UNESCO resource kit - science and technology educa...

UNESCO Module 24: Testing the quality of food - Teacher's Notes _
Page 2
Page 4: InActivity 3, students are asked to find out about the work of the food
inspection service in their area. One way to tackle this would be to invite an
inspector in to the class. He or she could give a talk and answer questions, but
students might be more actively involved if they were to interview the inspector
using an interview schedule drawn up in advance. They could then draw on the
ideas generated in Activities 1 and 2.
Finally, students are asked to write and present a short play, illustrating the
problems of food adulteration and the importance of the work of food inspectors.
An alternative would be to ask students to write a story or draw a strip cartoon
with the same theme.
Testing foods - Activity 2
Safety: Students should be warned that underno circumstances should they
taste any of the foodstuffs or other ma~erials used in these tests.
1 Testing the quality of ghee
Both ghee (clarified butter) and vegetable ghee are available internationally.
Look for tins in shops that sell Indian produce.
•• Sample A: Pure ghee
• Sample B: Ghee and vegetable ghee,
mixed in equal proportions
• Concentrated hydrochloric acid
:! Testing the purity of milk
• Sample C: Full-cream milk and water,
mixed in equal proportions
4. Sample D: Full-cream milk
;3 Testing adulterated spice powder
• Common salt (sodium chloride)
• Test tube
• Spatula
• Glass slide e.g. microscope slide
• Lactometer or hydrometer
You may need to experiment here to devise your own adulterated spice. Choose
a spice such as cumin or coriander with the same colour as the sand you intend
to adulterate it with. Grind the spice until it has the same coarseness as the sand.
Mix them together.
• Sample E: Unadulterated spice powder
• Sample F: Spice powder mixed with sand
An. obvious way to separate the mixture would be to mix it with water in a test
tube. The sand will sink more rapidly than the spice, which may float.
4- Testing other foods
You may like to devise some other food mixtures which students could test.