How can carbohydrates, lipids, and proteins be detected in foods?

The Benedict’s Test is the test which can detect carbohydrates and glucose in foods. During this process, the sample or the food is placed into a test tube and then some drops of Benedict's solution is added to it, and is then put into a beaker of boiling water. When the mixture of food and the Benedict substance turns reddish orange instead of staying blue, this means that it is positive. The mixture has simple sugar or has carbohydrates or glucose. On the other hand, lipids are tested using the brown paper test. When the paper turns transparent when a drop of food is put into it, it means that is is positive as well. When you want to test if the food has proteins, you have to test it with Biurets. Observe if the color change when you put some Biurets solution to the food sample. It is positive if the food turns light purple. Test if the food is positive with starches through the use of iodine. Food having iodine drops should turn purple instead of staying a yellow color.