PHYSICOCHEMICAL PROPERTIES OF EXTRACTED AND ACID MODIFIED STARCH FROM SOME IMPORTED AND IRAQI CORN GENOTYPES

The starch of ten corn genotypes (Sara, Al-Maha, Fajar -1-, Bagdad -3-, ZP.434*A, ZP.434*B, MSI*B, Dhqan, Corpeto, Dracma) were isolated, and purified to study their physicochemical and rheological properties. The capability of these natural and gelatinized starches to produce resistant starch by their responses to citric acid modification and increasing of their content of amylose also was studied. The results showed that there were significant differences among the starch in their characteristics, amylose content ranged from 19.935 to 31.095%, peak viscosity 400.00 - 584.66 AU, gel consistency 67- 121 mm, water release and light transmittance (clarity), 5.46 - 13.83%., 24.122 – 52.855% during 120h of storage respectively. On the other hand, citric acid modification of natural and gelatinized starch caused increasing of amylose content, and water binding. Acid modifying of starch increased swelling properties but caused decreasing of this characteristic for acid modified gelatinized starch.