Protein test

To test foods for protein, 1 cm³ of a chemical called Biuret A is mixed to 1 cm³ of a chemical called Biuret B.

The 2 cm³ of Biuret solution is then added to a boiling tube, using a measuring cylinder.

If the food is a solid it can either be shaken in 3 cm³ of water, and the resulting solution added to the Biuret solution in the boiling tube, or the food can be added directly to the tube.

If the food is already liquid e.g.. milk, 3 cm³ was added directly to the tube. If protein is present the solution turns purple as shown.

 

Safety

Biuret is an irritant, wash it off your hands if you spill any.