Chemistry Reference
In-Depth Information
5.7
APPLICATIONS
A particularly interesting application for xanthan gum, which takes
advantage of many of the properties described here, is its use in the
management of the rheology of liquids for patients suffering from swal-
lowing disorders known generally as dysphagia (Sworn
et al.
, 2008).
Swallowing is a very complex neuromuscular process, and there are
many disorders that can cause dysphagia. These include neurological
disorders, stroke, traumatic brain injury, Huntingdon's disease, mul-
tiple sclerosis, Parkinson's disease and cerebral palsy. Approximately
10 million Americans are evaluated with swallowing difficulties every
year and figures suggest that
14% of those aged over 60 are affected
by dyspahgia. Dysphagia is not directly associated with aging but is a
symptom of the degenerative diseases common in old age. Apart from
the obvious problems of potential dehydration and malnutrition due to
reduced food and fluid intake, other problems such as aspiration can
occur. Aspiration, which is the entry of food or fluids into the airway,
can lead to complications with the respiratory system, such as chronic
obstructive pulmonary disease or aspiration pneumonia.
The rheological properties of the bolus significantly influence the
swallowing process, and the use of hydrocolloids to control the rheology
can greatly help in the management of the condition. Hydrocolloid
thickeners are ideal for controlling the consistency of liquids and foods
and are an obvious choice for use in the management of dysphagia. To
be an effective thickener for this application, the following properties
are important:
∼
Easy dispersion at low mixing speeds.
Fast hydration (cold and hot).
Stable viscosity as a function of:
◦
time;
◦
temperature.
In addition to this, the thickener must perform in a variety of media such
as water, fruit juice, milk, tea and coffee.
The most widely used thickeners are modified starch (E1442), xan-
than and guar gum. Although all three are very effective thickeners, they
have very different rheological profiles. Products for this application are
often described in terms of consistency and some standards have been
proposed by the National Dysphagia Diet project based on viscosity at 50
per second. These are thin (1-50 mPa
·
s), nectar-like (51-350 mPa
·
s),
honey-like (351-1750 mPa
s). Us-
ing these criteria, the xanthan-based products are able to cover the
·
s) and spoon-thick (
>
1750 mPa
·
