Effect of Citric Acid on Thickeners Used in Products for People Suffering Oropharyngeal Dysphagia
Abstract
Dysphagia is a digestive disorder recognized by the World Health Organization (WHO) in the International Classification of Diseases (ICD) characterized by the difficulty in forming or moving the bolus from the mouth to the oesophagus that can cause the passage of food into the respiratory tract. Foods for people with dysphagia are prepared with products that modify viscosity to make them safer when ingested. The aim of this work is to establish the interaction between citric acid, widely used by the food industry, with different thickeners, both first and second range, in order to check whether they fulfil the functions for which they have been designed. The time stability and viscosity as a function of the hydration time of six thickeners and their behavior in the temperature range between 25 and 50 °C were determined. Thickener concentrations up to a maximum of 6% were used in combination with 3acid concentrations (0.5, 1 and 2%). In distilled water, the sedimentation of first range thickeners and the gelification of second range thickeners were checked, as well as the change from non-Newtonian to Newtonian behaviour after the hydrolysis process in both types of thickeners. In the presence of citric acid, the behaviour of both types of thickeners was analogous. Second range thickeners have been found to be much safer than first range thickeners in modifying the viscosity of liquids for people with dysphagia due to the fact that they do not sediment. .
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Introduction
Pulmonary aspiration is the passage of material generated in the stomach, esophagus, mouth or nose from the pharynx to the trachea and lungs. When this passage of material is related to the difficulty in moving food from the mouth to the stomach, it is known as dysphagia [1].
Dietary modifications should be individualized according to the type of dysfunction and the chewing and swallowing capacity of each patient. Thus, different consistency degrees have been standardized so that the patient can have the optimal diet and eat correctly ensuring that nutritional and water requirements are achieved. Consequently, the diet may vary from liquid to solid, through different degrees of consistency [2].
Although patients are sometimes unaware of the disorder, oropharyngeal dysphagia is a very common clinical condition, affecting more than 30% of stroke patients, 60-80% of patients with neurodegenerative diseases, 10-30% of adults over 65 years of age and more than 51% of elderly institutionalized patients [3].
Fluids are usually thickened to slow down their transit speed, to avoid aspiration of material into the respiratory tract and to improve transit into the oesophagus. However, names, level number of modification and characteristics vary within and between countries. In fact, over the past 30 years, as knowledge of dysphagia has grown, more technical definitions have emerged that delineate the difference between oesophageal and oropharyngeal dysphagia [4].
Conclusion
There is a direct correlation between the concentration of thickener and the degree of consistency. This fact indicates that rigorous monitoring of the relevant indications is required when preparing a standard sample since, if no rigorous action is taken, there is a risk of aspiration into the lung.
First range thickeners sediment when left to rest as a result of the high percentage of starch present in their composition. As the temperature increases, the starch swells and thickens, while the hydrocolloids containing gums in their composition (especially xanthan) remain stable.
So called second-range thickeners, which are made exclusively of gums and in some particular cases may contain a small amount of modified starch, allow a significantly lower amount of product to be used to obtain the desired viscosity, especially in the nectar and honey consistency grades, so that the visual appearance and taste of the thickened liquid is modified to a lesser extent.
It is proposed to extend the study of the interaction of thickeners with other food substances in order to achieve their purpose.