Downstream Techniques for Lactic Acid Purification Produced from the Biorefinery Approach

Abstract

ABSTRACT With the growing population and the drastic depletion of fossil fuels, the demand for the bioproduction of value-added products is increasing. Recently, lactic acid in polylactic acid (PLA) has been extensively explored for bioplastic applications and other traditional applications in the food industry, textile industry, and pharmaceutical industry. The limitation of large-scale production and application of PLA in bioplastic production hinders the economic production, which challenges downstream techniques for lactic acid purification. Valorizing waste biomass such as food waste, lignocellulosic biomass, dairy industry, and fruit and vegetable processing for cheap carbon sources will support the reduction of the production cost of lactic acid. Metabolic engineering approaches have been extensively studied, such as the overexpression of lactic acid genes from traditional producers and monocarboxylate transporter genes in microbial cell factories. Through this, the movement of lactate molecules across the membrane is improved, and various studies have reported the enhanced production of lactic acid. The purification of lactic acid has also been studied for a long time using various techniques such as precipitation, adsorption, esterification, liquid–liquid extraction, and membrane-based techniques. A detailed review of lactic acid purification techniques with a small emphasis on aqueous two-phase system methods is discussed in the paper.