猪肉加工过程中蛋白质分子结构及其营养价值变化的分子基础

Meat is a major and very important source of dietary proteins for human nutrition. Processing may change meat quality because it could cause meat protein oxidization and structural changes, which alters nutritional value of meat proteins. However, little is known about the relationship between processing-induced protein changes in particular to oxidation and gut health. In this project, such technologies as X-ray crystallography and LC-MS-MS will be applied to analyze changes in molecular structure and digestibility of major pork proteins including myoglobin, myosin and collagen during postmortem storage, curing and cooking in vivo and in vitro systems. Nutritional quality of those processed meats will be evaluated by animal feeding studies. Proteins extracted from four different meat proteins, soybean and casein will be fed to normal and glutaredoxin gene (GRX)-deficient mice for 9 months and then gut microbiota and mucosal gene expression, especially of those genes involved in antioxidant systems will be analyzed by using metagenomics and (meta)-transcriptomics. Multivariate analysis will be performed to interpret for the underlying linkage meat processing, gut microbiota and body health. Knowledge and technologies gained from this study will be beneficial for meat processing and consumption. Six to eight graduate students will participate in this project who are expected to publish 10 to 12 scientific papers including 3 to 4 high-impact papers （IF>5）.

肉是人类获取蛋白质等营养素的重要来源，加工会引起肉类蛋白质分子结构发生变化，进而影响蛋白质的营养价值，但目前缺乏这方面的系统研究。本项目拟采用晶体衍射、LC-MS-MS、宏基因组学和（宏）转录组学等方法，研究包装贮藏、腌制及煮制等工艺对肌红蛋白、肌球蛋白和胶原蛋白等主要肉蛋白质的分子结构和消化率的影响，以及纯蛋白在不同模拟体系中的变化规律；研究长期摄食不同加工肉制品的蛋白质后，正常和谷氧还蛋白（GRX）基因缺陷型小鼠肠道微生物和小肠上皮细胞内蛋白尤其是抗氧化蛋白基因表达的差异。通过关联分析，探究食物蛋白质分子结构变化（尤其是氧化）与肠道健康的内在联系，丰富肉品营养学理论基础，为肉类加工与合理消费提供一定的科学依据。预期培养研究生6-8名，发表研究SCI论文10-12篇，其中IF>5 论文3-4篇。

应用LC-MS/MS、XPS、拉曼光谱等技术，研究明确了腌制、煮制、乳化等方式加工出的产品的蛋白质消化特性差异，尤其是消化产物、蛋白质分子结构的差异及相互关系；发现真空/气调包装猪肉冷藏过程中蛋白质二级结构和三级结构均发生变化，提升蛋白质消化率。以肌动球蛋白、肌红蛋白和胶原蛋白为对象，研究发现蛋白质氧化是造成肉蛋白质消化特性改变的主要因素，明确了肉品“过度”加工（以高温长时间加热或高盐长时间腌制为特征）影响肉品分子结构和营养价值。进一步，采用cas9-crispr技术，构建了谷氧还蛋白Glrx基因敲除小鼠模型，同时应用免疫缺陷型小鼠（Rag1-/-）和野生型小鼠模型，研究揭示了饲喂干腌肉、红烧肉、乳化肠、水煮肉四种加工肉制品蛋白质后，小鼠肠道内容物中蛋白质和微生物的变化规律，以及与肝脏、脂肪、神经因子、免疫及代谢的相互关系。在此基础上，对动物实验中发现的重要微生物 Akkermansia muciniphila菌进行了培养，对其全基因组及代谢规律进行了分析，阐述了膳食和肠道之间的作用机制，为肉品加工和合理膳食提供了一定的理论基础，同时也为肉品加工工艺优化提供了理论支撑。项目实施过程中，发表论文26篇（其中SCI收录20篇，一区论文6篇），申请发明专利8项（其中国际专利2项，获得授权3项）。