I did a few SO2 measurements on red wine using titrets. When the first
drop of wine gets in, the liquid turns grayish-blue. As I continue to
allow more wine in, the hue turns more and more towards the color of
the wine. At some point (we'll call it point "A"), the hue seems to be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").

The question is: should I stop at point "A" or "B"?

"Franco" wrote in message
oups.com...
I did a few SO2 measurements on red wine using titrets. When the first
drop of wine gets in, the liquid turns grayish-blue. As I continue to
allow more wine in, the hue turns more and more towards the color of
the wine. At some point (we'll call it point "A"), the hue seems to be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").

The question is: should I stop at point "A" or "B"?

Neither - SO2 determination in red wines using titrets is next to worthless.

I happen to agree with Paul. Sometimes you can see the color change
easier than other times esp if you dilute the sample first, but even
then I have read that you should use an adjustment factor because the
reading is off by a certain amount in reds. I gave up on using Titrets
for reds because it seemed ridiculous.

Paul says titrets are worthless and I do agree they leave a lot to be
desired when testing red wine. But the alternative is pretty complicated
and I like laboratory testing. I've noticed that if you keep adding red
wine to a titret the redish color stays the same. I keep a used titret
(with the red color) around for a reference. When I test a red wine I make
sure to add increments of wine slowly, letting any color change develop
before adding more wine. If you are careful you can get the color change
from dark black to "red" and not add excessive wine sample. For my records
I use this first change from dark black to "red" as the end point. And as
the color changes I compare it to the "used titret" I keep as a standard. I
think this is about as good as you can do with titrets and red wine.

Bill Frazier
Olathe, Kansas USA

Franco wrote "At some point (we'll call it point "A"), the hue seems to be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").

William Frazier wrote:
Paul says titrets are worthless and I do agree they leave a lot to be
desired when testing red wine. But the alternative is pretty complicated
and I like laboratory testing. I've noticed that if you keep adding red
wine to a titret the redish color stays the same. I keep a used titret
(with the red color) around for a reference. When I test a red wine I make
sure to add increments of wine slowly, letting any color change develop
before adding more wine. If you are careful you can get the color change
from dark black to "red" and not add excessive wine sample. For my records
I use this first change from dark black to "red" as the end point. And as
the color changes I compare it to the "used titret" I keep as a standard. I
think this is about as good as you can do with titrets and red wine.

Bill Frazier
Olathe, Kansas USA

Franco wrote "At some point (we'll call it point "A"), the hue seems to be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").

William Frazier wrote:
Paul says titrets are worthless and I do agree they leave a lot to be
desired when testing red wine. But the alternative is pretty complicated
and I like laboratory testing. I've noticed that if you keep adding red
wine to a titret the redish color stays the same. I keep a used titret
(with the red color) around for a reference. When I test a red wine I make
sure to add increments of wine slowly, letting any color change develop
before adding more wine. If you are careful you can get the color change
from dark black to "red" and not add excessive wine sample. For my records
I use this first change from dark black to "red" as the end point. And as
the color changes I compare it to the "used titret" I keep as a standard. I
think this is about as good as you can do with titrets and red wine.

Bill Frazier
Olathe, Kansas USA

Franco wrote "At some point (we'll call it point "A"), the hue seems to be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").
Well since the consensus seems to be that titrets are useless for red
wine what should I use to check my SO2 levels?

"fasteddy999" wrote in message
oups.com...
William Frazier wrote:
Paul says titrets are worthless and I do agree they leave a lot to be
desired when testing red wine. But the alternative is pretty complicated
and I like laboratory testing. I've noticed that if you keep adding red
wine to a titret the redish color stays the same. I keep a used titret
(with the red color) around for a reference. When I test a red wine I
make
sure to add increments of wine slowly, letting any color change develop
before adding more wine. If you are careful you can get the color change
from dark black to "red" and not add excessive wine sample. For my
records
I use this first change from dark black to "red" as the end point. And
as
the color changes I compare it to the "used titret" I keep as a standard.
I
think this is about as good as you can do with titrets and red wine.

