Textural properties, microstructure and digestibility of mungbean starch–flaxseed protein composite gels

Mungbean starch (MBS)–flaxseed protein (FP) composite gels were prepared to explore the feasibility of developing soft gel food products. The mixtures of 8% MBS with 1%–4% FP formed smooth and soft-textured gels. Elasticity modulus and hardness of gels decreased with the increase of FP content, e.g., the hardness value reduced from 2.39 N for MBS alone gel to 1.00 N for composite gel (8% MBS+4% FP). The MBS-FP composite gels exhibited a microstructure in which FP granules were imbedded within the continuous MBS network, and the cross section showed a rough and irregular structure. Furthermore, the composite gel of 8% MBS+4% FP had a higher digestibility (53.3%, 2 h) than the MBS-alone gel (30.5%, 2 h). Mechanistically, amylose was released from MBS when heated and formed a three-dimensional network when cooled. Meanwhile, partially unfolded FP molecules were encapsulated in starch network to form semi-interpenetrating gel network. Therefore, MBS-FP composite gels can be prepared as novel, gelled food with a range of soft texture to meet the demand of different consumers, especially for those with swallowing challenges.