What causes the unrealistic bright green color in overcooked broccoli?

The unrealistic bright green color seen in overcooked broccoli is due to the presence of chlorophyllin. When broccoli is overcooked, the heat causes chlorophyll, the pigment that gives plants their green color, to break down into a different chemical structure. This degradation process involves the loss of the phytol tail, resulting in chlorophyllin, which is more water-soluble and has an intense, vibrant green hue. The transformation to chlorophyllin occurs primarily because of the prolonged cooking time and exposure to high temperatures. This newly formed pigment can give the broccoli a bright and sometimes unappealing color, which is often mistaken for being visually fresh, despite the loss of texture and nutrient quality.

In contrast, pheophorbide and pheophytin are other derivatives of chlorophyll that occur during the cooking process, but they do not contribute to the vibrant green color characteristic of chlorophyllin, instead often leading to duller shades. Regular chlorophyll typically remains stable under appropriate cooking conditions, but prolonged exposure to heat leads to its breakdown into less visually appealing compounds. This understanding is essential for cooking vegetables correctly to preserve their color and nutritional quality.