Optimization and Evaluation of Microencapsulation of Star Anise Oleoresin

Abstract

Microencapsulation is a novel approach to protect the spice oleoresin from light-, heat- and oxidation-associated degradation. Nevertheless, little information on microencapsulation of solvent-extracted star anise oleoresin is available. This study aimed to investigate the efficiency of spray-drying microencapsulation of solvent-extract star anise oleoresin with the use of maltodextrin and soy protein as wall materials at different temperatures and to evaluate the characteristics of the resultant microencapsules. Through mathematical modeling, spray-drying encapsulation of 5% oleoresin with 20% maltodextrin and 7.5% soy protein at an inlet temperature of 180C was considered the best to yield highly heat-, light- and humidity-stable microencapsules that had a regular shape with a complete, round, smooth, compact and noncracking exterior wall and normal internal structures. Practical Application Star anise is a very popular spice in China and many other Asian countries. However, oleoresin, the major flavoring ingredient in star anise, is volatile and light-, heat- and humidity-unstable. Therefore, preservation of star anise oleoresin poses a practical challenge to spice producers. A previous Chinese study reported microencapsulation of star anise oleoresin that was extracted with supercritical fluids. However, customers in China favor the flavor of solvent-extracted star anise oleoresin more than supercritical fluid-extracted star anise oleoresin. Moreover, the two wall materials, maltodextrin and soy protein, used in this study are both popular and cheap in China. Therefore, optimized spray-drying microencapsulation of solvent-extracted star anise oleoresin with maltodextrin and soy protein, demonstrated in this study, would greatly impact the current practice of star anise oleoresin processing and preservation.