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

Abstract

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.