Application of Pleurotus ostreatus β-glucans for oil–in–water emulsions encapsulation in powder

In this study, sunflower oil containing α-tocopherol (model for oxidizable lipophilic compounds) was encapsulated using a wall material made of maltodextrin and two different extracts rich in β-glucans and proteins, obtained from the basidiomycete Pleurotus ostreatus. A mixture of maltodextrin and acacia gum was used as control wall material. The aim was to assess P. ostreatus extracts as a sustainable and healthy alternative to common emulsifiers. After the evaluation of the emulsion stability, four powders were produced by spray drying and then analysed for the particle morphology and oil droplets distribution within the solid matrix (by scanning electron microscopy), the emulsion microstructure after their dissolution in water (by laser light diffraction) and the encapsulation efficiency (by solvent extraction of surface oil). In addition, powders were analysed in terms of oil protection against oxidation by spectroscopic determination of conjugated dienes and HPLC evaluation of vitamin E. Results showed that P. ostreatus extracts provided suitable emulsifying properties both in the liquid and in the spray dried emulsions. Moreover, it allowed excellent protection of vitamin E and polyunsaturated fatty acids against oxidation. Hence, P. ostreatus extracts can be exploited as innovative emulsifier to provide physical protection to functional, oxygen sensitive lipophilic ingredients by microencapsulation.