Sweetening & Renewed Fermentation

For the only the second time I have had a batch of wine that was stabilized, (sorbate and SO2) that had renewed fermentation in the bottle. Both wines were sweetend at bottling based on wife tests. Both were crystal clear had thrown no sediment in months. One was a Brew King kit (no F Pack, sweetend on my own as the wife thought it was too dry for here tastes) the other from Grapes. The Pinot Gris ended up a great sparkler! But I am getting tired of this. I suspect viable yeast were still in the wine, even though the sorbate would stop reproduction they would still put off CO2.

Most of my wines are 5-6 gal batches. Before investing in a micron filter system any suggestions? If filtering is the only way to really sweeten a wine and not have these problems can I do it in one filter/sweeten/bottle step?

Tom

Reply to
Tom
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Reply to
J Dixon

Make that "sweeten, filter and bottle", and yes, you can do it as a continuous process.

I've done sterile filtrations at home for years, when necessary. It's not as hard as it sounds. It's not as cheap as sorbate/sulfite, but I don't like the taste of sorbate. Membrane filter cartridgess are expensive, but if you take care to clean the wine up well and run it through a prefilter stage the membrane can be reused many times.

BTW, I'd recommend arresting the fermentation before dryness by chilling to stop the fermentation before dryness when the wine tastes right, bentoniting, settling well, and sterile filtering - as opposed to fermenting to dryness and adding back sussreserve or a dosage of sweetener. That's the way the best sweet wines are produced commercially.

Tom S

Reply to
Tom S

Tom:

I'm curious: for those of who can't or don't do sterile filtering (possible stripping of taste?) what if one uses a yeast that stops at

12%-ish (Cote des Blancs) and starts with enough sugar to make the P.A. higher than that. Will in-bottle ferment be prevented without sorbate or filtering because the yeast is incapable of functioning, even if some yeast cells remain?

Art S

Reply to
Art Schubert

Art, You may be interested in the following article by Steve Roberta. lum

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STERILE FILTRATION-SCIENCE VS MYTH

by Steve Roberta Department of Viticulture & Enology University of California, Davis September 1994

The question of whether sterile filtration harms wine flavor evokes much debate and emotion. Although there is little scientific research on the question, filtration proponents rightly emphasize the financial risks incurred by producers who choose not to filter. These risks are real.

Filtration proponents point out that wine flavor components are smaller than the pore size of the sterile filter membrane, and that insoluble filtrate doesn't possess significant flavor, anyway. Thus, proponents argue that there is no reason why filtration, properly performed, should affect wine flavor.

In the other camp are filtration opponents who believe they do taste a difference. They claim filtration strips wine of significant properties and flavors. However, one is hard pressed to obtain from opponents just what these properties and flavors are supposed to be. Nevertheless, they observe filtrate being removed from a wine and associate filtration with the taste difference they perceive. Thus, they conclude filtration is detrimental to wine flavor.

Encouraged by our professors to decide for ourselves who is right, we recently conducted an experiment which asked the question, "does sterile filtration create changes in wine that consumers can taste?"

From a supermarket shelf we selected five well-known, unfiltered Zinfandel, Pinot Noir, and Cabernet Sauvignon - vintage 1990 to 1992; and from the UC Davis cellar, one unfiltered Pinot Noir - vintage 1984. Four bottles of each wine were combined under nitrogen to eliminate bottle variation; half of the wine was sterile filtered, the other half was not filtered but was similarly processed.

Over five evenings our trained taste panel, consisting of 12 volunteer judges (none of whom were connected with the department of enology and viticulture at UC Davis) evaluated the wines by duo-trio testing. Two repetitions of each flight of each wine resulted in a mean correct response of 54%. The best correct response of any one panelist was 66.6%. There was no variance by wine, flight or panelist.

In other words,...................the panelists could do no better than random guessing. We thus conclude that the panelists could not detect a difference between filtered and unfiltered red wines, and from this can infer that there was no detectable difference in wine flavor as a result of the filtration.

Reply to
Lum

Thanks for the comments,

I will replace my sorbate before its used again.

With the kit I used the pre-measured dose as provided. I will have to check my notes on the Gewurtz as that was from grapes and I would have measured that one myself.

I make a fair amount of wine. In kits, grapes and a few country wines. Built a wine closet that holds 600 bottles. Most of which are mine. More grapes then kits now days.

