基于脂质组学对冷藏过程中草鱼肌肉脂肪酸变化机制的研究

There are the world's richest freshwater fish resources in China. The muscles of freshwater fish are easily corrupted during processing, transportation and sale. Their industrialization degree is rather low (less than 10%) and the corruption rate is more than 30%, which causes a great waste of resources and environmental pollution. Although many reports are documented on the fresh-keeping preservation of freshwater fish, their effect on shelf-life extension are ralatively limited. Previous studies, including our researches, demonstrated that lipid oxidation degradation is one of major causes of meat corruption of freshwater fish. Therefore, in order to put forward effective preservation strategies, the researches to uncover their corruption mechanisms become one of inevitable ways for further development of freshwater fish industry. In the present study, based on lipidomics，the technologies, including GC-NCL-MS and SPME-GC-MS, will be used to investigate the compositions, differences and dynamic changing regularity of free fatty acids, total fatty acids and the flavor substances of grass carp muscles at different corruption timepoints during chilled preservation. Then the key fatty acids closely related to corruption will be screened out to reveal the intrinsic relationship between lipid oxidation-hydrolysis and grass carp corruption. Furthermore, the association between lipid oxidation -hydrolysis and product flavor deterioration will be also clarified. Finally, the formation mechanism of corruption based on lipid oxidation-hydrolysis will be obtained and a theoretical basis will be built for development of new techniques and products of fresh preserved freshwater fish. It will be the first time to use lipidomics approaches to systematically study the corruption process of grass carp during chilled perservation. Through strategy and method innovation, new biological evidence related to corruption mechanisms of freshwater fish based on lipid oxidation and hydrolysis will be discovered. It will be theoretically and practically significant for the establishment of countermeasures for fresh preservation of freshwater fish products.

我国淡水鱼资源丰富，但因其肌肉易腐败变质，在储运、加工销售过程中腐败率达30%以上。尽管目前对其保鲜研究很多，但保鲜效果有限。淡水鱼肉的腐败原因甚多，其中脂质氧化降解对产品有着显著影响，开展鱼肉冷藏过程中肌肉脂肪酸的变化规律和机制研究，是淡水鱼腐败机制研究的基础。本项目拟运用脂质组学方法，利用GC-NCL-MS、SPME-GC-MS等检测手段，通过考察冷藏过程中不同腐败时间点草鱼肌肉游离脂肪酸和总脂肪酸的组成、差异及变化规律，揭示脂质氧化降解与草鱼腐败间的内在联系，筛选出与腐败密切相关的关键脂肪酸种类，阐明其与产品风味劣变的关联；获得基于脂质氧化降解的鱼肉腐败形成机制，为淡水鱼冷藏保鲜新技术及冷鲜鱼肉产品的开发提供理论依据。本项目在国内外率先运用脂质组学方法研究草鱼腐败进程，从脂质降解角度为揭示淡水鱼的腐败机制提供新的生物学依据，对淡水鱼保鲜新对策的建立，具有重要的理论和实际指导意义。

淡水鱼的腐败原因甚多，本研究主要利用GC-NCL-MS、SPME-GC-MS等检测手段，开展了冷藏过程中草鱼肌肉脂肪酸的变化规律和机制及脂质氧化降解与草鱼腐败间的内在联系研究，主要研究内容与结果如下：①从宏微观角度确定了草鱼冷藏腐败的关键时间点为6-8 d，此后肌肉脂肪严重氧化，TBARs值大于1 mg/kg，鱼片完全不可食。②确定了草鱼冷藏过程中特征游离脂肪酸和总脂肪酸的种类，分别为亚油酸与花生四烯酸，亚油酸与油酸。③明确了草鱼冷藏过程中各特征脂肪酸的动态变化规律，油酸、棕榈油酸等MUFA以及亚油酸、α-亚麻酸等PUFA，其相对含量随冷藏时间的延长显著降低，棕榈酸、硬脂酸等SFA的相对含量显著增加。④确定了草鱼冷藏过程中各特征风味物质的种类，新鲜至冷藏9 d和常温6 h的草鱼肌肉挥发性成分以羰基化合物和醇类为主导风味，且醇类物质含量较多；冷藏9 d及常温6 h后，酸类、胺类等低阈值物质明显增加，加之醛类物质的作用，此时表现为酸腐味和氨臭味明显。⑤阐明各特征脂肪酸与产品风味劣变的关联，随贮藏时间的延长，氮氧化合物、胺类和脂肪族芳香物质代表的传感器响应剧烈，可作为电子鼻检测草鱼肌肉新鲜度的重要依据。本研究筛选出与腐败密切相关的关键脂肪酸种类，阐明其与产品风味劣变的关联，对淡水鱼保鲜新对策的建立具有重要的理论和实际指导意义。通过项目的实施，共发表CSCD核心以上期刊论文13篇；申请国家发明专利2项；参加全国学术会议7次，作主题报告2次；1人入选2015年度湖湘青年英才支持计划，1人获湖南省青年科技奖，课题组获湖南省科学技术进步奖一等奖和中国技术市场协会金桥奖优秀项目奖各一项，获批成立湖南省水生资源食品加工工程技术研究中心，晋升教授和副教授各1人次，培养硕士研究生3名。总体而言，基本完成了原计划的研究内容，达到了预期目标。