Effects of processing with dry heat and wet heat on the antioxidant profile of sorghum

The effects of domestic processing with dry heat (F2-oven/milling; F3-milling/oven; F4-microwave oven/milling; F5-milling/microwave oven; F6-popped grains/milling) and wet heat (F7-cooking in water/drying/milling) on the antioxidant profile of sorghum flours (F1-raw flour) were evaluated. 3-Deoxyanthocyanidins and total phenolic compounds were stable to dry heat (retention between 96.1% and 106.3%) and reduced with wet heat. All processing with dry heat increased the vitamin E content (2,201.9-3,112.1 μg/100 g) and its retention, and reduced the carotenoids (4.78-17.27 μg/100 g). The antioxidant activity in processed flours with dry heat remained constant (F3 and F6) or increased (F2, F4 and F5) and decreased after processing with wet heat. Overall, the grains milled before processing in oven and in microwave oven retained more vitamin E and less carotenoids than those milled after these processing. In conclusion, dry heat did not affect the phenolic compounds and 3-deoxyanthocyanidins of sorghum, but increased the vitamin E and antioxidant activity, and reduced the carotenoids. The wet heat processing reduced all antioxidant compounds except carotenoids, which increased.