关键词: 大米淀粉, 普鲁兰酶, 脱支, 分子结构, 流变特性

Abstract: In the present study, debranched starches (DBS) from three rice varieties were prepared by treatment with pullulanase with the aim to investigate the effect of enzymatic hydrolysis on starch structure and rheological properties. The results showed that the crystallinity of rice starch decreased and the amorphous region increased after pullulanase treatment. The chain length distribution showed that the fine structures of the three rice starches were similar, the hydrolysis reaction was more effective for shorter side chains, and glutinous rice starch was more easily digested. There was no significant difference in the Fourier transform infrared spectra of debranched and raw rice starch except that the stretching vibration peak of ?OH was relatively enhanced. Upon the addition of pullulanase, the viscosity of starch paste decreased steeply especially for glutinous rice starch, which was more easily hydrolyzed than the other two rice starches. The rheological properties indicated that the starch granules became intermeshing and loosely arranged after hydrolysis. Moreover, the mobility was increased, and the solubility and water-holding capacity were enhanced. Glutinous rice starch was more sensitive to pullulanase treatment than the other rice starches. To conclude, debranching can improve starch gel properties and enhance starch fluidity .

Key words: rice starch, pullulanase, debranching, molecular structure, rheological properties