热处理强度对大豆分离蛋白凝胶形成能力的影响

为探究不同热处理强度对大豆分离蛋白凝胶形成能力的影响,并对两者之间的关系进行研究,采用热分析、圆二色谱、质构测定、SDS-PAGE等方法对蛋白样品的变性程度、二级结构以及凝胶性质进行分析。结果表明:SPI中7S与11S组分完全变性拟合方程分别为y=3.784 12×10~(13)x~(-6.521 6)和y=2.925 07×10~(11)x~(-4.818 1),凝胶强度和持水性分别在95℃处理30和50 min时出现最大值25.1 g和93%。凝胶强度与持水性均随着温度和时间的增加,呈现出先增加后减小的趋势。表面疏水性和表面巯基含量最大分别为364.4±23.76和6.936±0.050 68μM·g~(-1),表面性质测定结果表明凝胶形成能力的降低是由于加热条件较为剧烈时,蛋白质分子会重新将部分疏水区包埋,导致作用基团减少。本研究建立了热处理强度和凝胶强度与持水性的拟合方程,为目的不同的SPI凝胶制备提供参考,同时也为长保质期豆腐的工业化生产中煮浆工序的工艺参数提供一定指导。

Effect of Heat Treatment Conditions on Gel Formation Ability of Soybean Protein Isolate

In this paper,we studied the effects of different heat treatment conditions on the gel formation ability of soybean protein isolate and described the relationship between them.The denaturation degree,secondary structure and gel properties of protein samples were analyzed by thermal analysis,circular dichroism,texture determination and SDS-PAGE.The results showed that the complete denaturation equation of 7S and 11S components in SPI were y =3.784 12 × 1013x-6 521 6,and y =2.925 07 ×1011x-4.818 1.The gel strength and water holding capacity were 25.1 g and 93％ heated for 30 and 50 min at 95℃,respectively.The gel strength and water holding capacity increased firstly and then decreased with the increasing of temperature and time.The surface hydrophobicity and surface mercapto content were 364.4 ± 23.76 and 6.936 ± 0.050 68 μM·g-1,respectively.The results of surface properties showed that the decrease of gel formation ability was due to the fact that the protein molecules could be re-embed part of the hydrophobic region,resulting in declining in the number of acting groups.In this study,the heat treatment conditions and the fitting equation of the gel strength and water holding capacity were established,which provided reference for the preparation of different SPI gels,and provided some guidance for the process parameters of the cooking process in the industrial production of long-lasting tofu.