The particulate nature of single-cell protein (SCP) biomass: From cell characteristics to functionality and food applications

Intact SCP biomass (microalgae, fungi, yeast, and bacteria) is mainly used as supplements or fillers, while broader food applications are limited by incomplete understanding of its particulate nature, in which intact cells encapsulate intracellular components within a cell wall. This review therefore examined how the particulate nature of SCP biomass is shaped by production, and how it in turn determines the nutritional, safety, sensory, and techno-functional properties relevant for food applications. Comparison across microbial categories, species, and strains shows that the particulate nature of SCP biomass varies substantially due to differences in composition and structure, resulting in distinct cell characteristics such as permeability, rigidity, hydrophobicity, surface charge, and hydration behaviour. These characteristics are largely established during cultivation, and preserved or further modified by downstream processing. Through particle-level behaviour and molecular-level mechanisms, they shape application-relevant properties and thereby contribute to differences in suitability for food applications. Overall, SCP biomass is highly diverse and offers a wide range of functionalities, making it more than just filler material. This diversity, together with the possibility to steer biomass characteristics through cultivation and processing, enables tailored SCP biomass to meet different application needs. In the future, an application-oriented approach to SCP processing could help guide strain selection, cultivation, and downstream processing. Advancing this approach will require deeper mechanistic understanding of how production conditions shape functionality and may be further supported by machine learning to predict ingredient performance, ultimately supporting the development of more tailored and effective SCP ingredients for future food systems.