Development and characterization of a high hydrosoluble food ingredient using extruded whole chickpea flour and sequential alcalase® and α-amylase treatment

Abstract

Chickpea is an adequate source of proteins and starch which can be used to develop new nutritious and functional food products such as vegetable beverages. However, in order to use chickpea to develop a functional, healthy and nutritional beverage, its processing is needed to improve the digestibility and increase the quantity of soluble components into an aqueous system. Therefore, in the present research work, extrusion of whole chickpea and sequential hydrolyses with Alcalase® and α-amylase were evaluated to develop a high soluble chickpea-based food ingredient. The thermoplastic extrusion process was carried out varying processing moisture (15.6% or 22.55%), final barrel temperature (143 °C or 150 °C) and screw speed (450 rpm, 580 rpm, or 700 rpm) to generate three SME inputs (127.95 Wh/kg, 161.58 Wh/kg, and 199.13 Wh/kg). After extrusion, flours were hydrolyzed with Alcalase® and α-amylase in order to maximize soluble compounds after hydration. In general, extrusion did not affect chemical composition, but caused structural modifications that influenced changes in functional properties and modified in vitro protein and starch digestibilities. Extruded chickpea flours presented higher content of soluble proteins and increased starch hydrolysis after Alcalase® and α-amylase treatment, respectively. It was found that extrusion treatment of chickpea with a SME input of 127.95 Wh/kg produced at 22.5% processing moisture, 150 °C of final temperature and 580 rpm of screw speed in combination with the later Alcalase®/α-amylase treatments achieved the highest release of both soluble proteins (70%) and soluble solids (62%) and the highest degree of starch hydrolysis (84%). These results were used to transform whole chickpea flour into a valuable soluble food ingredient by means of a combination of extrusion and sequential Alcalase®/α-amylase treatment. This soluble food ingredient was freeze dried, milled and characterized in terms of chemical composition and protein quality. It was found that the resulting powder had 53.7%, 20.2% and 3.6% of reducing sugars, proteins, and fat contents, respectively. The soluble powder had an in vitro protein digestibility of 83.1%, a PDCAAS value of 0.831 and it did not present any limiting amino acids which suggest that this product had the potential to be used to develop instant chickpea beverages with an excellent nutrimental quality.