자색고구마 분말 첨가가 도넛과 튀김기름의 이화학적 특성과 산화안정성에 미치는 영향

Abstract

Purpose: This study investigated whether the addition of purple sweet potato powder (PSPP), which has significantly greater lipid-soluble radical scavenging activity than wheat flour, could provide oxidation stability for fried doughnuts. Methods: Deep-fried doughnuts were prepared by replacing 0~8% of wheat flour (WF) with PSPP, and the physicochemical properties and oxidation stabilities of deep-fried doughnuts and the oils used were evaluated. Results: On increasing the amount of PSPP, doughnut brownness (p<0.001), total reducing capacity (p=0.073), and DPPH radical scavenging activity (p<0.001) increased significantly. However, the colors of frying oils were not significantly altered, though yellowness increased (p<0.001) compared with fresh oil. These observations suggested anthocyanins in PSPP might not have migrated to the frying oil during deep-frying, but that the antioxidant activity of PSPP was effectively reflected in doughnuts. The primary and secondary lipid oxidation products in frying oils were not significantly different among groups, including fresh oil. Notably, the hydroperoxide content of doughnuts exhibited a strong inverse correlation with moisture content (ρ=-0.735, p<0.01), indicating that water in doughnuts might have acted as a reservoir of polar antioxidants. Conclusion: PSPP could be used as an antioxidant ingredient to provide oxidation stability to fried foods, and this effect appears to be due to its antioxidant effect and its water-holding capacity conferred by a high dietary fiber content.