So there I was, ready with a tea bag in one hand, a slice of lemon in the other and a couple of grandkids collared into being the audience. I said we were going to do a chemical experiment. They were not too excited. After all, they had seen tea being made before.

I think they assumed we were going to talk about, ho-hum, why tea becomes a lighter colour when lemon juice is added. Indeed, it does, because fermentation of tea leaves produces thearubigins, complex molecules in the polyphenol family with a nearly black colour. Addition of an acid like lemon juice makes a slight alteration in their molecular structure, resulting in a change in the wavelengths of light absorbed and reflected. The tea turns a lighter colour. But the kids were in for a surprise.

When I dunked the teabag in the hot water, the brew became a brilliant blue! Now there was an “oooh,” further amplified when a squeeze of lemon turned the tea into a crimson purple colour! And there was more amazement when the addition of baking soda, a base, first changed the colour back to blue, then to green! This obviously was no ordinary tea. It wasn’t. This was butterfly pea tea.

Butterfly pea is a plant found mostly in Southeast Asia that produces flowers with beautiful blue petals in the shape of a butterfly. It also produces pods with seeds that land it in the legume family, thus the term “pea.” Its botanical name, Clitoria ternatea, is also intriguing. It seems that during the 17th century, some botanist with an active imagination saw the flower as resembling a particular part of the female anatomy.

The blue colour of butterfly pea flowers is due to delphinidin, one of many anthocyanins responsible for the colour of flowers, berries, fruits, vegetables and even red........

© Montreal Gazette