Dept. of Mechanical Engineering, University College London, Torrington Place, London, UK.
J Food Sci. 2010 Aug 1;75(6):E330-8. doi: 10.1111/j.1750-3841.2010.01673.x.
Thickening agents based primarily on granulated maize starch are widely used in the care of patients with swallowing difficulties, increasing viscosity of consumed fluids. This slows bolus flow during swallowing, allowing airway protection to be more properly engaged. Thickened fluids have been shown to exhibit time-varying behavior and are non-Newtonian, complicating assessment of fluid thickness, potentially compromising efficacy of therapy. This work aimed to quantify the flow properties of fluids produced with commercial thickeners at shear rates representative of slow tipping in a beaker to fast swallowing. Results were presented as indices calculated using a power-law model representing apparent viscosity (consistency index) and non-Newtonian nature of flow (flow behavior index). Immediately following mixing, 3 fluid thicknesses showed distinct consistency indices and decreasing flow behavior index with increasing thickener concentration. An increase in consistency index over 30 min was observed, but only for samples that were repeatedly sheared during acquisition. Three-hour measurements showed changes in consistency index across fluids with the largest being a 25% rise from initial value. This may have implications for efficacy of treatment, as fluids are not always consumed immediately upon mixing. Flow behavior indices were comparable across thickeners exhibiting similar rises over time. The indices were a more complete method of quantifying flow properties compared with single viscosity measurements, allowing an increased depth of analysis. The non-Newtonian nature of fluids perhaps renders them particularly suitable for use as dysphagia therapies, and such analysis may allow the possibility of altering these properties to optimize therapeutic efficacy to be explored. Practical Application: Effective treatment of swallowing disorders relies upon the appropriate choice and subsequent reproduction of drinks thickened to one of a number of predetermined levels. Currently there are no agreed methods of measuring the thickness of these drinks in use and the specifications are subjective, relying on descriptions such as "syrup" thick. This research aims to further understanding of the flow properties of thickened drinks and bring a quantified measure of thickness closer to being a practical reality.
主要基于颗粒状玉米淀粉的增稠剂广泛用于吞咽困难患者的护理中，增加所消耗液体的粘度。这会减缓吞咽过程中的食团流动速度，从而更有效地保护气道。已证明增稠液体具有时变行为且呈非牛顿流体特性，这使得液体厚度的评估变得复杂，可能会影响治疗的效果。本研究旨在量化商业增稠剂在搅拌杯中缓慢倾斜至快速吞咽的剪切速率下产生的流体的流动特性。结果以使用表示表观粘度（稠度指数）和流动非牛顿特性（流动行为指数）的幂律模型计算的指数表示。混合后立即，3 种厚度的流体具有明显的稠度指数，且随着增稠剂浓度的增加，流动行为指数逐渐降低。在采集过程中反复进行剪切后，观察到 30 分钟内稠度指数增加。3 小时的测量结果显示，不同流体的稠度指数发生变化，最大变化幅度为初始值的 25%。这可能会影响治疗效果，因为混合后并非立即饮用。随着时间的推移，不同增稠剂的流动行为指数相似，呈上升趋势。与单一粘度测量相比，这些指数是量化流动特性的更完整方法，允许进行更深入的分析。流体的非牛顿特性可能使它们特别适合用作吞咽障碍治疗方法，并且这种分析可能允许探索改变这些特性以优化治疗效果的可能性。实际应用：吞咽障碍的有效治疗依赖于对经过适当选择和随后复制的特定预定水平的增稠饮料的正确选择和后续复制。目前，尚无用于测量这些饮料厚度的公认方法，而且规格是主观的，依赖于“糖浆”等描述。本研究旨在进一步了解增稠饮料的流动特性，并使厚度的量化测量更接近实际现实。
