Hydrolysed pea proteins mitigate in vitro wheat starch digestibility

Abstract

Possible inhibitory effects on wheat starch amylolysis of native and hydrolysed pea protein, in an extruded wheat snack matrix were investigated by using a combined in vitro dynamic gastric model (DGM) and a static duodenal digestion model (SDM). The matrix was prepared by blending wheat flour and pea proteins (12%, w/w) in their native or proteolyzed forms. Extruded snacks were ground, mixed with saliva and poured in the DGM-fundus. The slurry in the antrum was released simulating the in vivo emptying of the stomach and subsequently transferred to the SDM. Native pea protein did not influence the release of soluble glucans and glucose after complete gastric emptying into the vessel. However, the addition of hydrolysed pea protein significantly reduced starch amylolysis at the first 40 min of digestion. No inhibitory effect was observed at later digestion times. Fourier-Transform Infrared (FTIR) analysis of the extruded samples clearly indicated enhanced starch-protein interactions, where the magnitude of interaction found to be greatest in the blend with hydrolysed pea protein through hydrogen bonding. At our knowledge, this is the first study using DGM to determine the effect of exogenous protein on the digestibility of extruded wheat starch. The data suggested the possibility of using protease hydrolysed pea protein as an ingredient to formulate low glycemic food products.