Toward Sensor to Reproduce Human Sense - The Electronic Nose Artificial Olfaction Technology - page 121

milk, juice and tea. It is also used for the recognition, identification, classification
and discrimination of different kinds of liquid foodstuff and beverages.
E-tongue or taste sensors are committed to the automatic analysis of compli-
cated composition samples, to the recognition of their characteristic properties, and
generally they are assigned to fast qualitative analysis. The fundamental rule used
in E-tongues is based on electrochemical methods such as Potentiometry [ 7 , 8 ] and
voltammetry [ 9 ]. Also E-tongue has been developed with the principles based on
optical methods and impedance to mimic the basic taste sensations experienced by
humans [ 10 , 11 ].
Potentiometry is based on zero current technique, in which a potential across a
surface region on the working electrode is measured [ 12 ]. The various types of
membrane materials have been developed with different detection properties.
A Potentiometry devices are widely used for the measurement of a large number of
ionic classes and in that important is the pH-electrode; other examples are elec-
trodes for calcium, potassium, sodium and chloride.
The E-tongue tools offer the potential to provide taste evaluation during for-
mulation development or to be used as a quality-control tool, and thus significantly
reduce the amount of human testing. Another important benefit includes the
reduction of the dependence on human panels. Human panels in general present
several difficulties including health concerns, fatigue of tasters, maintaining the
motivation for tasting unpleasant compounds and the lack of analytical stan-
dardization. While it is necessary to develop good tasting treatments, the use of
sensory panelists is very difficult in this industry. This is due to the potential
toxicity of drugs and subjectivity of taste panelists. Problems in recruiting taste
panelists, enthusiasm and panel maintenance are significantly more difficult when
working with unlikable products.
5.4 Key Benefits of E-tongue Taste Evaluation
1. Helping to quantify bitterness of preparation actives when limited basic taste
information is available, especially if the supply is limited.
2. Developing suitable matching bitter placebos for blinded clinical testing.
3. Developing optimized taste-masked formulations.
4. Measuring efficiency of complication/coating within formulation.
5. Conduction comparator studies (benchmark analysis).
6. Serving a quality control traction for flavored product and excipient.
Difference is found in sense receptors, as in taste buds receptors on the tongue,
and smell receptors, embedded high in the lining of the nasal cavity. Gustatory
receptors respond to direct contact with water-soluble materials (e.g., sugar) and
olfactory receptors to generally water-insoluble, vaporous materials that may even
arise from a distant source. Many establishments choose to regard smell as dis-
tance chemoreception and taste as contact chemoreception.