Food Tests

Food Testing; 

Lets break it down

To test for starch in carbohydrates we use an iodine solution which is naturally yellow/red. This solution is placed onto the food (we often test this on potato) and if starch is present, the iodine solution will turn blue/black.

To test for reducing sugars (like monosaccharides (glucose and fructose) and disaccharides (maltose)), we use Benedict's solution which turns from blue to orangey/brick red colour when heated. Note sucrose is not a reducing sugar which means it will not react with Benedict's solution when heated.

When testing for protein, we use the Biuret's solution which will turn from blue to a mauve/purple colour when mixed with protein.

When testing for lipids, we use the emulsion test which involves placing a substance into ethanol and an equal volume of water. If lipids are present, a thick, white layer will form on top of the solution.

Chemical testing (Louis Reed)