Stability of lutein-based nanoemulsions under thermal and UVC-light exposure: Effect of lutein esterification and oil phase constitution

We evaluated the chemical and physical stabilities of lutein-delivery nanoemulsions and the effects of lutein esterification and oil phase composition. Oil-in-water nanoemulsions were formulated with free (LU) or esterified (LE) lutein, using soybean (S) or pumpkin seed (PS) oil, resulting in SLU, SLE, PSLU, and PSLE. Samples underwent physicochemical characterization and were stored under thermal (45 °C or 4 °C for 15 days) or UV-C light exposure (240 min). LU nanoemulsions showed greater chemical stability at 45 °C and under UV-C light than those with LE. LU nanoemulsions presented better stability at high temperature and under UV light compared to LE counterparts, particularly in S. At 4 °C, LE demonstrated improved stability in PS. PS-based nanoemulsions conferred enhanced protection, likely due to their antioxidant content. These findings challenge the common assumption that esterified carotenoids are inherently more stable and highlight the role of oil composition in carotenoid delivery systems.