大蒜美拉德反应期间有机硫化物调控的研究

Black garlic is a new type of garlic, which is developed by Maillard reaction. The final products are black in color with less or non-stimulating smell, a fruit-like sweetness, and are readily edible. It is reported that black garlic shows stronger antioxidant activity than fresh garlic. It has also been suggested that a class of γ-glutamyl-L-cysteine in fresh garlic are converted into allicin, which has stimulating smell, and S-allylcysteine(SAC), the water-soluble compound during Maillard reaction. However, the formation mechanism of SAC in black garlic are unclear. Therefore, production of black garlic is in the period of experience and its quality is not stable. The purpose of the present study is to investigate the catalytic reaction of γ-glutamyltranspeptidase during Maillard reaction of garlic and to illustrate the formation of pathway and mechnism for water-soluble organic sulfur compounds. On the basis of above conclusion, by changing the process parameters of Maillard reaction and control the activity of γ-glutamyltranspeptidase, we can enrich the organic sulfur compunds and get a stronger antioxidant activity black garlic, with more water-soluble organic sulfur compounds and less allicin which has irritative and spicy flavor. This study could provide theoretical support for preparing black garlic without stimulating smell, which has high antioxidation activity.

黑蒜是新鲜大蒜经过美拉德反应后的新型大蒜制品，色泽乌黑，刺激性气味很少甚至没有，却有类似水果的滋味，方便食用。据报道，黑蒜具有比新鲜大蒜更高的抗氧化活性以及其他生理功能。目前的研究认为，在美拉德反应期间，新鲜大蒜中的γ-谷氨酰半胱氨酸类化合物转化为具有刺激性气味的大蒜素和稳定的S-烯丙基-半胱氨酸(SAC)等水溶性有机硫化合物，但对SAC的生成机制并不明确。因此，黑蒜生产基本处于经验阶段，品质很不稳定。本课题拟对γ-谷氨酰转肽酶和蒜氨酸酶在大蒜美拉德反应期间的活性和所催化的反应进行研究，揭示水溶性有机硫化物生成的途径与机制。在此基础上，通过改变美拉德反应工艺参数，调控γ-谷氨酰转肽酶的活性，对水溶性有机硫化物进行富集，减少具有刺激性和辛辣味的脂溶性有机硫化物的产生，得到具有高抗氧化活性的黑蒜，为制备具有高抗氧化活性无刺激性气味的黑蒜提供理论支持。

项目对大蒜中γ-谷氨酰转肽酶、蒜氨酸酶进行了分离纯化，并对其酶学性质进行了研究。在此基础上，通过建立γ-谷氨酰转肽酶模拟体系，研究了水溶性有机硫化物的产生途径，并测定了美拉德反应产物黑蒜的抗氧化活性和理化特性。结果表明，SAC由γ-谷氨酰转肽酶的催化产生，提高γ-谷氨酰转肽酶酶活的方法可以提高大蒜中SAC含量。通过改变大蒜美拉德反应参数对大蒜中的γ-谷氨酰转肽酶、蒜氨酸酶以及多酚氧化酶、过氧化物酶等内源酶的活性进行调控，可以增加包含SAC在内的活性成分含量，从而提高大蒜产品的抗氧化等功能。此外，在美拉德反应之前进行预处理也可以调控大蒜中SAC等活性成分的含量。经过调控后，黑蒜的还原能力、对羟基自由基的清除率、超氧阴离子自由基的清除率及对DPPH自由基的清除率依次是未发生美拉德反应大蒜的12倍、3倍、10倍、16倍。项目资助发表SCI论文1篇、录用SCI论文2篇，发表核心论文8篇。项目投入经费24万元，支出23.9096万元，各项支出基本与预算相符。剩余经费0.0904万元，剩余经费计划用于本项目研究后续支出。