Why Do Purple Beans Turn Green?
Plants and vegetables are important living things to sustain man’s survival. We eat these plants in order to get important nutrients. Aside from the nutritious value we get from plants, we also notice that they are appetizing to eat because of their different colors. Just like the beans that we eat. If we have not seen beans before they are cooked, we will probably say that beans are green. The reality is, these green beans were once purple before cooking.
Purple beans turn green because of chemical change that happens when heat is applied. The purple color of the beans is the chemical pigment anthocyanins. It is also present in grapes and other purple fruits and vegetables. These anthocyanins change their color if there if acid applied. The green color in the beans is already present and once the anthocynin concentration drops because of acidity, then the green color will dominate the purple.
The purple color of vegetables loses its color once cooked because of too much heat. The heat decomposes the anthocyanin so the purple color will also be erased. This is the reason why purple beans become green when cooked. But then, once cooked, the same flavor is retained because anthocyanins are tasteless.
It’s interesting how living things have its own way of surprising humans. But what is actually the purpose of the purple if it will not retain its color when cooked?
The purple color in vegetable has a reason. Anthocynanin attracts insects so it helps the plants propagate. The purple color also protects the plants from ultraviolet radiation and the purple color gives the plants an attractive look.
If you want to let the purple color stay, then before cooking, the purple beans can be soaked in vinegar or lemon juice or avoid overcooking because too much heat will definitely turn the purple to green.