Selfsufficientish.com

There've been a couple of disasters or near-disasters posted here concerning exploding bottles (or, at least, a nagging worry that they might explode). Perhaps it's time to post a warning.

Any wine which has apparently finished its fermentation may not have done. Bubbling through the airlock may stop because:

a) the gasses are escaping via a badly-fitting bung.
b) it's too cold.
c) most of the yeast has shuffled off its mortal coil - but there are probably still a few cells which might begin to divide again and build up a new colony.
d) a balance of alcohol/sugar has been achieved which deactivates the yeast - until more air is introduced.
e) the fermentation has stuck.
f) a load of other reasons I've missed.

Under NONE of the above circumstances can you say that the fermentation will not start again. Which means that if you bottle your wine at this point, you may well be producing little bomblets.

To guarantee that there is no more yeast to cause a problem, you'd have to dose the wine with potassium sorbate or sodium sorbate (a substance found in a lot of foodstuffs - look for "stabiliser"). However, the use of this is questionable in "green" terms. The next best thing is the use of sodium metabisulphite (Campden tablets) which should be used at every racking in any case to prevent oxidation. Lots of people don't like this because it's a "chemical", but its only action is the production in the wine of small amounts of sulphur dioxide, a very effective bactericide (the traditional method of treating oak barrels was to burn a sulphur candle inside - with the same chemical results). Personally, I wouldn't dream of trying to make wine without it. However, metabisulphite does NOT kill yeast - it merely stuns it temporarily. The stunned yeast falls to the bottom of the fermentation vessel, the wine is racked off and Bob's your uncle - except how do you KNOW that you got rid of ALL of the yeast?

Then there's the "it's stopped bubbling and has fallen clear" method of judgement. That, I'm afraid, means absolutely nothing and is the worst possible indicator of bottle-readiness.

But why the rush? The safest way to treat wine after fermentation has apparently ceased is to rack it into another bulk container and stop it with a bored bung with the hole plugged by cotton wool for as long as your patience lasts. Keep your eyes on it. If it remains clear and doesn't throw any kind of deposit after, say, six months (and I wouldn't bottle anything before at least that much time had elapsed) and that six months includes a period of increasing temperatures, then you can swap the plugged bung for a solid bung. And then, if you really want to be kind to your wine, you'll leave it in bulk for another year or so anyway (maturation proceeds more efficiently in bulk than in bottle).

If it's still clear, THEN you bottle it. Result - no exploding bottles (unless you get the malo-lactic ferment which prompted this post but, believe me, spontaneous malo-lactic ferments are only slightly less rare than female popes).

What a mess-around, you may think. And it probably is - but it's safe.

So - leave your wines in demijohns for as long as you possibly can. It's better for the wine and it's healthier for you.

Here endeth ...

I agree, in principle, with not bottling too early. For me the problem is I make my wine at my parents' place, since thats where the fruit is grown and their place is much bigger than mine. Which means I have my parents going on at me to 'sort the wine out and get all these demijohns out of the way!' Hence the need to bottle for easier storage.

I never use Campden tablets, not so much because its a chemical as such (ashamedly, I do sterilise everything using chemicals ), but because I don't want sulphites in my wine. Avoiding them is one of the reasons I make my own. So, are there any alternatives? And if you know of any non-chemical alternatives for sterilising the equipment, that'd also be good!

I mostly bottle in Grolsch flip-top or regular beer bottles. If I get any fermentation post-bottling then at least nothing explodes 'cause the bottles can handle the stress. At least, if your hydrometer confirms that fermentation is done (no/little residual sugar).

Jandra

Ah - I never realised that asthma and allergies might be an issue with metabisulphite. I've done a bit of googling around, and the food industry appear to be looking at an alternative treatment with calcium sulphate and ascorbic acid. However, I know very little about it at this stage.

As for sterilisation, Milton - the stuff used for feeding bottles - is an accepted alternative. However, there may now be arguments against even that - I don't know. Straightforward boiling water can be use for sterilising your glassware.

But back to metabisulphite. At the moment, an awful lot of foodstuffs are treated with metabisulphite at a level way above what you would introduce into your wine by the proper use of Campden tablets. It's a moot point, then (unless you produce all of your own food), whether avoiding its use in winemaking actually would reduce your sulphite intake significantly. However, I take your point - every little helps.

I'll keep looking.