Fuente: WIPO "processing tomato" The invention belongs to the technical field of food processing, and particularly discloses a sour seasoning, a preparation method and application of the sour seasoning in hotpot condiment, the sour seasoning is obtained by performing microwave treatment on soaked oats, adding warm water for pulping and saccharifying, and fermenting with candida lipolytica, and the ratio of citric acid to erythritol in the sour seasoning is (5.2-5.5): 1. The preparation method comprises the following steps: soaking the raw material oat, carrying out microwave treatment, adding warm water, pulping and saccharifying, activating endogenous amylase of the oat in a short time, keeping the activity of the amylase, and further decomposing more starch to obtain fermentable sugar; and then adding a nitrogen source ammonium sulfate, inoculating candida lipolytica for fermentation to finally obtain the sour seasoning in which the ratio of citric acid to erythritol is (5.2-5.5): 1, and the sour prolonging time of the sour seasoning can be prolonged by more than 10 seconds. The sour seasoning is applied to preparation of the tomato hotpot condiment, can replace citric acid and part of sweetening agents, and has positive effects on protection of flavor, color and luster of sour soup.