Oxidizing Herbs Like Black Tea or Oolong Tea

This is inspired by my original posts Oxidizing Herbs like Black or Oolong Tea and Sage Tea made like Black Tea.

Oxidation is one of the key aspects of tea production.  Usually, oxidation is presented as being the main characteristic that distinguishes black teas (which are oxidized) from green teas (which are unoxidized).  Since writing my original post, I have learned a lot more about tea production, and I have researched and compiled a page on the oxidation of tea on RateTea.  This page goes into more depth, explaining how a lot of the ways in which the topic of oxidation is presented are oversimplifications.  If you want to learn more about this process, I recommend visiting that page.

This page is about something different: using an oxidation process similar to that used to produce black teas to process the leaves of other plants.

Herbal Teas Are Generally Not Deliberately Oxidized: A Few Exceptions

In many respects, herbal teas are often considered analogous to true teas from the Camellia sinensis plant.  Yet there is one key difference: the herbs used to produce most herbal teas are rarely oxidized.  Instead, most herbs are usually just collected and dried.  This process makes them most similar to white teas, which are the least processed of teas on the market.  The modest amount of oxidation that happens to these herbs is an unintended consequence of the drying process, not an intentional and essential part of processing.

Chamomile, like many herbs used in herbal tea, is gathered and dried without any additional processing to induce oxidation.

There are several notable exceptions to this trend.  Rooibos and honeybush, both referred to as South African red tea, are both produced through a process that involves oxidation, which can be interpreted as making them somewhat distant cousins of black tea.  Incidentally, rooibos is often discussed as being among the most “tea-like” of herbal teas, and this similarity in production may explain why.  The process used to oxidize rooibos and honeybush, however, is quite simple, involving collecting the leaf and letting it sit in heaps outdoors–less of a controlled process than tea goes through, but achieving similar results.

The following image is licensed under the Free Art License, courtesy of Wikimedia Commons:

Rooibos is traditionally oxidized during its production, turning it red, much like how black tea turns a dark color.

Yerba mate and Guayusa, the caffeinated herbal teas produced from species of holly plant native to South America, also are processed in a bit of a more involved way, although not necessarily one involving oxidation.  Often, the leaves are dried and aged, and then roasted, however, there are also un-aged and un-roasted versions on the market.  There is, however, a case of people processing Yerba mate more like tea, the Premium Yerba Mate Buds sold by Upton Tea.  But this sort of endeavour is very rare.

Being curious, however, I repeatedly asked myself the question: why don’t more people try to process herbs like black tea?  It may be difficult to get good results from such a project (I wasn’t a huge fan of the Yerba mate buds described above) but I at least wanted to try.

My Experiment: Oxidizing Common Sage, Lemon Balm, and Other Herbs

Some time ago, in the fall of 2009, shortly after launching RateTea, I became fascinated by the idea of applying a similar production process to herbs, to the one usually used to make black tea.  I tried this out on a few herbs, including common sage, Monarda sp. (Bee Balm, Wild Bergamot, Oswego tea), lemon balm, and various mints.

I experimented with a number of different attempts on the different herbs, but they all involved picking the leaf and bruising it shortly after harvest (before it dried out), and then allowing it to sit in a damp area until the leaf turned completely dark (this took a matter of hours).  To do this, I placed the leaves on a plate with a damp cloth over them, and stored them in a cool, dark area.  After the leaf was fully oxidized, I then heated the leaf very slightly using a toaster oven.

Trial and error taught me that, with tougher leaves like sage, extensive bruising is needed to ensure full oxidation.  The first few batches I attempted came out with splotchy oxidation.  With the tougher herbs, like common sage, I ended up using a rolling pin on a hard surface to crush the leaves.

Here is a photo from one batch of common sage, Salvia officinalis, where I had tightly twisted and rolled the leaf:

Leaves of common sage (Salvia officinalis) which have been bruised and allowed to oxidize similarly to black tea.

It was fun to see how the leaf can be formed into different shapes.  These leaves looked similar to a Ceylon Oolong tea, unfortunately discontinued, Shanti Tea’s Thousand Arrows.

The result of this process, flavor-wise, was also promising.  The oxidation seemed to improve the flavor and aroma of the sage, for drinking, as sage can be a bit dominating and harsh.  The other herbs also worked well, although some were better than others.  The best result in terms of flavor was lemon balm.  As I noted in my original post, lemon balm yielded the batch that came out most like black tea, and it had some floral tones that are absent in the straight dried herb, and was also more vegetal, but was less lemony.  Apple mint and the Monarda also yielded good results.

