Fungal Hydrolysis of Food Waste: Review of Used Substrates, Conditions, and Microorganisms

Abstract During food production significant amounts of organic waste is generated annually that can have a negative effect on the environment due to lack of efficient utilisation solutions and insufficient disposal practices. Fungi and their remarkable abilities to produce enzymes can be applied for hydrolysing different types of food waste in simpler sugars. Under optimal conditions, fungal hydrolysis of food waste can be rapid and efficient. Currently, the capacity of this process has only been briefly demonstrated in previous studies. This review describes different practices demonstrating the potential of fungal hydrolysis use for efficient resource management. The focus was on what organisms, waste substrates and parameters as temperature, pH level, have been applied in previous studies as well as glucose recovery yields. It was concluded that food waste can be efficiently hydrolysed and used as a substrate for the downstream production of value-added products using sequential fermentation. The optimal temperature was concluded to be above 45 °C, but the optimal pH level may vary depending on used organism and substate. In future research the possibility of optimizing fungal strains, creating mutants with enhanced enzyme-producing abilities, and application of more GRAS fungal species should be investigated. To conduct valorisation tests on new residues for fungal hydrolysis researchers must collaborate with manufacturers, thus exploring the suitability of a wider range of waste residues for fungal hydrolysis.