Microencapsulation of Extra Virgin Olive Oil by Spray Drying: Effect of Wall Materials Composition, Process Conditions, and Emulsification Method

Abstract

The objective of the study was to investigate the microencapsulation of extra virgin olive oil by spray drying to increase its stability and application area. The effects of homogenization rate, pump rate, i.e., flow rate of feeding emulsion and wall materials composition on physical and chemical properties of microencapsulated extra virgin olive oil powder (MEVOP) were evaluated. Maltodextrin (MD) and whey protein isolate (WPI) were used as wall materials and microencapsulation was carried out in a laboratory type spray dryer. The MD:WPI ratio as mixture variable and pump and homogenization rates as process variables were arranged through D-optimal combined design. The optimum wall materials composition and microencapsulation process conditions were determined as follows: 92 % (db) MD, 7 % (db) WPI, and 1 % (db) Tween 20 as wall materials composition and 17,500 rpm and 22 % homogenization and pump rates, respectively. The results showed that the wall materials composition was the most effective independent variables on physical properties in terms of moisture content, water activity, bulk and particle properties of powder as well as microencapsulation efficiency and oxidation stability of MEVOP during converting liquid extra virgin olive oil to powder form. The effects of emulsification methods in terms of rotor-stator and ultrasonic homogenization on physical and chemical properties of MEVOP were also comparatively investigated in this study. The MEVOP produced by ultrasonic homogenization had smaller particle size and lower microencapsulation efficiency than that of rotor-stator homogenization method. But microcapsules obtained by ultrasonic homogenization had better oxidative stability.