Tom

filter/sweeten/bottle

Reply to
Tom

Here are some suggestions you can use or not as they fit your style.

It is possible you are accidentally stirring up yeast sediment on the bottom of the carboy by pushing the wand all the way down and then accidentally moving it around on the bottom. Try racking with the wand only part way down and then pushing it deeper as necessary until it is an inch or so from the bottom. Then move the last bit of wine to a 1 or a 1/2 gal carboy to settle again.

When I sweeten I never bottle. Put it back in a carboy to set for another

2-3 weeks to see if there is any sign of fermentation before bottling. I always do this but I have never had this problem.

Ray

Reply to
Ray

Sounds definitive. Thanks. I'll file it away for reference.

I'm still curious about whether a yeast with modest alcohol tolerance can possibly do any damage if bottled at or near its alcohol limit with residual sugar but without filtration.

a.

Reply to
Art Schubert

Alcohol tolerance for a yeast is an average, not a tolerance. In general the yeast will quit at about a given point. But there could be (likely to be) yeast in the batch that have a higher tolerance than the average. There could even be some that quit at about the tolerance and then wake up hungry later. There are millions or even billions of yeast in a ferment and some of them will be radicals. Also, yeast are not very bright. They don't always understand how they are suppose to behave. You could even get a whole generation that are lazy and quit early. Use the tolerance as a guide but not as a target. ;o) Ray

Reply to
Ray

Ray's completely correct here, the alcohol tolerance is based on a whole heap of variables.

To guarantee the yeast you are using is the only yeast you would have to sterilise (not just sanitise) everything, i.e. steam everything used and pasteurise/sterile filter the juice. Otherwise the wide variety of yeasts that are ever present may provide something with a much higher capacity to ferment than your chosen yeast.

For example, in every winery I have worked in the indigenous yeasts have had capability to ferment just about anything with sugar (you would assume that the yeast population over the years gets slanted towards yeasts with some extreme fermentation properties). We once had some juice stored at 0 deg C, which started with plenty of free SO2 that started fermenting (we negelcted to keep checking the FSO2, lesson learnt!).

We also had a case of a yeast contaminating our Sauternes style wine in barrel. This yeast was quite happy chewing away at the malic acid in the wine, not the sugars! It took us a long time to figure out what was going on, the wine was cloudy and fizzy and looked to be sugar fermenting, but the Baume wasn't dropping. We had to pull it all from barrel and sterile filter it.

Nature always has a way of mucking your plans up!

Reply to
Robert Lee

Tom, I think John probably had it right when he suggested your sorbate might be old. Six to eight months after the jar is opened is about max shelf life for potassium sorbate. Most people don't buy sorbate in a jar, but rather buy a 1 or 2-ounce supply in a little ZipLoc bag. The shop owner bought it in a jar and opened it to fill those little bags. You have no idea when he did that because he didn't (and won't) date the bag. It might be four months old when you bought it.

I buy my sorbate in jars. The smallest amount I can buy in a jar is

55 grams. I buy 4-6 jars at a time. I never open one unless I have several carboys and several gallon jugs of wine to treat--the reason should be obvious. I date the jar when I break the seal and I throw it out 3/4 full six months later. If I don't do this, I won't be stabilizing my wine. I've tried using more to make up for the deterioration, but there is a level at which you can taste it and, like Tom S., I don't care for the taste.

By the way, how old is your potassium metabisulfite? It too has a shelf life--about a year. Campden is the same.

If you don't have a spare refrigerator for cold stabilizing your wines, think about getting one. Tom S. is right on that account.

Finally, Lum, Roberta's article is a classic and ought to be published at least here at least every six months. Please feel free to do it whenever appropriate. That's one broken record I can suffer through for the benefit of those just joining us.

I'm off for to California for the next 3 1/2 weeks. I'll tune in again in mid-January. Hope you all have personally rewarding holidays....

Jack Keller, The Winemaking Home Page

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Reply to
Jack Keller

Another point of view. Get a copy of C.J.J. Berry's book. You will find that he made *lots* of sweet wines and used neither chemical stabilizers (ie Sorbate) nor sterile filtration. (yes they were stabile in the bottle) For many years his writings were considered definitive by those who made "country" wines. Hard to argue with success.

