Has anyone read or had experience with using activated carbon on red
wine samples prior to remove phenols prior to testing residual sugar or
when using the ripper method? I was just thinking....

My reds almost always come up as 0.3 or .0.4 RS and they sure seem dry.
I was wondering if the color or phenol in red may affect Clinitest.

Joe

Joe Sallustio wrote "My reds almost always come up as 0.3 or .0.4 RS and
they sure seem dry.
I was wondering if the color or phenol in red may affect Clinitest."

Interesting point Joe. I haven't tested for RS with Clinitest but some of
my wine club friends do. If Clinitest is specific for glucose and we are
testing wine containing at least some intact sucrose there may be a problem.
I've been playing around with a diabetic Glucometer Elite tester as an
alternative to Clinitest (some wine club members make sparkling wines and
are especially concerned with RS). The method I've been using calls for
acid treatment of the wine sample to hydrolyze sucrose to glucose and
fructose. The meter then reads glucose and I multiply the answer by a
factor to arrive at RS. You would think that sucrose in wine would
hydrolyze to glucose and fructose due to the low pH. But, I get very
different RS results with and without the acid treatment. You might look
into this as part of the problem you've been having with Clinitest.

Bill Frazier
Olathe, Kansas USA

Hey Bill, Joe,

Clinitest isn't specific for glucose--it'll detect any reducing
sugars (including 5 membered ones, I think). But not sucrose.

The problem with using a diabetic's meter to test RS is that it
won't work. Depending on your yeasts, it can be the case that the
yeast will eat all of the glucose and leave all the fructose. You
can have (I've had it!) a wine with 1% fructose and NO glucose (had
to feed it glucose to get it going again) which will test as
absolutely dry with a diabetic's meter.

Dave, diabetic for 40 years now and wishing for a cheap easy test for
residual sugar.

William Frazier ) wrote:

Joe Sallustio wrote "My reds almost always come up as 0.3 or .0.4 RS and
they sure seem dry.
I was wondering if the color or phenol in red may affect Clinitest."

Interesting point Joe. I haven't tested for RS with Clinitest but some of
my wine club friends do. If Clinitest is specific for glucose and we are
testing wine containing at least some intact sucrose there may be a problem.
I've been playing around with a diabetic Glucometer Elite tester as an
alternative to Clinitest (some wine club members make sparkling wines and
are especially concerned with RS). The method I've been using calls for
acid treatment of the wine sample to hydrolyze sucrose to glucose and
fructose. The meter then reads glucose and I multiply the answer by a
factor to arrive at RS. You would think that sucrose in wine would
hydrolyze to glucose and fructose due to the low pH. But, I get very
different RS results with and without the acid treatment. You might look
into this as part of the problem you've been having with Clinitest.

Bill Frazier
Olathe, Kansas USA








--
Dave
************************************************** **************************
Dave Breeden

Thanks for the info. Dave. Do you know if the remaining fructose can be
fermented which would have an effect on the bottle pressure of a sparkling
wine? If fructose is the end of the line the Glucometer still might be
worth using to test for residule fermentable sugar.

Bill Frazier
Olathe, Kansas USA

"David C Breeden" wrote in message
...
The problem with using a diabetic's meter to test RS is that it
won't work. Depending on your yeasts, it can be the case that the
yeast will eat all of the glucose and leave all the fructose. You
can have (I've had it!) a wine with 1% fructose and NO glucose (had
to feed it glucose to get it going again) which will test as
absolutely dry with a diabetic's meter.

Dave, diabetic for 40 years now and wishing for a cheap easy test for
residual sugar.

William Frazier ) wrote:
Thanks for the info. Dave. Do you know if the remaining fructose can be
fermented which would have an effect on the bottle pressure of a sparkling
wine? If fructose is the end of the line the Glucometer still might be
worth using to test for residule fermentable sugar.

Bill Frazier
Olathe, Kansas USA

Hey Bill,

My understanding is that yeast CAN metabolize fructose, but prefer
gluocse. My fermentation stuck at 1% fructose, and wouldn't go
again until I added glucose.

But I don't know if you can count on that.

Dave
************************************************** **************************
Dave Breeden

"Joe Sallustio" wrote in message
ups.com...
Has anyone read or had experience with using activated carbon on red
wine samples prior to remove phenols prior to testing residual sugar or
when using the ripper method? I was just thinking....

I have had a really hard time running ripper on dark reds. Diluting with
distilled water helps some. The best solution is to do the aspiration
method or just send it to a lab.

