Time-Course Changes of the Fine Structure of Rice Starch Grains during Cooking Process by Scanning Electron Microscopy

Japanese Journal of Crop Science

Katsunori TAKAHASHI¹  Youji NITTA¹  Toshiaki MATSUDA¹ 

关键词: Amyloplast;    網目状構造;    Cooking;    アミ口プラスト;    Gelatinization process;    糊化過程;    Mesh-likes tructure;    炊飯;    Milled rice;    精白米;    Scanning electron microscopy;    走査電子顕微鏡;    Starch granule;    デンプン粒;   

DOI  :  10.1626/jcs.70.47

学科分类：农业科学（综合）

来源: Nihon Sakumotsu Gakkai / Crop Science Society of Japan

【 摘 要 】

Fine structural changes accompanied with the gelatinization of starch granules in milled rice grain during cooking were observed with a scanning electron microscope using three rice cultivars, Koshihikari, Kirara397 and Thailand rice (Indica type). In cv. Koshihikari, the change of starch grains started from the surface of the amyloplast envelope after 10 minutes of cooking(temperature at the central part of rice cooker was 45°C). After 15 minutes of cooking(51.3°C), starch granules in the first cell layer of a milled rice grain became swollen and a fibrous structure was observed on the surface of each starch granule. By the development of the mesh-like structure on the surface of starch granules, each amyloplast changed to one unit body after 20 minutes or cooking(98.5°C). Then, the bodies in each endosperm cell were fused and developed into the unit of irregular gel-like structure. The swelling of starch granules and the formation of irregular gel-like and mesh-like structures during cooking proccsses were faster in the outer layer than at the central part of a grain. These changes occurred faster in cv. Koshihikari than in Kirara 397 and Thailand rice. The pore size in the mesh-like structure was larger in the outer layer or agrain. We suggest that, in the gelatinization proccsses of starch, water molecules are incorporated into the insoluble high density amylopectin molecules as the main components of a starch grain resulting in swelling of starch and change to the soluble structure with a low molecular density.

【 授权许可】

Unknown