What do you think?

I would love to try this again some time soon.  I am still curious to know if anyone else has ever tried this sort of project.  I did not get any comments on my original post, as it was from before I had developed much of a following for my blog.  I would be especially interested to learn of attempts by people who have had some experience in or first-hand exposure to tea production.

Some questions for you:

• Do you find this idea as intriguing as I do?
• Have you ever tried processing any herbs in this manner, so as to encourage oxidation, or do you know anyone who has?
• Whether or not you have ever tried this, do you have any advice or suggestions about processing, perhaps from knowing a bit more about tea production than I do?
• Do you have any suggestions of herbs to try?

Adding Citric Acid to Teas or Herbal Blends

This post is inspired by an old post adding citric acid to teas, but it is much more than a rewrite of that post.

Most of us are familiar with the practice of adding lemon or lemon juice to tea.  The effect of adding lemon juice is most evident in black tea, producing an immediate chemical change in the tea, usually resulting in a noticeably lighter color, and a cup that is somewhat less bitter and astringent, but more sour.  A practice that is less familiar is one that some mainstream tea manufacturers do, particularly those dealing in herbal blends, which is adding citric acid to teas.

The following photo is by André Karwath and is licensed under CC BY-SA 2.5.

Citric acid is responsible for the characteristic sour flavor of lemons and lemon juice.

I was genuinely surprised when I first saw citric acid on the ingredient list of a packaged box of herbal teas.  This would not so much surprise me for a bottled or “ready-to-drink” tea, but for a tea bag, it was quite unexpected.  I think of herbal teas as being something that is made strictly from dried plant ingredients, so I do not expect to find an added pure chemical ingredient.  Some of the mainstream teas that include added citric acid are Celestial Seasonings’ Country Peach Passion and Lemon Zinger, and Tazo’s Passion and Calm.

On Citric Acid – The Chemical and its Production

Citric acid is a common organic acid that is named (and best-known) for being the main acid that imparts the characteristic sour flavor to citrus fruits like lemon and lime.  It is a common and safe food additive, used to impart a sour flavor to food and drink.  It can be isolated from citrus fruits, but is also commercially produced on a larger scale by using mold, such as Asperillus niger, to ferment sugar.

Citric acid is a pretty basic chemical in biochemistry.  It plays an essential role in all aerobic (oxygen-respiring) organisms through the citric acid cycle, also known as the Krebs cycle.  Here is a molecular diagram, for the chemistry-minded among us:

A graphical representation of the citric acid molecule

As someone who is highly skeptical of highly refined food additives, especially ones that consist of a single chemical, a natural question for me is: is added citric acid safe?

There’s not much to worry about with respect to citric acid, beyond its sourness.  Everything I’ve ever learned about it has taught me that it’s safe as a food additive.  However, the acidity itself though can sometimes be a concern.  For example, acidic drinks can soften tooth enamel, so it’s not a great idea to brush your teeth directly after drinking a cup of sour-tasting herbal tea.  Acidic drinks can also sting or irritate the mouth, especially if there is already a sensitive area like a burn.

Added Citric Acid is Not Necessary to Make Herbal Blends Sour

When I first discovered that some herbal teas contained added citric acid, I was curious to see which blends contained it and which did not.  One thing that surprised me was that the blends that were most sour did not necessarily correspond to the ones with added citric acid.

As examples, Celestial Seasonings Country Peach Passion and Tazo Calm are not among the most sour of herbal teas out there, but the famously sour Red Zinger does not (although some of the Zinger series blends do).  This is because Red Zinger uses Hibiscus as the main ingredient.  Hibiscus on its own, when brewed as an herbal tea, is intensely sour.

This photo was contributed by Popperipopp and is licensed under CC BY 3.0.

Sepals of the Hibiscus sabdariffa plant are a whole ingredient that can be added to tea or herbal blends to impart a sour flavor.

Why do tea companies not always use hibiscus?  It may be due to its color, and its peculiar flavor and aroma.  Even small amounts of hibiscus impart an intense purple-red color that may not be desirable in all blends.  But hibiscus also has a characteristic aroma, which I describe as being somewhat like berries but also a lot like cooked fruit or jam.  I sometimes find this aroma a bit overpowering, so it makes sense that companies would want to look for other ways to make their blends sour.

