Methanol?

Of what I know, Methanol will be produced by any yeast if the correct nutrients are present. You will find that if you were to test pretty much any alcoholic product, you would most likely find methanol of various concentraions. You will find, though, that any product that has been fermented with vast amounts of cellulose and certain types of starches (pectin) for extended amounts of time will have higher concentraions of methanol. IE a white wine will have a lower amount of Methanol then say a Shiraz which has been fermented with the skins. This is not to say that all yeasts will produce the same amount of methanol under the same conditions.

Without knowing what you are trying to do (and how etc.), it is hard to tell if you may produce methanol, or more precisely how much. If you can tell us, we will be able to help you.

Rob

Chris F wrote:

Andrew, sorry, but you are some way off. It's NOT the pectic enzyme that causes the trouble. The pectin itself is. The pectic enzyme breaks down pectin, that is the source of methanol. So if you use pectic enzyme in juice that containes pectin, you can get rid of almost all methanolproduction, provided you toss the yeast in after a few hours of enzyme-activity. Then, throw away the first 40-50 ml of alcohol (if you are distilling) that can contain any trace of methanol and a lot of off-flavours. Perfectly safe. If you use water and sugar, citric acid, yeast-nutrients and turbo yeast, you wille have no methanol whatsoever. What you don't produce, can't be distilled.

Ed

No flowers, no bees; no leaves on the trees; no wonder; november.

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Sorry, I wasn't clear, and you are correct.

But, as a commercial winemaker I only deal with grape juices, where there are always pectins, therefore use of pectic enzymes will always produce methanol - which agrees with what you say, just coming from the effect, not the cause! And when I talked about distillation, I meant production of brandy or SVR, which is an (increasingly) uncommon destination for wines these days.

Actually, I think *that's* the wrong way round.

Methanol results from the hydrolysis of pectin by pectin methylesterase enzymes (PME). It's the action of the PME which produces the methanol. Since PME is one of the enzymes typically used in most commercial pectic enzyme preparations, use of most pectic enzymes will result in increased methanol production.

This increase, however, is usually low (at least in grape wines) and most of the methanol resulting from it is reputed to be lost with CO2 during fermentation.

Ben

Improved Winemaking

I guess what this is indicating is that if you are going to distill the wine to brandy, do not use pectic enzyme. After all, if you are going to distill it, you do not need for it to clear.

Ray

Methanol boils at 148*F, 30* below ethanol. I suspect it shouldn't be much of a problem with most wines; to be honest, this is the first I've read of methanol being involved in the fermentation process. Anyone have any figures on % of methanol in =any= known wines? Bob

In "Concepts in Wine Chemistry," Margalit indicates that wines can contain "from 40 to several hundred milligrams per liter" of methanol. Lum Del Mar, California, USA

Thanks! That hardly seems worth bothering with. I let my wines sit in the carboy with an airlock for a year at least before bottling; it's got to come out early with such a low boiling point........

I don't think it is a question of whether it is a problem in wine. But when you distill the wine you will concentrate the methanol and then it can be a problem.

Ray

Because of its low boiling point, the methanol is present in the first portion of the distillate (called "the heads"). This portion is dicarded, thus removing the high concentration of methanol from the distilled beverage. The methanol content of wine which is to be distilled is not really an issue.

Ben

Improved Winemaking

But if you are producing wine for distillation, then less methanol is better, as not all of it is distilled early - there is no magic point at which methanol disappears, instead it gradually decreases. It is often desirable to retain some of the heads, as they are often strongly aromatic alcohols and esters, and the cut for heads with a higher methanol component must be made later than for lower methanol components.

Probably the best solution for wines that are to be distilled is a centrifuge, but at around AUD90k even my commercial winery won't be buying one of them soon...