OPTIMIZATION OF THE LACTIC ACID FERMENTATION FROM TOFU SOUR LIQUID AND APPLICATION IN THE PRODUCTION OF ANTIBACTERIAL SOAP AGAINST Propionibacterium acnes PO

Abstract

The objectives of this study were to screen for a strain of lactic acid bacteria to attempt the production of soap with the inhibitory effect on Propionibacterium acnes PO. Twenty strains of lactic acid bacteria were screened for lactic acid production and antibacterial properties. The optimal conditions for lactic acid fermentation including inoculation density (10⁵, 10⁶, and 10⁷ cells/mL), initial sugar content (3, 6, and 9% w/v), and pH level (5, 6, and 7) were investigated. Along with, the suitable blending content of fermented tofu sour liquid form soap with inhibitory effect on P. acnes. The results showed that Lactobacillus plantarum L39 could create 7.35 g/L acid lactic from tofu sour liquid and possess inhibitory effects with 16.00 mm inhibitory distance. The suitable conditions for lactic acid fermentation were determined at the initial sugar content of 8% (w/v), pH 5.6, and inoculum density of 10⁷ cells/mL with final lactic acid of 10.275 g/L. Soap produced from fermented liquid with 20% blending content (w/w) showed an inhibitory effect on P. acnes with a 15.67mm inhibitory zone with sensorial results of 86.6% texture score, 86.6% color score, and 93.44% odor score.