What do you think?  How do you feel about added citric acid in tea or herbal blends?

Here are some questions that you can answer in the comments, or in a follow-up blog post of your own.

• Did you know that some tea companies add citric acid to their herbal blends, or is this a new realization for you?
• Are you bothered by the practice of adding citric acid rather than relying on whole ingredients like herbs or spices, or is it fine with you?
• How do you feel about sour-tasting blends in general?  Do you tend to like or dislike them?  How sour is too sour to you?
• Do you ever add lemon to your tea?

My personal opinion?  I don’t have a big problem with added citric acid, but I think I would prefer blends made from whole ingredients.  Either way, I don’t like sour tastes much in my tea or herb tea.  I avoid both added citric acid, and blends that have too much hibiscus or other naturally-sour whole ingredients.

Locally Grown Tea and Herbal Tea – Sustainability, Ecology, Economics

This is an update and rewrite of an original article, Locally Grown Tea, which was published Nov. 23, 2009, on my tea blog.

There are a wide variety of issues relating the topic of sustainability and tea.  RateTea’s page on sustainability and tea summarizes most of these issues. Topics like fair trade, organic certification, and composting are ones that most people in the tea world are familiar with, and that a fair amount has already been written about. This post is about a different issue, one that people in Western countries don’t think about much, which is the topic of locally grown tea.

People don’t talk much about locally grown tea in the U.S. and Western Europe. It’s generally assumed that tea grows in warm, tropical climates and needs to be imported in these countries. But this is not strictly true; as I will show below, the reasons tea is imported are a complex combination of economic, historical, and ecological factors. The tea plant, Camellia sinensis, is a relatively hardy plant, and while it generally likes a humid subtropical climate and can also be grown in humid tropical regions, it can be grown farther north than many people realize.  Many of the famous tea-growing regions, such as the Darjeeling district of India, or nearby Nepal, are located at a high altitude where the temperature can actually get fairly cold and sometimes drop below freezing in the winter.

The zones where tea cultivation is commercial feasible are also restricted by the humidity and rainfall; tea likes a wet climate, especially during the growing season.  Most of the regions important in tea production have a strongly seasonal rainfall pattern, such as the Asian monsoon in India and China, and the bimodal seasonal rainfall pattern characteristic of Kenya.

The following map shows the world’s humid subtropical zones, where most of the historical tea-growing regions are located.  Tea can also be grown in a few other climate zones too, including humid tropical climates, tropical wet-dry areas, and moderate maritime climates:

A map of the world’s humid subtropical climate zones.

This map is taken from Wikimedia Commons; the original was by Peel, M. C., Finlayson, B. L., and McMahon, T. A. (University of Melbourne).  The map is Licensed under CC BY-SA 3.0.

The continental U.S. and western Europe have a number of areas suitable for growing tea.  In the U.S., there are two commercial tea plantations whose tea can be easily purchased:

• Sakuma Brothers Tea – Grown in the Skagit Valley of Washington State

• The Charleston Tea Plantation – Owned by Bigelow Tea and located near Charleston, SC

In addition to these two tea gardens, I have also heard of a small commercial tea operation in Alabama, although I haven’t been able to find its tea for sale anywhere and I do not know if it is still in operation.

Individual gardeners and Botanic gardens have cultivated specimens of the tea plant in much colder regions, on the east coast north to Delaware and perhaps even farther north, and in slightly drier regions as well, like wetter parts of California.  These regions are not necessarily suitable for commercial tea production, however.  The Southeastern U.S. and the Gulf Coast, together with a small moderate region of the Pacific Northwest are probably the only regions in the continental U.S. whose climate would work well for tea cultivation.

Why Locally Grown Tea (or Locally Produced Anything) is Beneficial

Locally grown produce, and locally produced goods,, including tea, promotes sustainability in a number of ways.

• Reducing transportation costs –  In the case of tea, which is lightweight relative to its price, these costs are not huge, but anyone who has bought tea online and paid the shipping costs knows that they are not negligible.
• Promoting self-sufficiency – Local production helps make each region less dependent on the outside world.  While complete self-sufficiency is not a goal that everyone wants, some degree of self-sufficiency can be important for stabilizing the world’s economy, by protecting each region from economic fluctuations in other regions.
• Diversity – Diversity is especially noticeable in tea production, as with any type of food product based on freshly harvested plants.  Because the conditions in which tea (or any plant) is grown, impact its flavor, and because the climate and soil conditions vary from one region to the next, each area will produce tea (and other types of produce or food products) with its own unique characteristics of flavor and aroma.
• Education and awareness – There is something illuminating and highly educational about being able to physically visit the place where an agricultural product is produced, and see how the plants are grown.  When food plants are grown locally, people can visit the farms and gardens where the plants are grown, and see them for themselves, getting a sort of awareness and knowledge that cannot be obtained from books or the internet alone.

