Infected bottles?

So I brewed a porter a few months ago and cracked open a 500 ml bottled last night.

To my surprise, I lost most of it in the sink since it kept foaming out of the bottle. My friend, who brewed with me, had the same thing happen to him with one of his bottle and he told me it had a sour taste, so it was definitely infected.

This makes me believe my bottle was also infected, but from the small sample I've got to drink out of it, it wasn't sour at all. It tasted like a normal porter.

Can infection occur without leaving any taste?

The bottles have been kept at room temp ever since the bottling, not sure if it's relevant or not. Also, the bung fell in the carboy right before fermentation. It was sanitized so it shouldn't have infected the batch. I put a sanitized foil paper over the carboy's neck to prevent infection.

I took a few look at the carboy during the fermentation to make sure the batch wasn't infected and it did look clean. No sign of infections at all.

So yeah, if it isn't infection, what can cause my bottle of porter to overfoam and leave no undesired taste behind?

Thank you.

When you bottle you typically rack your beer into a bottling bucket which has the priming sugar that has been dissolved in water poured into the bottom. Normally the swirling motion of the beer exiting from the tubing mixes this solution into the beer. Sometimes the sugar solution doesn't mix well leaving you with some bottles carbonated nearly normal and some overcarbonated which will cause the beer to foam our of the bottles. I've begun a new method, begining to rack the beer so there is some beer in the bucket and then add the sugar. I also use a sanitized spoon to gently stir the priming solution in.

Too much priming sugar can also cause overcarbing and foaming, and if the bottles were at room temp when you opened one, trying popping a few in the refridgerator for a couple of days before trying again to let the CO2 dissolve back into the beer. Then taste, and if its funky, probably a bug. If it tastes fine, probably just overcarbed.

Yeah, sounds overcarbed, if they still foam quite a bit after being in the fridge, take each one and barely pry on the cap to release some C02, and recrimp the cap back with your capper.

I had a batch do exactly like you describe.

They were great for the first month or so after carbing up.

Then, one night, I opened one that kept foaming and foaming. Horribly bitter, astringent taste.

The next one kept foaming, as well... but the beer was good.

Some were bitter, some not, but once they stated getting foamy, they all were that way. It did not get better. Had to dump the batch.

homebrewdad said:

I had a batch do exactly like you describe.

They were great for the first month or so after carbing up.

Then, one night, I opened one that kept foaming and foaming. Horribly bitter, astringent taste.

The next one kept foaming, as well... but the beer was good.

Some were bitter, some not, but once they stated getting foamy, they all were that way. It did not get better. Had to dump the batch.

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Ever found out what caused it?