Alkaline or acidic? The foam that appears on some teas.

Jim

On Thu, 16 Oct 2008 05:39:59 -0700 (PDT), Space Cowboy
> wrote:

>Alkaline or acidic? The foam that appears on some teas.

pH paper?

On Oct 16, 5:18*pm, Square Peg > wrote:
> On Thu, 16 Oct 2008 05:39:59 -0700 (PDT), Space Cowboy
>
> > wrote:
> >Alkaline or acidic? *The foam that appears on some teas.
>
> pH paper?

Tea is generally about pH 6 to 6.5 i.e mildly acid side of neutral. I
don't believe acidity has any affect on foam or vice versa. I
generally suspect washing up detergent when I see foam on catering
tea. However, tea seed contains high level of saponin (a natural
surfactant - 10 to 15% by weight and an important industrial source).
Tea leaf has trace levels of saponin (not much - it's toxic), which
may on occasion be sufficient to cause a surface froth. I am not
aware what field conditions encourage saponin in tea leaf - a nice
study for someone.

Nigel at Teacraft

Nigel > writes:

> On Oct 16, 5:18*pm, Square Peg > wrote:
> > On Thu, 16 Oct 2008 05:39:59 -0700 (PDT), Space Cowboy
> >
> > > wrote:
> > >Alkaline or acidic? *The foam that appears on some teas.
> >
> > pH paper?
>
> Tea is generally about pH 6 to 6.5 i.e mildly acid side of neutral.
> I don't believe acidity has any affect on foam or vice versa. I
> generally suspect washing up detergent when I see foam on catering
> tea. However, tea seed contains high level of saponin (a natural
> surfactant - 10 to 15% by weight and an important industrial
> source). Tea leaf has trace levels of saponin (not much - it's
> toxic), which may on occasion be sufficient to cause a surface
> froth. I am not aware what field conditions encourage saponin in
> tea leaf - a nice study for someone.

I hope saponin isn't tremendously toxic?

I've noticed a foamy or scummy froth often when brewing young, raw
Pu'er. I rarely see it with other teas.

Disclaimer: No detergent comes in contact with my teaware, just
sodium bicarbonate.

/Lew
---
Lew Perin /
http://www.panix.com/~perin/babelcarp.html

i only observed lots of "foam"/"froth" with some yunnan golds which
have lots of little tiny "hairs" /dust that will (i suppose) allow
little bubbles to form and persist when water is poured

SN > writes:

> i only observed lots of "foam"/"froth" with some yunnan golds which
> have lots of little tiny "hairs" /dust that will (i suppose) allow
> little bubbles to form and persist when water is poured

Sure, the "hairs" occur a lot in early spring green tea as well. But
they aren't what I was talking about, and I suspect they aren't what
Jim referred to, either.

/Lew
---
Lew Perin /
http://www.panix.com/~perin/babelcarp.html

Actually I first noticed the phenomena years ago when I drank a green
tea with lots of dust from hairs. They give the bubbles a silky look.
It seems more prominent with whole leaf green teas and less with
rolled or twisted My acquifer water has it shares of minerals and I
think exaggerates the problem. I always do a vigorous pour so the
leaves seem to be crawling out of my drinking glass. When I was using
a cylindrical pot I could amost create a head on some of the teas.
Sometimes the foam sticks around or disappears back into solution.
Ive tried test strips in the past but not much agent to cause a
reaction. I think this might be more noticeable if you like viewing
the agony of the leaves. Im drinking a Yunnan black which bubbles up
around the few leaves that rise to the surface before infusing and
sinking. Those bubbles remain behind till the first sip. I only use
a brush to clean.

Jim

PS Im posting from my breakfast nook with my wireless EEEPC. I dont
have to worry about the puppy chewing through a CAT cable but waits
for me to drop some toast crumbs instead. The best thing so far the
Linux Gui navigation keys act like Windows. I wished I could say that
about the MAC.

On Oct 17, 11:42 am, Lewis Perin > wrote:
> SN > writes:
> > i only observed lots of "foam"/"froth" with some yunnan golds which
> > have lots of little tiny "hairs" /dust that will (i suppose) allow
> > little bubbles to form and persist when water is poured
>
> Sure, the "hairs" occur a lot in early spring green tea as well. But
> they aren't what I was talking about, and I suspect they aren't what
> Jim referred to, either.
>
> /Lew
> ---
> Lew Perin /