Influence of storage time at room temperature on the physicochemical properties of cassava starch films

The influence of storage time on colour, moisture content, crystallinity and mechanical performance of edible cassava starch films containing glycerol and sorbate, were studied. The effect of the pH of the film forming systems was also evaluated. It was observed that, for storage times of 4 weeks or longer, tan 6 curves shifted to higher temperatures independently of the pH. Films obtained from systems of pH 5 showed a decrease in the intensity of the loss tangent-peak observed between -30 and 10 degrees C, fact that is in accordance with a slight increase in the crystalline fraction. At room temperature, E ' increased and tan delta decreased between 2 and 4 weeks trends that are in accordance with the increase in crystallinity and the decrease in moisture content observed with storage time. Colour parameters and sorbate content did not change significantly along 8 week-storage, showing that sorbate was not destroyed along the period studied. It can be concluded that changes of starch along storage were mostly responsible for the changes observed in mechanical properties. (c) 2007 Elsevier Ltd. All rights reserved.