On 2006-01-21 21:01:37 -0800, "Knack" > said:

>
> "S. Chancellor" > wrote in message
> news:2006012101041475249-dnewsgr@mephitkicksassorg...
>> On 2006-01-20 22:51:20 -0800, "Knack" > said:
>
>> It's not fermentation, it's due to oxidation of the chlorophyl.
>
> Chlorophyl may in fact be the phytochemical that the color of green tea
> leaves may be most attributed to.
>
> Technically your explanation (oxidation) is "closer" than mine (fermentation).
> http://www.britannica.com/eb/article-65377
>
> However for some reason that oxidation must be the result of or
> supported by fermentation
> http://www.tenren.com/fermentation.html
>
> Consider the following evidence:
> 1) Cold filtered tap water contains more oxygen than heated water.
> 2) The coldness inside of a fridge inhibits spoilage due to bacteria,
> molds, and yeast.
>
> So if the darker hues of the beverage are due only to greater degrees
> of oxidation, then one could deduce the fallacy that a refrigerator
> brewed green tea should be darker than any hot brewed green tea. But
> that is not the case unless one puts that pitcher of cold brew on the
> kitchen counter for several days, which warms it to room temperature,
> thus favoring fermentation ;-)

While discoloration in some tea may be due to fermentation, the amount
of time my tea changes colors is far too little to be due to true
fermentation. Bacteria just doesn't work that quickly. It is true that
there is more oxygen in cold water, but it's not as reactive without a
catalyst. To give you an example, at my work, we process quartz air
filters for the EAP to determine carbon content in ambient air for
regulatory purposes. We do this by counting the carbon which is
converted to methane by oxidation. In order to convert the carbon to
methane, not only do we have to add oxygen to the environment the
filters are in, but we also have to heat it up to around 800 Celsius to
get all the carbon to oxidize. We are not fermenting the carbon,
we're increasing the chemical volatility of the oxygen and carbon to
get them to react. The same thing is true if you keep your tea hot for
too long.

I think we're arguing about nothing though. The website you cited
about tea fermentation says this:

"The term fermentation when applied to tea is something of a misnomer,
as the term actually refers to how much a tea is allowed to undergo
enzymatic oxidation by allowing the freshly picked tea leaves to dry.
This enzymatic oxidation process may be stopped by either pan frying or
steaming the leaves before they are completely dried out. One method of
classifying teas are is based on the degree of fermentation"
As you can see, this isn't a bacterial or yeast fermentation, but
rather an enzymatic oxidation of the tea leaves. The enzymes are
denatured in green tea by steaming or pan-firing so that they won't
function as catalysts anymore. However, oxygen can still darken the
leaves over time naturally, and this can even happen rapidly without
enzymes provided the temperature is hot enough. (Such as leaving it on
a warmer like I was doing.)
> BTW, I'm not suggesting that anyone should drink any tea that's been
> sitting at room temperature for more than a day. My remarks are only
> for making experimental observations. Personally I try to consume all
> hot brewed tea in one sitting, and all cold brewed tea (while still
> cold) by the 3rd day after it began steeping.

If you leave it sitting out for THREE days you'll probably have REAL
fermentation and then you get kombucha tea or somesuch :P You need to
add sugar to it to get much going though.

>
>> I brew a pot of green tea with a automatic drip brewer at work
>> occasionally. Depending on the tea it will be light green to start
>> with and get progressively darker throughout the day until i've drank
>> it all The flavor becomes less 'green' as it gets darker.
>
> S.C. these are very interesting observations. I've read about some tea
> brews having green colored hues and have seen some photos of them. Ever
> since I began drinking tea I've always wanted to be able to make a tea
> that appears as in the photo at
> http://www.o-cha.com/
> That would be so impressive to serve when entertaining!

My tea does not brew quite that green, and some of it brews quite
brown. The first loose green tea I bought and tried was Stash loose
leaf. I bought it after trying some kind of loose green my boss gave
to a coworker (who shared it with me a few weeks ago.) I promptly ran
out of it and purchased two types of gunpowder, which I have a post
about here. If you can identify the tea on the left in the tall yellow
container you should get a green fruity tasting tea from it.


-S.