Effects of cooking methods on the anthocyanin levels and antioxidant activity of a local Turkish sweetpotato [ipomoea batatas (l.) lam] cultivar Hatay Kırmızı: Boiling, steaming and frying effects

The study was conducted on the anthocyanin (TA) level and antioxidant activity (AA) of a local genotype of sweetpotato (Hatay Kirmizi) and heating process effects including boiling, steaming, frying on TA and AA levels. The anthocyanin calibration graph of standard cyanidin-3-glucoside gave linear equation (y= 0.0113x+ 0.0045 ; R2 = 0.9986). Anthocyanin level of sweetpotato Hatay Kirmizi (as cyanidin-3-glucoside (C3G) equivalent) was determined as 11992 ± 15.86 mg/100g) (n=8) (p≤0.05). Anthocyanins were detected as 13767 ± 8.94 mg/100g; 24756 ± 6.70 mg/100g; 6755 ± 10.22 mg/100g in boiled, steamed and fried sweetpotatoes, respectively (n=2) (p≤0.05). The total anthocyanins increased as 1.14 fold after boiling process and increased 3.22 fold after steaming process and decreased 1.78 fold after frying process (p≤0.05). It was determined that steaming process, was the most effective among the heat-treated sweetpotatoes (HTSPs). Antioxidant activities of the HTSPs was 78.76%, 89.67%, 97.92% and 57.89% (as radical inhibition percent), respectively. With using steaming process, radical inhibition percent increased 1.24 fold. Tubers of sweetpotato Hatay Kirmizi can be consumed not only steamed > boiled > fried forms but also can be processed into food products, such as muffins, cookies, biscuits, breakfast foods with longer shelf-life, and improved characteristics. It was proposed that sweetpotato Hatay Kirmizi can be processed into flour and used as a thickener, antioxidant enhancer and color source in industrial powder soups, gravy, extruder snacks, and some bakery products