Abstract:Fermentation characteristics by a Lactobacillus fermentum strain that can utilize citric acid in citrus fruits such as green plum were studied. Results showed that L. fermentum could grow in the basic culture medium with citric acid as the main source of carbon and energy. Citric acid metabolism yielded small amounts of acetic acid and lactic acid; hence, the total titratable acid content in the culture medium could be reduced by more than 50%. The strain has a high tolerance to ethanol, as ethanol concentration greater than nine percent (v/v) inhibits growth of the strain and citric acid metabolism. The strain is sensitive to sulfite; and the growth of the strain and citric acid metabolism are completely inhibited by 0.5 mM of sodium sulfite. Sucrose improved the growth of the strain and increased citric acid metabolism; however, no significant decrease in sucrose was observed during fermentation, indicating that the ability to utilize sucrose is low in the presence of citric acid.
