Extraction of Fermented Lactic Acid with Hydrophilic Organic Solvents using Salting-out and Sugaring-out

Lactic acid is a component of biodegradable polymers, and efficient fermentation and separation systems for lactic acid production are desirable. In this study, salting-out and sugaring-out extraction of lactic acid from actual fermentation solutions were investigated using hydrophilic organic solvents. The salt-tolerant Tetragenococcus halophilus NRIC 0098 and the ethanol-tolerant Lactobacillus fructivorans NRIC 0224 were used in the salting-out and sugaring-out extraction, respectively. Potassium hydrogen phosphate and sucrose were the most suitable reagenrs for salting-out and sugaring-out extraction, respectively. Lactic acid fermentation and salting-out or sugaring-out extraction were performed simultaneously. However, only a small amount of lactic acid was produced due to inhibition of the bacteria by the hydrophilic organic solvents used. Therefore, lactic acid was fermented in the presence of K2HPO4 and sucrose, and lactic acid was extracted by adding hydrophilic organic solvents after the fermentation. In both cases, lactic acid extractabilities of about 60 – 70% into the upper phase were achieved.