It basically identifies two components that make coffee bitter, both due to roasting. My thoughts are: does tea that is roasted longer taste comparatively bitter? (I say comparative b/c you can probably always brew in such a way as to reduce bitterness). I have a pretty seriously roasted Tie Guan Yin that may fit that bill, but I've also tried some green pu-ers where bitterness seems to dominate (I don't think pu-er is really roasted, is it?) Second: is bitter something we would want to get rid of anyway? I kind of like a bitter edge sometimes. I try to keep it at the edge, but I think bitterness can be a good thing. I wonder if changing coffee brewing parameters would reduce bitterness--looks like they tested the brew rather than the bean here.
On Aug 22, 2:20 am, cha bing snipped-for-privacy@yahoo.com wrote:
Both interesting and thought provoking.
The threshold reaction to Bitter taste appears to be much lower in the USA than Europe. Robust CTC teas are the most popular in Britain but the lighter more mellow orthodox teas are preferred in the USA. An English Breakfast tea is principally blended from East African CTC teas that we with enthusiasm would say are pungent and astringent but are disliked in the New World as being too bitter. Sweet tea so popular in the US south, and tea bag tea generally, based on almost tasteless non bitter South American orthodox teas, is anathema to most of us over here. The cultural acceptance in the USA of black teas brewed in below boiling water I believe is due to this method resulting in a less bitter liquor. With the exception of the excellent micro brewery beers I suspect that American commercial beers (Lites!) have the same lack of bitterness compared to European preferred brews - the standard beer of Britain is even ordered as "a pint of Bitter ".
However, bitterness in tea derives from different sources than in coffee. Coffee is roasted at a much higher temperature than is any tea. Product temperature (in the bean) will reach well above 200 degrees C when pyrolysis occurs - a heat producing (exothermic) reaction breaking down carbon to CO2 that actually supplies 12% of the energy required for the roasting. (Financially hard pressed tea producers should be so lucky!) The pyrolysis products give the typical brown color and roasted coffee aroma (nobody would choose to drink coffee made from green coffee beans), but pyrolysis also produces some very bitter compounds - and the higher the roast the more there is of them. Normal teas are dried at the much lower temperature of 95-105 degrees C and while some browning (and flavor production) occurs in oxidised teas when sugars and amino acids react (by heat induced Maillard reaction - similar to browning of roasting meat) this in tea occurs sub 100 degrees C. The only teas dried much above 100 deg C are the so called roasted ones - mainly some oolongs and greens. Traditionally this is done in a charcoal fired wok and, while the temperature of the wok surface is definitely very hot (I have seen 160 deg C quoted) the actual leaf temperature is less than this as it is constantly stirred and moved away from the hot metal. As the leaf dries the temperature is reduced but is nevertheless is hot enough to produce the roasted flavor - in those tea types where it is required. In black tea too high a temperature is bad - called by the tea maker "high firing" or "bakey" if only a touch high - and is a character required in some teas - Darjeelings are typically high fired. If too high it's termed "burnt" and value drops like a stone. Chosen Oolongs are allowed the high fired character when it is called "roasted" - but it does not I think impart any bitterness.
Nigel, Thanks so much for your post. I have been obsessed with collecting this type of information lately. So I guess bitterness and heat aren't really associated factors in tea. But I have also heard that roasting tea makes it sweet in some respects. As I'm trying to figure out how roasting affects a tea's taste, I wonder if you'd be able to characterize what the "bakey" taste is like. Really, what I am looking for is a description of a scale: at one end would be the no- roast tea, and at the other would be the "bakey" or "burnt" tea. In between would be something that is sweet? Maybe there are too many other factors at play to be able to nail down this roasted flavor without simply drinking lots of teas and seeing the differences for myself.
I will attempt to give you a scale but two caveats here: words are inadequate descriptors of the spectrum of tastes that can be found in a tea cup. And many "good tastes" become bad when present to excess; but excess varies widely for different people. Some will bridle at a slight smokiness in a Yunnan while others cheerfully drink Lapsang Souchong, the more tarry the better. Roasting is accepted in some teas but is not in others, hence the degree and type of roasted flavor can be positive or negative depending on your perspective.
In a well made Assam for instance there is a tendency to maltiness - this is a flavor produced during drying (also known as firing and to some as roasting). "Malty" is a sweet positive aroma/taste/flavor (ISO term 2148 - a desirable characteristic in some teas that have been fully fired, suggestive of malt or caramel). Slightly further along the scale or spectrum is "biscuity" (ISO term 2108 - a liquor having a characteristic reminiscent of biscuits (cookies)) - this is also seen by some as acceptable in an Assam, though perhaps not in a Ceylon. Bordering on either side of acceptability we have "fully fired" (ISO term 2134 - describes the liquor of a tea which has been slightly over fired during manufacture) and "high fired" (ISO term
2142 - describes the liquor of a tea which has had too much firing. It is generally undesirable except in the case of certain Darjeelings where it is a great asset). Into the really unacceptable flavor area comes "bakey" (ISO term 2107 - an unpleasant characteristic noticeable in liquors of teas which have been subjected to higher than desirable temperatures during the firing (drying) operation) and "burnt" (ISO term 2114 - an undesirable characteristic found in the liquor of teas which have been subjected to abnormally high temperatures during firing; a degree worse than "bakey"). Then we have "cooked" (ISO term
2124 - a liquor burnt to such an extent that all other tea characteristics are hidden) - that's about a bad as it gets. Sweet (though not really recognized as a tasting term) probably in the above case tails off with high fired when bitterness creeps in - but again beware, both sweet and bitter can be present to greater degrees due to other factors than drying.
ISO tasting terms quoted from international standard ISO 6078-1982 Black Tea - Vocabulary, unfortunately ISO has not produced a standard for green teas or oolongs
Nigel at Teacraft
Note that these positive characters merging into defects are due just to a 10-15 degree F difference in dryer temperature.
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