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.摘要 本研究旨在评估乳清分离蛋白（whey protein isolate, WPI）与益生元生物聚合物菊糖（inulin, IN）、低聚果糖（oligofructose, OL）作为壁材，对红胡椒油树脂微胶囊的理化性质、形态学特征及热稳定性的影响。本研究采用喷雾干燥工艺，设置三组处理方案：WPI组、WPI/IN组与WPI/OL组，所有乳液均通过超声辅助制备，配方为30%（w/w）壁材、5%（w/w）油树脂，其中WPI/IN与WPI/OL组采用5:1（w/w）的替换比例。研究结果表明，WPI可增大油滴及复溶后粉末的粒径，进而提升包埋效率。WPI组与WPI/OL组展现出更优的抗氧化能力，而WPI/IN组与WPI/OL组的粉末溶解度更佳。所制备的微胶囊呈球形结构，表面带有一定粗糙度但无破损，这有利于油树脂的保留。此外，微胶囊壁材未出现明确的晶区。添加益生元生物聚合物会降低壁材的起始降解温度，削弱其热稳定性。综上，将乳清分离蛋白与菊糖、低聚果糖复配，适用于制备用于红胡椒油树脂喷雾干燥微胶囊化的乳液。