛋白质的变性温度和热焓值。在酶处理90 min时,由于转氨酶变性失去活性及大豆分离蛋白的部分变性,蛋白质塑料的拉伸性能反而下降。对大豆分离蛋白的预热处理降低了转氨酶的催化聚合反应,且变性后的大豆分离蛋白制备的塑料拉伸性能大大降低。     

加工条件对大豆分离蛋白塑料特性的影响

研究了在大豆分离蛋白塑料的热压过程中,成型时间、温度、压力和增塑剂的添加量对其透光率、拉伸强度、伸长率和吸水率的影响,得到了热压形成大豆分离蛋白塑料的最佳工艺条件。     

磷酸盐对大豆分离蛋白塑料性能影响的研究

研究了酸性磷酸盐(六偏磷酸钠和焦磷酸二氢二钠)和碱性磷酸盐(焦磷酸钠)对20%甘油增塑的大豆分离蛋白塑料拉伸性能、吸水性能、微观结构和蛋白质变性温度Td的影响。结果表明,添加磷酸盐使甘油增塑的大豆分离蛋白塑料由柔性转变为刚性。焦磷酸钠大大增加了塑料的吸水率,而添加较高剂量的六偏磷酸钠或焦磷酸二氢二钠降低了塑料的吸水率。添加8%的焦磷酸二氢二钠使大豆分离蛋白的变性温度降低了近10℃。酸性磷酸盐可以作为制备刚性大豆分离蛋白塑料的良好填充剂。     

大豆分离蛋白的热压改性研究

通过大豆分离蛋白(SPI)直接热压和经环氧氯丙烷修饰后再热压,探讨热压过程中蛋白分子表面巯基含量、蛋白分子表面疏水性以及蛋白分子形状的变化.结果表明,热压后蛋白分子表面巯基含量降低、蛋白分子表面疏水性增强,SPI球蛋白结构被破坏.     

改性对大豆分离蛋白可降解材料力学性能的影响

利用环氧氯丙烷对大豆分离蛋白(SPI)进行改性制备可生物降解材料,探讨了改性制备因素对大豆分离蛋白可降解材料力学性能的影响.结果表明,改性制备因素对材料的力学性能有显著影响;材料形成过程中的抗拉强度与分子表面巯基含量的变化没有必然的联系;经改性后可在SPI分子间形成交联大分子,同时维持蛋白分子空间构象的作用力也会对材料的力学性能产生影响.     

环氧氯丙烷增塑大豆蛋白的机理研究

本文利用傅立叶红外光谱仪(FTIR)对环氧氯丙烷增塑的大豆蛋白内部分子结构进行了深入分析,利用扫描电子显微镜(SEM)对不同增塑剂增塑的大豆蛋白材料断面概貌进行了比较,总结了环氧氯丙烷增塑大豆蛋白材料表现出高强度、低吸水率和低伸长率特点的原因以及环氧氯丙烷增塑大豆蛋白的机理。     

Enhanced bactericidal action and masking of allergen structure of soy protein by attachment of chitosan through Maillard‐type protein‐polysaccharide conjugation

The soy protein‐chitosan conjugate was formed by the Maillard reaction in dry state (relative humidity 65%) at 60°C for 2 weeks to improve the functional properties. The antimicrobial activity of the Maillard‐type soy protein‐chitosan conjugates enhanced 2–3 times that of soy protein‐chitosan mixture. The soy protein‐chitosan conjugate showed excellent emulsifying property with the progress of Maillard‐type conjugation. The allergenicity of soy protein was greatly decreased by the attachment of chitosan through Maillard reaction. The immonoblotting analysis with patient's sera revealed that soy protein‐chitosan conjugate was more effective to mask the allergen structure of soy protein causing from 34 kDa‐protein (Gly m Bd 30K) than soy protein‐galactomannan conjugate. The Western blotting showed that allergen (34 kDa‐protein) was completely masked by soy protein‐chitosan conjugation, while it was not completely masked by soy protein‐galactomannan conjugation.     

