Structural Properties of Cold Water Extractable ${\alpha}-D-glucan$ in Rice Flours

쌀가루 냉수추출 ${\alpha}-D-glucan$의 분자구조적 특성

The structural properties of cold water extractable ${\alpha}-D-glucan$ in rice flours obtained by various milling methods were investigated. The blue value, ${\lambda}_{max}$ values of the iodine complex and ${\beta}-amylolysis$ limit of the cold water extractable ${\alpha}-D-glucan$ were in the range of $0.026{\sim}0.030,\;518{\sim}522\;nm$ and $52.7{\sim}59.6%$, respectively, indicating these materials were composed mainly of amylopectin-like polymer. The gel chromatography on Sepharose CL-2B indicated that the cold water extractable ${\alpha}-D-glucan$ had lower molecular weight but wider molecular weight distribution than that of the original rice amylopectin. The Sephadex G-50 gel chromatography showed that the unit chain distribution of cold water extratable ${\alpha}-D-glucan$ after debranching with pullulanase was similar to that of rice amylopectin. And the ion chromatography of the distribution pattern of the chain length below D.P.30 in the debranched ${\alpha}-D-glucan$ indicated only blade-milled flour was similar to the amylopectin, but in the amount of unit chain below D.P.10, all the ${\alpha}-D-glucan$ in rice flours was higher than that of amylopectin.

쌀가루로부터 추출한 냉수가용 ${\alpha}-D-glucan$의 blue value는 $0.026{\sim}0.030$, 극대흡수파장은 $518{\sim}522nm$, ${\beta}-amyolysis\;limit$는 $52.7{\sim}59.6%$ 정도의 범위를 나타내어 이들 물질은 아밀로펙틴에 유사한 성질을 지니고 있었으며, 또한 이들 ${\alpha}-D-glucan$에 가지절단효소인 pullulanase를 처리한 후 분해물의 쇄장분포를 조사한 결과 이들 ${\alpha}-D-glucan$은 쌀아밀로펙틴의 unit chain 분포와 유사하였고, 또한 이들 분해물에 대해 중합도 30 이하의 쇄장분포는 쌀가루 냉수추출 ${\alpha}-D-glucan$ 중 blade mill의 것만이 아밀로펙틴과 유사한 쇄장분포를 나타내었고 중합도 10 이하의 구성비에 있어서는 냉수추출 ${\alpha}-D-glucan$의 것이 아밀로펙틴보다 높았다.