Can microbial biomass deliver the techno-functional properties required for more sustainable, animal-free foods? A quantitative synthesis linking microbial biomass type, processing, and techno-functionality.

The rising population levels and shift to protein-rich diets are increasing the harmful environmental impact of conventional food systems at unprecedented levels. To circumvent the inefficiency of traditional agricultural practices, natural microbial biomass (MB) of fungi, bacteria, yeasts and microalgae, emerges as an alternative source of nutritional protein that can be converted to microbial foods, as it relies on closed-system, climate-independent and efficient production. Although the environmental and nutritional benefits are widely studied, the techno-functional properties (foaming, emulsifying, gelling, oil and water retention properties) of MB and associated ingredients (whole-cell ingredients, cell-disrupted ingredients and protein-enriched extracts) are underexplored. This review compiled the current body of knowledge on MB production processes (bioproduction, nucleic acid reduction treatments, downstream processing (DSP) to an appealing product) and their described impact on techno-functionality, as well as compared all reported techno-functional properties of MB-based ingredients and food products. MB-based ingredients show promising techno-functional potential, especially in water and oil retention properties, and versatility compared to their plant counterparts. We identified key issues hindering MB commercialization, including the lack of standardized terminology and methodology, limited synergies between upstream and DSP, insufficient diversity in selected strains, ingredient types and final applications, and lack of interdisciplinary research. Strategies to address these challenges include focusing on properties beyond macromolecular composition, using computational approaches for faster screening, and critically evaluating DSP steps. These strategies ensure that the required techno-functional and sensory properties can be achieved without compromising the potential of MB for environmental sustainability and consumer acceptance.