Production of stable emulsions using beta-glucans extracted from Pleurotus ostreatus to encapsulate oxidisable compounds

The basidiomycete Pleurotus ostreatus is a sustainable food source known to be rich in beta-glucans, functional compounds in mushrooms recognised for their numerous health, nutraceutical and physicochemical properties. The aim of the present study was to extract beta-glucans from P. ostreatus powder and to study the feasibility of using the extract to prepare oil-in-water emulsions formulated for the encapsulation of lipophilic antioxidants by spray drying e.g. with an oil droplet size about 2mm, a dry matter content of 40% w/w and with a physical stability of at least 2 h. Hot-water soluble beta-glucans fraction was extracted from P. ostreatus powder following a method adapted from Synytsya et al., (2009). Emulsions were prepared by rotor-stator homogenisation using maltodextrin DE12 as wall material, beta-glucans extract as emulsifier and commercial sunflower oil as a model for lipophilic active compounds. The emulsion stability was estimated from the evolution over time of the oil droplet size distribution measured by laser light diffraction. Extracts containing up to 27% w/w watersoluble beta-glucans were produced. Physically stable mono-modal emulsions were obtained when MD/beta-glucans weight ratio was lower than about 500 to avoid depletion and beta-glucans/oil weight ratio was more than 0.014 to stabilize oil droplets. The usage of emulsifiers made-up by polymeric constituents with inherent bioactivity, such as mushroom beta-glucans, could be a sustainable and healthy alternative to common emulsifiers.