Degradation of Starch Granules by Alpha‐Amylase of Streptomyces precox NA‐273

The action of purified α‐amylase of Streptomyces precox NA‐273 on starch granules of normal maize and potato was studied. The hydrolysis was followed by measuring total soluble carbohydrates and glucose released. Patterns of degradation were observed by scanning electron microscopy (SEM). The main soluble product was maltose, small amounts of glucose and higher oligosaccharides were always observed. By SEM, attack started small pits on the surfaces of maize starch granules, pits increased in number and in size, and pores penetrated into the inner portions of the granules toward the center. The enzyme seemed to degrade the inner portion of starch granules better than the well‐known general α‐amylases.