Upscaling fermentation of onion by Laetiporus sulphureus: Process optimization, aroma characterization, and application in plant-based meat alternatives

This study aimed to scale up and optimize Laetiporus sulphureus-mediated onion fermentation and explore its potential to introduce meat-like aroma to plant-based foods. The process was successfully scaled from flask to bioreactor, maintaining the aroma profile without off-flavors. Aeration and vitamin B1 and C supplementation significantly increased key aroma compounds: (E,Z)-2,4-decadienal and (E,E)-2,4-decadienal reached odor activity values of up to 142 and 261, respectively, compared to 63 and 28 in the standard bioreactor fermentation. Dimethyl disulfide and methyl propyl disulfide, associated with "onion-like" notes, were reduced below 1 (vs. 38). Benzothiazole, potentially contributing to "meat-like" aroma, increased to 1. Cytotoxicity assays confirmed 100% cell viability, indicating safety. Flavored water and oil phases obtained from flask fermentation, extracted in situ, were applied to pea protein-based burger patties, and significantly enhanced "meat-like" and "tallow-like" odor attributes. These findings support the use of fungal fermentation to improve the flavor of plant-based meat alternatives.