Impact of the oil load on the oxidation of microencapsulated oil powders

Abstract

The effect of the oil load on the oxidation of microencapsulated fish oil powders was investigated. The oil load was varied between 4.95 and 20.33%(w/w) by spray drying O/W emulsions with different oil to matrix ratios (0.05, 0.1, 0.15 and 0.2(w/w)), whereas solid content (45%(w/w)) and soy protein isolate to oil ratio (0.15(w/w)) were kept constant. A standardized size fraction of particles (50-80 µm) was stored for 82 days and hydroperoxides and anisidine value measured in the total- and encapsulated oil. Oxidation was limited by the oxygen amount rather than by the oil load. The absolute amount of oxidation products (per powder mass) increased with the oil load, which was explained by oxygen diffusion. Calculating oxidation products per oil mass resulted in a faster oxidation of the powder with 5% oil, whereas the oxidation rate for oil loads ≥10%(w/w) was similar, due to a scavenging effect of oil droplets.

Keywords: Microencapsulation; Oil load; Oil to matrix ratio; Oxidation; Spray drying.