Oxidative stability of eicosapentaenoic acid and docosahexaenoic acid in krill oil microencapsulated by spray drying

Abstract

Krill oil (KO) is rich in polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which have many health benefits. However, the oil is unstable owing to its high degree of unsaturation. The oil was microencapsulated using maltodextrin (MD) with a dextrose equivalent of 19 as a wall material to improve its stability. A saponin (Quillayanin) and sodium caseinate were also used as emulsifiers, and rosemary oil (RO) extract or sodium ascorbate was used as an antioxidant. The microencapsulated KO samples were stored at 25, 50, or 70°C to examine the stability of EPA and DHA in the KO. The surface-oil ratios of the KO encapsulated powders by spray-drying were from 4.2 wt% to 52.2 wt% and depended significantly on the reconstituted oil-droplet diameter, 0.48 µm to 9.29 µm. For the microcapsules prepared from emulsions with smaller oil droplets, the surface-oil ratios of EPA and DHA were higher, but the fatty acids were less stable at 50 and 70°C. On the other hand, both EPA and DHA in the microcapsules prepared from emulsions with small oil droplets with 3 wt% Quillayanin, 1 wt% RO, and 2 wt% sodium ascorbate were stable at 25°C. The chemical compensation held for the destabilization of both EPA and DHA in microencapsulated KO.