Relationship between Molecular Structure of Acid-Hydrolyzed Rich Starch and Retrogradation

산처리 쌀전분의 분자구조와 노화속도

The relationship between the molecular structure of acid-hydrolyzed rice starch and the retrogradation rate of starch gel was investigated. The molecular structure of starch was modified by acid hydrolysis with 1 N HCl at $35^{\circ}C$. The molecular weight of starch decreased as acid hydrolysis time was increased. At the early stage of hydrolysis up to 3 hr, the branching point of amylopectin was degraded and thereafter both ${\alpha}-1,4\;and\;{\alpha}-1,6$ linkages were hydrolyzed. The starch gel (50%) stored at $20^{\circ}C$ revealed that the rapid retrogradation occurred during 4 hr of storage which was more pronounced as the hydrolysis time increased. The degree of retrogradation of starch gels after 4 hr storage showed a linear relationship with the yield of hydrolyzate. These results suggested that the retrogradation of starch gel was accelerated by degradation of ${\alpha}-1,6$ linkages with acid.

쌀 전분을 1 N 염산용액으로 가수분해하였을 때 가수분해율은 1시간에 0.31%, 3시간에 0.39%, 12시간에 0.7%, 72시간 후에 4.7%이었다. 전분은 산에 의하여 ${\alpha}-1,4$ 결합과 ${\alpha}-1,6$ 결합이 모두 분해되었는데, 산처리 전분의 요드 반응과 분자량 분포로 보아, 산처리 3시간까지는 ${\alpha}-1,6$ 결합이 분해되었으며, 그 이후부터는 ${\alpha}-1,4$ 결합도 분해되기 시작하였다. 산처리 전분겔 (50%)의 초기 노화도는 산가수분해 정도와 정의 상관 관계를 보였고, 산에 의한 아밀로펙틴의 ${\alpha}-1,6$ 결합의 분해는 노화를 촉진 시켰다.