Tea Steeping Factors – Altitude, Temps and Times

by Jason Walker on April 13, 2014

in Member Content

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Steep Tea Gaiwan

A traditional teabag is designed to remove the magic of making tea. Blenders work to mix the right ratio of leaves so that the taste profile is the same in every bag, year after year. Once you know what you brew from this bag, you can use the same parameters and get the same results. The magic that comes with unique leaves from distinct locations is gone.

That is not to say that a well-steeped cup of quality tea is dependent upon the work of the tea fairy. Science has shown that key components in tea can be released  depending on our steeping behaviors. We also know more about how location can affect the components in tea leaves.

Several studies have looked at tea steeping processes. Most of these studies have looked at a few main chemical components in tea.

1. Caffeine – that crystaline xanthine alkaloid we have come to know so well,
2. Catechins – phenols studied for their antioxidant properties. Catechins also contribute to the astringent and bitter character of tea.
3. Amino acids – these are often associated with flavor and aroma compounds.

A brief tour of the research shows how altitude and steeping parameters relate to these components.

Altitude

Taiwan high mountain teas are prized for their aromas and more delicate character. Part of the reason these teas are gentler, or smoother appears to be because they have fewer catechins. In particular, simpler catechins, like EC and EGC are not converted to ECG and EGCG. The study posits that lower temperatures in these mountains prevent these astringent catechins from forming. This suggests exploring whether  teas from higher elevations and those grown in cooler conditions are frequently less astringent. Similarly, it may also hold true that spring and late autumn teas (grown and harvested during the cooler parts of the year) will be less astringent than the same tea harvested during warmer parts of the year.

On the other hand, EGCG is one of the most abundant antioxidants in tea and one of the most studied. If you are looking to maximize the health benefits of the tea you drink, higher astringency associated with EGCG may be preferred.

Time & Temp

Aside from water conditions which have been explored here, steep time and temperature are key factors. The remaining major factor would be ratio of leaf to water.

Before looking at the results of steep time and temperatures, it is important to consider how different size and shapes may contribute to findings. A Japanese sencha consisting of fine filaments may yield dramatically different results from a tightly rolled wulong.

In order to understand how leaf format can affect steeping results, I looked at teabag teas and loose leaf teas being steeped.

The teabag study examined 3 grams of different teas (green, black, wulong, pu’er, etc.) in teabags. In order to simulate Chinese gongfu steeping practices, these teas were steeped:

a) up to 8 times; 30 seconds each time,
b) progressively longer steepings; with identical bags removed after intervals of 30 seconds up to a maximum of 4 minutes. The first bag was removed after 30 seconds, the second after 1 minute, the third after 1.5 minutes, etc.

These results revealed that cooler water (approx 160° F) yielded greater caffeine and catechin content on the second steep. Hotter water (approx 185° to 212° F) steeps saw highest levels of caffeine and catechins in the 1st steep.

Interestingly, the results also showed that the total amount of caffeine, catechins, and gallic acids in the repeated 30 sec infusions was greater than the 8 bags steeped at progressively longer intervals.

For finer teas like Japanese sencha, this suggests a couple of ideas to consider when steeping at home. Many Japanese greens are steeped at lower temperatures, between 160° and 180° F. If using brief steeps,  you could expect the second pot to be more caffeinated and more astringent than the first. Secondly, time sitting in the pot means water can cool more and leaves get agitated less compared to frequent, briefer steeps. The result may be smoother, less astringent cups of tea.

Instead of equal time per steep, it is often the case that subsequent steeps are longer. Another study looked at how oolongs  performed after a series of 10 steeps. With 195° F water, catechin levels rose through the first 6 steeps and then began a decline.

Amino acids related to flavor/aroma were at their highest levels during the 3rd through 5th steeps. Other fragrance compounds peaked during the 2nd steep. Caffeine released  at a relatively steady pace through the 2nd through 10th steeps.

For wulongs (oolongs) this study supports the theory of  the 2nd – 5th steeps being optimal steeps, with the 2nd more fragrant than sweet.

Is it possible to steep too long? From the perspective of antioxidant activity, steeping at 212 F for 10 minutes resulted in poorer results.

With so many parameters in types of tea and steeping method, it can be hard to conclusively answer all questions about the best way to steep. It is very possible that there is no one best way. Still it does help to have a guide in avoiding ways that will lead to poorer results. Life is too short to drink bad tea.

Works Cited

Chen, G.H. et al., Catechin content and its degree of galloylation in oolong tea were inversely correlated with cultivation altitude, Journal of Food and Drug Analysis (2014).

Li, S.C. et al., Effect of different extraction conditions on compositions of oolong tea infusions. Department of Food Science, National Taiwan Ocean University, July 2006.

Su, X. et. al., Polyphenolic Profile and Antioxidant Activities of Oolong Tea Infusion under Various Steeping Conditions, International Journal of Molecular Sciences, 2007, 8, 1196-1205.

Yang, D. J. et al., Effects of different steeping methods and storage on caffeine, catechins and gallic acid in bag tea infusions, Journal of Chromatography, A 1156 (2007) 312-320.

 

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Walker Tea Review- a tea blog with tea reviews and tea tastings.
Want to see a tea reviewed? Contact me: jason@walkerteareview.com

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