Tea Geek: Understanding CO2 Decaffeination

Caffeine Chemical Makeup - Decaffeination Doesn't Remove It All!

Chemical Makeup of Caffeine

Is decaffeinated tea something you drink regularly? Ever wonder how tea is decaffeinated? The process for decaffeinating tea is much like washing dishes in a sink, though with a few extra steps so you actually end up with clean dishes (tea) rather than dishes that have sat in swirling, dirty water (albeit with a bit of soap for good measure).

As you may know, there are several methods by which tea (and coffee for that matter) are decaffeinated. While coffee has the “swiss water method” in addition, tea is predominantly decaffeinated using one of two methods, the ethyl acetate or the CO2 method. While the ethyl acetate method is referred to as natural decaffeination, the chemical, an organic solvent technically, appears in many products including nail polish remover and cigarettes. Doesn’t exactly leave a great taste in your mouth to learn that, does it? This is one of the reasons why high quality tea companies like Dominion Tea, steer clear of “natural decaffeination”.

Given that we humans generally exhale carbon dioxide (CO2), its use in decaffeination is something that consumers find much more appealing than the alternatives. You may have heard the CO2 process referred to as a CO2 bath or as using supercritical CObut what is this really?

Tea Decaffeination with Supercritical CO2

Diagram of phases of CO2 - supercritical fluid is used in decaffeination.

Carbon Dioxide at various temperatures and pressures. (Public Domain)

In a nutshell supercritical CO2 is carbon dioxide held under very high pressure in a state where this gas actually becomes somewhat liquid (almost a thick fog). Remove the pressure and the liquid turns into a gas and evaporates. Nice, clean and simple. However, you wouldn’t to wash dishes in a sink and simply pull the plug, leaving the detergent and all the leftover food and grease to sit and dry back onto the dishes would you? So clearly this process has a couple extra steps…

The process for decaffeinating tea with supercritical COrequires some mechanism to separate the caffeine from the tea so it doesn’t remain after the CO2 is removed. There are several methods for doing this, all starting with tea in a closed container of CO2 at 3,700 to 5,000 pounds of pressure per square inch! After “bathing” the tea in supercritical CO2, various mechanisms are used to move the caffeine away from the tea before pressure is removed and the leftover COevaporates.

Incidentally, the leftover caffeine isn’t pitched. Instead, its sold to other companies which use it in soda, sports products, and even some foods.

Challenges with Supercritical CO2 Decaffeination

There are several challenges with this process of producing decaf tea, some technical, and some with the resulting product. The removal of caffeine tends also to remove other flavor compounds since carbon dioxide can’t perfectly target only caffeine. So the various methods seek to try to limit removal of other “good” compounds or add them back. Each of these processes add time and cost to the end product. Some are more energy, time, and labor intensive than others. However, all methods result in a cost per pound of decaf tea that is significantly higher than that of fully caffeinated tea.

Technical challenges aside, from a consumer perspective the decaf tea costs more to purchase, may have a flat or at least less flavor, and still has a low level of caffeine in it. Since it still has caffeine, even drinking decaf tea in the afternoon or evenings can leave some with jitters or trouble falling asleep.

Since the labor and cost of decaf tea is high, and comes with less flavor, companies typically only decaffeinate a select number of teas. In the case of Dominion Tea, this is why you won’t find a lot of decaffeinated tea options. We do have a couple (Earl Grey Decaf and Summer Peach Decaf), however we prefer to focus on great tasting fully caffeine free options with a rooibos or honeybush base or select herbal teas.

