摘要
为了探究葡聚糖接枝作用对玉米醇溶蛋白结构和乳化性的影响,明确蛋白质结构与功能性的关系,本研究以玉米醇溶蛋白(Zein)和不同分子量(6、20、40和70 k Da)葡聚糖(dextran,DX)为原料,采用湿热法制备Zein-DX接枝物,并对接枝物的结构和乳化性进行研究。结果表明,低分子量(6 k Da)DX具有更高的反应活性,赖氨酸和精氨酸是参与Zein与DX接枝反应的主要氨基酸。傅里叶红外光谱(fourier transform infrared,FTIR)证明了DX以共价键与Zein形成了复合物。DX的共价接枝能够导致Zein荧光猝灭的发生,降低Zein的热稳定性,改善Zein的乳化活性(emulsifying activity index,EAI)和乳化稳定性(emulsifying stability index,ESI)。低分子量(6 k Da)DX与Zein形成的接枝物最大发射波长发生显著红移,三级结构变的松散,具有更低的热稳定性,且EAI最高达到(23.28±0.71)m2/g。然而,高分子量(70 k Da)DX与Zein形成的接枝物ESI高达(26.44±0.47)min,高于其他Zein-DX接枝物样品。乳状液粒径和流变性分析表明,随着DX分子量的增加,乳状液粒径降低,黏度增加,这与ESI的研究结果相符。研究结果可为改善玉米蛋白功能性和深入了解玉米蛋白改性机制提供理论依据。
In order to investigate the effect of conjugation by dextran on the structure and emulsifying property of zein and the relationship between protein structure and functional properties, zein-dextran conjugates were prepared by conjugating zein and dextran with different molecular weights（6, 20, 40 and 70 k Da） under wet-heated Maillard reaction at 85 ℃ for 2 h. The free amino content, degree of graft, colour and amino acid content for zein-dextran conjugates were measured by UV-vis（ultra-violet-visible） spectrophotometer, colorimeter and automatic amino acid analyzer. For the zein-dextran conjugates, the free amino content was reduced, and a＊ and b＊ increased, while L＊ decreased in comparison with native zein, indicating the covalent graft reaction between protein and polysaccharide. As the decrease of the molecular weight of dextran, the conjugate prepared by zein and dextran with low molecular weight（6 k Da） had lower free amino content, higher degree of graft and darker colour, which suggested that the dextran with low molecular weight（6 k Da） was more reactive. The amino acid analysis indicated that lysine and arginine were the main amino acids involved in conjugation reaction between zein and dextran. The structures of conjugates were researched using Fourier transform infrared spectroscopy（FTIR）, intrinsic fluorescence spectroscopy and differential scanning calorimetry（DSC）. FTIR demonstrated that zein and dextran with different molecular weights could form the covalent conjugates. The covalent conjugation of dextran could result in the fluorescence quenching of zein and reduce the thermal stability of zein. The bathochromic shift of fluorescence emission maximum wavelength for the conjugate prepared by zein and dextran with low molecular weight（6 k Da） occurred, leading to looser tertiary structure. Moreover, zein conjugating with the dextran with 6 k Da molecular weight had lower thermal stability, revealing that zein-dextran conjugate with higher degree of graft had a l
作者
赵城彬
张浩
鄢健楠
许秀颖
刘美宏
曹勇
吴玉柱
刘景圣
Zhao Chengbin;Zhang Hao;Yan Jiannan;Xu Xiuying;Liu Meihong;Cao Yong;Wu Yuzhu;Liu Jingsheng(College of Food Science and Engineering,National Engineering Laboratory for Wheat and Corn Deep Processing,Jilin Agricultural University,Changchun 130118,China;College of Life Science,Northeast Agricultural University,Harbin 150030,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2018年第14期288-295,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划项目(2016YFD0400702)
现代农业产业技术体系建设专项(CARS-02-30)
吉林省教育厅科学研究项目(JJKH20180654KJ)
吉林农业大学科研启动基金资助项目(201715)
