Effect of tempering moisture and infrared heating temperature on the nutritional properties of desi chickpea and hull-less barley flours, and their blends

The impact of infrared heating surface temperature and tempering moisture on the nutritional properties of desi chickpea, hull-less barley, and their blends were examined. Specifically, this included changes to the level of anti-nutritive factors (i.e., trypsin/chymotrypsin inhibitors, total phenolics and condensed tannins), amino acid composition and in vitro protein digestibility. Results indicated that both temperature and the tempering/temperature treatment caused a reduction in levels of all anti-nutritional factors for both flours, and the effect was more prominent in the tempering-temperature combination. The amino acid composition of both flours was not substantially changed with tempering or infrared heating. The amino acid scores (AAS) of chickpea and barley flours, as determined by the first limiting amino acid using the FAO/WHO reference pattern found in the case of barley to be limiting in lysine with an AAS of ~0.9, whereas for chickpea flour, threonine was limiting and had an AAS of ~0.6. The in vitro protein digestibility of chickpea samples was found to increase from 76% to 79% with the tempering-heat (135 °C) combination, whereas barley flour increased from 72% to 79% when directly heated to 135 °C (without tempering). In vitro protein digestibility corrected amino acid score (IV-PDCAAS) was found to increase from 65% to 71% for chickpea flour and 44% to 52% for barley flour, respectively with tempering-temperature (135 °C) combination indicating that tempering with infrared heating can improve the nutritional value of both flours. The addition of chickpea flour to the barley flour acted to improve the nutritional properties (IV-PDCAAS), to an extent depending on the concentration of chickpea flour present.