Flower Blooms In Your Tea Cup? It's Water Absorption as Entertainment
Topics: Chemistry, Food
Every time I drive from the South Bay to the East Bay, I pass the Numi tea factory and start to crave a hot cup. I love tea–the ritual of heating and pouring the water, the warm mug in my hands and the slow sipping as it cools–and Numi makes some of my favorites.
Knowing this, a friend recently gave me a Numi gift box: "FLOWERING TEATM handsewn leaves blossom when steeped." Pleased but confused, I did some research, and quickly figured it out.
Did you ever get those pill-shaped foam toys when you were a kid? You'd throw one in water, the capsule would dissolve, and the foam would expand into a huge dinosaur or shark.
Flowering tea is the classy grown-up version of grow monsters.
The teas don't expand quite as much as the toys, so you might be able to guess they're using a different technology. Grow monsters showed up in the 1970s, using super-absorbent polymers originally developed for medicine and hygiene (think diapers). Super-absorbent polymers are long-chain molecules that bind with water so enthusiastically that they can absorb up to 500 times their weight. (I presume that's why it says "expands hundreds of times!" on some toy packages; an inch-long capsule certainly does not expand to a 40-foot dinosaur.)
Blooming teas don't contain any super-absorbent polymers—only tea leaves and flowers. But because they've been dried, they have a lot of room to expand when soaked in water again. A Star Trek alien once called humans "ugly bags of mostly water," and the same could be said of almost all Earthling animals and plants. Fresh tea leaves contain 75-80% water, but are dried down to 2-7% before being sold as tea (flowering or otherwise). When you add water to this dried biological bundle, it readily expands and uncurls according to the whim of the tea artist.
Of course, San Franscisco hipsters are keen to debate whether it is truly hip or merely a "gimmick." Apparently, no one is sure how long blooming tea has been around. It might be just a few decades old (about the same age as grow monsters–coincidence?) but there are thousand-year-old Chinese references to "display teas." These weren't quite the same as modern blooming teas, because nobody actually drank the water the display teas were steeped in–they were strictly for entertainment.
Just like grow monsters, come to think of it.Tags: absorption, kqed, polymers, QUEST, tea, toys, water