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Photos of experiment using Quavers to demonstrate digestion
These pictures show the results of this simple demonstration - an RGS original!
Quavers are a readily available snack food. You could probably get similar results with other puffed starch-based foods, such as prawn crackers. I have recently had reasonable results with cylinders of puffed starch which are used as lightweight packing material for parcels etc. These are biodegradable, unlike expanded polystyrene or other plastic materials.
The two larger beakers act as water baths containing either iced water ("cold") or water at about 40°C ("warm").
Into each are placed two smaller beakers, one containing water and one containing a 1% solution of (fungal) amylase.
These are left to come to the temperature of the water bath, as checked by the thermometers.
At this stage, a quaver is placed into each liquid and observed at regular intervals. It is useful to have a glass rod in each small beaker to help extract the contents.
After some time - about 5-10 minutes, the quaver in the warm amylase cannot be identified - it has been digested into a cloudy liquid. After a few more minutes the quaver in the cold amylase may start to disintegrate. Here you will see that it has broken into half, so it is in the Petri dish in front of the beaker.
Both quavers in water alone retain their integrity, although they are rather soggy! They can be seen suspended from the glass rods.
