Han Yingying, Du Jinhua
College of Food Science and Engineering, Shandong Agricultural University, Tai'an 271018, China.
College of Food Science and Engineering, Shandong Agricultural University, Tai'an 271018, China.
Food Res Int. 2022 Sep;159:111645. doi: 10.1016/j.foodres.2022.111645. Epub 2022 Jul 8.
Understanding pectin structure and pectinase activity was important to control methanol content in apple wine. Therefore, this study compared inoculated fermentation (I), spontaneous fermentation (S) and inoculated fermentation combined with CaCl treatment (I & CaCl) to explore their differences in methanol production, pectin peak molecular weight (Mp), and the activities of pectin methyl esterase (PME), pectin lyase (PL) and polygalacturonase (PG). The results showed that the activities of PME, PL and PG were intensively inhibited during fermentation; however, they still retained 3.41-5.84% (PME), 9.46-17.71% (PL) and 9.17-10.31% (PG) of the initial activities after aging for 30 days. Therefore, the methanol content was increased in all three aged wines even aging at 4 °C. CaCl promoted the PME and PL activities, and thus accelerated the methanol production. Because the pectin with Mp 3.07 kDa was retained by CaCl, the highest pectin content was found in wine I & CaCl (160.69 mg/L), which was 95.47 mg/L higher than that in wine I, and 107.03 mg/L higher than that in wine S. In group S, the long lag period allowed pectin to withstand the pectinases inherent in apple juice for a long time, which was conducive to the cleavage of pectin to Mp lower than 3 kDa continuously, its further degradation led to the lowest pectin content (53.65 mg/L) in wine. Hence, inhibiting the pectinases activities, or shortening the aging period would play an important role in decreasing the methanol content in apple wine.
了解果胶结构和果胶酶活性对于控制苹果酒中的甲醇含量至关重要。因此，本研究比较了接种发酵（I）、自然发酵（S）和接种发酵结合氯化钙处理（I & CaCl），以探讨它们在甲醇产量、果胶峰值分子量（Mp）以及果胶甲酯酶（PME）、果胶裂解酶（PL）和多聚半乳糖醛酸酶（PG）活性方面的差异。结果表明，发酵过程中PME、PL和PG的活性受到强烈抑制；然而，陈酿30天后，它们仍保留了初始活性的3.41 - 5.84%（PME）、9.46 - 17.71%（PL）和9.17 - 10.31%（PG）。因此，即使在4°C下陈酿，所有三种陈酿葡萄酒中的甲醇含量都有所增加。氯化钙促进了PME和PL的活性，从而加速了甲醇的产生。由于分子量为3.07 kDa的果胶被氯化钙保留，在葡萄酒I & CaCl中发现的果胶含量最高（160.69 mg/L），比葡萄酒I高95.47 mg/L，比葡萄酒S高107.03 mg/L。在S组中，较长的延迟期使果胶能够长时间抵抗苹果汁中固有的果胶酶，这有利于果胶持续裂解为低于3 kDa的Mp，其进一步降解导致葡萄酒中的果胶含量最低（53.65 mg/L）。因此，抑制果胶酶活性或缩短陈酿期对降低苹果酒中的甲醇含量具有重要作用。
