Leveraging waste for natural antioxidant production: the effect of direct ultrasound fortification of sunflower oil with saffron by-products to enhance oxidative stability

Abstract This investigation evaluates the effect of saffron by-products on the oxidative stability of sunflower oil under accelerated storage conditions. Sunflower oil was directly supplemented, using ultrasound treatment with petals, stamens, and leaves at 0.2%, 0.4%, and 0.6% (wt/wt) for each antioxidant. The treatments underwent an accelerated heating process at 60 °C for 12 weeks. Samples were taken bi-weekly to assess free fatty acids formation, primary oxidation products (peroxide value and K232 value), secondary oxidation products (anisidine and K270 value), total oxidation value, and pigments content. The Rancimat test, fatty acid profile, iodine value, and oxidisability value were evaluated. The results indicated that the saffron by-product extracts contained high levels of total phenolic compounds (87.23 and 39.23 mg of GAE g−1 in petals and stamens, respectively) and total flavonoid content (109.78 and 33.11 mg / QE g−1 for petals and stamens, respectively), exhibiting significant antioxidant activity as evidenced by ferric reducing antioxidant powder and free radical neutralisation potency assays. The incorporation of saffron by-products has improved the stability of the SO, with the greatest effectiveness observed when combined with the stamens, followed by the petals and leaves. This study shows that the direct ultrasonic enrichment green method offers a rapid approach without recourse to chemicals solvents.