酒糟结合多酚的抗氧化活性及对α-淀粉酶荧光特性的影响

Antioxidant activity of bound polyphenols from distiller’s grains and the effects on fluorescence characteristics of α-amylase

中文关键词:  酒糟  结合多酚  超声辅助  抗氧化性  荧光光谱

英文关键词:distiller’s grains  bound polyphenols  α-amylase  antioxidant activity  fluorescence spectrum

中文摘要:

      目的 优化酒糟中结合多酚提取工艺, 并探究其抗氧化活性及对α-淀粉酶荧光特性的影响。方法 以酿酒后废弃的啤酒糟为原料, 用超声辅助酸解法提取其中的结合多酚, 利用单因素实验分别比较不同超声功率、硫酸体积浓度和料液比对酒糟结合多酚的多酚含量、总黄酮含量、1,1-二苯基-2-三硝基苯肼自由基(1,1-diphenyl-2-picrylhydrazyl radical, DPPH·)清除率、2,2’-联氮-二(3-乙基-苯并噻唑啉-6-磺酸)二铵盐阳离子自由基[2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt anion radical, ABTS+·]清除能力、铁离子还原/抗氧化能力的影响, 并分析各抗氧化指标间的相关性; 探究各最优提取条件下, 酒糟结合多酚对α-淀粉酶荧光淬灭性的影响。结果 提取功率500 W、酸体积浓度8%及料液比1:50 (g/mL)条件下所得酒糟结合多酚中总酚和总黄酮含量最高, 分别为2.177 mg GAE/g和2.831 mg RE/g。相关性分析结果表明, 酸浓度的提高可能增加酒糟中脂溶性多酚化合物的溶出, 而令水溶性多酚化合物的相对含量减少。荧光光谱结果显示, 连续加入酒糟结合多酚后, α-淀粉酶的最大发射波长略有蓝移, 瑞利散射线强度和荧光峰的相对强度均有不同程度的降低。结论 提取所得酒糟结合多酚具有一定抗氧化活性, 在一定范围内提升超声功率可以显著提高酒糟结合多酚的提取率。酒糟结合多酚的加入导致α-淀粉酶的构空间象发生了变化, 两者之间的相互作用增加了α-淀粉酶中氨基酸残基的疏水性, 荧光淬灭方式为静态淬灭。本研究为酒糟中结合多酚类化合物的开发利用提供了一定的理论基础。

英文摘要:

      Objective To optimize the extraction process of bound polyphenols in distiller’s grains, and explore the antioxidant activity and the effects on fluorescence characteristics of α-amylase. Methods Using discarded beer lees after brewing as raw materials, ultrasound assisted acid hydrolysis was used to extract bound polyphenols. Single factor experiments were conducted to compare the effects of different ultrasonic power, sulfuric acid volume concentration, and solid-liquid ratio on the polyphenol content, total flavonoid content, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) clearance ability, 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt anion radical (ABTS+·) clearance ability and ferric ion reducing antioxidant power of bound polyphenols from distiller's grains, and the correlation between various antioxidant indicators were analyzed. The effect of distiller’s grains bound polyphenols on the fluorescence quenching of α-amylase was determined under various optimal extraction conditions. Results Under the conditions of ultrasonic power of 500 W, acid volume concentration of 8%, and solid-liquid ratio of 1:50 (g/mL), the total phenolic and total flavone content in the bound polyphenols of distiller’s grains were the highest, at 2.177 mg GAE/g and 2.831 mg RE/g, respectively. The correlation analysis results indicated that an increase in acid concentration might enhance the dissolution of lipid soluble polyphenols in distiller’s grains, while reducing the relative content of water-soluble polyphenols. The fluorescence spectrum results had shown that after continuous addition of distiller’s grains bound polyphenols, the maximum emission wavelength of α-amylase was slightly blue shifted, and the intensity of Rayleigh scattered rays and the relative intensity of fluorescence peak were reduced to varying degrees. Conclusion The extracted distiller’s grains bound polyphenols have certain antioxidant capacities, and increasing ultrasonic power within a certain range can significantly improve the extraction rate of distiller’s grains bound polyphenols. And the addition of distiller’s grains bound polyphenols can result in changes of the spatial construction of α-amylase, and the interaction between enzyme and bound polyphenols has increased the hydrophobicity of amino acid residues in α-amylase. Besides, the type of fluorescence quenching is static quenching. This study provides a theoretical basis for the development and utilization of bound polyphenols in distiller’s grains.