Effect of carrier oil on α-tocopherol encapsulation in ora-pro-nobis (Pereskia aculeata Miller) mucilage-whey protein isolate microparticles

Abstract

Microparticles of whey protein isolate (WPI) and ora-pro-nobis mucilage (OPN) encapsulated α-tocopherol were made using long-chain unsaturated (e.g., canola oil (CA)) or medium-chain saturated oil (e.g., coconut oil (CO)) as the carrier oil. Microparticles were produced from CO- or CA-in-water emulsions by freeze-drying emulsions with various ratios of WPI/OPN. Before freeze dying, emulsions exhibited Newtonian or shear-thinning behavior. Drying yields for freeze-dried emulsions ranged between 74.1% and 87.1% w/w, depending on the biopolymers-to-oil ratio and varied depending on whether CA or CO was used as the carrier. WPI:OPN ratios (between 23:1 and 7:1) nor oil phase (e.g., CO or CA) significantly affected the physical properties (e.g., oil retention, water content, and activity) of the dried powder between treatments. Higher powder bulk density (0.22 g cm−3) and encapsulation efficiency (79.8% w/w) were obtained from freeze-drying CO-, compared to CA-in-water emulsions and with higher concentrations of OPN. Over 35 days, α-tocopherol retention and degradation kinetics differed between CO and CA and was dependent on relative humidity. Bioaccessibility of encapsulated α-tocopherol was higher with WPI/OPN and CA (55.0 ± 1.89%) compared to CO (42.4 ± 1.78%), while the rate of α-tocopherol release and induction time for release were statically equal.