Malia Wollan, writing for The New York Times:

The team of color scientists hovered in their white coats and hairnets, staring down at a clear plastic box full of strangely colored M&Ms. “They look like pebbles, ugly little pebbles,” said Rebecca Robbins, the color-chemistry manager for Mars Chocolate. She propped open the lid to show off a muted array of gray, tan, mauve, pale purple and sickly pink chocolate nuggets. Each attenuated shade was the disappointing outcome of an early attempt by Mars to replace a bright, artificial dye with natural pigments extracted from algae, roots, seeds and other parts of plants. Not a single piece of candy in this tackle box of failure looked edible — let alone tempting.