OVHA Chat

Does anyone know if contamination can cause over carbonation? Any info would be appreciated

Hmm...

I would say contamination, if anything, might cause under carbonation. Here's my reasoning : there is only so much sugar in a bottle that the leftover organisms can convert into CO2 at a given rate. If anything, 'bad stuff' would inhibit the conversion of CO2, making it a less than optimal conversion.

Now, on the other hand, maybe there were sulphur-type gases (or god knows what) produced. What does the beer taste like? what method did you use?

Two words for you, my friend, StarSan

This is taken from John Palmer's online How to Brew book:

Symptom: The bottles are overcarbonated.

Cause 1: Too much sugar You used too much priming sugar
Cure: Vent and re-cap all of the bottles.

Cause 2: Bottled too soon You bottled before fermentation was complete.
Cure: Vent and re-cap all of the bottles.

Cause 3: Wild yeast A gusher bug has gotten into the beer. Gusher bugs and wild yeasts are a real problem as they will keep on fermenting the beer until there is nothing left but fizzy bitter alcoholic water. The real danger with overcarbonation is exploding bottles. Bottle grenades can be very dangerous both from flying glass and from glass slivers left in the carpet.
Cures: Refrigerate the bottles and drink them while there is still some flavor left.


Not sure what Gusher bugs are but I would guess that they are bacteria.

Wild yeast and bacteria infections can cause overcarbonation. Both should cause off flavors or smells. If the beer tastes & smell like it should, the overcarbonation probably is the result of to much priming sugar added at bottling or too much residual sugar left from fermentation. If added priming sugar is not well mixed you could have over & under carbonated bottles from the same batch.

I once got a case of gusher bugs and it took three weeks a doctor and a small comb to get rid of them.

*

ok, that's just nasty...

There are several bacteria that cause serious problems, including overcarbonation. The worst ones require nitrate in the water, which they use like oxygen, making large amounts of hydrogen sulfide and acetaldehyde. You won't drink any of that stuff, believe me.

The other more common problem is lactic acid bacteria that ferment the alcohol (and sugars) to lactic acid. Sourkraut smell and VERY acid taste are the result. Most beer will eventually sour from residual lactic acid bacteria (they like the same condtions yeast does), but large amounts make it go really fast. Rigorous sanitation is the only solution.

Wild yeast will do their nasty work in the fermenters, so it won't be a surprise when you crack a bottle open -- it will be nasty going in.

Peter