Microstructure and Texture of Process Cheese,Milk Curds,and Caseinate Curds Containing Native or Boiled Soy Proteins

Scanning electron microscopy was used to examine the internal microstructure of process cheese, process cheese containing native soy protein, process cheese containing boiled soy protein, rennet coagulated milk curd, milk curd containing native soy protein, milk curd containing boiled soy protein, rennet coagulated caseinate curd, caseinate curd containing native soy protein, and caseinate curd containing boiled soy protein. Textural characteristics were determined with an Instron Food Testing System. Soy proteins caused the fine network microstructure of processed cheese to change to coarse porous structure. Hardness of cheese was lowered, but cohesiveness was increased by adding soy protein to process cheese. In milk curd, particles of soy protein were clustered in groups in micrographs. Cohesiveness of milk curd was lowered by native soy protein and even more by boiled soy protein. Hardness and springiness were lowered by boiled soy protein. Boiled soy protein was more extensively aggregated than was native soy protein. Soy proteins were not clearly distinguishable from casein in the micrograph of caseinate curds. Soy proteins reduced hardness and cohesiveness of caseinate curd but not as drastically as in milk curd.     

不同大豆蛋白对小麦面条加工品质和血糖生成指数的影响

为改善小麦面条品质,在小麦粉中添加大豆蛋白(全脂豆粉、脱脂豆粉、大豆分离蛋白、大豆浓缩蛋白、大豆组织蛋白),以拉伸特性、蒸煮特性、微观结构以及血糖生成指数为评价指标,研究大豆蛋白添加量(0%、5%、10%、15%、20%)对面条加工品质及血糖生成指数的影响。结果表明:随蛋白添加量的增加,脱脂豆粉、全脂豆粉的增加使面条的拉断力呈明显上升趋势,拉伸距离呈先上升后下降趋势,大豆分离蛋白、大豆浓缩蛋白添加量的增加使拉断力呈先上升后下降趋势,拉伸距离呈下降趋势,而大豆组织蛋白的增加使面条拉伸性能均逐渐降低;当大豆蛋白添加量为10%时,混合粉面条拉伸特性较优;五种大豆蛋白的添加均使面条的烹煮损失率及断条率上升,全脂豆粉的增加使面条的吸水率、膨胀率逐渐下降,其余四种均使其上升;微观结构表明,脱脂豆粉和全脂豆粉的添加使混合粉面条的面筋网络结构更加连续均匀,而其余三种大豆蛋白添加量的增加造成混合粉面条微观结构的劣变;利用体外复合酶方法测定GI值,血糖生成指数依次为:小麦粉 > 脱脂豆粉 > 全脂豆粉 > 大豆组织蛋白 > 大豆浓缩蛋白 > 大豆分离蛋白。     

Improving Functional Properties of Soy Protein Hydrolysate by Conjugation with Curdlan

ABSTRACT:  Soy protein hydrolysate was conjugated with curdlan through the naturally occurring Maillard reaction to extend its application in food processing. The gel-forming and emulsifying properties of soy protein hydrolysates were significantly improved ( P < 0.05) by conjugation with curdlan. The soy protein hydrolysate–curdlan conjugate (SPHCC)–soy protein isolate (SPI) mixed gel had a much thicker network than the soy protein hydrolysate and SPI mixed gel judged from scanning electron microscopic images. The improvement of gelling properties of soy protein hydrolysate by curdlan-conjugate was attributed to both the decrease in the repulsive forces among soy protein hydrolysates and the increase in the solubility. The covalent binding of soy protein hydrolysates and curdlan also showed a profound effect on the antioxidative activity of the soy protein hydrolysates. The higher antioxidative activity of SPHCC was related to the peptide reductants produced from the Maillard reaction and the higher emulsifying property of SPHCC. The conjugates of soy protein hydrolysate and curdlan can be used as a functional food additive having excellent gel-forming, emulsifying properties and antioxidative activity.     

