A single-enzyme system for starch digestibility screening and its relevance to understanding and predicting the glycaemic index of food products
A single-enzyme system for starch digestibility screening and its relevance to understanding and predicting the glycaemic index of food products
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DOI：
10.1039/c9fo00603f
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发表时间：
2019-08-01
期刊：
影响因子：
6.1
通讯作者：
Warren, Frederick J.
中科院分区：
文献类型：
--
作者：
Edwards, Cathrina H.;Cochetel, Noriane;Warren, Frederick J.
目前，人们对增加提供更健康的碳水化合物食品，特别是那些在体内测量时具有低血糖指数（GI）的碳水化合物食品非常感兴趣。对许多富含淀粉的食物的代谢反应很大程度上是由淀粉水解的速率和程度的差异驱动的。因此，从高通量体外淀粉分解试验中获得的酶动力学参数具有快速预测富含淀粉食品GI的潜力。本研究的目的是评估淀粉消化率筛选方法和酶动力学参数在比较和预测一系列富含碳水化合物的食物的GI中的有用性。将GI范围为36至81的富含淀粉的食物（n = 20）在旋转混合器上在37 ℃下在固定的酶-底物比率（4U/10 mg淀粉）下用猪胰α-淀粉酶消化90分钟。通过定量在整个孵育过程中收集的等分试样中的还原糖浓度来确定淀粉消化进程。获得淀粉消化率指数（C-20、C-60、C-90、HI、C-无穷大和k），并与GI值进行比较。消化率曲线显示，在广泛的测试食品的淀粉淀粉分解的差异。除速率常数k外，体外淀粉消化率指数与GI显着相关（p < 0.01）。在所有测试的指标中，C-90和C-无穷大与匹配食品的GI的体内排名相关性最强（T-b = 0.596，p < 0.001和T-b = 0.599，p < 0.01），然而，对于一些消化较慢的食物，所获得的消化率曲线在90分钟内是线性的，这意味着C-从一级动力学分析不能获得无穷大和k。C-90与绝对GI值的相关性最强（r = 0.724，p < 0.001）。总体淀粉消化率曲线反映了不同GI食品的淀粉淀粉分解差异，C-90提供了所有产品类别中绝对和相对GI值的最佳指示。体外淀粉消化率筛选方法显示出快速预测GI值的潜力，并推荐用于早期食品开发和机理研究。
There is currently great interest in increasing provisions of healthier carbohydrate foods, particularly those that possess a low Glycaemic Index (GI) when measured in vivo. The metabolic response to many starch-rich foods is driven largely by differences in the rate and extent of starch amylolysis. Enzyme-kinetic parameters obtained from high-throughput in vitro amylolysis assays therefore have potential for rapid prediction of GI for starch-rich foods. The aim of this study was to evaluate the usefulness of a starch digestibility screening method and resulting enzyme-kinetic parameters in comparing and predicting the GI of a range of carbohydrate-rich foods. Starch-rich foods (n = 20) with GI ranging from 36 to 81 were digested by porcine pancreatic alpha-amylase for 90 min under a fixed enzyme-substrate ratio (4 U/10 mg starch) at 37 degrees C on a rotary mixer. Starch digestion progress was determined by quantification of reducing sugar concentration in aliquots collected throughout the incubation. Indices of starch digestibility (C-20, C-60, C-90, HI, C-infinity, and k) were obtained and compared with GI values. Digestibility curves revealed differences in the starch amylolysis for the broad range of foods tested. In vitro starch digestibility indices were significantly correlated (p < 0.01) with GI, with the exception of the rate constant, k. Out of all the indices tested, C-90 and C-infinity were the most strongly correlated with in vivo rankings for GI of matched food products (T-b = 0.596, p < 0.001 and T-b = 0.599, p < 0.01, respectively), however the digestibility plots obtained for some of the more slowly digested foods were linear over 90 min meaning that C-infinity and k could not be obtained from first order kinetic analysis. C-90 was most strongly correlated with the absolute GI values (r = 0.724, p < 0.001). Overall starch digestibility profiles reflected differences in starch amylolysis for food with varying GI, and C-90 provided the best indication of absolute and relative GI values across all product categories. The in vitro starch digestibility screening method shows potential for rapid prediction of GI values and is recommended for early stage food product development and for mechanistic studies.