Characteristics of traditional Chinese acidic rice soup (rice-acid) prepared with different fermentation methods

Rice-acid, a Chinese traditional acidic rice soup (rice-acid), is widely accepted by consumers due to its unique flavor and anti-oxidation, anti-aging and immunity enhancement functions. This study confirmed that L-lactic acid and malic acid were the main organic acids in rice-acid. Low-temperature rice-acid samples produced by enterprises had the highest signal intensity of sour taste. The total content of free amino acids in different fermented rice-acid samples were in the range of 0.003-0.468 mg/g. 42 key volatile flavor compounds were identified in rice-acid. 8 volatile compounds with a higher contribution to the aroma of rice-acid were respectively acetic acid, 1-octen-3-ol, 2-heptanol, ethyl acetate, propyl propionate, hexanal, nonanal, and 2,3-butanedione. The interaction between lactic acid bacteria (3.00 x 10(3)-7.02 x 10(6) CFU/mL) and yeasts (5.04 x 10(4)-2.25 x 10(8) CFU/mL) affected the formation of taste and aroma components in rice-acid. The physicochemical characteristics including titratable acidity, pH, reducing sugars, amino acid nitrogen, gammaaminobutyric acid showed significant differences between low-temperature fermentation samples and high temperature fermentation samples. In addition, relationships linking all data through Pearson coefficient correlation were also reported. In summary, the study can be used to improve the quality of rice-acid products. (C) 2022 Beijing Academy of Food Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.

Automated summary

Rice-acid, a traditional Chinese acidic rice soup, is popular for its unique flavor and health benefits. This study identified the main organic acids and volatile flavor compounds in rice-acid. The interaction between lactic acid bacteria and yeasts affected the taste and aroma components. The physicochemical characteristics showed significant differences between low-temperature and high-temperature fermentation samples.