Phytochemicals and antioxidant activity in criollo corn varieties from mexico after nixtamalization and tortilla preparation

Corn Zea mays is a major grain worldwide and a significant source carbohydrate and phytochemical compounds. An evaluation of total phenolic compounds (TPC), anthocyanin and carotenoid contents in 25 criollo corn varieties, including white, yellow, blue, red and spotted varieties was made, subjected to no treatment (whole grain), to the thermal/alkaline process of nixtamalization and to tortilla preparation. The untreated blue varieties had the highest overall content of TPC, anthocyanins and carotenoids, followed by the spotted, red, yellow and white varieties. After thermal alkaline processing, TPC increased in the yellow and white varieties, less so that in the red and spotted varieties and decreased in the blue varieties. Anthocyanin content in the colored varieties decreased notably with processing, while carotenoid content generally increased in yellow and white varieties. Antioxidant activity was highest in the untreated yellow and white varieties, followed by the spotted, red and blue varieties. Thermal alkaline processing diminished this activity in the yellow and white varieties but increased it in the spotted, red and blue varieties. The tested criollo corn varieties are good sources of phenolic compounds, anthocyanins and carotenoids, and exhibit antioxidant activity, although these vary between varieties after thermal alkaline processing with nixtamalization.