红香酥梨采后货架期有机酸含量的变化

Changes of Organic Acid Content of Hongxiangsu Pear during Postharvest Shelf Life

利用高效液相色谱法(HPLC)对红香酥梨果实采后货架期有机酸含量的动态变化进行了研究。结果表明,共分离出酒石酸、L-苹果酸、乳酸、柠檬酸、琥珀酸和D-苹果酸等6种有机酸,其总含量为(3.53±0.21)g/kg;成熟的红香酥梨果实属于苹果酸优势型,其主要有机酸为苹果酸,占总有机酸含量的81.82%±0.38%,其中,苹果酸的2种异构体L-苹果酸和D-苹果酸含量分别占总有机酸含量的57.86%±0.71%和23.97%±1.09%;柠檬酸含量次之,占总有机酸含量的8.57%±0.25%;酒石酸、琥珀酸和乳酸含量较低,占总有机酸含量的比例均低于5%;红香酥梨果实总有机酸含量变化在货架期表现为前期上升、中期下降、后期再上升的趋势,说明货架前期果实有机酸含量仍在积累,且主要积累的是D-苹果酸含量;货架中期有机酸含量因消耗、转化的加强而降低,且在第20天时达到最低点,其中,柠檬酸下降幅度最大;货架后期可能由于果实开始衰老,其他物质转化为有机酸使其含量升高。

The dynamic changes of organic acid content of Hongxiangsu pear fruit during the postharvest shelf life were studied by high performance liquid chromatography(HPLC).The results showed that six organic acids including tartaric acid,L(-)-malic acid,lactic acid,citric acid,succinic acid and D(+)-malic acid were separated,and the total content was(3.53±0.21)g/kg.Hongxiangsu pear was classified as malic dominant type because of malic acid was the main organic acid,accounting for 81.82%±0.38%of the total organic acid.And its isomers L(-)-malic acid and D(+)-malic acid accounted for 57.86%±0.71%and 23.97%±1.09%of the total organic acid,respectively.Citric acid took second place,accounting for 8.57%±0.25%of the total organic acid.The content of tartaric acid,succinic acid and lactic acid was the lower,and the proportion of total organic acid content was less than 5%.The content of total organic acids in the fruit of Hongxiangsu pear showed a trend of increasing in the early stage,decreasing in the middle stage and increasing again in the later stage,it indicated that the organic acid in the early stage was still accumulated,and the main accumulation was D(+)-malic acid.In the middle stage,the organic acid decreased due to the increase of consumption and conversion,and reached the lowest point at 20 d,among them,the citric acid decreased the most.In the later stage of shelf life,the fruit might begin to age,and other substances were converted into organic acids to increase their content.