Whey protein isolate and prebiotic biopolymers to stabilize pink-pepper oleoresin microcapsules

Abstract

The objective of this work was to evaluate the use of whey protein isolate (WPI) associated with the prebiotic biopolymers inulin (IN) and oligofructose (OL) as a wall material on the physicochemical, morphological and thermal stability of pink-pepper oleoresin microcapsules. For spray drying in the treatments (WPI, WPI/IN, and WPI/OL), ultrasound-assisted emulsions were used, being prepared with 30% (w/w) wall material, 5% (w/w) oleoresin, and a 5:1 (w/w) replacement ratio for the WPI/IN and WPI/OL treatments. WPI increased the size of the oil droplets and of the reconstituted powder, which provided a greater encapsulation efficiency. The WPI and WPI/OL treatments showed a better antioxidant capacity, whereas WPI/IN and WPI/OL provided a better powder solubility. The microcapsules showed a spherical structure with some roughness, but no rupture, which favored the retention of oleoresin. Moreover, the microcapsule walls had no defined crystalline region. The addition of prebiotic biopolymers decreased the temperature at which the wall material started to degrade, decreasing its thermal stability. The use of WPI associated with inulin and oligofructose is suitable for the production of emulsions for the spray-drying microencapsulation of pink-pepper oleoresin.