Use of Cereals and Other Starch‑Rich By‑Products in Fungal Protein Production: Opportunities and Challenges

The growing worldwide need for sustainable, high-quality protein sources has intensified interest in single-cell protein (SCP) production, particularly mycoproteins derived from filamentous fungi. This shift is further driven by global sustainability priorities articulated by regulatory bodies, which promote resource efficiency, waste valorization, and sustainable food systems. Despite their high carbohydrate potential, the agricultural sector generates vast quantities of starch-rich by-products. Examples include broken rice, cassava peels, potato waste and cereal processing residues, that remain largely underutilized, thereby contributing substantially to environmental pollution. This literature review examines the potential of starch‑based agricultural by‑products as low‑cost, renewable feedstocks for mycoprotein production in support of the Sustainable Development Goals (SDGs). These by‑products include broken rice, cassava peels, potato waste, and cereal processing residues, which remain largely underutilized despite their high carbohydrate content. Key topics include pretreatment and enzymatic hydrolysis strategies, fungal fermentation using Neurospora and Fusarium spp., and process optimization to maximize biomass yield and feedstock valorization. Life cycle assessments indicate reduced greenhouse gas emissions compared with conventional protein sources, highlighting the potential of starch residues in circular bioeconomy systems. Furthermore, considerations related to process design, environmental benefits and techno-economic feasibility are evaluated in the context of converting starch residues into fungal protein. In summary, the evidence suggests that valorizing starch by-products for mycoprotein fermentation, used as a protein alternative and as an ingredient, represents a promising strategy to reduce waste management costs, lower production costs and support global food sustainability.