Relationships between the Duration of Organic Farming Culture and Amylographic Characteristics and Mineral Contents of Rice

The amylographic characteristics of milled rice and mineral contents (including nitrogen) of brown rice, which were produced under an organic farming culture (no chemical ferilizers, all of the rice residues returned to the paddy fields) were determined for 1 to as long as 16 years. The maximum viscosity and breakdown values of rice flour increased with increasing duration of the organic farming culture. The contents of minerals in the rice grain, produced one year after the beginning of organic farming culture, were similar to those of the rice from a customary farming culture. The N, P and K contents decreased with the duration of organic farming culture, but the Mg content increased gradually. These changes in the content of the elements were the greatest during the first 5 years. The Mg/K ratio, which is thought to be a suitable index of the eating quality of cooked rice, gave significant correlations with both the maximum viscosity and breakdown values. These results suggested that the eating quality of cooked rice by organic farming culture was better due to increases of rice starch stickiness and of the Mg/K ratio.