大豆皂苷与豆乳组分相互作用导致苦涩味变化的机理及其调控途径研究

The bitterness and astringency of soymilk have been a durable problem that besets soybean industry at home and abroad. There are few effective techniques related to lessening the unpleasant bitter and astringent flavor since the mechanisms of how these flavors come about remain ambiguous. This study aims at reducing the bitterness and astringency in soymilk and focuses on the existing form and flavoring effects of soybean saponins, which is the main astringent compound in soymilk. Modern analytical methods such as separation and fractionation, chromatography and spectroscopy as well as electronic tongue will be used along with the application of multiple sensory and physiological analyzing approaches, for example, cell culture and electrobiology. The mechanisms of how soybean saponin tastes bitter and astringent by binding with taste receptor and conducting physiological signals would be made clear. Specifically, the interactions between saponins and other co-existing soymilk components, especially soy protein, lipids (oil bodies), phospholipids, as well as the chemical principles of the changes in flavor owing to these interactions would be investigated at length. Upon realizing these, new approaches to reducing the bitterness and astringency can be brought forward so that a soymilk with less of these unpleasant flavors can be attained without affecting the physiological functions of saponins. This study would be a significant guidance to the establishment and improvement of soymilk sensory quality evaluation and regulation system, which might help in the innovation of soymilk processing technologies and promote the development of soymilk industry.

豆乳的苦涩味一直是困扰国内外豆乳行业的难题，生产中不但缺少解决的技术手段，而且在理论上对豆乳苦涩味呈现机理也不明确。本研究以降低豆乳的苦涩味为核心，围绕豆乳中主要苦涩味物质大豆皂苷的存在状态与呈味作用，采用组分分离、光谱及色谱、电子舌等现代仪器分析方法以及细胞培养和电生物学等感官生理学分析方法，揭示大豆皂苷与味蕾受体结合传导苦涩味信号而呈现苦涩味的机理，深入分析豆乳组分尤其是大豆蛋白、脂肪（油脂体）、磷脂等共存化合物与皂苷的相互作用，明确其相互作用导致呈味性变化的食品化学原理，从而提出降低豆乳苦涩味的新途径，达到既能充分利用豆乳中皂苷的生理活性功能，又能降低苦涩味改善豆乳食用品质的目的。这一研究将对建立和完善豆乳感官品质评价和调控体系，创新豆乳加工新技术，促进该行业发展有重要的指导意义。

本课题以降低豆乳的苦涩味为核心，围绕豆乳中大豆皂苷的存在状态与呈味作用，采用组分分离、仪器分析、分子模拟等方法及手段，分析大豆皂苷与豆乳中蛋白质、油脂体等组分的相互作用及其在豆乳加工过程中的迁移规律，探究由此引起的豆乳呈味变化，从而提出降低豆乳苦涩味的新途径，达到充分利用豆乳中皂苷生理活性功能同时改善豆乳食用品质的目的。按照课题计划要求，已基本完成预期目标。. 实现了大豆皂苷的高效提取、单体分离制备及定性、定量分析，完善了复杂基质中测定总大豆皂苷含量的样品前处理方法；利用分子模拟方法进行大豆皂苷单体与苦味同源受体模型的分子对接，确认了大豆皂苷呈苦的单体差异及关键结合位点、结合力作用力；建立了豆乳苦味和涩感的感官评价方法，比较了不同结合状态的大豆皂苷及不同加工处理后豆乳的呈味特点；探究了加工过程中大豆皂苷的分布情况及在豆乳中的结合、游离迁移规律，明确了大豆蛋白等与皂苷的相互作用的形式、内在驱动力，及其对苦涩味感知的影响；结合热处理、调节煮浆压力、蛋白浓度、pH等加工处理过程中大豆蛋白的聚集行为与性质变化的分析，探究了大豆皂苷结合状态的改变，从而提出改善豆乳苦涩味的调控途径。课题成果不仅具有基础理论研究价值，更将为豆乳加工生产技术的革新、豆乳产品品质的提升提供有力的支撑。