Microencapsulation of enzymatically destabilized virgin coconut oil by spray drying technique: Optimization of process parameters, quality assessment and studies on physico-chemical characteristics of microcapsule

Abstract

Microencapsulation has gained importance in the recent decade due to its barrier properties and effective release of biochemicals. Virgin coconut oil (VCO) was obtained by enzymatic destabilization with the combination of enzymes papain (0.05 % (w/w)) and cellulase with an efficiency in oil extraction of 72.36 %. The aim of the investigation was microencapsulation of medium-chain fatty acids from coconut milk by spray drying and study the physico-chemical properties of the extracted VCO with morphological studies on the obtained microcapsules. The physicochemical properties (Iodine value = 4.24; Free Fatty Acid= 0.3 ±0.007 %; saponification value = 254 ± 4.16 (KOH/g of oil); peroxide value = 0.71 ±0.014 (meqO2/kg)) of the extracted VCO were analyzed. Medium chain fatty acids (C12: lauric acid, C10: capric acid, C8: caprylic acid) constituted 66 % of the extracted VCO, and Lauric acid (C12:0) was the most abundant medium chain fatty acid (52.7 ± 1.27 %). A five-levelled central composite rotatable design was employed with 20 runs to study the effect of inlet temperature, VCO concentration, and wall material concentration on encapsulation efficiency, oil loading %, moisture content, bulk density, water activity, and total color difference. The optimum process parameters for spray drying of VCO with best encapsulation efficiency (77.77 %), oil loading % (35.12 %), moisture content (4.69 %), bulk density (522.22 kg m-3), water activity (0.37), and total color difference (12.42) were found to be 75:25 (% w/w), proportions of GA (Gum arabic) and MD (Maltodextrin) in the wall material solution concentration, 25 (% w/w), VCO concentration and inlet air temperature of 160℃. The obtained VCO microparticle was analyzed for its powder characteristics with Carr index (2.27-11.50) and Hausner ratio (1.02-1.13), indicating good flowability. The spherical shape and smooth exterior surface of the microparticles, revealed by SEM pictures, ensured the protection and retention of VCO inside the microcapsules.