Modelling of methylcellulose thermogelation as a function of polymer concentration and dissolution media properties

A large number of factors can influence hydrocolloid properties, but little basic research has been performed on this topic, mainly evaluating one factor at a time. The aim of this work was to study the thermogelation of methylcellulose as a function of polymer concentration (1-3 g/100 g), and pH (4-10) and salt concentration (50-150 mmol/L) of the aqueous dissolution buffer. To simultaneously evaluate the effects of the different factors and of their interactions, a Box Behnken Design of Experiment was applied. Thermogelation was evaluated by means of fundamental and empirical rheological methods. Significant response surface models describing methylcellulose structuring properties as a function of the three considered factors were calculated. In particular, buffer pH and concentration seemed to mainly influence the fundamental rheological behavior of the methylcellulose systems, whereas variables evaluated at higher strains were especially affected by the polymer concentration. The salt-out effect of the phosphate salts used is also discussed. The obtained models represent a first step for a deeper knowledge of the molecular interactions in food systems. They could be exploited in the development of new foods, making easier the modulation of the structural and textural features of products.