Biotransformation of agro-industrial waste via fungal co-culture: Unlocking nutritional and functional potentials

This study presents a novel upcycling strategy by employing co-culture solid-state fermentation (SSF) with food-grade fungi Aspergillus awamori and Aspergillus oryzae to enhance the nutritional and functional properties of lignocellulosic food by-products. Distilled spent grain (DSG) is a major by-product of Chinese liquor production, traditionally underutilized as low-value feed. Data showed co-culture fermentation significantly improved water-soluble protein by 55 % and soluble dietary fiber by 4-fold compared to unfermented DSG. Phytic acid content was reduced by 41 % under co-culture, higher than the 21 % reduction achieved with A. awamori alone. Simulated in vitro gastrointestinal digestion revealed that the protein digestibility of fermented DSG matrix was enhanced to 36 % after co-culture, versus 20 % with monoculture by A. awamori . Additionally, functional property analysis showed the enhancements in water holding capacity, water absorption index, and fat absorption capacity of fermented DSG. These findings reveal the advantage of the interaction between A. awamori and A. oryzae, to achieve a deeper bioconversion of DSG and significant improvements in the nutritional and functional properties of the fermented product. This study offers a potential model for upcycling agro-industrial lignocellulosic residues into fiber- and protein-enriched functional foods using a fungal co-culture fermentation strategy.