Isolation and Identification of Lactic Acid Bacteria in Yunnan Sweet Rice Wine and Study on Antioxidant Activity and Volatile Components of Fermented Sweet Rice Wine

To explore the high-quality microbial resources of sweet rice wine in Yunnan, traditional cultivation, Gram staining, catalase test, and 16S rDNA gene sequence analysis were employed to screen dominant strains based on their growth curves, acid tolerance, bile salt resistance, temperature resistance, and ethanol resistance. The antioxidant activities and the volatile components of the fermented sweet rice wine were analyzed. The results indicated that 26 strains of lactic acid bacteria were isolated and identified, and they were classified into the following species: Levilactobacillus brevis, Limosilactobacillus fermentum, Lacticaseibacillus paracasei, Lacticaseibacillus casei, Lactiplantibacillus plantarum, Pediococcus pentosaceus, and Leuconostoc mesenteroides. Seven strains of lactic acid bacteria exhibited excellent tolerance, with Lactobacillus brevis TC-2 demonstrating the strongest resistance to temperature and acidity. Compared to the control group (CK group), the DPPH· scavenging ability of sweet rice wine fermented by Lactobacillus brevis TC-2 increased by 59.47%, and the TOPSIS method was used to evaluate its antioxidant capacity, showing that it had the strongest activity. The volatile components of sweet rice wine fermented by Lactobacillus brevis TC-2 became more diverse, with an increase of 13 additional volatile components compared to the CK group. Among these, the relative contents of benzyl acetate, ethyl myristate, ethyl palmitate, and 2,2,4-trimethyl-1,3-pentanediol diisobutanoate were the highest, at 1.06%, 2.41%, 4.84%, and 9.48%, respectively. In summary, the fermentation of sweet rice wine with TC-2 enhances antioxidant activity and improves its flavor, providing a reference and theoretical basis for the development of sweet rice wine.