 

Sources:

US Patent US4976979 A – Process for the decaffeination of tea, by Hubertus Klima, Erwin Schutz, Heinz-Rudiger Vollbrecht, https://google.com/patents/US4976979

US Patent US5288511 A – Supercritical carbon dioxide decaffeination of acidified coffee, by Peter T. Kazlas, Richard D. Novak, Raymond J. Robey, https://google.com/patents/US5288511

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Honeybush – The Other South African Tisane

Honeybush is closely related to rooibos which also grows in South Africa

Honeybush, also known as Cyclopia, of South Africa

Rooibos is not the only tisane which calls South Africa home. While rooibos has captured the most attention, and been subject to at least two attempts to trademark the name, honeybush is a very close cousin. Honeybush is used as a base for a wide variety of products and can be used in cooking. It is also caffeine free making it popular in the afternoon. Although similar to rooibos in many ways, it is has a bit sweeter taste providing an equally delicious infusion.

Honeybush Production

There are many similarities between honeybush and rooibos. Not only are they both from South Africa but they both come from the Fynbos region. Specifically they come from the Western Cape, South Africa, around the Cederburg Mountains. The product is chopped into fine pieces and normally fermented before packaging and shipment. As a variation, green honeybush is produced without the fermentation step. Like rooibos it also comes from the legume family, though this family is quite large and includes 16,000 others.

Though there are many similarities, there is a large difference in cultivation.  Most honeybush is harvested from 20+ species of wild cyclopia bushes. About 70% is harvested by hand in remote regions of South Africa with about 30% coming from commercially planted bushes.  Global demand from the Germany, the US, and other locations is increasing however, so this plant is increasingly planted and harvested from commercial plantations.

History of Honeybush

South African castle built by the Dutch East India Company

Dutch East India Company – Castle of Good Hope

Like rooibos this tisane has its roots dating back hundreds of years to consumption by native bushman or Khoisan people. According to the Institute for Traditional Medicine, honeybush infusions have likely been around for hundreds of years. The Dutch “discovered” it while exploring the plants and animals around a fort near what is now Cape Town when it was a stopover for trade between Asia and the Netherlands. The purchase of the Cape Colony by the British and subsequent adoption of English helped further spread knowledge of honeybush and probably rooibos as well.

Honeybush Future

Production of honeybush has been rapidly increasing to meet growing international demand for this tisane. Not only does it make a great base for caffeine free tisane infusions but there is also potential for health benefits as well.  According to the South African Honeybush Tea Association (SAHTA) which formed in 1999, there is a substantial amount of research occurring around potential health benefits from anti-oxidants and other compounds. Its consumption may help prevent cancer or offer alternatives to hormone replacement therapy.  Much still needs to be done to validate these ideas as well as meet existing commercial demand. To satisfy these needs SAHTA also actively works to improve cultivation, biodiversity, and sustainability practices to increase production and ensure continued availability.

Honeybush tea infusions are often consumed straight, although they may also be consumed with milk and sugar. Honeybush blends well with a wide variety of ingredients including ginger, lemon myrtle, lemon grass, fennel, and even caramel pieces. Be sure to have a look at the recipes provided by SAHTA on its website for honeybush tea punch, tarts, and muffins.

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Tisanes and Herbals

Tisanes and herbals are often referred to as tea, however these drinks normally do not contain any camellia sinensis (tea).  Instead they are made from seeds, leaves, roots, flowers, bark, fruits and may also be referred to as infusions or botanicals.  There are a huge variety of tisane and herbal drinks since it seems almost anything that is safe for human consumption can be infused (soaked in hot water) or decocted (heated in water to a boil allowing evaporation of much of the water).

Tisanes and herbals are consumed around the world offering a great many tastes, aromas, and flavors.  Some originated many hundreds or thousands of years ago while many are more modern attempts to offer new tastes or capitalize on popular fads.

Just a Few Tisanes & Herbals

Organic Raspberry Rooibos Tisane, Organic Red Raspberry Leaf, Organic Hibiscus, Organic Calendula

Adirondack Berries – A Rooibos Based Tisane

Rooibos has been consumed in South Africa for hundreds of years by native people and European settlers.  Native to the Fynbos region of South Africa’s Southwestern Cedarburg Mountains, Rooibos is a tisane produced from finely chopped Aspalathus linearis of the legume family.  This drink enjoys growing popularity around the world and makes a great base for a naturally caffeine free drink.

