Postbiotics from cheese whey: Inactivation methods and biological activity of selected microorganisms

Abstract

A postbiotic is defined as a preparation of inanimate microorganisms and/or their components that confer a health benefit to the host, with potential applications for modulating the gut microbiota and managing metabolic diseases. While still understudied, postbiotics are gaining attention for their therapeutic possibilities, particularly due to their longer shelf life and safety profile compared to other biotic options. Many food industries are reusing by-products to create functional food ingredients; however, about half of the cheese whey produced by the cheese industry is still discarded untreated, contributing to significant land and water pollution. This study explores cheese whey as a matrix for producing postbiotics through three inactivation methods: pasteurization, thermal sterilization, and ultrasound inactivation. Four microorganisms were selected and tested, including two commercial probiotics (Lactobacillus acidophilus LA3 and Lactobacillus acidophilus LA5); and two strains from the BIOTEC collection (Kluyveromyces lactis BIOTEC009 and Lentilactobacillus kefiri BIOTEC013) isolated from artisanal milk kefir. The fermentative behavior of these microorganisms in cheese whey was analyzed, and the antioxidant, anti-diabetic, and anti-inflammatory properties of the postbiotic preparations were evaluated through several assays and compared to a control group of the same microorganisms without prior inactivation. These results indicated that the postbiotic preparations exhibited desirable properties, often matching or surpassing the bioactivity of live preparations. The thermal sterilization treatment seems to be especially noteworthy, as it managed to enhance the antioxidant capacity of all strains, while the ultrasound treatment seemed favorable for anti-inflammatory properties. Lactobacillus acidophilus LA3 stood out as the strain with the best bioactivity overall, even with its treatments, although, there was no single combination of strain and treatment that was the best for every assay. A techno-economic analysis was carried out by doing a simulation of an industrial- scale process to produce postbiotics using two inactivation methods, pasteurization and sterilization. The analysis concluded that for the parameters established, the project is environmentally friendly and both scenarios can be financially viable with a payback time of the initial investment of 4-5 years.