Abstract
Starch samples of rice and glutinous rice starches were adjusted to 27 % of moisture and heated at $100^{\circ}C$ for 16 hours, respectively. After the treatment, their physicochemical properties were investigated. The granule shapes of all the starches were polygonal and they became slightly bigger in their sizes after the treatment. All their X-ray diffraction patterns were A types. The specific gravity of the starches decreased to 1.03-1.09 by the treatment. The water binding capacity of rice starches increased, while that of glutinous counterparts slightly decreased. Almost no change in the amount of amylose included was found. Swelling power and solubility were increased with the increase of temperature. At a certain temperature, however, the solubility of the treated starches increased when the swelling power decreased. The initial gelatinization temperatures of Akkibare, Yongmun, and Taebaek starches were $60{\sim}65^{\circ}C$ but those of glutinous rice starch and U.S.A. rice starch were $55{\sim}60^{\circ}C$ and $70{\sim}75^{\circ}C$, respectively, as measured by transmittance. The gelatinization temperature of the treated starches was higher than that of the untreated starches.
멥쌀 전분(아끼바레, 용문벼, 태백벼, 미국쌀)과 찹쌀 전분의 수분을 27 %로 조절하여 $100^{\circ}C$에서 16시간 열처리한 후 이화학적 성질을 조사하였다. 쌀 전분 입자는 다면체로 표면이 부드럽고 매끈하였으며 수분-열처리하면 크기가 약간 커졌고 X-선 회절도로 부터 얻은 결정형은 모두 A형이었다. 수분-열처리하면 쌀 전분의 비중은 $1.03{\sim}1.09$로 감소했고, 물결합 능력은 멥쌀 전분은 증가하였으나 찹쌀 전분은 약간 감소하였다. 아밀로오스 함량은 거의 변화가 없었다. 팽화력과 용해도는 온도가 상승함에 따라 증가하였으며 일정 온도에서 수분-열처리 전분의 용해도는 증가했으나 팽화력은 감소하였다. 광투과도에 의한 호화개시 온도는 아끼바레, 용문벼, 태백벼 전분은 $60{\sim}65^{\circ}C$였고 찹쌀 전분은 $55{\sim}60^{\circ}C$, 미국쌀 전분은 $70{\sim}75^{\circ}C$였으며 수분-열처리시 호화개시 온도는 상승하였다.
(Department of Food and Nutrition, Chonnam National University)