Changes in Nutritional and Techno-Functional Properties of Whole Grain Maize Flours Induced by Dry-Heat Treatment

The present study was carried out to demonstrate the effects of dry heat treatment (DHT) at different temperatures (100, 125, 135, 150, and 165 °C) on the nutritional and techno-functional properties of white, blue, and yellow whole grain maize flour. Results showed that DHT increased the insoluble dietary fiber and free phenolic compounds of the investigated maize flours, while the bound phenolic compounds, anthocyanins, and pasting properties decreased with the rising of the applied temperature. The application of DHT caused the most notable changes regarding the amount of dietary fiber. Content of NDF (neutral detergent fiber) ranged from 11.48% to 44.35%, 14.19% to 37.84%, and 15.15% to 45.86% in white, yellow, and blue maize samples, respectively. Furthermore, at the highest temperature applied in the DHT (165 °C) the content of soluble free phenolic compounds in yellow and blue maize flour samples was 1.2- and 1.4-fold higher compared to control flour samples. DHT significantly improved the functionality of maize flour in terms of water absorption capacity, water solubility, and digestibility, thus it can be effectively used to make up for the poor functionality of raw maize flour. This study shows that DHT at moderate temperatures (125-135 °C), could be a viable solution for the pre-processing of maize flour to enhance the potential for its utilization in the food industry.