Purple beans? Preposterous!

Purple Beans get their colorful hue from a
natural group of chemicals called anthocyanins.

(Click any photo to enlarge)

Our Royal Burgundy Beans were ready to start harvesting in the garden today.  In reading articles on these beautiful purple beans, I found that there is a natural group of chemicals, called anthocyanins, that puts the purple in purple green beans, as well as in grapes, plums and purple broccoli. It is also found in some blue hued flowers.

Yellows and oranges veggie colors come from carotenoids, which also are responsible for certain reds in plants. In the case of beets, the red comes from yet another natural pigment, called betacyanin.

The Chameleon of Veggies: We all know that chameleons change the color of their skin to blend in with their environment… but did you know that when you steam or boil purple beans that they turn green?! They do! The heat of cooking causes decomposition of anthocyanin. The less anthocyanin, the less purple.

Cooked Purple Bean to the Left
Raw Purple Bean to the right...

A similar thing happens when you cook red cabbage. It turns colorless after awhile. You can also expect purple broccoli, purple asparagus, purple tomatillos, even purple peppers to lose their purple color after cooking. Red peppers stay red, though, because carotenoids give them their red color.

So why plant purple beans if it’s going to turn green anyway after you cook it? They taste the same as green beans, so why?

1. In nature, anthocyanins help in attracting insects to flowers and protecting plants from ultraviolet radiation, which is why you find purple in so many mountain plants. Carrot shoulders exposed to sunlight sometimes even turn a purple hue.

2. The color can be very pretty in the vegetable garden.

3. Because Royal Burgundy's leaves stay green, it is easier to pick out the purple pods from among the leaves making it easier to pick them.

4. Because of their purple color, green cabbage worms on purple broccoli and red cabbage as well as other insects on the purple beans are more noticeable for birds to find and eat!

So, what if you want to keep the purple color when you eat them? Well, there is always the option of raw… but I did read another article where someone was able to have the purple beans retain their pretty purple color for a great salad idea. They cooked the purple beans until al dente and then cooled them. They then soaked them in lemon juice, olive oil, onions, garlic, and seasonings. After soaking the beans over night, some of the purple hue came back. Sounds like a good experiment for a beautiful salad!