Optimization of a Wall Material Formulation to Microencapsulate a Grape Seed Extract Using a Mixture Design of Experiments

The microencapsulation by spray drying of a commercial grape seed extract (GSE) using maltodextrin (MD), mesquite gum (MG), and zein (Z) as wall materials was investigated. A mixture design of experiments (MDOE) with the three wall material components was used to find optimal wall material formulations. The parameters used to evaluate the microcapsules obtained were encapsulation efficiency (EE), encapsulation productivity (EP), release of the core material in water (RE Water), hygroscopicity (MH), and degree of caking (CD). Four optimal formulations were then selected and evaluated including antioxidant activity (AA), release of the core material at pH 1, 4, 7, and 10, and in simulated gastric (GF) and intestinal fluid (IF), morphology and glass transition temperature (Tg). Microcapsules had a smooth surface with sizes ranging from 4 to 16 mu m, a Tg of 160 +/- 1 A degrees C, and an AA of 1.90 A +/- 0.05 mmoles Trolox/g. The two formulations with the most optimal results were T3 (44 % MG-56 % Z) and T4 (34 % MD-66 % Z), with an EE of 85 % and 82 % and an EP of 98 % and 99 %, respectively. The release was between 50 % to 52 % for T3 and 52 % to 55 % for T4 at the different pHs. The RE in GF and IF were 70 % and 63 %, respectively, for T3, and 71 % and 63 % for T4; most of the release happened during the first hour. Both formulations protected the GSE from thermal degradation at temperatures up to 180 A degrees C.