Dried Hibiscus in Aswan Souk

Dried Hibiscus for Karkade or Hibiscus Tea

Karkade, also known as Hibiscus Tea, and a myriad other names, is consumed around the world in places as diverse as Australia, the Middle East, the Caribbean and parts of Asia.  It features a tart, cranberry like taste and deep red color.  The first consumption as a drink is difficult to pin down but it is noted as being edible as far back as the late 1600’s.  More recently one can thank Celestial Seasonings for increasing awareness of this drink, marketed as “Red Zinger” starting in 1972.

Liang Cha is a Chinese herb tisane originating from Guangzhou Province.  Literally translating to “cold tea” it is thought to literally cool the body temperature which can be a big plus in the summer months in this part of China.  That said, this herb tea seems to have a great many variations though Chrysanthemum seems to be a common name attributed to it. (Guangzhou.chn.info, 2014)

Paspanguwa, also known as “Five Potions” comes from Sri Lanka and is considered to be an Ayurvedic remedy to tread colds and fever.  In fact, the Sri Lankan Government setup the Sri Lankan Ayurvedic Drug Company in 1969 offering, among other things, Paspanguwa which it considers a drug (Fernando, 2009).  The name “five-potions” comes from the five ingredients (though others are often added), Mollugo cerviana, Solanum virginianum, Coriander seed, Long pepper, and Ginger.  It is often served with a sweetner.

Glass Jar of Kombucha

Kombucha Mature by Mgarten, CC BY-SA 3.0

Kombucha, unlike the other drinks discussed, is actually made from the tea leaf, and is not an infusion or decoction.  Instead, it is sweetened black tea that has been fermented with bacteria and yeast.  Originating in Northeastern China in the 1900’s, Kobucha became popular as a health drink although such claims haven’t been established and indeed the drink, when improperly prepared may cause severe side effects and death (Centers for Disease Control, 1995).

Summing Up – Tisanes & Herbals

In many cases tisanes and herbals became popular for their stimulant, relaxant, or sedative properties.  These days many different tisane and herbal drinks are being consumed for perceived health benefits; everything from curing colds to curing cancer and everything in between.  However, the health claims attached to most tisanes and herbal drinks have not been validated through rigorous testing and, since many are considered neither food nor drug, they are not routinely evaluated by the FDA or USDA.  Further, no data had been provided to the FDA as of 2003 to support any claims of health benefits from tisanes or herbals (Nass, 2003).

From our perspective, while there may well be health benefits to some herbal and tisane infusions, there may also be risks, especially from high consumption and drug interactions.  Therefore, we prefer focus instead on the historical and cultural background behind tisanes, yet consume only a limited few.

Works Cited
Centers for Disease Control. (1995, 12 08). Unexplained Severe Illness Possibly Associated with Consumption of Kombucha Tea — Iowa, 1995. Atlanta, GA, US.

Encyclopedia Britannica Company. (2014, 06 17). Miriam-Webster. Retrieved from Tisane: http://www.merriam-webster.com/dictionary/tisane

Fernando, N. M. (2009, 09 18). Sri Lanka Ayurveda Drugs Corporation – four decades of progress. Sri Lanka.

Guangzhou.chn.info. (2014, 06 18). Cantonese Liang Cha, Herb Tea. Retrieved from Guangzhou.chn.info: http://guangzhou.chn.info/dining/liang-cha/herb-tea.html

Nass, R. (2003). Is the Health Food Store and Oxymoron. Retrieved from Naturally Dangerous: Surprising Facts About Food, Health, and the Environment: http://www.stanford.edu/~jpc/Chapter3.htm#_Herbal_Teas_Are

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Beyond the Teabag – 5 Things To Upgrade Your Tea Experience

For so many Americans, our only exposure to tea is from teabags, the tea served at Chinese restaurants, or those few selections offered at one of the nationwide chains.  Are you aware that there are 6 major types of tea and hundreds of options when you consider growing conditions, manufacturing methods, and local variations?  Unlike other beverages there is something for everyone, however too much choice can often be overwhelming.  Here are a few of our thoughts to simplify your early experience with loose leaf tea and tisanes:

