Cutting a slice of the watermelon collected from the market and extracts its juice.  Juice can keep in test tube or a common white glass used in house.

Then we have to add same amount of coconut oil as compared to extracted juice in it. The solution (coconut oil + juice) must be shaken for a minute. After that the solution containing glass or test tube should be kept in a proper place without stirring.

After 5 mins, if there is colourless water in the bottom of the glass or tube,  then it confirms the watermelon is free from any dye. Because watermelon contains an organic dye compound  Lycophene which reacts with organic part of coconut oil appearing as a yellow layer on the top of the test tube/ glass. Thus, the remaining inorganic compound water of the watermelon takes the place in the bottom of the tube.

But if there is pink or red colour appeared in the bottom of the glass or tube, then watermelon is contaminated with artificial dyes. Because, organic compound Lycophene of watermelon does not react with artificial inorganic dye such as ‘Red- 40’ used in watermelon. Thus, the dye remains in the bottom of theteflon tube/ glass as red or pink coloured solution.