Abstract:The aim of this study was to investigate the changes of organic acids during the natural fermentation of Citrus macrocarpa. A method for the determination of seven organic acids in fermented Citrus macrocarpa was established through using high performance liquid chromatography （HPLC）. The changes of the organic acid contents with fermentation time were determined， the change patterns were analyzed using non-metric multidimensional scaling （NMDS） and the effect of natural fermentation on the change in taste of Citrus microcarpa pulp was investigated with cluster analysis. The results showed that the seven organic acids exhibited excellent linearity within the standard curve concentration range， with the limits of detection （LODs） ranging from 0.114 to 0.416 μg/mL and the limits of quantification （LOQs） ranging from 0.393 to 1.388 μg/mL. The RSD of the precision peak area was within 6.72%， the RSD of the retention time was within 0.12%， the recoveries of the spiked standards ranged from 93.29% to 102.74%， the stability and the RSD of repeatability experiments were within 3.67%. The natural fermentation significantly changed the content of the seven organic acids， and the fermentation period from 0 to 56 days can be divided into three periods： the initial fermentation period from 0 to 7 days， the stable fermentation period from 10 to 35 days， and the later fermentation period from 42 to 56 days. During the initial fermentation period， the total amount of organic acids increased gradually， with notable increases in citric acid， tartaric acid， oxalic acid， acetic acid， and succinic acid， enhancing the sour taste of Citrus microcarpa pulp. During the stable period of fermentation， the changes of citric acid and tartaric acid tended to stabilize， increasing the taste richness and mildness of Citrus microcarpa pulp. In the late stage of fermentation， the citric acid and tartaric acid showed a significant decrease， improving the acidity and bitterness as well as enhancing the richness of the taste. In conclusion， natural fermentation can significantly alter the organic acid content of Citrus macrocarpa， which contributes to the improvement of its taste.