食品科学 ›› 2019, Vol. 40 ›› Issue (4): 34-41.doi: 10.7506/spkx1002-6630-20171227-346

• 食品化学 • 上一篇    下一篇

过氧自由基氧化对米糠蛋白结构和功能性质的影响

尤翔宇,黄慧敏,吴晓娟,吴?伟*   

  1. (稻谷及副产物深加工国家工程实验室,中南林业科技大学食品科学与工程学院,湖南?长沙 410004)
  • 出版日期:2019-02-25 发布日期:2019-03-05
  • 基金资助:
    国家自然科学基金面上项目(31771918);国家级大学生创新创业训练平台项目(201810538014); 湖南省大学生研究性学习与创新性实验计划项目(湘教通〔2018〕255号)

Effects of Oxidative Modification by Peroxyl Radicals on the Structural and Functional Properties of Rice Bran Protein

YOU Xiangyu, HUANG Huimin, WU Xiaojuan, WU Wei*   

  1. (National Engineering Laboratory for Rice and By-Product Deep Processing, School of Food Science and Engineering, Central South University of Forestry and Technology, Changsha 410004, China)
  • Online:2019-02-25 Published:2019-03-05

摘要: 采用不同浓度的2,2’-盐酸脒基丙烷(2,2’-azobis(2-amidinopropane),AAPH)有氧热分解产生的过氧自由基氧化米糠蛋白,研究过氧自由基氧化对米糠蛋白结构和功能性质的影响。结果显示:随着AAPH浓度的增加,米糠蛋白羰基、二硫键和二酪氨酸含量分别从2.0?nmol/mg、12.04?nmol/mg和84.54增加到7.09?nmol/mg、14.69?nmol/mg和127.1,游离巯基含量从23.97?nmol/mg下降到15.29?nmol/mg。过氧自由基氧化导致米糠蛋白α-螺旋和无规卷曲相对含量下降,β-折叠相对含量增加,氨基酸残基侧链含量先增加后略微下降;同时使得米糠蛋白表面疏水性和内源荧光强度下降,最大荧光峰位蓝移。过氧自由基氧化对蛋白质亚基结构影响较小,可同时使得米糠蛋白多肽链聚集和主肽链部分断裂形成多肽。随着AAPH浓度的增加,米糠蛋白溶解性逐渐降低,持水性、持油性、起泡能力、泡沫稳定性、乳化性和乳化稳定性先上升后下降。

关键词: 过氧自由基, 米糠蛋白, 蛋白质氧化, 结构, 功能性质

Abstract: Effects of oxidative modification by peroxyl radicals derived from oxidative thermal decomposition of 2,2’-azobis(2-amidinopropane) (AAPH) at different concentrations on the structural and functional properties of rice bran protein were investigated. The results indicated that as AAPH concentration increased, protein carbonyl, disulfide, and dityrosine contents of rice bran protein increased from 2.0 nmol/mg, 12.04 nmol/mg, and 84.54 to 7.09 nmol/mg, 14.69 nmol/mg, and 127.1, respectively, while free sulfhydryl content decreased from 23.97 to 15.29 nmol/mg. Oxidative modification by peroxyl radicals resulted in a decrease in α-helix and random coil content and an increase in β-sheet content. Besides, the content of amino acid side chains firstly increased, and then slightly decreased after this treatment, which also led to a decreased in surface hydrophobicity and intrinsic fluorescence intensity accompanied by a blue shift of the maximum emission wavelength. Nevertheless, oxidative modification by peroxyl radicals had no significant impact on the subunit structure of rice bran protein, but caused polypeptide chain aggregation of rice bran protein accompanied by partial rupture of the major polypeptide chain to form peptides. As AAPH concentration increased, rice bran protein solubility gradually decreased; however, water-holding capacity, oil-holding capacity, foaming activity, foaming stability, emulsifying activity, and emulsiong stability firstly increased and then decreased.

Key words: peroxy radicals, rice bran protein, protein oxidation, structure, functional properties

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