“Investigating the Synergistic Effects of Curcumin on the Oxidative Stability of Flaxseed (Linum usitatissimum) Oil: A Kinetic Study”

Flaxseed oil, rich in polyunsaturated fatty acids such as α-linolenic acid (50%–60%) and essential vitamins (E and A), is highly susceptible to oxidation, leading to the formation of harmful by-products that diminish its nutritional value. Addressing this oxidative instability is critical for preserving the oil’s health benefits. While synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are commonly used to mitigate oxidation, they pose potential carcinogenic risks, prompting the search for safer, natural alternatives. Curcumin, derived from turmeric, has shown to exhibit potent antioxidant properties due to its unique molecular structure, including both phenolic and beta-diketone moieties, making it an attractive candidate for replacing synthetic antioxidants. This study aimed to use peroxidase and TBARS tests to investigate the comparative effects of curcumin and BHT on the oxidative stability of flaxseed oil. Results demonstrated that curcumin at higher concentrations (500 and 1000 ppm) significantly improved the oil’s resistance to oxidation, as indicated by lower peroxide and TBARS values during storage at elevated temperatures. Activation energy (Ea) calculated from TBARS tests increased in case of 500 and 1000 ppm curcumin, which proves inhibitory effect of antioxidants toward the oxidation reaction in these samples. In terms of Ea calculated from peroxide value, a decrease is seen for samples containing 200 ppm BHT and 500 ppm curcumin which shows the ease of the oxidation process and lower shelf life in these samples compared to the ones containing 200 and 1000 ppm of curcumin. In the current study, the change in entropy (ΔS) decreases to 1000 ppm curcumin which explains the slower rate of oxidation in this case. Also, higher concentration of curcumin could inhibit an increase in the acid value at all temperature conditions, especially at 97°C. Furthermore, curcumin exhibited superior antioxidant efficacy compared to BHT, suggesting its potential as a natural antioxidant in food applications. This research underscores the importance of curcumin in enhancing the shelf life and oxidative stability of flaxseed oil, offering a natural, safer alternative to synthetic antioxidants in the food industry.