Sequential extraction optimization of compounds of interest from spent brewer's yeast biomass treated by Pulsed Electric Fields

The brewing industry produces significant volumes of spent brewer's yeast (SBY), which presents an intriguing opportunity for valorization. This study aims to optimize the extraction of various compounds of interest from electroporated SBY located both in the cytoplasm (amino acids, glutathione and proteins) and in the cell walls (mannoproteins). The optimization of the extraction time, temperature and pH, allowed obtaining an extract rich in glutathione of 2.31 ± 0.15 mg/g dw after 1 h of incubation (pH 8; 30 °C) and, a second extract rich in amino acids (155.74 ± 7.83 mg/g dw) and proteins (331.70 ± 15.64 mg/g dw) after a second incubation (37 °C, 47 h) of the biomass. To achieve comprehensive valorization of SBY, the exhausted yeast biomass was incubated with lyticase to extract mannoproteins from the cell wall. This study showcases the efficacy of a multiple response function in optimizing valuable compound extraction from electroporated SBY, aligning with circularity principles.