Valorization of Spent Brewer's Yeast Bioactive Components via an Optimized Ultrasonication Process

The increasing need for sustainable waste management and food fortification requires continuous agri-food biotechnological innovation. Spent brewer's yeast (SBY) is a mass-produced underutilized by-product of the brewery industry and has elevated bioactive potential. The current study presents a streamlined ultrasonic SBY cell lysis method, with the main goal of bioactive compound valorization. The influence of selected ultrasonication parameters on protein release and, implicitly, on the cell disruption efficiency, was assessed. The SBY derivatives resulting from the ultrasonic cell lysis were SBY extracts (SBYEs) and cell walls (SBYCWs), which were evaluated in terms of protein content, antioxidant activity (AOA) and total polyphenol content. Scanning electron microscopy (SEM) and FT-IR spectroscopy were used to characterize SBYCWs in relation to the morphological and chemical transformations that follow ultrasonic yeast cell disruption. The optimal ultrasonication conditions of 6.25% SBY concentration, 40 degrees C and 33.33% duty cycle (DC) ensured the most efficient lysis. The SBY derivatives with the most elevated antioxidant activity were obtained at temperatures below 60 degrees C. SBYCWs had the highest polyphenol content and a relatively high content of beta-glucan under these parameters. Optical microscopy and SEM confirmed the release of intracellular content and separation of SBYCWs.

Automated summary

This study focuses on the valorization of spent brewer's yeast (SBY) and presents an efficient ultrasonic cell lysis method to release bioactive compounds. Different ultrasonication parameters were evaluated to optimize the cell disruption efficiency. The SBY derivatives, including SBY extracts (SBYEs) and cell walls (SBYCWs), were characterized in terms of protein content, antioxidant activity (AOA) and total polyphenol content. The results showed that optimal ultrasonication conditions resulted in efficient cell lysis and the SBYCWs obtained under specific parameters exhibited the highest polyphenol content and relatively high beta-glucan content. The release and separation of intracellular content were confirmed by microscopy techniques.