Chlorella sorokiniana: Exploring the techno-functional properties of microalgae fractions in a food biorefinery

• Functionality changes arose from both component separation and structural changes. • Cell disruption and centrifugation greatly increased foaming and gelling abilities. • Acid precipitation resulted in partial protein denaturation. • The crude protein exhibited higher foaming abilities than the purified protein. • All fractions showed low emulsifying stability. With the increasing need for sustainable sources of protein, microalgae have gained attention for their high protein content and minimal resource requirements. However, the production of highly purified protein isolates often results in low yield and does not promote the efficient use of biomaterials, limiting economic viability for applications. Less refined protein fractions and by-products from the extraction process may already offer valuable functionalities, providing opportunities for cost-effective, sustainable, and tailored ingredient production to meet the needs of diverse food products. Therefore, this study aims to assess the techno-functionality of fractions with different levels of refinement and by-products produced through the biorefinery process of the microalgae Chlorella sorokiniana . Using a food biorefinery method, C. sorokiniana was processed into six fractions, including four protein fractions and two by-products. The fractions were analysed with respect to composition and techno-functional properties. Cell disruption and centrifugation emerged as key steps, yielding a moderately refined protein fraction (59% nitrogen-based protein purity and a yield of 0.51 g/g) with the highest foam stability (34-fold increase) and gel strength (818-fold increase) compared with the original biomass. Further purification through acid precipitation caused partial protein denaturation and did not increase functionality. This study demonstrates that the techno-functionality of microalgae SCP is influenced by the degree of refinement and the specific biorefinery steps applied. Notably, less refined fractions show potential as functional ingredients for targeted food applications, highlighting how processing strategies can be tailored to improve utilization efficiency and maximize the practical value of microalgae as a protein source.