基于主成分分析和聚类分析的火龙果酵素抗氧化功能评价

Evaluation of antioxidant activity of Pitaya Jiaosu based on principal component analysis and cluster analysis

对火龙果酵素发酵过程中17个时间点发酵液的总多酚含量、ABTS自由基清除能力、还原力和pH值进行跟踪检测,并采用主成分分析和聚类分析,探讨发酵时间对火龙果酵素抗氧化功能的影响.结果表明:随着发酵时间的延长,发酵液中总多酚含量、ABTS自由基清除能力和还原力总体上呈增加的趋势;发酵液的pH值呈缓慢降低的趋势,从4.28降到4.08;发酵液中总多酚含量与ABTS自由基清除能力和还原力呈显著相关性.主成分分析结果表明:发酵至456d以后,综合评价指标达到最高值且趋于稳定,说明在此时间范围内火龙果酵素的抗氧化能力较优.在类间距离为10时,聚类分析可将发酵过程分为3类,即显著变化期、平缓期和缓慢增长期.

Changes of total polyphenols content,ABTS free radical scavenging ability,reducing power and pH were studied during Pitaya Jiaosu fermentation.Principal component analysis and cluster analysis were also carried out to evaluate the effect of fermentation time on antioxidant activeities of Pitaya Jiaosu.The results showed that the total polyphenols,ABTS free radical scavenging ability and reducing power increased during the fermentation process.The pH value of Pitaya Jiaosu decreased slowly from 4.28 to 4.08.ABTS free radical scavenging ability and reducing power showed highly significant correlation with the content of total phenolics.Principal component analysis indicated that antioxidant activity of Pitaya Jiaosu was highest after 456 days of fermentation and then changed slowly.The diffident time points were divided into 3 categories by cluster analysis when rescaled distance cluster was 10.These stages were significant changed phase,gently changed phase and slowly increased phase.