He did so by running the ferments until the yeast reached it's AT (Alcohol Toxicity point). The alcohol then acts as a poison and kills the yeast leaving any remaining sugars as "residual". In fact, until the advent of chemical stabilizers and sterile filtration, this was the most commonly used method of producing sweet wines. (Fortifying to raise the alcohol level above the AT was the other "common" method)

It worked then and it still does. I routinely make several of these "old fashioned" (residual sugar) ferments each year. And, if you go to Jack's site you will find that many of the "old" recipes there are designed to be this kind of ferment.

Of course, you must always be on guard for anything "strange" that may get into your wine and be prepared to deal with it. But this is no different than any other wine.

Let me add a copy of a previous post which you may find helpful:

...................................................................... ................

Jeff

When (or if) a ferment will "end" (die off) depends on which yeast strain is used and how much sugar is in the must. It is really quite simple to determine this when planning a ferment. First, go to:

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Print this if you can. Note the "Alcohol Tolerance" (AT) column. This tells you how high each type of yeast can go.

Second, Get a decent (full range) Sugar/SG chart with a PA column.

Third, (example) Take an SG reading of the must. Look at the PA column on the SG/Sugar chart for that reading.

Next, compare the PA to the AT of the yeast you have elected to use. If the PA is *less* than the AT, you will end up with a dry wine with alcohol equal to that PA. BUT - if the PA is *greater* than the AT, the ferment will "end" (die off) with alcohol equal to the AT and there will be "residual" sugar left in the wine. Just how much sugar will remain can be determined by locating the AT *number* in the PA column of the SG/Sugar chart. The *difference* between this number and the PA of the must will tell you how much sugar will remain.

Of course, there are a myriad of variables, but this method will give you very good "working" estimates for planning your ferments. This is especially important when doing "old fashioned" (residual sugar) ferments because it allows you to balance residual sugar levels against the somewhat elevated alcohol levels encountered when doing such ferments. HTH

FWIW - If you are going to do "old" recipes, you will be best served by selecting yeasts with ATs in the 13-14% range.

....................................................................... .............

HTMS

Reply to
frederick ploegman

Sorry Jack and Lum,

But, I don't think that study proves anything. It does not take into account aging unfiltered vs aging filtered. Don't get me wrong, I'm not promoting unfiltered wines, nor promoting filtering, I think each has it's place depending on wine style, but that study is just plain flawed. It doesn't match what would happen to a wine based on the decision to filter or not.

If I take a bottle of '82 Lafite and filter half of it now, no, I wouldn't expect to taste a difference between the filtered and unfiltered wine, but would the wine be the same if the wine maker had decided to filter it 20 years ago?

The world may never know.

Andy

Reply to
JEP

Andy,

I agree that an experiment such as this can't address what will happen to filtered wine in 20 years. But, it seems to me that Roberta's experiment does prove that a tight filtration did not significantly change the near term characteristics of _those_ particular wines. Perhaps the most important aspect is that an experiment was done. Measurements were made, data was collected and analyzed and the results presented. That's a lot different than speculation.

Regards, lum

Reply to
Lum

Our local brewshop owner suggested using ascorbic acid rather than sorbate or potasium metabisulfate as a means to stop yeast. We've done more than a dozen wine kits, half requiring sweetening prior to bottleing, and have had no problems.

The ascorbic acid he had on hand was used in beer brewing, and he recommended using the same quantities as were recommended for beer.

Reply to
Mike Eaton

Hmm. Ascorbic acid, vitamin C, doesn't stop or prevent fermentation. It will, however, oxidixe your wine if you don't have adequate levels of SO2.

Maybe the shop owner got confused by the linguistic similarity between sorbate and ascorbic?

Dave

**************************************************************************** Dave Breeden snipped-for-privacy@lightlink.com
Reply to
David C Breeden
Reply to
frederick ploegman

I thought that odd too. I'm not sure how ascorbic acid can arrest fermentation at any reasonable level. I'm wondering if the sweetener was sugar or 'wine conditioner'. I have seen bottles of that and it's usually a combination of a sugar and sorbate. I have heard of people using ascorbic acid in place of sulfite, but do not understand the reasoning given. I do not do that; I sweeten, filter and sorbate whites that are going to have any residual sugar. (My filtering setup is far from sterile, it's a minijet.)

Regards, Joe

Reply to
Joe Sallustio

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