摘要
以传统碱溶酸沉制备米糠蛋白所用的盐酸为对照,采用酒石酸、苹果酸、柠檬酸3种有机酸分别在pH 4.0、3.5、3.0、2.0条件下酸沉制备米糠蛋白,研究有机酸酸沉对米糠蛋白结构的影响。结果表明,同种有机酸在不同pH值条件下酸沉,当酸沉pH值下降时,米糠蛋白总巯基含量和α-螺旋相对含量无显著变化,游离巯基含量和无规卷曲相对含量上升,β-折叠和β-转角相对含量下降,内源荧光强度和表面疏水性先增加后下降。相比盐酸酸沉,有机酸在相同pH值条件下酸沉制备米糠蛋白的总巯基、二级结构组成和表面疏水性无显著差异,但游离巯基含量下降、内源荧光强度升高。分子质量分布、粒径分布及电泳结果表明,较低pH值条件下的酸沉可导致米糠蛋白结构发生部分解离和聚集,但没有形成新的亚基和高分子质量聚集体。
In order to assess the effect of acid precipitation with different organic acids on the structure of rice bran protein,tartaric,malic,and citric acid were separately used to prepare rice bran protein at varying pH values(4.0,3.5,3.0,and 2.0)in comparison with hydrochloric acid as control.The results indicated that for each organic acid,total sulphydryl andα-helix content of rice bran protein did not significantly change with decreasing pH,whereas free sulphydryl and random coil content increased,β-sheet andβ-turn content decreased and intrinsic fluorescence intensity and surface hydrophobicity firstly increased and then decreased.Total sulphydryl content,secondary structure composition and surface hydrophobicity of rice bran protein prepared with organic acids did not significantly differ from those of rice bran protein obtained with hydrochloric acid,whereas a decrease in free sulphydryl content was observed together with an increase in intrinsic fluorescence intensity.The results of molecular mass distribution,particle size distribution,and electrophoresis indicated that acid precipitation at low pH resulted in partial dissociation and aggregation of rice bran protein without leading to the formation of new subunits and high molecular weight aggregates.
作者
吴伟
吴晓娟
杨滔滔
WU Wei;WU Xiaojuan;YANG Taotao(National Engineering Laboratory for Rice and By-Product Deep Processing,College of Food Science and Engineering,Central South University of Forestry and Technology,Changsha 410004,China)
出处
《食品科学》
EI
CAS
CSCD
北大核心
2018年第16期40-46,共7页
Food Science
基金
国家自然科学基金面上项目(31771918)
公益性行业(农业)科研专项(201303071)。
关键词
米糠蛋白
有机酸
酸沉
结构特征
rice bran protein
organic acid
acid precipitation
structural characteristics
