Effect of heat-moisture treatment of proso millet grain on physicochemical properties of flour and produced cookies

Today, production and improvement of the quality of gluten-free products for Celiac patients are one of the major challenges in the food industry. Physical modification methods such as heat-moisture and microwave treatments can be used to improve the performance of flour and gluten-free products in the baking industry. The goal of this study was to investigate the effects of heat-moisture treatment at three relative humidity (RH) levels of 10, 15, 20% at 90 and 110 °C, to improve the quality of grain millet, and different ratios of of millet flour: rice flour (50:50, 25:75, 15:85) to be used in the formulation of gluten-free cookie. In this regard, physicochemical characteristics of millet (moisture, fat, protein, ash, fiber), flour (water absorption, oil absorption, color) and cookie (diameter, thickness, spread ratio, color, texture) were investigated. The results showed that the heat-moisture treatment had a significant effect on water holding capacity and oil absorption capacity of the samples (p<0.05), in a direct and reverse trend, respectively. Using flour from treated seeds in the gluten-free cookie improved baking loss, water activity, texture parameters, and sensory acceptance. By increasing heat-moisture treatment, the amount of baking loss, water activity and hardness of cookies decreased. Heat-moisture treatment had a significant effect (p˂0.05) on the spreadability and color of the cookies. Increase in the intensity of the treatment led to higher spreadability and darker color with high redness value The Sensory evaluation also showed that texture scores were high for most cookies made from treated millet flour, but the cookie obtained from the 25% replacement level of millet flour under 90 °C and 10% moisture content had the lowest score in the texture.