Fungal solid-state fermentation of crops and their by-products to obtain protein resources: The next frontier of food industry

Over the past three decades, solid-state fermentation (SSF) has gained much attention in biotechnology, allowing efficient production of feed, fuels, industrial enzymes, etc., accompanied by less wastewater and less risk of contamination than submerged fermentation (SmF). Meanwhile, mycoproteins obtained using plant biomass to culture fungi have good nutritional values and interesting functional properties. As the environmental burden of producing high-quality protein grows, there is an ongoing discussion about alternatives to conventional animal proteins; mycoprotein production via SSF may offer a potential solution. This review conducted a visualization analysis on related studies, demonstrating research hotspots and trends in the development of fungal SSF, and compared fermentation conditions under different circumstances. We further discussed the protein profile of crops and their by-products, and the effects of fungal SSF on protein content, amino acid composition, bioaccessibility, etc. Lately, the technical feasibility and extant limitations of this design are summarized. SSF promotes the conversion of residual biomass into edible ingredients or enzymes, alleviating the environmental impact of the food industry with the development of this technology. The fermentation substrate is diversifying from mainly agro-industrial waste. Most crops and their by-products contain significant amounts of plant proteins, existing studies confirm that fungal SSF can further improve the nutritional profile and bioaccessibility. Such solutions accelerate the decoupling of the food industry from arable land and enable the production of high value-added crops. The protein content and amino acid composition of edible fungi are more desirable than those of general fungi and are expected to contribute to the exploration of meat analogs.