火龙果酵素在发酵过程中功能成分变化规律及其与抗氧化相关性

Correlation between functional composition and antioxidant capacity during the fermentation of pitaya jiaosu

对火龙果酵素发酵487 d过程中总酸、有机酸、总多酚等功能成分的变化及其与抗氧化的相关性进行研究,其中抗氧化能力通过ABTS自由基清除能力和还原力来检测;此外,利用主成分分析法、因子分析法对不同发酵时间的火龙果酵素总酸含量、p H、总多酚含量、ABTS自由基清除能力和还原力5个评价指标进行分析。结果表明：随着发酵时间的延长,火龙果酵素发酵液中总酸、总多酚含量总体上呈逐步增加的趋势,发酵液的p H呈缓慢降低的趋势,从3.75降到3.40;利用高效液相色谱（HPLC）法检测有机酸,从火龙果原料和火龙果酵素发酵液中分别检测到9种和8种有机酸,原料中苹果酸的含量较多,发酵液中乳酸和醋酸的含量较多。与原料相比,酵素发酵液中新检测到了莽草酸;富马酸和抗坏血酸在原料中含量极少,酵素发酵液中则未检测到;火龙果经发酵后,检测到的8种有机酸的含量均有所增加。抗氧化分析结果表明：火龙果酵素发酵过程中ABTS自由基清除能力、还原力总体上呈逐步增加趋势;火龙果酵素发酵过程中总多酚含量、总酸含量、莽草酸和醋酸与ABTS自由基清除能力之间呈中度相关,总多酚含量还原力之间呈中度相关。主成分分析和因子分析结果显示：从检测指标中提取出2个因子,代表了抗氧化因子和环境因子;发酵至359 d时,综合评价指标达到最高值且趋于稳定。

The correlations between total acid content（TAC）,organic acids content,total polyphenol content（TPC）and antioxidant capacity were studied during the pitaya fermentation for 487 days. Two antioxidant acitivity assays,2,2-azinobis（3-ethylbenzothiazoline-6-sulfonic acid）（ABTS^＋·）free radical scavenging activity and reducing power were employed for reference measurements. Besides,principal component analysis and factor analysis were also carried out to evaluate the effect of 5 indicators for total acid content（TAC）,total polyphenol content（TPC）,p H,ABTS free radical scavenging activity and reducing power. The results showed that TAC and TPC were gradually increased during the fermentation process. The p H value of pitaya jiaosu decreased slowly from 3.75 to 3.40. There were 9 kinds of organic acids in pitaya and 8 kinds of organic acids in the fermentation of pitaya jiaosu with HPLC analysis. The contents of malic acid in pitaya and lactic acid,acetic acid in pitaya jiaosu were the highest. Compared to pitaya,pitaya jiaosu contained shikimic acid but no fumaric acid and ascorbic acid which were rare in pitaya. In the process of fermentation,the content of 8 kinds of organic acids increased. ABTS free radical scavenging activity and reducing power were gradually increased.TPC,TAC,the content of shikimic acid and acetic acid were moderately correlated with ABTS free radical scavenging ability. TPC also showed moderately correlation with reducing power. Then two principal components of 5 indicators were obtained through principal component analysis and factor analysis,which represented antioxidant capacity and environmental factor. The comprehensive evaluation index for pitaya jiaosu was highest after 359 days and then changed slowly.