Application of digital image analysis method to study the gelatinization process of starch/ sodium chloride solution systems

The digital image analysis, integral optical density (IOD) method, combined with “the model of response difference of crystallite change (MRDCC)” and “the model of gelatinization process (GP)”was applied to further study the gelatinization of corn starch, potato starch, and pea starch in different concentrations of NaCl solutions. It was found that the addition of non-aqueous media not only affected the gelatinization temperature, but also impacted on the whole gelatinization process and effected differently at different stages of gelatinization. NaCl solution of 1, 3 and 4 mol/L (M) rose the GP curve of corn starch while 2 M had little effects on it; for potato starch, it seemed that NaCl gave little efforts on GP curve while 1 M rose the GP curve at the relative biggest degree; for pea starch, it performed two stage gelatinization process in different concentration of NaCl solution, this may due to the resultant force of heat, plasticizer, solute and expansion power and more studies were needed to reveal the gelatinization mechanism. Compared with the loss of crystalline structure (long-ordered structure), the disappearance of the molecular helix-coil structure (short-ordered structure) contributed greater to the DSC enthalpy, which could be deduced from the GP model.