Gelation behavior and mechanism of Nicandra physalodes (Linn.) Gaertn. seeds pectin induced by Glucono–delta–lactone

In this study, the physicochemical properties of pectin from Nicandra physalodes (Linn.) Gaertn. seeds (NPGSP) were analysed firstly, and the rheological behavior, microstructure and gelation mechanism of NPGSP gels induced by Glucono–delta–lactone (GDL) were investigated. The hardness of NPGSP gels was increased from 26.27 g to 226.77 g when increasing GDL concentration from 0 % (pH = 4.0) to 1.35 % (pH = 3.0), and the thermal stability was improved. The peak around 1617 cm −1 was decreased as the adsorption peak of the free carboxyl groups was attenuated with addition of GDL. GDL increased the crystalline degree of NPGSP gels, and its microstructure exhibited more smaller spores . Molecular dynamics was performed on systems of pectin and gluconic acid (GDL hydrolysis product), indicating that inter–molecular hydrogen bonds and van der Waals forces were the main interactions to promote gels formation. Overall, NPGSP has the potential commercial value for developing as a thickener in food processing.