Saffron (Crocus sativus L.) stigmas as a potential natural additive to improve oxidative stability attributes of sunflower (Helianthus annuus L.) oil stored under different conditions

Abstract

The aim of our study was to explore the antioxidant potential of Moroccan saffron stigmas (SS) and examine their performance as a natural antioxidant in enhancing the stability and quality properties of edible sunflower oil (SO), with a focus on understanding the critical importance of edible oil stability for predicting quality deterioration during storage. Bearing this in mind, our research was designed to compare the efficacy of three concentrations of dried SS (at 0.2%, 0.3%, and 0.6%) against tocobiol (a synthetic antioxidant) as a positive control (at 0.3% concentration). This comparison was conducted under three distinct storage conditions namely accelerated ageing (60 °C), exposure to light at ambient temperature, and darkness, to evaluate their impact on preventing severe oxidation and extending oil shelf-life. Oxidation state evolution was evaluated through peroxide value (PV), free fatty acid (FFA), anisidine value (p-AV), K₂₇₀ value (conjugated trienes), total oxidation index (TOTOX), iodine value (IV), and fatty acid composition (FA). Our results revealed notable differences in stability tracking parameters. Specifically, these parameters were higher in samples stored under accelerated conditions, followed by the samples stored in ambient light, while those stored in darkness showed the highest stability among the three storage conditions. Supplementation of sunflower oil with SS and tocobiol significantly enhanced its oxidation stability. Notably, SS exhibited exceptional effectiveness in stabilizing sunflower oil regardless of SS dose, with the highest efficacy observed at 0.6%. This was evidenced by the slower rate of oxidation parameters under various storage conditions, highlighting a superior antioxidant activity compared to both the non-enriched oil and tocobiol-enriched oil. Furthermore, saffron stigmas, used as a natural supplement, contributed to the preservation of polyunsaturated fatty acids, indicating its potential as a robust source of natural antioxidants in sunflower oil. These attributes position SS as a promising alternative to synthetic antioxidants, offering opportunities to enhance the nutritional quality and extend edible oil shelf-life.