Metabisulphite, as a reducing agent may well have a precipetating
effect on certain proteins in solution. Alcohol in general also has a
precipetating effect on proteins (though generally in higher conc),
but together with the metabisulphide it may just about turn the cards.
It may explain the haze. Then, a gelatine fining simultaneously with
the metabisulphide addition after the last racking should get rid of
the problem.

A quick test you could try is to have a sample of your cloudy wine,
add some contact lens cleaner (containing proteases) and see if the
haze disappears.

Rene.

"Rene" wrote:

Metabisulphite, as a reducing agent may well have a precipetating
effect on certain proteins in solution. Alcohol in general also has a
precipetating effect on proteins (though generally in higher conc),
but together with the metabisulphide it may just about turn the cards.
It may explain the haze. Then, a gelatine fining simultaneously with
the metabisulphide addition after the last racking should get rid of
the problem.

A quick test you could try is to have a sample of your cloudy wine,
add some contact lens cleaner (containing proteases) and see if the
haze disappears.

Rene,

Thanks for the info, but I'm a little confused:

I think of precipitation as suspended solids dropping out of solution and
sinking to the bottom. Are we in agreement on this usage?

Do you mean that two reducing agents in combination may have the opposite
effect, i.e. to form a haze rather than cause precipitation?

If so, why doesn't this occur more frequently? Are there any predictable
(and thus avoidable) circumstances under which this might occur?

I'm now wondering if the two inexplicable hazes I've had in the past (with
apple wine!) have been a result of the S2O5 additions after all (although
they didn't occur in already clear wine, but rather the wine just failed to
clear without a great deal of fining).

Thanks.

"Negodki" wrote in message
...
"Rene" wrote:

Metabisulphite, as a reducing agent may well have a precipetating
effect on certain proteins in solution. Alcohol in general also has a
precipetating effect on proteins (though generally in higher conc),
but together with the metabisulphide it may just about turn the cards.
It may explain the haze. Then, a gelatine fining simultaneously with
the metabisulphide addition after the last racking should get rid of
the problem.

A quick test you could try is to have a sample of your cloudy wine,
add some contact lens cleaner (containing proteases) and see if the
haze disappears.

Rene,

Thanks for the info, but I'm a little confused:

I think of precipitation as suspended solids dropping out of solution and
sinking to the bottom. Are we in agreement on this usage?

Do you mean that two reducing agents in combination may have the opposite
effect, i.e. to form a haze rather than cause precipitation?

If so, why doesn't this occur more frequently? Are there any predictable
(and thus avoidable) circumstances under which this might occur?

I'm now wondering if the two inexplicable hazes I've had in the past (with
apple wine!) have been a result of the S2O5 additions after all (although
they didn't occur in already clear wine, but rather the wine just failed
to
clear without a great deal of fining).

Thanks.


Gentlemen,
Now I am confused. (Seems to happen often these days).
Why would adding a protein (gelatin) precipitate protein?
lum

"Negodki" wrote in message

I think of precipitation as suspended solids dropping out of solution and
sinking to the bottom. Are we in agreement on this usage?

Yes. Think of my explanation as of flocking of protein. It will settle
eventually, therefore my use of the word precipetate. It might take a
long time though, and a gelatine fining would then be preferable to
accelerate this process.

Do you mean that two reducing agents in combination may have the opposite
effect, i.e. to form a haze rather than cause precipitation?
If so, why doesn't this occur more frequently? Are there any predictable
(and thus avoidable) circumstances under which this might occur?

??, do not exactly know what you mean, but when the haze is settled,
it's a precipetate. Anyway, it is very difficult to reason what
exactly is going on as wine is such a complex mix and constantly
changing ('aging').
If my explanation is right it would imply apples are rich in reducible
proteins/amino acid groups. Don't really know about that, it is just a
logical guess yet. Cidermakers should know more about these things.

I'm now wondering if the two inexplicable hazes I've had in the past (with
apple wine!) have been a result of the S2O5 additions after all (although
they didn't occur in already clear wine, but rather the wine just failed to
clear without a great deal of fining).

Thanks.

"Rene" wrote in message
om...
"Negodki" wrote in message

I think of precipitation as suspended solids dropping out of solution
and
sinking to the bottom. Are we in agreement on this usage?

Yes. Think of my explanation as of flocking of protein. It will settle
eventually, therefore my use of the word precipetate. It might take a
long time though, and a gelatine fining would then be preferable to
accelerate this process.

