Strategy for Revalorization of Cheese Whey Streams to Produce Phenyllactic Acid †

Abstract

Cheese whey (CW) is the residual liquid waste from cheese manufacturing industries, and it is rich in diverse nutrients with the potential for usage as a growth matrix for sustaining lactic acid bacteria (LAB) fermentation. Lactic acid (LA), phenyllactic acid (PLA), and their derivatives are green chemicals that can be produced by LAB metabolism with the revalorization of CW. LA and PLA are known for their antimicrobial properties, immunoregulatory functions, and production of biobased polymers (biodegradable plastics) like poly lactic acid and poly-phenyl lactic acid; hence, they find numerous applications in agricultural/food-based, pharmaceutical, biochemistry, or medical fields, as well as in antibiotic supplements in livestock feeds for animal husbandry. Herewith, we discuss our experimental strategy/concept (that can be implemented) for the microbial fermentation of cheese whey streams using robust LAB co-cultures to produce 3-PLA through sequential steps, adding a note upon their possible applications hereof. It is proposed that various food matrices, like raw cow milk, fermented cow milk, and fermented table olives, will be screened for the isolation of robust lactic acid bacteria that can be used as starter cultures for the fermentation of cheese whey liquids for producing augmented levels of LA and/or PLA. Moreover, we discuss the feasibility of practically producing PLA using an orchestrated assemblage of simple procedures, viz., isolating robust LAB strains from natural food matrices, tailoring LAB growth using a selective medium sustenance, adopting adaptive evolution procedures for improving resistance to higher temperatures and tolerance to lactic acid and/or cheese whey (low-cost substrate), and using FTIR and HPLC tools for analyzing the PLA content produced. Two Lactobacillus isolates (CM30_001 and CMW_10−3), sourced from raw cow milk and fermented cow milk whey, were found to produce 3-PLA contents of 39 mg/L and 32 mg/L in batch fermentation, using this proposed strategy. © 2023 by the author.