Korompokis Konstantinos, Deleu Lomme J, De Brier Niels, Delcour Jan A
Laboratory of Food Chemistry and Biochemistry and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Leuven, Belgium.
Belgian Red Cross, Motstraat 42, B-2800 Mechelen, Belgium.
Foods. 2021 Feb 2;10(2):303. doi: 10.3390/foods10020303.
The fine molecular structure of starch governs its functionality and digestibility, and enzymatic approaches can be utilized to tailor its properties. The aim of this study was to investigate the in situ modification of starch by amylomaltase (AMM) from Thermus thermophilus in model starch systems subjected to hydrothermal treatments under standardized conditions and the relationship between molecular structure, rheological properties and in vitro digestibility. When low dosages of AMM were added to a wheat starch suspension prior to submitting it to a temperature-time profile in a Rapid Visco Analyzer, the increased peak viscosity observed was attributed to partial depolymerization of amylose, which facilitated starch swelling and viscosity development. At higher dosages, the effect was smaller. The low cold paste viscosity as a result of the activity of AMM reflected substantial amylose depolymerization. At the same time, amylopectin chains were substantially elongated. The longer amylopectin chains were positively correlated ( = 0.96) with the melting enthalpies of retrograded starches, which, in turn, were negatively correlated with the extent ( = 0.92) and rate ( = 0.79) of in vitro digestion. It was concluded that AMM has the potential to be used to deliver novel starch functionalities and enhance its nutritional properties.
淀粉的精细分子结构决定了其功能和消化率，酶法可用于调整其性质。本研究的目的是研究嗜热栖热菌的淀粉麦芽糖酶（AMM）在标准化条件下对经过水热处理的模型淀粉体系中淀粉的原位修饰，以及分子结构、流变学性质和体外消化率之间的关系。当在快速粘度分析仪中对小麦淀粉悬浮液进行温度-时间曲线处理之前加入低剂量的AMM时，观察到的峰值粘度增加归因于直链淀粉的部分解聚，这促进了淀粉的膨胀和粘度的增加。在较高剂量下，这种效果较小。AMM活性导致的低温糊化粘度较低反映了直链淀粉的大量解聚。同时，支链淀粉链显著延长。较长的支链淀粉链与回生淀粉的熔化焓呈正相关（r = 0.96），而回生淀粉的熔化焓又与体外消化的程度（r = 0.92）和速率（r = 0.79）呈负相关。得出的结论是，AMM有潜力用于赋予淀粉新的功能并增强其营养特性。