Locally grown tea is not widely available in the U.S. and western Europe, so these benefits are typically not available with respect to tea drinking and purchasing.

Why So Few Locally Grown Teas in Western Countries?

Above I demonstrated that climate alone cannot fully explain why only a negligible amount of tea is grown in the United States.

One tempting answer to this question is in the economics of labor costs, and differences in wealth between different countries.  Most tea is picked by hand, which creates prohibitive labor costs in countries with high wages.  The United States and the countries in Western Europe are very wealthy.  To give you an idea of how wealthy, you can check out the PPP (Purchasing Power Parity) per capita, a measure of the average spending power per person, for various countries.  According to the World Bank’s figures, the United States is about $48K (measured in international dollars), the UK about $35K, and Germany about $39K.  The major tea-growing regions, on the other hand, are much poorer.  India’s PPP is about $3.6K, China’s about $8.5K, and Kenya only $1.7K.

PPP (Purchasing Power Parity) is a relatively good coarse indicator of wealth.

Japan, however, proves that economics cannot explain everything.  Japan’s PPP is on par with most of the countries in Western Europe, yet it is a major tea producer.

I suspect that the other main explanation is historical.  Once an industry gets established in a country and becomes culturally important, the country will find ways to keep that industry thriving  Japan is known for high-quality teas which often fetch a higher price on the market than the bulk black tea that constitutes most of the output of many of the major tea-producing countries.

Locally Grown Herbal Teas – A Closely Related Subject

For some reason, there is often a disconnect, or at least a weaker connection than I would expect, between connoisseurs of true tea, and enthusiasts of herbal teas (or, more technically, herbal infusions or tisanes, a word I don’t use much).  But I am interested in both, and in fact I became interested in tea primarily through herbal teas brewed from plants that I would grow myself in my parent’s garden while I was growing up.  Here is a picture of two of my favorite plants, Apple mint (or Wooly mint, the plant with fuzzy, rounded leaves), and peppermint, the plant with darker, narrower leaves.

Apple mint (Mentha suaveolens) and Peppermint (Mentha × piperita) in the garden at my parents’ house

Herbal teas, encompassing virtually any plant used in tea other than the tea plant, grow virtually everywhere that plants grow, from the tropics to the arctic. Different arrays of plants can be grown in different regions. North America and Western Europe, in particular, are the origins of a countless variety of delicious herbal teas which are familiar in Western traditions, and which are ingredients in the mainstream brands of herbal teas found in a typical supermarket.

Many of these can be easily grown in your own garden or backyard. Many plants used for tea, such as mint, are aggressive in certain climate zones, and can be grown in massive quantities with minimal effort. In addition to growing tea yourself, many herb teas are available locally–not just through small retailers but also from friends and neighbors who might have more gardening space (or expertise) than you do.  And for caffeine lovers, there is even a caffeinated plant, Yaupon, a close relative of the plants used to make Yerba mate and Guayusa, which is native to the Southeastern U.S. and is a good bit more cold-hardy than the tea plant.

If you are a tea enthusiast, but want to support the idea of locally-produced teas for reasons of sustainability, economics, or becoming more connected to and aware of what you are drinking, you would do well to explore the world of herbal infusions.

What do you think?  Please share your feedback with me!

Here are some questions for you; please answer either here, or on a follow-up blog post of your own:

• For tea drinkers in Western countries: do you ever think about locally-grown tea?  Have you ever tried one of the few teas grown in your own country, or in a Western country?
• For gardeners: have you ever tried, or would you ever try to grow the tea plant?
• For tea drinkers: are you also interested in herbal teas?  Would the promise of promoting sustainability and becoming more connected to what you are drinking make you more interested in or more likely to buy, grow, or drink herbal teas?
• For gardeners: do you grow any herbs that you use to make herbal teas?  What are your favorites?
• And for anyone: have you ever tried the caffeinated drink made from Yaupon?  I’ve tried Yerba Mate and Guayusa, but not yet Yaupon.