Lupinus sprouts a new and potential ingredient in extrusion process: Physicochemical, nutritional and structural evaluation

Abstract

The objective of this study was to determine the optimal conditions of the extrusion cooking process using ungerminated Lupinus angustifolius flour, to later develop snacks with germinated flours for 3, 5 and 7 days. The optimal conditions were 16% feed moisture, 152 °C die temperature, and 47/53% lupinus/corn starch proportion. The water absorption and solubility index, bulk density, and ΔE values increased in extrudates with 7 days sprouted flour (EG7) (4.32 g/g, 19.68%, 643.60 kg/m3, 24.13 respectively). EG7 presented the lowest values in sectional expansion index and hardness (1.69 and 50.98 N respectively). Furthermore, trypsin inhibitors were inactivated during the extrusion process, and a reduction in phytic acid content was observed in the extruded products containing germinated flours. The concentration of phenolic compounds and flavonoids were higher in the extruded products with 47/53% lupinus germinated for 3 days /corn starch proportion. Changes in the components of the secondary structure protein were observed, improving protein digestibility in extrudates with sprouted flours. The combination of processes can be an alternative for the development of a snack with improved physicochemical and nutritional properties. Industrial relevanceThe results show that sprouting and extrusion are emerging techniques in food engineering that, when combined, make it possible to obtain innovative snacks with potential benefits to human health. Lupinus sprouts are a potential ingredient that allows increasing the nutritional, physicochemical and functional properties of extruded snacks; offering an alternative of healthy plant-based snacks, given its growing demand by the consumer.