فعاليت آنتي‌ اكسيداني عصاره پوست سيب ‌زميني راجا

Antioxidant activity of potato (Solatium tuberosum, raja) peel extract

Background and objectives: Phenolic compounds, commonly found in plants, retard oxidative degradation of lipids and thereby improve the quality and nutritional value of foods. Using synthetic antioxidants has begun to be restricted because of their health risks and toxicity. In the present study extraction of phenolics from Raja potato peel was determined and the effects of Raja potato peel extract as a natural antioxidant in refined soybean oil were investigated. Materials and methods: Phenolic compounds of potato peels were extracted by two different solvent extraction methods-perculation with methanol, and an ultrasound-assisted method using different solvents, including methanol, ethanol, hexane, acetone and water. The total phenolic compound contents of the extracts were determined by the Folin-Ciocalteu method. Two methods were used to determine the oxidative activity the potato peel extracts in refined soybean oil-the oven test and the Rancimat method. Oxidation was periodically assessed by measuring the peroxide and thiobarbituric acid values. Results: The maximum amount of extract was obtained with water (15.5%), followed by methanol (6.9%), while the maximum amount of phenolics was obtained with methanol (680.68 HgGAE/gdw) using the ultrasound method. After 16 days storage at 63°C, the soybean oil samples containing the methanolic extract of potato peels showed lower peroxide and thiobarbituric acid values than the control sample, indicating strong antioxidant activity. Also, the Rancimat method revealed that the Raja peel extract, at concentrations of 1600 and 2400 ppm, exhibited strong antioxidant activity. Conclusion: Sonication increased the total phenolic compounds of the potato peel extract and shortened the extraction times. In addition, the Raja potato peel extract proved to have a strong antioxidant activity, comparable to that of the synthetic antioxidants BHA and BHT.