外源褪黑素对酿酒酵母发酵及抗氧化体系的影响

本文研究了外源褪黑素对酿酒酵母发酵能力、主发酵产物、抗氧化体系和抗氧化能力的影响,并测定了褪黑素含量的变化。发现对照组在发酵的第8 d发酵基本停止,处理组直到发酵的第14 d发酵终止,但最终的CO2总失重量、残糖和酒精含量无显著影响。褪黑素在发酵的第8 d及以后能显著地降低海藻糖、甘油的生成量,发酵第8 d时,对照组甘油含量达到最大值6.25 g/L,而低、中、高浓度褪黑素处理组甘油含量比对照组分别低7.57%、12.29%、11.99%。低浓度的褪黑素能刺激酵母超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性提高,减少丙二醛(MDA)的积累,发酵结束时低、中浓度褪黑素处理组SOD酶活分别比对照组高68.15%和59.89%,低、中、高褪黑素处理组CAT酶活分别是对照组的2.85、2.87、1.84倍,同时高浓度褪黑素处理组的MDA含量只有对照组的71.44%。发酵液抗氧化能力随褪黑素浓度增加而增强强,褪黑素含量在发酵过程中逐渐降低,后期趋于稳定。

Effect of Exogenous Melatonin on Ethanol Fermentation and Antioxidant Activity of Saccharomyces cerevisiae

The effect of exogenous melatonin on ethanol fermentation ability, major fermentation products, antioxidant system, and total antioxidant ability of Saccharomyces cerevisiae was investigated; in addition, the melatonin content in S. cerevisiae was determined. The results showed that fermentation ended on day 8 in the control group, while it continued until day 14 in the treatment groups; however, the total CO2 weight loss, residual sugar content, and alcohol content did not differ significantly between the control and melatonin treatment groups at the end of fermentation. There was a significant decrease in the production of trehalose and glycerol in the treatment groups (after day 8) compared to that observed in the control. The glycerol content in the groups treated with low, medium, and high concentrations of melatonin was observed to be lower by 7.57%, 12.29%, and 11.99%, respectively, compared to that in the control group, which attained a maximum level of 6.25 g/L on day 8. Low concentration melatonin treatment stimulated the activity of superoxide dismutase (SOD) and catalase (CAT) enzymes, and reduced the accumulation of malondialdehyde (MDA) during fermentation. The activity of the SOD was increased in the 0.01 and 1 mg/L melatonin treatment groups by 68.15% and 59.89%, respectively, compared to that in the control; conversely, the CAT activity in the low, medium, and high melatonin treatment groups was observed to increase by 2.85-, 2.87-, and 1.84-fold, respectively, compared to that in the control at the end of fermentation. MDA content in the high melatonin treatment group was 71.44% that of the control (at the end of fermentation). There was an increase in the antioxidant activity of the broth treated with melatonin corresponding to the increase in melatonin concentration. Melatonin concentration gradually decreased during fermentation to reach a steady state level towards the end of the process.