Bill Frazier
Olathe, Kansas USA

Franco wrote "At some point (we'll call it point "A"), the hue seems to
be
the same as the wine, except that it is lighter (less saturated, like
if you diluted wine with some water). After that point, if I keep
adding wine, the hue remains the same, and the "amount" of color
(saturation) continues to increase until it looks the same as the wine
(point "B").
Well since the consensus seems to be that titrets are useless for red
wine what should I use to check my SO2 levels?

You can get an analysis done from a lab for about $12. To me, this is
worthwhile for my wine in 120 liter barrel. If you have small quantities
in glass carboys you can guestimate using SWAG (scientific wild ass guess)
by keeping track and a record of how much you have added since beginning and
during racking. This will probably put you in the ballpark unless you are
using a barrel. Here is a link that should help out a lot:

http://www.brsquared.org/wine/Articles/SO2/SO2.htm

The consensus is not that titrets are useless for red wine. That is
just one opinion. If you read some of the good books, like Margalit, or
Iverson, they talk about how to use titrets with red wine. If they
thought that it was "next to worthless", they would have probably said
so instead of explaining how to do it. The consensus is that it is
somewhat difficult to find the endpoint, and also that readings are
generally too high because some substances like tannins react with the
titrating agent. I wish people like Mr. Paul E. Lehmann would not go
around expressing their opinions as if they were facts.

fasteddy999 wrote:

Well since the consensus seems to be that titrets are useless for red
wine what should I use to check my SO2 levels?

Accuvin has paper strip, colour change based tests for several
variables, including free S)2. They have 2 colour strips for that one -
for low range 0-40ppm and for 40ppm and higher. The cost is about S2.50
per test, so more than titres but less than lab tests. I can't comment
on accuracy but heard one good report (no bad).

Vinoferm provides an alternative to titrets. It's also a Ripper test
but it works the opposite way, by adding iodine to 10 ml of wine, so
the colour change is reversed. The accuracy of reading seems better
because the scale is linear across the range, not like titrets. I've
been using it for whites instead of titrets, but did only one test so
far on reds - I remember the reason was that the result was much lower
than what I got by titrets, so I didn't know which test to believe.
Either that or I did the test wrong. I'll give it another try soon as I
have some reds close to bottling.

For the Vinoferm test, the iodine solution has a short shelf life,
that's the main drawback. On the other hand, it encourages frequent
testing as the cost is all up front and the solution life is limited.
So I'm finding it's cheaper and safer overall than titrets.

The "eyeballing" approach of guessing how much sulfite wine needs is
too rough in my experience. I tend to do this on whites in the early
stages and on reds in general because of the endpoint determination
issues, and the result in general is the wines get more sulfite than
they need.

For example, I've made some Riesling and Gewurz this year, both cold
fermented and stopped with some residual sugar. The only sulfite
addition was 40-50 ppm when I was stopping the fermentation. After this
the wines were racked once, fined with bentonite and sparkalloid,
cold-stabilized outside for 2-3 months, racked again, and filtered with
MiniJet through #2 pads once and #3 pads twice. After all this, the
sulfite is now between 20-28 ppm now, and it's the first time I can't
smell it on the finished wine. The point being that if I didn't test
before filtering and retest after, I would have had added at least
another 40ppm to each batch and ended with a sulfite bomb. The pH on
these is 3.1-3.2, that's why the sulfite is so noticeable.

Pp

"Franco" wrote in message
oups.com...
The consensus is not that titrets are useless for red wine. That is
just one opinion. If you read some of the good books, like Margalit, or
Iverson, they talk about how to use titrets with red wine. If they
thought that it was "next to worthless", they would have probably said
so instead of explaining how to do it. The consensus is that it is
somewhat difficult to find the endpoint, and also that readings are
generally too high because some substances like tannins react with the
titrating agent. I wish people like Mr. Paul E. Lehmann would not go
around expressing their opinions as if they were facts.

If you continue reading, you will find other experts who state that they are
next to worthless for red wine analysis. If you like them and trust them
for red wine, then by all means use them, but, MOST people will find them
next to worthless. YOU will be misleading people by telling them that they
are accurate for determining SO2 in red wines.

