The effect of soaking, steaming, and dehydration on the microstructure, physicochemical properties and in vitro starch digestibility of flour produced from Lablab purpureus (L.) Sweet (hyacinth bean)

Abstract

Hyacinth bean flour was produced from legume grains subjected to steaming and dehydration treatments, prior to soaking to improve utilization as potential functional food ingredients. The morphological characteristics of starch granules extensively changed in response to processing with a distinct variation in the chemical composition of samples studied. Potassium (215.33–326.33 mg/100 g), sodium (19.30–24.57 mg/100 g), and phosphorous (148.67–178.33 mg/100 g) were among the main contributors to total variation whereby individual minerals exhibited different leaching responses to processing treatments. There were significant correlations (p < .05) present among total starch (48.66–51.02 g/100 g), chemical constituents, and physicochemical properties studied. High water penetration potential was identified for samples produced by steaming and dehydration which can be attributed to high levels of swelling and water solubility at lower temperatures (60–70°C). In samples produced by steam‐dehydration, a significant improvement in resistant starch (23.44 g/100 g dry starch) content was observed. Practical applications This study presents the application of processing methods (soaking, steaming, dehydration) to improve the nutritional characteristics and physicochemical properties of hyacinth bean flour for application as ingredients to produce value‐added legume‐based food products. Such processing approaches could potentially improve the value of hyacinth bean by diversifying its use and helping to improve the competitiveness of the legume grain sector. By adopting statistical methods, findings are expected to provide valuable knowledge on nutrient loss and preservation during processing.

Vacuum impregnation as a sustainable technology to obtain iron-fortified broad bean (Vicia faba) flours

“…51 The lower WSI of soaked-autoclaved flours may be attributed to the denaturation of proteins and the fact that before obtaining the flour, during the cooking of seeds, the soluble compounds of the broad beans could be leached out in the steam that condenses around them. 52,54 Results with the same tendency were reported by Naiker et al 49 and Simons and Hall. 52 Naiker et al 49 determined the WSI and SP of soaked and soaked-autoclaved hyacinth bean flours at different temperatures, and Simons and Hall 52 determined the WAI and WSI of raw and cooked pinto bean flours.…”

“…25,48 Kumar et al 48 who measured the BD of soaked broad bean flour and pressure-cooked broad bean flour, obtained results with the same tendency but with lower values (0.58 and 0.71 g mL −1 , respectively). Naiker et al 49 also reported the same tendency but with hyacinth bean flour.…”

Structural and physicochemical characterization of porous starch prepared by enzymatic hydrolysis, solvent‐exchange, and freeze–thaw cross‐linking treatments

“…The low gelatinization and retrogradation properties shown in the DSC results of FT reflect in its low swelling power and high‐solubility results. The high swelling powers of the starches may also be related to the hydrophilic nature of hyacinth bean (Naiker et al ., 2020) (Table 3).…”

“…In vitro starch digestibility was determined using the method described by Naiker et al . (2020) with minor modifications. In brief, 500 mg of the sample was stirred in 1 mL of porcine α‐amylase (Sigma 86250; 1.5 U mg −1 of carbonate buffer pH 7).…”

“…Hyacinth bean ( Lablab purpureus ) is a versatile drought‐tolerant legume grown predominantly in Asia and Africa (Kokila et al ., 2014; Naeem et al ., 2020). Hyacinth bean flour has been shown to have mostly starch (48.66%–51.02%) and protein (27.35%–29.47%) (Naiker et al ., 2020). Hyacinth bean has also been shown to be an excellent source of essential amino acids and fatty acids, tocopherols, bioactive components, and carotenoids (Habib et al ., 2017).…”