Carotenoid-enriched oil preparation and stability analysis during storage: Influence of oils' chain length and fatty acid saturation

Carotenoids are lipophilic pigments with polyene skeletons, which possess great benefits to human health. In this study, medium-chain triglyceride (MCT) and four long-chain triglycerides (LCTs), namely, soybean oil, sunflower seed oil, palm oil, and cottonseed oil, were applied as carriers to enrich carotenoids from Lycium barbarum L. by the freeze-thaw method. The fatty acid composition, thermal properties, and rheological properties of the carotenoid-enriched oils were determined. The carotenoid retention ratio (CRR) and peroxide value (POV) of the prepared oils were assessed during 56 days of storage. Kinetic analysis was conducted for CRR; meanwhile, a multivariate quadratic regression model was implemented to explain the POV changes. Results showed that the CRR of carotenoid-enriched oils decreased gradually following first-order kinetics. The CRR of MCT with low POV generation rate was significantly (p<0.05) lower than that of LCTs. Long-chain oils were beneficial for carotenoids stability. The carotenoid-enriched cottonseed oil (CCO) performed the best at 45 C for 56 days, given the low monounsaturated fatty acids and slow POV generation rate. Thus, oils' chain length and fatty acid saturation would influence delivery material and delivery carrier stability, LCT with high saturation would be an ideal delivery system for carotenoids.