Microencapsulation of avocado oil by spray drying using whey protein and maltodextrin

Cold pressed avocado oil was microencapsulated by spray drying in four different wall systems consisting of whey protein isolate (WPI) alone or in combination with maltodextrin (MD) DE 5 at various ratios (90 : 10, 50 : 50 and 10 : 90). The WPI only or WPI/MD (90 : 10) powders were spherical and smooth, whereas the WPI/MD (50 : 50 and 10 : 90) powders exhibited pronounced surface collapse. Increasing the MD ratio resulted in higher bulk density and wettability, probably due to more compact physical structure and hydrophilic wall matrix. Surface free oil contents and microencapsulation efficiencies of powders were 11-16% and 45-66%, respectively, and no significant differences were observed between the samples. The crude avocado oil used in this study appeared to be stable against oxidation at cold and ambient temperatures, irrespective of microencapsulation. However, at high temperature of 60 degrees C, the oxidative stability decreased significantly in all cases but it was improved to some extent by microencapsulation.