竹叶酵素发酵过程中代谢产物及抗氧化活性的变化

Study on the Changes of Material Metabolism and Antioxidant Activity of Bamboo Leaf Jiaosu during the Fermentation Process

摘要:

对竹叶酵素发酵过程中不同发酵时间的乙醇、总酸、乳酸、醋酸、总酚的含量和pH值进行了跟踪检测，考察各代谢产物与各抗氧化指标(DPPH自由基清除能力、ABTS自由基清除能力和还原力)相关性，并利用主成分分析建立竹叶酵素发酵过程中综合指标变化评价方法。结果表明，竹叶酵素发酵过程中，乙醇含量从第10 d后的0.55%增加至180 d的2.73%，达到最高；总酸含量经发酵100 d上升至4.78 mg/mL后逐渐下降，发酵过程中pH值从4.37降至3.54后趋于稳定；乳酸和醋酸含量在前60 d快速上升，之后开始趋于平缓；总酚含量持续上升积累至0.63 mg/mL，与对DPPH、ABTS自由基的清除率和还原力均分别呈极显著的正相关(p<0.01)。结论：竹叶酵素抗氧化性较好，尤其对ABTS自由基的清除能力较强，总酚含量可作为评价竹叶酵素抗氧化性的指标。综合评价指标(CEI)在第230 d时最高，可作为判定前发酵参考终点和补料发酵时间点的依据。

Abstract:

In this study, the ethanol, total acid, lactic acid, acetic acid, total phenolic pH value and antioxidant index (DPPH free radical scavenging ability, ABTS free radical scavenging ability and reducing power) were investigated. Principal component analysis was used to establish an evaluation method of the changes of comprehensive indexes for Bamboo Leaf Jiaosu during the fermentation process. The results showed that during the fermentation of bamboo leaf Jiaosu, the ethanol content increased from 0.55% at day 10 to 2.73% at day 180, reaching the highest level; after 100 days of fermentation, the total acid content increased to 4.78 mg/mL and gradually decreased. During the fermentation, the pH value decreased from 4.37 to 3.54 and then stabilized. Lactic acid and acetic acid content increased rapidly in the first 60 days, and then began to level off; The total phenolic content continued to rise and accumulated to 0.63 mg/mL, which showed the significant correlation between total phenolic content and DPPH radical scavenging rate, ABTS radical scavenging rate and reducing force, respectively (p<0.01). Conclusion: Bamboo leaf Jiaosu has good antioxidant activity, especially for ABTS radical scavenging ability. The total phenolic content can be used as an index to evaluate the antioxidant activity of bamboo leaf Jiaosu. The comprehensive evaluation index (CEI) reached the highest value on the 230 th day and can be used as the basis for determining the pre-fermentation end point and the reference of the fed-batch fermentation time point.