Department of Chemical and Process Engineering, Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, GU2 7XH, UK.
Food Funct. 2020 May 1;11(5):4363-4375. doi: 10.1039/c9fo02327e. Epub 2020 May 6.
Swallowing disorders deteriorate significantly the quality of life and can be life-threatening. Texture modification using shear thinning food thickeners has been proven to be effective in the management of dysphagia. Some studies have recently considered the positive role of cohesiveness, but there is still an insufficient understanding of the effect of the rheological properties of the liquid bolus on the dynamics of bolus transport, particularly when elasticity and extensional properties are combined with a shear thinning behaviour. This study combines steady shear, SAOS and capillary breakage extensional rheometry with an in vitro method to characterize the oral transport of viscoelastic liquids. Bolus velocity and bolus length were measured from exit in vitro experiments using image analysis and related to shear and extensional properties. A theory describing the bolus dynamics shows that the elastic and extensional properties do not influence significantly the oral transit dynamics. Conversely, in vitro results suggest that the extensional properties can affect the transition from the oral to the pharyngeal phase of swallowing, where thin, viscoelastic liquids lead to a fast transit, lower oral post-swallow residues and more compact bolus with a smoother surface, which may suggest a lower risk of fragmentation. This mechanistic explanation suggests that the benefit of the extensional properties of thin viscoelastic liquids in the management of dysphagia should be further evaluated in clinical trials.
吞咽障碍显著降低生活质量，并可能危及生命。已证实使用剪切稀化食品增稠剂来改变质地可有效治疗吞咽困难。最近的一些研究考虑了内聚性的积极作用，但对于液滴流变性对食团输送动力学的影响，尤其是当弹性和拉伸性能与剪切稀化行为结合时，仍缺乏足够的了解。本研究将稳态剪切、SAOS 和毛细射流拉伸流变学与体外方法相结合，用于表征粘弹性液体的口腔输送。通过图像分析从体外实验的出口测量食团速度和长度，并将其与剪切和拉伸性能相关联。描述食团动力学的理论表明，弹性和拉伸性能不会显著影响口腔通过动力学。相反，体外结果表明，拉伸性能可能会影响吞咽的口腔到咽阶段的转变，其中稀薄的粘弹性液体导致快速通过，口腔吞咽后残留物减少，食团更紧凑，表面更光滑，这可能表明碎片形成的风险较低。这种机械解释表明，应在临床试验中进一步评估稀薄粘弹性液体的拉伸性能对吞咽困难管理的益处。