If you have a "significant" quantity of wine in barrel, do you advocate
using questionable data or spending $12 to get an analysis? Remember, you
are not only risking the wine but the barrel itself by exposing it to
contaminated wine.

Franco,
I still use titrettes on red wine but do consider the practice
questionable, that's why I haven't commented on this thread until now.
I have both of those books and Margalit does not necessarily say that
using titrettes on reds is acceptable. Titrettes are a reverse Ripper
test so I do see what you are getting at, if you follow his procedure
to the tee and gain the experience necessary to see the red disappear
in the sample you can try it. Both he and Iverson note that tannins
among other things interferes with this method. He recommends a few
other chemicals beside the titrettes for his process too. Iverson's
procedure is simpler but there has to be a reason Margalit tells you to
add H2SO4 and starch. I'm not a chemist, I'm an Instrumentation and
Controls guy so I just follow the process when i don't know enough
about what to question.

I guess what soured me on them is two things.

One, I have had a red come out slightly effervescent in the bottle, it
could have been a little residual sugar, it could have been ML. The
wine is good but not something I would give away, it's flawed.

The other thing is Chemetrics, the manufacturer of titrettes. They
specifically state they are not designed for red wines. I'm assuming
that is due to the interference from the other constituents normally
present in reds

I am considering setting up for an AO measurement process but I make
enough and am geeky enough to think it's worth it. I would not suggest
that is the right way to go for someone making 30 gallons or less of
wine a year.

Don't get me wrong, I'm not trying to be argumentative, I'm just saying
they are not cut and dry with reds as I see it.

Joe

Don't put words in my mouth. I never said that titrets are "accurate"
for determining free SO2 in red wines. I am saying that they are not
"next to worthless". Must everything be black or white? If you study
science or engineering, you will know that there is no such thing as
something being accurate. Experiments are accurate enough or not
accurate enough according to the requirements. So titrets might not be
accurate enough for you and your large batch of wine aging in a barrel,
but they can help a home winemaker with 5 gallons of red who wants to
know whether his free SO2 is closer to 10, 50, or 100 PPM. Can you see
the difference?

Thanks for the info Pp. I've been looking for a way to avoid an A-O
set up so these kits interest me. Accuvin tells me thier S02 kits
(suitable for both red and white wine) have a shelf life of 4 months
and they're working on trying to extend that. Do you recall what the
Vinoferm shelf life is?

RD

I did a search for the Accuvin SO2 test and someone here had contacted
the Accuvin about the shelf life and it is only 4 months. Interesting
that in the same thread, Tom S. says that the iodine for the ripper
test will last a long time if stored properly. Still, it seems like a
lot of lab equipment and other supplies are necessary, plus the setup
time is lengthy for the ripper test.

I won't post a link for the thread (started by Paul, incidentally)
since it turns out extremely long but a search of Accuvin SO2 will turn
it up

I posted a thread awhile back lamenting the lack of a good test for SO2
for those of us making small quantities of red wine (5 gallon batches).
No one had a good answer except for the lab test which seems a little
much for small batches. If the Accuvin had a longer shelf life I would
give it a go.

Sure hope a better method comes along soon, because this is the number
one area of winemaking that I struggle with the most. I don't like
guessing on the SO2 but don't want invest a small fortune in money and
time in the tests.

Incidentally, for those of you who send samples to a lab. How many
times do you send the sample for one batch of wine? It seems to me this
should be done at crush and then again every time wine is racked and
also at bottling. At $12 a pop plus the waiting for sample results,
this appears to be the drawback to me.

Ya know, this just started to make me think.... I'm wondering if I
can't find a membrane to selectively pass SO2/EtOH/H20. H+ would come
thru as well. If said membrane exists, this would be an easy read, in
theory, assuming 'free' SO2 doesn't rapidly dissipate. We used to use
membranes at work to selectively pass a whole slew of chemicals, and
the surfaces could be treated as needed for greater or less selection.

Interesting thought Mkike- thanks for triggering it.