Sake, the Japanese rice wine, contains a variety of oligosaccharides and glucosides produced by fungal enzymes during the brewing process. This study investigates the effect of knocking out the Aspergillus oryzae α-glucosidase (agdA) gene on the transglycosylation products in brewed sake. In addition to α-ethyl glucoside and α-glyceryl glucoside, the amount of two compounds that have molecular mass values similar to that of ethyl maltose decreased by agdA gene knockout. Both compounds were synthesized, in vitro, from maltose and ethanol with purified agdA. Nuclear magnetic resonance analysis identified the two compounds as ethyl α-maltoside and ethyl α-isomaltoside, respectively, which are novel compounds in sake as well as in the natural environment. Quantitative analysis of 111 commercially available types of sake showed that these novel compounds were widely present at concentrations of several hundred mg/L, suggesting that both of them are ones of the common glycosides in sake.

中文翻译：

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在米酒中，米曲霉的α-葡萄糖苷酶A在酿造过程中，转糖基化形成了新型的糖苷乙基α-麦芽糖苷和乙基α-异麦芽糖苷。

日本米酒Sake中含有多种由发酵过程中的真菌酶产生的低聚糖和葡糖苷。这项研究研究了敲除米曲霉α-葡萄糖苷酶（agdA）基因对酿造清酒中转糖基化产物的影响。除了α-乙基葡糖苷和α-甘油基葡糖苷外，通过agdA基因敲除，具有与乙基麦芽糖相似的分子量值的两种化合物的量也减少了。两种化合物均由麦芽糖和乙醇与纯化的agdA体外合成。核磁共振分析确定了两种化合物，分别是乙基α-麦芽糖苷和乙基α-异麦芽糖苷，无论是在自然环境还是在自然环境中，都是新颖的化合物。