DHA/EPA磷脂结构变化对冷藏鲟鱼子酱单羰基类气味物质形成的影响机制

冷藏鲟鱼子酱气味品质不可控是制约其规模化生产的关键瓶颈问题。二十二碳六烯酸/二十碳五烯酸磷脂（DHA/EPA磷脂）降解生成单羰基化合物（VMCs）是鲟鱼子酱气味形成的主要途径。申请人前期发现，鲟鱼子酱冷藏过程中含量变化显著的DHA/EPA磷脂具有不同的结构，但其立体结构、微观结构等差异对VMCs形成的影响及机制仍不明确。基于此，项目将基于分子感官科学揭示冷藏期关键VMCs组成与气味属性变化规律，明确气味品质变化的标志物即“靶向”VMCs；根据磷脂组学和自由基反应理论从特征基团、酰化位置等方面探明DHA/EPA磷脂结构变化，揭示“DHA/EPA磷脂→氢过氧化物→VMCs”自动氧化途径；基于密度泛函理论建立定量构效关系模型，从立体结构和微观结构双角度阐明DHA/EPA磷脂结构变化对VMCs形成的影响机制。项目将为富含DHA/EPA食品加工及贮藏过程中风味定向调控的方法与技术开发提供理论依据。

The uncontrollable flavor during storage is the key bottleneck problem which restricts the scale of sturgeon caviar industry. The degradation of eicosapentaenoic acid/ docosahexaenoic acid-rich phospholipids (DHA/EPA-rich phospholipids) into volatile mono-carbonyl compounds (VMCs) is an important pathway of odor formation. The applicant previously found that the contents of DHA/EPA-rich phospholipid molecules with different structures in refrigerated sturgeon caviar changed significantly. However, the effects and mechanisms of molecular structure changes such as characteristic group and acylation position on the formation of VMCs are still unclear. Therefore, this project will define the “targeted” VMCs for quality evaluation by revealing the dynamic change of key VMCs composition and odor properties during refrigerated storage through sensory omics; Based on lipidomics and free radical reaction theory, the molecular structure changes of DHA/EPA-rich phospholipids will be identified from the characteristic groups and acylation positions, etc. Combined with the dynamic monitoring of free radicals and hydroperoxides, the auto-oxidation pathway “DHA/EPA-rich phospholipids → hydroperoxides → VMCs” will be deduced; Based on density functional theory, the quantitative structure-activity relationship will be studied and the structural factors of DHA/EPA-rich phospholipid molecules affecting the odor intensity of VMCs will be finally analyzed. This project will provide a theoretical basis for the development of odor regulation methods and techniques in DHA/EPA-rich foods during processing and storage.