Kuroda Hisao, Furusho Shigeki, Maeba Hideo, Takashio Masachika
Frontier Laboratories of Value Creation, Sapporo Breweries Ltd., 10 Okatohme, Yaizu, Shizuoka 425-0013, Japan.
Biosci Biotechnol Biochem. 2003 Apr;67(4):691-7. doi: 10.1271/bbb.67.691.
To characterize the factors involved in the production of volatile aldehydes during mashing, a model mashing experiment was done. After we inactivated the endogenous lipoxygenase (LOX) activity in the mash by mashing at 70 degrees C for 30 min, further incubation with recombinant barley LOX-1 stimulated the accumulation of 2(E)-nonenal; however, this effect was significantly reduced by boiling the mash sample. The result suggests that both LOX-1 and a heat-stable enzymatic factor are involved in the production of 2(E)-nonenal during mashing. Malt contained fatty acid hydroperoxide lyase-like activity (HPL-like activity) that transformed 9-hydroperoxy-10(E), 12(Z)-octadecadienoic and 13-hydroperoxy-9(Z), 11(E)-octadecadienoic acid into 2(E)-nonenal and hexanal, respectively. Proteinase K sensitivity tests showed that they are distinct factors. 9-HPL-like activity survived through the mashing at 70 degrees C for 30 min but was inactivated by boiling, suggesting it will be the heat-stable enzymatic factor found in the model mashing experiment.
为了确定糖化过程中挥发性醛类生成所涉及的因素，进行了一次模拟糖化实验。在70℃下糖化30分钟使糖化醪中的内源性脂氧合酶（LOX）失活后，再与重组大麦LOX-1一起孵育会刺激2(E)-壬烯醛的积累；然而，将糖化醪样品煮沸后，这种效应显著降低。结果表明，LOX-1和一种热稳定的酶因子都参与了糖化过程中2(E)-壬烯醛的生成。麦芽含有脂肪酸氢过氧化物裂解酶样活性（HPL样活性），可分别将9-氢过氧-10(E),12(Z)-十八碳二烯酸和13-氢过氧-9(Z),11(E)-十八碳二烯酸转化为2(E)-壬烯醛和己醛。蛋白酶K敏感性测试表明它们是不同的因子。9-HPL样活性在70℃下糖化30分钟后仍存在，但煮沸后失活，这表明它就是模拟糖化实验中发现的热稳定酶因子。
