Detecting additives

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Detecting additives How can we detect
food additives?
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A lunch box full of additives? It will certainly
contain some additives but is this a bad thing?
Many additives are helpful and safe. But how can
we be sure what is in our lunch?
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Collect any food sample. You will need to remove
all packaging and weigh out a portion of the
foodstuff.
4
Prepare your food sample by liquidising it. In
some cases you may need to add special solvents.
Any chemicals in the food will dissolve in the
solvent.
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The mixture is filtered to remove the solid
debris. This gives a clear liquid containing a
mixture of chemicals from the original food which
can be used to make a chromatogram.
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This diagram shows what a chromatogram looks like
at the start of the experiment. All of the
substances are arranged in a line. The solvent
will move up the paper and drag the chemicals
with it.
Citric acid Anthocyanin Trisodium
citrate Aspartame Saccharin Potassium sorbate
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After an hour, each known substance has moved a
different amount along the chromatogram. Some
chemicals are coloured, others are sprayed to
make them show up. We can use these positions to
recognise unknown chemicals.
Citric acid Anthocyanin Trisodium
citrate Aspartame Saccharin Potassium sorbate
8
This diagram shows a chromatogram of a fruit
drink. Compare the positions of the substances
with the known additives from the previous slide.
If they match you know which additives are in
your drink!
Unknown