香醋加工中煎醋处理物质变化规律及其对香醋品质与功能特性影响机制研究

Vinegar is one of the most important traditional condiments in China. Distinct heating treatments are applied during the production of different vinegars.Decoction, among these, is exclusive to aromatic vinegar as indispensable characteristic procedure. During decoction, raw vinegar obtained by leaching is first mixed with sugar (2% w/w, sucrose content > 98%), then heated to keep slightly boiling for more than 60 minutes. Decoction plays a vital role in the formation of final flavor and quality. However, still huge obscurity lies on the change in substances and resultant quality and functional activities of vinegar induced by decoction. This project based on the earlier findings emphasizes on revealing change in compounds during decoction using GC-O-MS, GC-MS, high-resolution LC-MS-MS, real-time qPCR and high-throughput sequencing combined with cell and mouse models. Highlights are the mechanism underpinning the melanoidin formation, the bonds between melanoidins and phenolics, the effect of generated compounds on final quality and flavor of vinegar, and the structure-activity relationship between these compounds and the antioxidativecapacityas well as modulation on gut microbiota. The project is expected to facilitate the elucidation on the compounds in relation to quality modified by the processing procedure of traditional fermented condiments in China and provide theory guide on quality control, functionality development and improvement of traditional foods.

食醋是我国重要的传统调味品，不同食醋加工中的热处理形式各具特色。煎醋处理是香醋独有、且不可或缺的重要步骤，是将淋醋所得的生醋和占其比重2%的糖（蔗糖含量大于98%）混合，加热至微沸，并保持至少60分钟。该处理对于终产品食醋的风味和品质等影响巨大。但是迄今为止，其过程中物质的变化及其对于品质和功能特性的影响尚有诸多不明确的地方。基于申请人的前期研究，本项目拟采用GC-O-MS、GC-MS、高分辨LC-MS-MS、real-timeqPCR、高通量测序等表征手段和细胞、小鼠等体外和动物模型，重点研究煎醋前后的物质变化规律，尤其是类黑精的形成机制、类黑精上酚类结合形态，形成的物质如何影响食醋终产品品质和风味，以及这些物质与抗氧化、肠道菌群调节等功能特性间的构效关系。研究结果将会有利于明确我国传统发酵调味品的加工过程的物质基础及其与品质之间关系，为传统食品的品质调控及功能发掘和提升提供理论指导。

项目以我国镇江香醋的煎醋特色工艺过程中的功能变化与物质基础、煎醋等对于肠道菌群的影响和调节等为主要研究内容，重点进行了以下工作：1）在明确了煎醋对其抗氧化活性的影响的基础上，从类黑精的形成角度进行了物质基础分析；2）煎醋过程中的类黑精的键合种类不同，对于抗氧化活性的影响也不同，明确了其构效关系；3）从抗氧化、抗炎、抗纤维化等多个角度，采用体外、细胞等模式，全面分析了食醋类黑精的功效；4）采用动物模型，详细分析了煎醋等过程对于食醋的调节肠道菌群的效果的影响。.研究结果表明：结合体外消化的CAA和经典的DPPH和ORAC法，发现煎醋对香醋自由基清除能力显著提高；煎醋结束时，醋类黑精已经是香醋主要的抗氧化因子，可以贡献约50%的香醋自由基清除能力，而以非共价键键合于醋类黑精上的小分子成分（MBC）能够贡献超过89%的醋类黑精抗氧化能力，醋类黑精中能被上端胃肠道利用的酚类中的85%是来自于MBC，类黑精是食醋酚类的“储藏库”，MBC中的酚类决定了醋类黑精的抗氧化活性；采用秀丽隐杆线虫模型，验证了醋粉类黑精的体内抗氧化活性：醋粉类黑精提高了野生型秀丽隐杆线虫对百草枯诱导的氧化应激的耐受性，醋粉类黑精的抗氧化作用受胁迫应答转录因子DAF-16/FOXO和RSKS-1的影响。醋粉类黑精通过激活SIRT1和SIRT3，提高细胞NAD+水平，至少部分地消除了巨噬细胞中乙醇诱导的炎症和氧化应激。在TGFβ1诱导的肝星状细胞系LX-2细胞中，醋粉类黑精显著抑制了SMAD3的磷酸化；醋粉类黑精和SMAD3磷酸化抑制剂SIS3联合处理可协同抑制促纤维生成基因的表达。以上的研究结果充分显示了传统工艺的科学基础，同时相关发现可以为功能性食醋产品的开发提供良好的理论基础和实践指导。.