Coupling process of phase separation and gelation in konjac glucomannan and gelatin system

Abstract

The influence of konjac glucomannan (KGM) on the cool-induced gelation of gelatin was investigated using dynamic oscillatory rheological measurements at low strain amplitude and microstructural analysis by fluorescence microscopy. Rheological tests were measured during gel formation, including isothermal cooling and heating/cooling at a constant rate. The transition of phase compatibility to segregative phase separation with increase of KGM concentration was observed on KGM/gelatin mixture systems at 40 °C. The structural and mechanical of these hydrogels are dominated by the interplay between phase separation and gelation. In compatible phase status, the presence of KGM prolonged the gelation to occur for disordering the gelatin coil-helix transition, decreased the gel strength. The consequence of phase separation was dependent on KGM concentrations, resulting in bicontinuous microstructures. In the case of phase separation, the gelation was accelerated. It was demonstrated that by using different protein-polysaccharide mixtures at phase compatibility or separation concentrations could be feasible ways to control micro-networks and apply structural design in food formulation.