Effect of process variables on the microencapsulation of vitamin a palmitate by gelatin-acacia coacervation

Microcapsules of vitamin A palmitate were prepared by gelatin-acacia comple x coacervation. The effects of colloid mixing ratio, core-to-wall ratio, ha rdening agent, concentration of core solution, and drying method on the coa cervation process and the properties of the microcapsules were investigated . The microcapsules of vitamin A palmitate were prepared using different we ight ratios of gelatin and acacia, that is, 2:3, 1: 1, and 3:2 under contro lled conditions. The other factors studied were 1: 1, 1: 2, and 1: 3 core-t o-wall ratios; 30, 60, and 120 min of hardening time; 2, 5, and 10 ml of fo rmaldehyde per 280 g of coacervation system as a hardening agent; and 30%, 40%, and 50% w/w vitamin A palmitate in corn oil as a core material. The dr ying methods used were air drying, hot air at 40 degreesC, and freeze-dryin g. The results showed that spherical microcapsules were obtained for all co nditions except for 30 min of hardening time, which did not result in micro capsules. The optimum conditions for free-flowing microcapsules with a high percentage of entrapped drug were 1: 1 gelatin-to-acacia ratio and 1:2 cor e-to-wall ratio when hardening with 2 ml formaldehyde for 60 min and using 40% w/w vitamin A palmitate in com oil as the core concentration. In additi on, drying the microcapsules by freeze-drying provided microcapsules with e xcellent appearance.