Evaluation of Oxidative Stability and Quality Parameters of Sunflower Oil Enriched With Different Levels of Retinyl...

This study aimed to evaluate the oxidative stability and vitamin A retention of fortified sunflower oil intended for edible use, under different storage conditions over a six-month period. Sunflower oil samples were enriched with retinyl palmitate in four concentrations (15,30,60,90 μg/g) and stored in transparent and brown glass bottles under daylight and dark conditions for six months. Oxidative stabilities of the samples (Rancimat) were measured at the beginning of the study. The other analysis including retinyl palmitate levels, peroxide value, conjugated diene and triene, and free fatty acids contents were performed at the beginning and monthly intervals over a six-month storage period. The results were evaluated using some statistical tests at significance levels of p < 0.05 and p < 0.001. The analysis revealed that, at the end of the sixth month, the highest levels of retinyl palmitate were retained in the groups fortified with 90 μg/g and stored in dark conditions, specifically in transparent bottles (89.39 ± 1.38 μg/g) and brown bottles (80.87 ± 4.05 μg/g). The highest peroxide values were observed after storage in the control group stored under light conditions in transparent bottles (43.92 ± 4.65 meq O₂/kg oil), and in the group fortified with 15 μg/g under the same conditions (55.66 ± 14.12 meq O₂/kg oil). Enriched sunflower oil exhibited a statistically significant increase in free fatty acid contents over time. In conclusion, storage time, light exposure, and bottle color significantly influenced oxidation and quality parameters. Proper storage conditions, particularly protection from light, are essential for maintaining the stability of retinyl palmitate-enriched sunflower oil. Based on these findings, it is recommended that vitamin A-enriched sunflower oils be stored in brown or light-resistant bottles, kept away from direct light, and consumed relatively promptly to minimize oxidative degradation and preserve vitamin A stability.