Does cooking destroy the vitamin C in tomatoes and cherries, or does it concentrate it? Many people assume raw produce is always healthier. This project puts that idea to the test. You blend raw tomatoes and cherries with water, then split each into two samples. One stays raw. The other is heated on a hot plate. You prepare an iodine-starch solution that turns dark purple. Adding drops of each fruit sample causes the purple color to fade. The more it fades, the more vitamin C is present. Compare the color changes between raw and cooked samples to see which form holds more vitamin C.