Microbial D-lactic acid production, In Situ separation and recovery from mature and young coconut husk hydrolysate fermentation broth

Underutilized Malaysian Agro-Industrial Wastes as Sustainable Carbon Sources for Lactic Acid Production

“…Lactic acid is produced naturally by LAB, which are found in many fermented foods such as yogurt, cheese, and sauerkraut. Lactic acid has received Generally Recognized As Safe (GRAS) status from the FDA [13], which widens its application to not only the food industry, but also pharmaceuticals, bioplastics and biomedical industries [14,15]. In general, lactic acid exists in two isomeric forms, L-and D-lactic acid, which differ in their configuration.…”

“…For example, LAB L. coryniformis subp. Torquens produced D-lactic acid [14,15] while L. Palantarum produced a mixture of DL-lactic acid. Various fungal species of the Rhizopus genus, such as Rhizopus oryzae, are able to produce optically pure L(+)-lactic acid.…”

“…Currently, LAB are known as the main safe industrial-scale lactic acid producers for food application. However, other factors such as temperature of fermentation, agitation speed, substrate concentrations and the presence of inhibitors in fermentation media are crucial in ensuring optimal production of lactic acid via fermentation techniques [15].…”

“…For the saccharification process, techniques such as enzymatic, acidic or alkaline hydrolysis were commonly used to release the fermentable sugars from polysaccharides. Enzymatic hydrolysis offers better advantages than other methods, as it is more effective, specific and produces no inhibitors [15,19]. The next stage is the fermentation of the hydrolysate by selected microorganisms to produce lactic acid.…”

“…The author reported the highest monomeric sugar conversion from coconut husk when enzymatic hydrolysis was employed compared to acid hydrolysis. In addition, Din et al [32] and Din et al [15] have successfully produced D-lactic acid through a combination of alkaline pretreatment, enzymatic hydrolysis by Accellerase 1500, and fermentation by Lactobacillus coryniformis subsp. Torquens utilizing mature and young coconut husk.…”