State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu Province, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu Province, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, Jiangsu Province, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu Province, China; School of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu Province, China; Synergetic Innovation Center of Food Safety and Nutrition, Jiangnan University, Wuxi 214122, Jiangsu Province, China; International Joint Laboratory on Food Safety, Jiangnan University, Wuxi 214122, Jiangsu Province, China.
Carbohydr Polym. 2023 Nov 15;320:121190. doi: 10.1016/j.carbpol.2023.121190. Epub 2023 Jul 11.
Hydrolysis of highly concentrated soluble starch (60%, w/w) was performed using sequential α-amylases from Bacillus stearothermophilus (T, 0.2%, w/w) and Bacillus amyloliquefaciens (B, 0.1%, w/w) to identify their possible action patterns. We found that T reduced the average molecular weight (Mw) of soluble starch from 52,827 Da to 31,914 Da and significantly affected its branched chain length. Compared with soluble starch, the chains with DP 6-12 and DP ≥ 13 in the T samples were diminished by 46% and 96%, respectively. This resulted in an attenuation in the proportions of exterior and inner chains, as well as low iodine binding capacity of the hydrolysates. In contrast, a slower decrease in the average Mw of soluble starch occurred after TB incubation, and the level of DP 6-12 further lowered, causing a gradual decline in the iodine binding capacity of the hydrolysates. Gathered data revealed an unusual action pattern of sequential α-amylase treatment at high substrate concentrations. Bacillus stearothermophilus α-amylase exhibited more pronounced endo-hydrolysis of amylopectin, whereas the attack of Bacillus amyloliquefaciens α-amylase on the exterior chains was enhanced in amylopectin residues. These findings suggest that the synergy of various α-amylases is an effective strategy to promote the dextrinization of highly concentrated starch and finely modify the molecular structure of starch.
采用嗜热脂肪芽孢杆菌（T，0.2%，w/w）和地衣芽孢杆菌（B，0.1%，w/w）的顺序α-淀粉酶对高浓度可溶性淀粉（60%，w/w）进行水解，以确定其可能的作用模式。我们发现 T 将可溶性淀粉的平均分子量（Mw）从 52827 Da 降低到 31914 Da，并显著影响其支链长度。与可溶性淀粉相比，T 样品中 DP6-12 和 DP≥13 的链分别减少了 46%和 96%。这导致水解产物中外部和内部链的比例降低，以及碘结合能力降低。相比之下，在 TB 孵育后，可溶性淀粉的平均 Mw 下降较慢，DP6-12 的水平进一步降低，导致水解产物的碘结合能力逐渐降低。收集到的数据揭示了在高底物浓度下顺序α-淀粉酶处理的一种不寻常作用模式。嗜热脂肪芽孢杆菌α-淀粉酶对支链淀粉表现出更明显的内切作用，而地衣芽孢杆菌α-淀粉酶对支链淀粉残基外部链的攻击增强。这些发现表明，各种α-淀粉酶的协同作用是促进高浓度淀粉糊化和精细修饰淀粉分子结构的有效策略。
