2002 Volume 71 Issue 3 Pages 349-354
This study was carried out to demonstrate the effect of high air temperature and the insufficient solar radiation during the ripening period on the palatability and physicochemical properties of rice produced in 1999. Using eight cultivars in Fukuoka Prefecture, we compared the grain ripening and physicochemical properties of rice produced in 1999 with those in 1996 and 1998, years that were characterized by normal air temperature and normal solar radiation, high air temperature and normal solar radiation, respectively. Since the 1000-grain weight and grain thickness of rice in 1999 were lower than in 1996 and 1998, the rice in 1999 ripened insufficently. Milled rice in 1999 showed lower amylose content and breakdown values, and a higher protein content and Hardness/Adhesiveness ratio (H/A3) than in 1996 and 1998. The 1000-grain weight of brown rice produced from 1994 to 2000 showed a negative correlation with the amylose content of milled rice in each year, and the 1000-grain weight of brown rice produced from 1995 to 2000 showed a positive correlation with the protein content of milled rice in each year. As a result, insufficient grain filling caused the increase of amylose content and the decrease of protein content. It was concluded that the shortage of solar radiation in 1999 was due to insufficient grain filling, which led to the abnormal physicochmical properties. Furthermore, it was estimated that not only were the physicochemical properties of rice in 1999 inferior to those of rice produced in 1996 and 1998, but also was the palatability of rice.
