School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
Int J Biol Macromol. 2018 Feb;107(Pt B):1758-1764. doi: 10.1016/j.ijbiomac.2017.10.049. Epub 2017 Oct 10.
Granular corn starch, waxy corn starch, potato starch and tapioca starch were modified using the α-d-glucan branching enzyme (1,4-α-d-glucan:1,4-α-d-glucan 6-α-d-(1,4-α-d-glucano)-transferase, GBE, EC 2.4.1.18) from Geobacillus thermoglucosidans. The GBE-catalyzed modification caused a time-dependent increase in the ratios of α-1,6 linkages to total glycosidic linkages, as well as reductions in the average chain length and relative crystallinity. These modifications lowered the in vitro digestibility of the starch. Modification with GBE caused varying degrees of change in the in vitro digestibility of starches obtained from different sources. The highest slowly digestible starch (SDS) and resistant starch (RS) contents were found in modified tapioca starch. After modification of tapioca starch with GBE for 10h, the ratio of α-1,6 linkages to total glycosidic linkages was increased by 11.5%, while its relative crystallinity was decreased by 22.9%. Meanwhile, the SDS and RS contents of tapioca starch were increased by 47.3% and 13.5%, respectively. These results demonstrate that the digestibility of starch can be lowered through GBE modification, which may aid the development of modified starches that are digested more slowly.
颗粒玉米淀粉、蜡质玉米淀粉、马铃薯淀粉和木薯淀粉用来自嗜热解糖梭菌的α-1,4-葡聚糖分支酶（1,4-α-D-葡聚糖：1,4-α-D-葡聚糖 6-α-D-（1,4-α-D-葡聚糖基）-转移酶，GBE，EC 2.4.1.18）进行了修饰。GBE 催化的修饰导致 α-1,6 键与总糖苷键的比例随时间的推移而增加，同时平均链长和相对结晶度降低。这些修饰降低了淀粉的体外消化率。GBE 修饰导致不同来源的淀粉的体外消化率发生不同程度的变化。经 GBE 修饰的木薯淀粉具有最高的慢消化淀粉（SDS）和抗性淀粉（RS）含量。在 GBE 修饰木薯淀粉 10h 后，α-1,6 键与总糖苷键的比例增加了 11.5%，而相对结晶度降低了 22.9%。同时，木薯淀粉的 SDS 和 RS 含量分别增加了 47.3%和 13.5%。这些结果表明，通过 GBE 修饰可以降低淀粉的消化率，这可能有助于开发消化更慢的改性淀粉。
