Design, Preparation and Characterization of Nationally Representative Synthetic Food Waste for Reproducible Waste Valorization Research

Food waste is a readily digestible and fermentable feedstock for waste to energy bioprocesses. Approximately one third of food is wasted, thus making improvements in food waste valorization is essential for a circular economy. Laboratory results must be reproducible and as representative of scaled performance as possible to facilitate knowledge sharing between research groups. Food waste used in laboratory studies is often collected in situ or overly simplistic synthetic mixtures are used. Food waste collected in situ from any one local source at a single time point (e.g., grab samples from a cafeteria or restaurant) are not reproducible or nationally representative; additionally, overly simple synthetic mixtures are reproducible, but lack the complexity of real food waste and are not nationally representative. Thus, an adequately complex, reproducible, and nationally representative food waste recipe is needed to standardize the feedstocks used in laboratory scale food waste digestion and fermentation studies. In this work, we developed a food waste recipe made from widely and commercially available ingredients which is based on national-scale food wastage data in the United States. The nationally representative food waste mixture was 45.4% carbohydrates, 32.5% lipids, and 13.4% proteins. The biomethane potential was 495 ± 44 mL CH4/g VS and the food waste mixture was suitable for use in low-pH bench-scale arrested anaerobic digesters. This design approach can be adapted for other regions and countries where food loss data are available.