Abstract
The pore size distribution curves of rice, corn, potato, sweet potato and kuzu starches were investigated to elucidate the relationship between the types of A, B and C forms and their porosity. Pore size distribution curves in the regions of pore radii 4 to 10.5 Å and 10.5 to 300 A were determined by the micropore (MP) method from the moisture adsorption isotherms and the Barrett Joyner Halenda (BJH) method from the moisture desorption isotherms, respectively. Moisture content at higher water activity than 0. 4, saturated moisture content and hysteresis loop of B form (potato) starch were larger than those of C form (kuzu, sweet potato) and A form (rice, corn) starches. The maximum peak at the vicinity of pore radius 8 A was observed not in the A and C form starches but in the B form starch . The plots of pore volume in the region of pore radii 10.5 to 300 A and B form percentage gave a straight line with correlation coefficient of 0.955.
