Food waste for bioproduct production and potential strategies for high feedstock variability

Unavoidable food wastes could be an important feedstock for industrial biotechnology, whilst their valorization could provide added value for the food processor. However, despite their abundance and low costs, the heterogenous/mixed nature of these food wastes produced by food processors and consumers leads to a high degree of variability in carbon and nitrogen content, as well as specific substrates in food waste hydrolysate have limited their use for bioproduct synthesis. These wastes are often instead used in anaerobic digestion and mixed microbial culture, creating a significant gap in their use for higher value biochemical production via pure and single microbial culture. To directly investigate this knowledge gap, various waste streams produced by a single food processor were enzymatically hydrolyzed and characterized, and the degree of variability with regard to substrates, carbon, and nitrogen quantified. The impact of hydrolysate variability on the viability and performance of polyhydroxyalkanoates biopolymers production using bacteria (Cupriavidus necator) and archaea (Haloferax mediterranei) as well as sophorolipids biosurfactants production with the yeast (Starmerella bombicola) was then elucidated at laboratory-scale. After which, strategies implemented during this experimental proof-of-concept study and beyond for improved industrial-scale valorization which addresses the high variability of food waste hydrolysate were then discussed in-depth, including media standardization and high non-selective microbial organisms growth-associated product synthesis. The Insights provided would be beneficial for future endeavors aiming to utilize food wastes as feedstocks for industrial biotechnology.