Do you mean that two reducing agents in combination may have the
opposite
effect, i.e. to form a haze rather than cause precipitation?
If so, why doesn't this occur more frequently? Are there any predictable
(and thus avoidable) circumstances under which this might occur?

??, do not exactly know what you mean, but when the haze is settled,
it's a precipetate. Anyway, it is very difficult to reason what
exactly is going on as wine is such a complex mix and constantly
changing ('aging').
If my explanation is right it would imply apples are rich in reducible
proteins/amino acid groups. Don't really know about that, it is just a
logical guess yet. Cidermakers should know more about these things.

I'm now wondering if the two inexplicable hazes I've had in the past
(with
apple wine!) have been a result of the S2O5 additions after all
(although
they didn't occur in already clear wine, but rather the wine just failed
to
clear without a great deal of fining).

Thanks.

I don't want to get into defining "precipitation." But, fining wine with
gelatin will not drop out protein. Gelatin is a protein. Fining with
Bentonite is the usual way of removing protein.
lum
lum

Sure Lum is right! My mistake:

I don't want to get into defining "precipitation." But, fining wine with
gelatin will not drop out protein. Gelatin is a protein. Fining with
Bentonite is the usual way of removing protein.
lum
lum

"Negodki" wrote in message ...
snip
To make up a 10% solution, mix 25 grams potassium metabisulphite powder or
crystals with 250 ml. (about a cup) of warm water. Stir it well, to insure
all the powder is dissolved. Distilled is best, but if your tap water is
drinkable it will do. Store it in a dark glass or white plastic jar with a
good lid. It will last indefinitely. One teaspoon (50 ml) of this solution
is equivalent to one campden tablet, and is the amount you should normally
add per gallon of must. If you use a graduated syringe, you can make
accurate measurements for smaller containers.

This is nitpicking, I know - it doesn't sound like you were shooting
for accuracy here - but for a 10% solution you want 25 grams in 225 ml
of water, not 250.

- Mark W.

"Mark Willstatter" wrote"

This is nitpicking, I know - it doesn't sound like you were shooting
for accuracy here - but for a 10% solution you want 25 grams in 225 ml
of water, not 250.

You are apparently attempting to include the volume of the meta, and
calculating 25g / (225 ml + 25 ml) = 10 %, but 25 grams of metabisulphite
does not become 25 ml of liquid in solution!

I don't know the actual figure for meta, but sugar in solution increases the
volume by ~0.645 ml / gm, depending on temperature [Source: American
Winemaking Society], so if we were dealing with sugar, and nitpicking, the
equation would be:

25 gms sugar / 10 % - (25 gms sugar x .645 ml / gm) = 233.875 mls
water at standard temperature

I believe meta in solution increases the volume by far less than 0.5 ml / gm
(this is verified by my own rough measurements), in which case my formula is
more accurate. If it were more than .5 ml / gm, yours would be the more
accurate. If it were more than 1.4 ml / gm, neither formula would be
correct.

But there is probably more than this 1% potential error in the measuring
cups, spoons and thermometer we will be using, as well as in our ability to
fill the vessels to a precise volume.

As you said, I'm not shooting for more than +/- 10 % accuracy. If I were, I
would be determining the difference between the weight of the primary when
empty and its weight when full, and computing the volume of the must based
on its SG. Then I would add the meta by weight, not by teaspoon or graduated
syringe. And then I would still miss Mars by 10,000,000 kilometers because
of some other factor I hadn't considered.

Negodki wrote:

And then I would still miss Mars by 10,000,000 kilometers because
of some other factor I hadn't considered.

Probably from converting from imperial to metric back to US units and
messing it up somewhere along the line! :^)

--
charles

"Once ... in the wilds of Afghanistan, I lost my corkscrew, and we were
forced to live on nothing but food and water for days."
- W.C. Fields

A solution to the 10 % solution: Rather than worry about the volume of the
meta in solution, weigh the 25 grams of meta in a graduated cylinder, and
fill it to the 250 ml level.

I am wondering if this is a sign that your wine should be cleared with
finings. I agree (but don't know 8-) that you likely have something
in the campden tablet acting as a precipitating agent. I just added
the clarifier to a couple of white wine kits in carboys. They looked
very clear, but when I added the clarifier they turned cloudy, and
after only a couple of hours, I notice sediment on the bottom of the
carboys, where there was none before.