Navigating practical applications of food waste valorisation based on the effects of food waste origins and storage conditions

Food wastes used as feedstock in biorefineries are of both research and market interest for solving related environmental issues and valorising to value-added products. However, the distinct conditions and characteristics governing the valorisation of different types of food waste remain to be addressed, such as different origins and storage conditions of food wastes. In this study, the characteristics of four types of food waste (student canteen waste, bakery waste, Chinese food waste, and Western food waste) after designed storage experiments (storage temperature - 4 degrees C, 25 degrees C, and 35 degrees C; storage duration 1-3 days) were first investigated, followed by enzymatic hydrolysis to obtain food waste hydrolysates that can be applied to microalgal fermentation. The results showed that the characteristics of the food wastes and their corresponding hydrolysates differed based on their origins. Furthermore, cultivation of the microalgae Euglena gracilis demonstrated the feasibility of using food waste hydrolysates as the sole nutrient source, and both the origin and storage conditions of food wastes were found to affect microalgal growth and paramylon production. Possible inhibitors that could account for the different performances of food waste hydrolysates were identified by untargeted metabolite analysis. In summary, this study provides insights into the application of different types of food waste under complex conditions in biorefineries and the utilisation of their hydrolysates via in-depth metabolite analysis.