Utilisation of yeast biomass to stabilise oil-in-water emulsions

This study aimed to understand the role of yeast biomass in stabilising oil-in-water emulsions. Three food-grade yeast strains (Saccharomyces cerevisiae (SC) including two non-conventional strains of yeast (NC₁ and NC₂)) were cultured using batch fermentation to obtain their biomass (size range 1-10 μm) and were used to stabilise 5-20 wt% oil-in-water emulsions. The oil-in-water emulsions, stabilised by biomass demonstrated varying stabilisation capacities, with SC preventing droplet coalescence for four weeks with mean droplet size (d [4,3]) ∼ 12 μm whilst emulsions made using NC₁ or NC₂ showed rapid coalescence within a week. Washing of the SC biomass resulted in emulsion destabilisation and increase of interfacial tension of the n-tetradecane/water interface, associated with removal of loosely-bound proteins from the cells. In summary, our findings pinpoints the potential contribution from other surface-active agents such as surface/ secreted proteins in the SC biomass stabilising the emulsions droplets rather than a true Pickering stabilisation.