  1. Start simple with a black, oolong, green or blended tea.  If you prefer no caffeine then consider an herbal or rooibos.
  2. Loose leaf tea is easy to make:  Start with a good infuser or use a good paper filter.  Avoid the stereotypical tea ball and go with something large to allow room for the tea to move around while steeping.
  3. If making black, oolong, or pu’erh, use boiling water and steep 1 tsp per 8 oz mug, no longer than 5 minutes.  If you are like us, you use a large mug or travel tumbler, so make sure you know roughly how much water is in your mug of choice and adjust the amount of tea accordingly.
  4. When steeping green, yellow, and white tea, allow boiling water to cool 3-4 minutes before adding tea.  Never use boiling water with these.  Use 1 tsp per 8 oz of water for green tea or 1 Tbsp per 8 oz for white tea or yellow tea.  Don’t steep any longer than 3-5 minutes.
  5. Steep 1 tsp per 8 oz of water for pure herbals (those containing no tea at all), rooibos, and honey bush for 7-10 minutes with boiling water.

More Ways to Upgrade Your Tea Experience

If the top five list above doesn’t quite satisfy your need, here are a few other things to be aware of.

Re-using an infuser after simply knocking out the prior tea leaves yields a mixture of the old and new leaves.

The result of adding boiling water to an emptied, but not really clean, fine mesh infuser.

  • Green tea really does not need to be bitter.  The key is to make sure you do NOT use boiling water.  With green tea you really want 170-185 degrees Fahrenheit and you don’t want to steep longer than 5 minutes.  Steeping at a lower temperature is often better.
  • If you use a fine mesh infuser, be sure to at least rinse it with boiling water before adding a new tea.  If you are like us, you are very busy and it’s so tempting to just knock out the last tea leaves and refill.  Without rinsing with boiling water you end up with lots of contamination from the last tea you brewed.
  • It pays to pre-heat your mug when steeping black, oolong, and pu’erh teas.  Adding boiling water to a mug, especially a ceramic mug, will almost instantly drop the temperature below 200 degrees.  If you add boiling water to your mug first, discard, and refill a second time for steeping you will keep the temperature higher for a longer period of time adding to the intensity.

Start Simple Then Experiment

Most teas do come with recommended times and loose tea per 8 oz serving size.  These more specific suggestions are certainly a better starting point than the general guidance above.  However, if you are new to loose leaf tea there really is no need to make it overly complicated.  Find something you like, use a good infuser or single use tea filter, and follow the general time and temperature guidance above.  As you drink tea more often you might try to start varying the amount of tea you use, as well as temperature and time to see how the taste varies, perhaps finding a combination more to your specific taste.

Clay Yixing Teapot in Hot Water

Yixing Teapot by Flickr SOLO-ASSA, CC BY-SA 2.0

Making tea can, of course, be a lot more involved if you want it to be.  We didn’t talk about specialty teapots, gaiwan sets, or the myriad other accessories and techniques for steeping.  Nor did we talk about making your own blends or baking tea on your own.  These are all topics for another day if and when the curiosity arises.

Know someone who could benefit from this post?  Please share and help others experience loose leaf tea.  And be sure to like us on Facebook or follow us on Twitter for more information on tea, its history, and culture.

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Rooibos: A South African Specialty

Options for tea drinkers abound with green, white, oolong, black and more as we have discussed earlier.  Also well-known are the many tisane blends; be they pure herbals or herbal tea blends.  Rooibos represents another option for an infused tisane and one that is growing in popularity due to its caffeine free nature and mix of anti-oxidants.   Camellia Sinensis naturally has caffeine as a self-defense mechanism, and decaffeinated tea in the U.S is allowed to have up to 5% residual caffeine. The rooibos plant has no caffeine at all.  Rooibos also enjoys significant popularity for the wide variety of anti-oxidants it contains including aspalathin which is only found in rooibos.

