Laboratory for Flow Control, Faculty of Engineering, Hokkaido University, Sapporo, Japan.
Department of Rehabilitation Medicine, Hokkaido University Hospital, Sapporo, Japan.
J Texture Stud. 2022 Aug;53(4):444-452. doi: 10.1111/jtxs.12679. Epub 2022 Apr 24.
We have developed an effective method for evaluating time-resolved rheological functionalities of swallowed foods using ultrasonic spinning rheometry (USR). USR can obtain variations over time in the rheological properties of fluids despite the fluids being in heterogeneous and nonequilibrium conditions. In addition, USR can evaluate time variations of shear-thinning property changing in a few seconds. Demonstrations were conducted with typical thickener solutions: starch, guar gum, and xanthan gum-based solutions, with alpha-amylase as a digestive enzyme. The flow curve of the starch-based solutions lowered with time, and a few minutes after addition of the amylase, the viscosity dropped to one-hundredth of the original value. In contrast, the guar gum- and xanthan gum-based solutions maintained the original viscosities as generally known. Applying the power law fitting to series of these flow curves, the time variation of the shear-thinning property is quantitatively characterized by the plots on typical K-n space, where K and n are parameters in the model, consistency index and power law exponent. The qualitative characteristics of the thickeners are successfully quantified in the K-n space, and this will be a practical tool for evaluating the time-resolved rheological properties of swallowed foods.
我们开发了一种使用超声旋转流变仪（USR）评估吞咽食品的时变流变功能的有效方法。USR 可以在流体处于非均相和非平衡状态下，获得流体流变特性随时间的变化。此外，USR 可以在几秒钟内评估剪切稀化特性的时变。使用典型的增稠剂溶液（淀粉、瓜尔胶和黄原胶基溶液）和作为消化酶的α-淀粉酶进行了演示。淀粉基溶液的流动曲线随时间降低，加入淀粉酶几分钟后，粘度降至原始值的百分之一。相比之下，正如通常所知，瓜尔胶和黄原胶基溶液保持了原始的粘度。对这些流动曲线进行幂律拟合，通过典型的 K-n 空间上的图来定量描述剪切稀化特性的时间变化，其中 K 和 n 是模型中的参数，分别为稠度指数和幂律指数。在 K-n 空间中成功地量化了增稠剂的定性特征，这将成为评估吞咽食品的时变流变特性的实用工具。