My reds almost always come up as 0.3 or .0.4 RS and they sure seem dry.
I was wondering if the color or phenol in red may affect Clinitest.

You're probably measuring non-fermentable sugars. They typically fall in
that range.

Tom S
www.chateauburbank.com

David C Breeden wrote:
William Frazier ) wrote:
Thanks for the info. Dave. Do you know if the remaining fructose can be
fermented which would have an effect on the bottle pressure of a sparkling
wine? If fructose is the end of the line the Glucometer still might be
worth using to test for residule fermentable sugar.

Bill Frazier
Olathe, Kansas USA

Hey Bill,

My understanding is that yeast CAN metabolize fructose, but prefer
gluocse. My fermentation stuck at 1% fructose, and wouldn't go
again until I added glucose.

But I don't know if you can count on that.

Dave
************************************************** **************************
Dave Breeden


Fructose is fully metabolizable. The major metabolic pathway for sugar
is called glycolysis. Normally an enzyme called glucokinase uses
glucose into glucose 6 phosphate, which is then turned into fructose 6
phosphate.. There is another less specific enzyme (hexokinase) that
can utilize several 6 carbon sugars, including fructose and make
fructose 6 phosphate.


The problem with clintest I believe is that it tests for REDUCING
sugars. That is it uses the reduction of copper to affect a color
change. The problem with wine is that there are many things that can
reduce the copper. Sulfite is a reducing agent for instance....so are
the anthocyanins in red wine.

"Droopy" wrote in message
oups.com...

David C Breeden wrote:
William Frazier ) wrote:
Thanks for the info. Dave. Do you know if the remaining fructose can
be
fermented which would have an effect on the bottle pressure of a
sparkling
wine? If fructose is the end of the line the Glucometer still might be
worth using to test for residule fermentable sugar.

Bill Frazier
Olathe, Kansas USA

Hey Bill,

My understanding is that yeast CAN metabolize fructose, but prefer
gluocse. My fermentation stuck at 1% fructose, and wouldn't go
again until I added glucose.

But I don't know if you can count on that.

Dave

************************************************** **************************
Dave Breeden



Fructose is fully metabolizable. The major metabolic pathway for sugar
is called glycolysis. Normally an enzyme called glucokinase uses
glucose into glucose 6 phosphate, which is then turned into fructose 6
phosphate.. There is another less specific enzyme (hexokinase) that
can utilize several 6 carbon sugars, including fructose and make
fructose 6 phosphate.


The problem with clintest I believe is that it tests for REDUCING
sugars. That is it uses the reduction of copper to affect a color
change. The problem with wine is that there are many things that can
reduce the copper. Sulfite is a reducing agent for instance....so are
the anthocyanins in red wine.

Very interesting post Droopy.
Thank you.
Could you provide a reference for "anthocyanins being a reducing agent for
copper?"
Lum
Del Mar, California, USA

Lum Eisenman wrote:
Very interesting post Droopy.
Thank you.
Could you provide a reference for "anthocyanins being a reducing agent for
copper?"
Lum
Del Mar, California, USA

I do not know of any specific research. I was speaking of more general
chemistry knowledge (I use a copper reduction assay all the time to
determine protein content in samples, and there are a lot of
interfering substances).

I did look around and found an ACS article on standardized methods to
determine levels of "antioxidant phenolics" which anthocyanins are.
they describe a copper reduction assay in it.

http://tinyurl.com/qdans

I have not read it to determine if it is a probable problem in using
the clintest with reds though....but to me at least it seems very
liekly.

Lum Eisenman wrote:
Very interesting post Droopy.
Thank you.
Could you provide a reference for "anthocyanins being a reducing agent for
copper?"
Lum
Del Mar, California, USA

sorry for the double, but here is a very old article that has reference
(page 6) to sulfites affecting the clinitest (Benedict's reagent)
reaction.

"Droopy" wrote in message
oups.com...

Lum Eisenman wrote:
Very interesting post Droopy.
Thank you.
Could you provide a reference for "anthocyanins being a reducing agent
for
copper?"
Lum
Del Mar, California, USA

sorry for the double, but here is a very old article that has reference
(page 6) to sulfites affecting the clinitest (Benedict's reagent)
reaction.

Thanks much Droopy.
Lum

Thanks all. I did try activated carbon on a sample prior to using
clinitest, it has no effect at the level I used.

Joe