Abstract
The distribution coefficients, Kapp, of non-electrolytes of different molecular masses on a tapioca starch gel were measured at a temperature range of 25 – 60°C. The swelling pressure of the gel was estimated from the coefficients at each temperature, and was observed to increase from 1 to 3 MPa with a temperature increase from 25 to 50°C. The swelling pressure, however, decreased at 60°C. The decrease was ascribed to the gelatinization of tapioca starch, which was observed using differential scanning calorimetry. The temperature dependency of the swelling pressure suggested a significant effect of gelatinization on the distribution equilibrium of a solute on the starch gel. The experimentally observed Kapp values of electrolytes (0.5 to 0.8) were lower than the values calculated using the swelling pressure and specific molecular volumes of the electrolytes. This suggested the involvement of another factor, such as an electrostatic interaction, in the distribution of electrolytes on the gel.