Improvement of the Functionalities of Soy Protein Isolate through Chemical Phosphorylation

A method of chemical phosphorylation was developed to modify soy protein so as to improve its functional properties. The reaction was carried out by incubating soy protein isolate and cyclic sodium trimetaphosphate in an aqueous solution at pH 11.5 and 35°C for about 3 hours. The reactions ensued were the phosphoesterification of serine residues and the phosphoramidation of lysine residues in soy protein. The phosphorylated soy protein isolate prepared there-from exhibited much improved functional properties in terms of aqueous solubility, water-holding capacity, emulsifiability and whippability. The nutritive bioavailability of soy protein isolate was not impaired by phosphorylation.     

Effects of Enzyme Modified Soy Protein on Rennet-Induced Reconstituted Nonfat Dry Milk Coagulum Properties

Soy protein was hydrolyzed by trypsin, pepsin and α-chymotrypsin. Effects of adding hydrolyzed soy protein on rennet-induced nonfat milk coagulum texture and syneresis were studied. Pepsin-modified soy protein increased coagulum firmness and syneresis greater than untreated soy protein. Soy protein hydrolyzed with trypsin for 150 min and added to nonfat milk increased coagulum firmness greater than nonfat milk with no soy protein added. Chymotrypsin-modified soy protein acted similarly to the trypsin modified soy protein except the coagulum firmness was less than nonfat milk alone. Soy protein hydrolyzed by trypsin followed by pepsin increased coagulum firmness more than hydrolysis by a single enzyme and was close to nonfat milk without soy protein.     

大豆分离蛋白对湿米粉储藏品质的影响

以湿米粉储藏过程中硬度、蒸煮损失和断条率的变化为指标,研究大豆分离蛋白对湿米粉品质的影响。结果表明,大豆分离蛋白会导致湿米粉硬度的升高,但在储藏过程中添加大豆分离蛋白的湿米粉硬度低于未添加大豆分离蛋白的湿米粉,这表明大豆分离蛋白可显著改善湿米粉在储藏过程中的硬度升高现象;当大豆分离蛋白添加量低于4%时,湿米粉的蒸煮损失和断条率均随大豆分离蛋白添加量的增加而下降;但大豆分离蛋白添加量达6%时,湿米粉的蒸煮损失和断条率上升。结果表明适量的大豆分离蛋白可改善湿米粉的食用品质,但大豆分离蛋白添加量不是越多越好。差示热量扫描和微观结构分析发现大豆分离蛋白可抑制湿米粉中淀粉的回生,赋予米粉蜂窝状多孔结构,有利于米粉在储藏过程中保持水分不发生迁移从而提高湿米粉品质。     

CERTAIN FUNCTIONAL PROPERTIES OF SUNFLOWER MEAL PRODUCTS

Certain functional properties including water absorption, fat absorption, emulsification, whippability and foam stability were determined on the sunflower flour, protein concentrates and isolate. The results were also compared to those obtained on soy products. Data on water and fat absorption studies suggest that soy products are more hydrophilic in nature while sunflower material exhibited greater lipophilic properties than the soy products. Emulsification tests showed that sunflower flour was superior to all other soy and sunflower products. In general, whipping properties of soy and sunflower isolates were similar, while less whippability was observed for the soy flour and protein concentrates. Whipped foams produced by soy and sunflower protein isolates and sunflower flour were more stable than soy flour, soy and sunflower protein concentrates.     

预热变性程度对大豆蛋白凝胶性质的影响

以非还原SDS-PAGE表征大豆蛋白的预热变性程度,并采用质构分析、流变分析研究预热变性程度对大豆蛋白凝胶性质的影响。SDS-PAGE结果表明,随着加热温度的升高蛋白质变性速率逐渐增大,相同加热时间条件下,蛋白质变性程度随加热温度升高呈S型曲线上升。质构、流变分析结果表明:随着预热变性程度的增大,大豆蛋白凝胶硬度先增大后减小,变性程度为86.11%时凝胶硬度最大,是未经预热变性的大豆蛋白凝胶硬度的2.15倍;凝胶弹性则随预热变性程度的增大持续增大;变性程度在22.28%以上时大豆蛋白形成凝胶更快,但完全变性大豆蛋白在形成凝胶时的降温阶段不能形成很好的凝胶结构。粒径分析结果表明,预热变性程度对大豆蛋白凝胶性质的影响与蛋白质预热变性时形成的聚集体尺寸及形态有关。