We have demonstrated that potatoes contain significant levels of antioxidants important to human health; however, since potatoes are not consumed raw, it is important to determine the effects of cooking/processing on these levels. Therefore, the changes in phenolic and carotenoid content and total antioxidant activity in potatoes were investigated using combinations of storage and cooking methods. Fresh and stored tubers (110 days at 4 °C) of 17 potato cultivars, both raw and cooked (microwaved, boiled, baked, fried), were analyzed for antioxidant activity using the DPPH method. In addition, carotenoid levels were determined for each treatment based on the absorbance of the methanol extraction (oxygenated phenolics and carotenoids) at 445 nm and the hexane extraction (non-oxygenated carotenoids) at 450 nm. Total antioxidant activity as well as carotenoid levels were significantly affected by both genotype and cooking method. Across extraction methods, the microwave and fry cooking treatments were generally highest in antioxidant activity, while boiling was the lowest. Oxygenated carotenoids were significantly affected by storage, while the non-oxygenated carotenoids were unaffected.
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