LIFE SCIENCE

Detailed explanation-1: -If the protein is present and the solution will turn into deep purple color. The protein is absent in the solution; it appears in blue.

Detailed explanation-2: -A color change from yellow or brown to a blue-black color indicates that starch is present.

Detailed explanation-3: -If starch is present in the food sample, iodine, when added, will change color from orange to blue black. A reagent called Biuret solution can be added to a food sample to test for the presence of proteins. If protein is present in the sample, the solution will change color from blue to purple.

Detailed explanation-4: -In the biuret determination of wheat protein, starch, color substances and lipids ex-tractable with an alkaline solution such as biuret reagent were found to interfere with the biuret method.

Detailed explanation-5: -Biuret solution is a blue liquid that changes to purple color when it reacts with proteins present in food. Biuret solution is made by mixing copper sulfate with sodium hydroxide. Copper sulfate gives a typical blue color to this solution, which is turned to purple after reacting with the proteins.