黑蒜品质形成的机理及其控制

China is an important garlic production country its output accounts for 3/4 of the world total output. In some areas of China, Garlic industry has become a pivotal pillar ndustry to earn foreign exchange and increase farmers' income. However, our garlic products are mainly marketed domestically and internationally in forms of raw materials and the primarily processed products, so they are low-value added, volatile to acute inter-annual price fluctuation and severely confined to further development. Black garlic is made of fresh garlic, which processed under high temperature and humidity, eliminated of its smell and endowed with antioxidant activity. At present, the quality of black garlic products on the market are varied. The processing time under high temperature is long and the energy consumption is high, which mainly due to the unclear mechanism of the garlic browning. It is scientifically important to look into the quality formation mechanism of black garlic and to control browning process efficiently which not only can shorten processing time and reduce energy consumption but also can promote the generation of the functional materials and guarantee black garlic products' quality, function and safety. This study aims to, through systematic research, identify the origin and ways of the reducing sugar during the browning reaction, clarify the browning process and regular patterns, and expound on the quality forming mechanism, function and security of the garlic. All these will serve as a theoretical basis for bettering the quality of black garlic.

我国是大蒜的主要生产国，产量占世界总产量的四分之三。大蒜已成为我国部分地区出口创汇、农民增收的重要支柱产业。但我大蒜主要以原料和初级加工产品面向国际和国内市场，致使其附加值低，年度间价格波动剧烈，严重影响了大蒜产业的发展。 黑蒜是一种鲜蒜通过控制温度和湿度，经过高温熟化而形成的、去除了大蒜臭味并增强了其抗氧化生理活性的大蒜深加工产品。目前，市场上的黑蒜产品质量良莠不齐，且高温加工时间长，能耗高，其主要原因是对黑蒜褐变和品质形成的机理研究尚不清楚。因此，研究黑蒜品质形成的特点及机理，有效的控制褐变过程，除可缩短加工时间、降低能耗以外，对于促进黑蒜功能物质的生成，保证黑蒜产品的品质、功能作用和安全性皆具有十分重要的科学意义。 本课题拟通过系统研究，阐明大蒜褐变反应中还原糖的来源及产生途径，弄清褐变发生的进程、规律，阐明黑蒜的品质形成机理、功能及安全性，为生产上提高黑蒜产品的质量提供理依据。

黑蒜是鲜蒜通过控制温度和湿度，经过高温熟化而形成的、去除了大蒜臭味并增强了其抗氧化生理活性的大蒜深加工产品。褐变是形成黑蒜独有品质的主要因素。由于对黑蒜褐变和品质形成机理研究不清楚，导致目前市场上的黑蒜产品质量良莠不齐，且高温加工时间长，能耗高，产品质量安全指标不稳定。. 本课题针对黑蒜品质的形成规律，通过研究预处理方式、加工温度和湿度对黑蒜中各物质成分的影响，确定了加工过程中的美拉德反应和大蒜多糖降解是黑蒜品质形成的关键因素。研究发现高温是黑蒜加工过程中多糖降解的主要途径，几乎没有果聚糖酶的参与。课题进一步研究了温度对多糖降解规律的影响及降解产物的功能作用，确定了黑蒜具有润肠通便作用及对小鼠肠道菌群的影响。大蒜黑变是形成黑蒜品质的重要因素，通过对黑变过程中物质的解析发现了乳酸、5-羟甲基糠醛、尿苷、腺苷、(1S,3S)-MTCC咔啉类生物碱、(1R,3S)-MTCC咔啉类生物碱、2-乙酰基吡咯七种物质，并确定了其体外及CAA细胞抗氧化活性。项目同时通过体外模拟黑变过程进一步探究大蒜黑变的机理，为揭示黑蒜品质形成机理提供理论依据。课题组对黑蒜功能研究时，发现了其能引起肠道菌群中厚壁菌门与拟杆菌门比例下降，而厚壁菌门与拟杆菌门的数量比与人体肥胖程度密切相关，这一发现为进一步研究黑蒜存在的功能提供了新的研究方向。此外，研究中还发现了黑蒜加工过程中存在着内生菌，其是否与黑蒜的加工品质形成有关，尚需要进一步探索。