Emulsifying properties of minimally processed Chlamydomonas reinhardtii microalgae ingredients

Microalgae, particularly when minimally processed, are promising sources of sustainable, functional ingredients, yet the effect of cultivation and processing on emulsifying performance remains poorly understood. In this study, Chlamydomonas reinhardtii strains with distinct cell-wall architectures were cultivated under nitrogen-replete and nitrogen-limited conditions to modulate protein content and lipid droplet (LD) abundance, and pulsed electric fields were used as pretreatment for selective extraction. Resulting extracts and cell suspensions were evaluated for emulsification capacity, droplet size evolution, and interfacial properties. The presence of LDs consistently enhanced droplet breakup and was associated with improved emulsion stability across most systems. For LD-free systems, emulsion stability could not be reliably linked to protein concentration, interfacial adsorption, or interfacial viscoelasticity, highlighting limits in predictability for minimally processed systems. Cell suspensions achieved higher emulsification capacities than extracts. This likely reflects the combined contributions of higher protein contents, particulate matter, and other naturally occurring emulsifiers. Overall, LD-rich extracts show strong potential as microalgal emulsifiers, but further work is needed to improve the predictability of the performance of minimally processed microalgal emulsifiers, enabling their reliable use in food.