Cederberg Mountain Region of South Africa

Cederberg Mountain Region of South Africa

The scientific name for rooibos, which comes from Afrikaans meaning “red bush”, is Aspalathus Linearis.  Coming from the legume family, rooibos is related to beans, peas, clover, and peanuts, though the family also includes over 16,000 other species.  It is a shrub that grows up to 6’ in height with green, needle shaped leaves and yellow flowers.

Rooibos is only grown in one location in the world, the valleys of the Cederberg Mountain region of Western Cape, South Africa, to the north of Cape Town (South African National Biodiversity Institute, 2007).

Rooibos - Aspalathus Linearis

The Rooibos Bush – Aspalathus Linearis

Production of finished rooibos for export comes from both the needle shaped leaves and bits of small stem.  The leaves of the plant and small stems are harvested from January to March, the South African Summer to Fall season.  After harvesting they are cut into small pieces and bruised, similar to the bruising of tea leaves to bring out flavor and encourage oxidation.  After bruising, the leaves are traditionally moistened and allowed to oxidize in piles before drying in thin layers in the sun.  This oxidation process is what produces the deep red-brown color and its sweet, woody taste and aroma.  In much the same way that green tea is produced by preventing the fermentation process, green rooibos is also produced by skipping the fermentation stage and moving straight from cutting to drying in the sun.

Rooibos has been consumed by local Khoisan inhabitants for more than 300 years.  The arriving Dutch settlers to South Africa in the 1700’s started to consume rooibos due to the high cost of imported black tea.  Commercial production began in the 1930’s and more recently its anti-oxidant properties have attracted significant demand, initially from Japan but now from many other countries as well.  In fact, exports have increased over 700% from 1993 to 2003. (Hansen, 2006)

While rooibos is increasing in popularity and is a significant crop for the Western Cape region of South Africa, there are concerns both about the impact of production on the environment as well as the threat to rooibos from climate change.

Regions of South Africa

Western Cape, South Africa with Rooibos Growing Region Highlighted in Yellow

Rooibos comes from one of the most biologically diverse regions of the world and the birthplace of modern humans.  The area has several distinct regions ranging from coastal, to lowland fynbos (shrubs with varied shapes and sizes), and mountains with many others in between. (Fynbos Forum, 2005) The specific region where rooibos is grown recently was designated a World Heritage Site, yet the majority of land is privately owned, so the need for responsible land use and development practices has driven the South African Rooibos Council to develop Right Rooibos, a program to foster sustainable production practices for the industry and support production while protecting the environment.

More recently farmers have noted increasing temperatures and drier conditions, both of which are being attributed to climate change.  This trend, if it continues is expected to make it harder to grow rooibos and eventually could mean the demise of the industry. (Price, 2012)  And since rooibos, thus far, has not been successfully cultivated anywhere else in the world, the end of rooibos in South Africa would mean the end of rooibos globally.

For now, we continue to enjoy rooibos and wish the best for sustainable farming practices under the Right Rooibos program.  We love rooibos straight or blended with more traditional teas and herbals.  How about you?  Have you tried rooibos?

Tell us what you think.  Post a comment here, message us on Twitter, or leave a note on Facebook.

Works Cited

Fynbos Forum. (2005). Ecosystem Guidelines for Environmental Assessment in the Western Cape. Sounth Africa.

Hansen, T. (2006). Sustainable Rooibos Initiative. Greater Cederberg Biodiversity Cooridor & South African Rooibos Council.

Price, C. (2012, February 28). Climate change threat to rooibos tea. Retrieved February 12, 2014, from Mail & Guardian: http://mg.co.za/article/2012-02-28-climate-change-threat-to-rooibos-tea/

South African National Biodiversity Institute. (2007, June). Aspalathus linearis. Retrieved February 10, 2014, from PlantZAfrica.com: http://www.plantzafrica.com/plantab/aspallinearis.htm

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