Microencapsulation properties of wall systems consisting of WHPI and carbohydrates

Abstract

Microencapsulation allows entrapment, protection and delivery of sensitive desired nutrients and other food ingredients and compounds. The research has investigated the encapsulation, by spray drying (SD), of a model oil in wall systems consisting of blends of wheat proteins isolate (WHPI) and maltodextrins (MD, DE 5 or 15) or corn syrup solids (CSS, DE 24). Wall solutions contained 2.5–10% (w/w) WHPI and 17.5–10% (w/w) MD or CSS. Oil load in core-in-wall emulsions (CIWE) ranged from 25 to 75% (w/w). Mean particle diameter in CIWE was smaller than 0.5 µm. Surface excess in the CIWE ranged from 1.544 to 6.497 mg/mL and was influenced (p < 0.05) by the composition of the CIWE. Microcapsules exhibited structural characteristics that are typical to spray dried microcapsules and a limited extent of surface indentation. In all cases, the protein-coated lipid droplets were embedded throughout the wall matrices and no visible cracks connecting the core domains with the environment could be detected. Core retention during microencapsulation ranged from 77.7 to 97.2% and was governed by a combined influence of the wall composition and wall-to core ratio (p < 0.05). Microencapsulation efficiency, MEE, ranged from 11.71 to 97.79% and was significantly (p < 0.05) affected by the combined influence of the composition of the wall matrices, the DE value of the COH and by the wall-to-core ratio in the CIWE. Results indicated that wall solutions containing 2.5–10% WHPI and 17.5–10% maltodextrins can offer opportunities for microencapsulation, by spray drying, of high oil load. Results thus open a new horizon for utilization of WHPI as microencapsulating agent in food applications.