Li Dan, Fu Xuexia, Mu Siyu, Fei Teng, Zhao Yakun, Fu Jingchao, Lee Byung-Hoo, Ma Yanli, Zhao Jian, Hou Jumin, Li Xiaolei, Li Zhiyao
Key Laboratory of Agro-products Processing Technology, Jilin Provincial Department of Education, Changchun University, Changchun 130022, People's Republic of China; Key Laboratory of Human Health Status Identification and Function Enhancement, Jilin Provincial Department of Science and Technology, Changchun University, Changchun 130022, People's Republic of China.
Key Laboratory of Agro-products Processing Technology, Jilin Provincial Department of Education, Changchun University, Changchun 130022, People's Republic of China.
Int J Biol Macromol. 2021 Jul 31;183:1248-1256. doi: 10.1016/j.ijbiomac.2021.05.032. Epub 2021 May 15.
Potato starch with high viscosity and digestibility cannot be added into some foods. To address this issue, a novel starch-acting enzyme 4,6-α-glucosyltransferase from Streptococcus thermophilus (StGtfB) was used. StGtfB decreased the iodine affinity and the molecular weight, but increased the degree of branching of starch at a mode quite different from glycogen 1,4-α-glucan branching enzyme (GBE). StGtfB at 5 U/g substrate mainly introduced DP 1-7 into amylose (AMY) or DP 1-12 branches into amylopectin (AMP), and increased the ratio of short- to long-branches from 0.32 to 2.22 or from 0.41 to 2.50. The DP 3 branch chain was the most abundant in both StGtfB-modified AMY and StGtfB-modified AMP. The DP < 6 branch chain contents in StGtfB-modified AMY were 42.68%, much higher than those of GBE-modified AMY. StGtfB significantly decreased viscoelasticity but still kept pseudoplasticity of starch. The modifications also slowed down the glucose generation rate of products at the mammalian mucosal α-glucosidase level. The slowly digestible fraction in potato starch increased from 34.29% to 53.22% using StGtfB of 5 U/g starch. This low viscoelastic and slowly digestible potato starch had great potential with respect to low and stable postprandial blood glucose.
高粘度和高消化率的马铃薯淀粉不能添加到某些食品中。为了解决这个问题，使用了一种来自嗜热链球菌的新型淀粉作用酶4,6-α-葡糖基转移酶（StGtfB）。StGtfB降低了淀粉与碘的亲和力和分子量，但以一种与糖原1,4-α-葡聚糖分支酶（GBE）截然不同的方式增加了淀粉的分支度。每克底物添加5单位的StGtfB主要将DP 1-7引入直链淀粉（AMY）或DP 1-12分支引入支链淀粉（AMP），并将短链与长链分支的比例从0.32提高到2.22，或从0.41提高到2.50。DP 3支链在StGtfB修饰的AMY和StGtfB修饰的AMP中最为丰富。StGtfB修饰的AMY中DP<6的支链含量为42.68%，远高于GBE修饰的AMY。StGtfB显著降低了淀粉的粘弹性，但仍保持淀粉的假塑性。这些修饰还降低了哺乳动物黏膜α-葡糖苷酶水平下产物的葡萄糖生成速率。使用每克淀粉5单位的StGtfB，马铃薯淀粉中缓慢消化部分的比例从34.29%增加到53.22%。这种低粘弹性和缓慢消化的马铃薯淀粉对于降低和稳定餐后血糖具有巨大潜力。
