Rheological characterisation of the gelation behaviour of maltodextrin aqueous solutions

As a prelude to the study of its co-gelation with other biopolymers, the gelation behaviour of maltodextrin Paselli SA2 has been investigated in detail. Our work extends that done previously and leads to a number of interesting new findings, regarding maltodextrin gel behaviour. Studies were made of the effect of maltodextrin concentration and temperature on gelation using viscosity, small amplitude oscillatory and spectrophotometry measurements. Our results show that the c* concentration is close to the critical gelation concentration and in the region of 17%. A linear equation relating the three parameters, gel time, concentration and gelation temperature is obtained. Data obtained from rheology experiments also allow master curves to be constructed, which can be used to predict gel behaviour for any concentration or gelation temperature in the range studied. We find that the cascade model cannot be applied to our results for maltodextrin gelation. This is probably due to gelation being more closely related to a colloidal aggregation. Furthermore, a study on the influence of temperature of dissolution points out an optimum dissolution temperature leading to a quicker and stronger gel. The effect is not well understood but the presence of nuclei (aggregates of double helices of amylose) is a possible explanation.