There is much folklore about tea.
This short article about a small study blows a significant amount of folklore away:
- black, green and white tea have the same amount of caffeine
- differing levels of oxidation do not account for differing caffeine levels in different teas.
- white “silver needle” tea ( made from tea leaf buds only) and Assam tea have the most caffeine
- it takes 6 minutes of steeping to get 80% of the caffeine out of tea leaves, not 30 seconds.
Too Easy to be True
De-bunking the At-Home Decaffeination Myth
Story by Bruce Richardson
Photos by Ben Richardson
It was too simple to be true.
For years, many of us in the tea industry have been guilty of touting an at-home decaffeination procedure that gave wide-eyed hope to tea lovers who wanted great taste and less caffeine. The modus operandi went something like this: Caffeine is water-soluble. Thus, it is one of the first ingredients released into the water during the steeping process. Be assured that 80% of the caffeine in either a teabag or loose tea leaves is released after a 30-second infusion. Simply pour off the initial wash and then re-infuse the tea leaves with hot water and brew as usual. You have saved yourself from 25mg of caffeine and your cardiologist will be happy.
If it was that easy, there would be little use for all the effort and money expended to commercially decaffeinate tea.
I first became aware of this “home wash” method in 1994 at a tea conference in New England. All of us in attendance made it a part of our teaching repertoire. I couldn’t wait to spread the caffeine-lite scheme. I remember customers in my tearoom looking at me as if I were a genius when I told them that I could magically “de-caffeinate” any tea on my menu in the privacy of my kitchen. I don’t know how many customers’ sleepless nights I was responsible for during my 14 years of retail business.
All of us on the tea speaking circuit were guilty of spreading the myth. But, who can blame us? When the current tea renaissance began, there was little documented research and few reputable tea books to turn to for answers. We simply repeated much of tea’s oral tradition that had accumulated for centuries. We were all blissfully ignorant until science began to catch up with the growth in the specialty tea market.
After a few years, I became a doubter of the home decaffeination myth. A couple of scientific papers were rumored to have challenged the popular method. At the 2005 World Tea Expo, I asked the author of a best-selling caffeine book if the caffeine quick wash was reliable. Without hesitating, he told me “yes.” But, where was the proof?
Alas, science at the college level has proven that author, and the rest of us “tea experts” wrong.
A college chemistry professor brews up a test.
In early 2008, Dr. Bruce Branan, Professor of Chemistry at Asbury College (Wilmore, KY) contacted me about the possibility of doing chemical analysis tests on tea using their newly acquired lab equipment. He had a few tea lovers in his family and he knew I lived nearby. He had been reading about the health benefits of tea polyphenols and he asked for suggestions on potential studies using tea.
Dr. Branan and I talked about several possibilities before I told him of my doubts concerning caffeine removal using the simple hot water wash. I told him the tea world would be grateful if he could conduct a study on caffeine content in several common loose leaf teas. He said it would be easy to analyze and that he had a student, Micah Buckel, who would make it his summer project. I supplied the teas and Micah ran the study.
Using standardized testing procedures, eight teas were brewed for three minutes in seven ounces of water. The infusions were then filtered and the liquid was analyzed using High Performance Liquid Chromatography with UV detection. The tea leaves were infused a second time, steeped three minutes, and analyzed. A similar third steeping and analysis followed.
Micah’s findings took the steam out of the simple caffeine wash assumption.
He found that a three-minute infusion removes 46-70% of the caffeine from a cup of tea. This is a far cry from our 30-second/80% removal claim. In fact, it would take a six-minute infusion to remove 80% of the caffeine!
Does green tea have less caffeine than black tea?
A by-product of the Asbury study deflated another popular tea caffeine misconception. Tea internet sites are filled with contradictory assumptions about caffeine content found in the four major tea families. Many claim that green teas have less caffeine than oolong or black tea, and white tea has the least of all. The theory assumes that oxidation is the key to caffeine intensification.
Again, modern laboratory equipment is able to disprove this assumption.
White tea does not have less caffeine than green, oolong, or black teas. Most of the tea studied in the Asbury lab (white, green or black) contained around 57-58 mg of caffeine per 7-ounce cup. The Chinese white tea and the Assam black tea both contained the highest caffeine content. Most tea drinkers would suspect those results from an Assam tea, but few would think a China white tea would have such high levels of caffeine. By the way, Camellia assamica plants, found in Assam, have higher caffeine content than Chinese varietals.
Before beginning the study, I turned to one of the tea industry’s most knowledgeable consultants, Nigel Melican, founder and managing director of Teacraft, Ltd. He has spent much of his life helping establish tea gardens and advising manufacturers in the art of producing teas for various markets around the world.
Nigel knows how to manipulate the caffeine content of tea bushes-both in the field and in the factory. He claims that several factors help determine caffeine content in tea. It begins with the propagation of the bush. Plants grown from seeds can produce twice as much tea caffeine as clonals. The addition of nitrogen fertilizer can add another 10% to the normal caffeine level. Caffeine also varies by the picking season. Teas plucked in cooler weather might produce less caffeine than those harvested in the fast growing hot months. Even the location of the leaf on the stem can be an indicator of caffeine potential.
“Caffeine varies in the fresh green leaf depending on fineness of pluck,” Nigel says. “For any tea, be it black, green or white, the caffeine is highest in the bud. Silver needle (white tea) is 100% bud and has the highest caffeine content.”
Nigel Melican’s caffeine percentage findings are:
Second leaf- 3.6%
Two leaves and a bud-4.2%
“If your white tea is 100% bud then it’s going to be one-third higher in caffeine content than green tea made from two leaves and a bud,” Nigel added.
He went on to point out that the caffeine level continues to change after the tea arrives in the factory due to the temperature and withering time.
What should tea consumers do?
Over 85% of Americans use significant amounts of caffeine on a daily basis. Most tea drinkers, assuming they are not prone to heart palpitations or other medical problems diagnosed by their physician, can easily handle 200mg of caffeine in their diet per day. If you are trying to cut down on caffeine, you should look at using the same tea leaves for multiple infusions because the caffeine content will be lower with each cup. High quality oolongs and green teas are perfect for this scenario.
If your doctor is asking you to cut caffeine completely out of your diet, you should switch to a commercially decaffeinated tea or a caffeine-free herbal. (Remember, caffeine is not present in herbals unless they are blended with tea leaves.) One should always consult with a doctor if you have any questions about caffeine’s effect upon your health. After all, until the FDA says we can label tea for its health benefits, tea will be considered a healthy beverage and not a medicine.
This article appears in the January 2009 edition of Fresh Cup magazine. Copyrighted material.
For further reading: ‘Tea preparation and its influence on methylxanthine concentration,’ appeared in Food Research International Vol 29, Nos 3-4, pp. 325-330. (FRI is copyright of the Canadian Institute of Food Science and Technology)
“Tea and the rate of its infusion” by Professor Michael Spiro. Published in Chemistry in New Zealand, 1981, pp172-174.