Effect of Tempering Moisture and Infrared Heating Temperature on the Functional and Nutritional Properties of Desi Chickpea and Hull-less Barley Flours, and Their Blends
Bai, Tian 1991-
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The overall goal of this research was to investigate the effect of tempering moisture and infrared heating surface temperature on the functional and nutritional properties of Desi chickpea and hull-less barley flours, and their blends. Specifically, chickpea (initial moisture content 6.29%) and barley (initial moisture content 6.65%) seeds were tempered to 20% moisture content or left un-tempered followed by infrared heating to reach a surface temperature of 115 or 135oC. The infrared heating process was conducted independently for three times under the same condition to obtain triplicate samples. The seeds were then milled into flour for the subsequent analysis of their physicochemical and functional properties, levels of anti-nutritional compounds and in vitro protein digestibility. In the first study, the impact of infrared heating surface temperature and tempering moisture on the functional properties of Desi chickpea, hull-less barley, and their blends were examined. Neither of the factors was found to significantly affect the proximate composition (i.e., protein, lipid, and ash) of the flours (p>0.05). The content of protein, lipid, and ash was ~25%, 6% and 3% in chickpea flour, and 11%, 2% and 2% in barley flour, respectively. However, the levels of gelatinized starch were found to significantly increase with the combined tempering-heat treatment in each flour (p<0.05). The solubility of chickpea and barley proteins were found to be significantly reduced by the combined tempering-heat treatment from 70% and 27% in the untreated samples to 44% and 11% in the treated chickpea and barley flour, respectively due to protein denaturation (p<0.05), despite the surface charge of both flours increasing. The oil holding capacity was found not to be affected by either factor (p>0.05), which was around 1.1 and 1.3 g/g of chickpea and barley flour respectively, whereas the water hydration capacity was significantly increased from 1.1 and 1.4 to 1.8 and 2.8 g/g of flour in chickpeas and barley respectively (p<0.05). The effect of infrared heating and tempering on the emulsion and foaming properties differed between flours. In the case of chickpea flour, emulsion activity (EA) increased and foaming capacity (FC) decreased significantly (p<0.05) with the combined tempering-heat treatments, whereas emulsion (ES) and foaming (FS) stabilities showed no significant difference before and after treatments. In the case of barley flour, EA and ES were found both to decrease with the combined tempering-heat treatment, whereas solutions became non-foaming with either temperature or the tempering-heat combination relative to the control. Based on rapid visco-analysis, the viscosity of the barley and chickpea flour suspensions, in general, had reduced viscosity and increased pasting temperatures both with temperature or the tempering-heat combination. These trends were more pronounced with tempering and at the higher temperature (135oC) in both chickpea (p<0.05) and barley flour (p>0.05). Based on the aforementioned results, chickpea and barley flours tempered to 20% moisture and heated to 135oC were subsequently blended at chickpea: barley ratio of 20:80, 40:60, 60:40 and 80:20. The physicochemical and functional properties of the blends showed a gradient change in accordance with their blending ratios. In the second study, the impact of infrared heating surface temperature and tempering moisture on the levels of anti-nutritional factors (i.e., trypsin/chymotrypsin inhibitors, total phenolics and condensed tannins), amino acid composition and in vitro protein digestibility properties of Desi chickpea, hull-less barley, and their blends were examined. 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-heat combination (p<0.05). The amino acid composition of both flours was found not to be 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 ~0.7, whereas for chickpea flour, threonine was limiting and had an AAS of ~0.9. The in vitro protein digestibility of chickpea samples was found to increase from 76% to 79% with the tempering-heat (135oC) combination, whereas barley flour increased from 72% to 79% when directly heated to 135oC (without tempering). In vitro protein digestibility corrected amino acid score (IV-PDCAAS) was found to increase from 0.65 to 0.71 for chickpea flour and 0.44 to 0.52 for barley flour, respectively with tempering-heat (135oC) 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.
DegreeMaster of Science (M.Sc.)
DepartmentFood and Bioproduct Sciences
SupervisorNickerson, Michael T.
CommitteeEskiw, Christopher H.; Shand, Phyllis J.; House, James D.; Arganosa, Gene
Copyright DateJune 2018