Impacts of infrared heating and tempering on the chemical composition, morphological, functional properties of navy bean and chickpea flours

In the present study, navy bean and chickpea seeds were tempered to 20% or 30% moisture content and exposed to infrared heating at surface temperatures 120 °C or 140 °C. The resulting flours were evaluated in terms of their physicochemical, functional, color and morphological properties. Proximate composition of flours was not affected by infrared heating unlike α-amylase and gelatinized starch content which were determined highly susceptible to infrared heating due to inhibitory effects of high surface temperatures on enzyme activity and increase in starch gelatinization with high temperatures. The surface hydrophobicity results from chickpea and navy bean increased up to 3 folds after the treatment. Scanning electron microscope (SEM) results showed that high surface temperature (140 °C) caused more significant changes to the starch structure in chickpea flours than navy bean flours. Water hydration capacity of flours increased; however, solubility, oil emulsification and foaming ability of flours were adversely affected by the infrared treatment. The protein quality and starch digestibility of each pulses were enriched using infrared heating with tempering. Overall, the effect of infrared heating on pulse seeds might be related to surface temperature, tempering moisture, final moisture content of seeds, seed size, and seed composition. Our results will be useful for designing processes to enhance the properties of pulse-derived functional materials.