Nutritional and Functional Properties of Microbial Proteins as Food Ingredients: A Review

The growing global demand for sustainable protein sources has accelerated interest in microbial proteins as promising alternatives to conventional animal- and plant-based proteins. This review comprehensively summarizes the nutritional value, functional properties, safety, and food application potential of microbial proteins derived from yeast, filamentous fungi(mycoprotein), bacteria, and microalgae. A bibliometric analysis revealed that previous research has primarily focused on microbial genetics, metabolism, and animal nutrition, whereas comprehensive evaluations of microbial proteins as human food ingredients remain limited. Microbial proteins generally contain high protein levels with well-balanced essential amino acid profiles, making them effective complements to cereal-based diets. However, protein digestibility and bioavailability vary considerably depending on microbial species, cell wall composition, and processing methods. Technologies such as cell disruption, protein concentration, fermentation, and enzymatic treatment substantially improve protein quality by enhancing enzyme accessibility. Beyond their nutritional advantages, microbial proteins exhibit diverse functional properties, including solubility, emulsifying capacity, foaming ability, gel formation, and water- and oil-holding capacities, which are strongly influenced by microbial structure and processing conditions. Safety considerations, including nucleic acid content, toxins, endotoxins, allergenicity, and regulatory compliance, remain essential for commercial application. Overall, microbial proteins represent highly sustainable and nutritionally valuable food ingredients with significant potential for future food systems. Their successful utilization will depend on the integrated optimization of microbial strain selection, production processes, protein quality, functional performance, safety assessment, and consumer acceptance.