Resources - Safety Info

Safety in Testing for Taste and Odour

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From November 1996 issue of ‘Crucible’ Volume 28.2.

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Testing for Taste:

Taste experiments are normally run to test for the four kinds of taste receptors in the tongue. Students should be directed to run this experiment as a class in the school cafeteria, or BETTER, at home, using the following household chemicals:

TASTE SOLUTION USED (1)
salt dilute table salt solution (10 % NaCl)
sweet dilute solution of sugar
sour dilute solution of vinegar (2:1)
bitter very strong cold tea or coffee

Students should be directed to do the following:

  • Apply each solution, using a new toothpick or a Q-tip, to the tip, sides, centre and back of the tongue.
  • Wash the mouth after each tasting.

If the teacher sees fit to run the experiment in class, the following precautions should be adopted. The equipment should be sterile, not reusable, and chemicals should be bought fresh from the supermarket.

  • Do not force students to run the experiment.
  • Fully explain to the students the hazards of contaminated material.
  • Ask students if they have any food or drug allergies.
  • Use chemicals from the supermarket, and leave in original containers.
  • Put the solutions to be used in clear new plastic cups, properly labelled. Do not use beakers or any containers that may be used in other experiments.
  • Put a number of toothpicks or Q-tips in each solution.
  • Ask students to dispose of used toothpicks or Q-tips in a specially labelled container. You may use a clear covered plastic cup, with an opening in the centre to allow the Q-tips to go through. Such cup may be disposed of with the biological samples.
  • For the bitter taste, commercially prepared PTC paper (phenylthiocarbamide, known also as phenylthiourea) may be used. Be aware that the LD50 (lethal dose for 50% of a rabbit population) is 40 mg/kg. (2)

Testing for Odour

Some vapours and gases are toxic and/or corrosive. These should not be tested. For other odours, students should be directed to do the following when testing for odour:

  • Take a deep breath, and hold it, so no more air can be inhaled.
  • Fan the vapour or gas gently towards their noses.
  • Exhale the air you inhaled, clearing the nose from any vapour or gas.

References

1. Morholt, Brandwein & Joseph: "Sourcebook for the Biological Sciences," 2nd ed., published by Harcourt, Brace & World, Inc. (1966).

2. N.I.Sax: "Dangerous Properties of Industrial Material," 5th ed., published by Van Nostrand Reinhold Company (1979).