Expert: Matt Dick - 5/14/2009

Question
I had a bit of an issue (clearly). About a week ago one of my bottles exploded. They had only been bottled the week before so it seemed like an awful lot of carbonation/pressure. I looked at some of the other bottles and there was a little ring of foam at the neck as if it was still fermenting. I cracked one and it came gushing out. A second, same result. Third time, a champagne-like explosion. I knew I had a problem. So, thinking I had bottled prematurely I opened each bottle and poured the beer back into the carboy. I made sure the carboy, bottles, and opener were sanitized using a bucket of sanitizing solution and, even with the ridiculous amount of head, was able to salvage just about 4 gallons of the original 5 gallon batch. A week has passed and there is a small sedimentary ring in the carboy. My fear is contamination. Is the ring automatically mean it is contaminated like I think?
Please tell me I am wrong, that the ring could be something else. I have seen really contaminated beer that looked pretty sick but I have only been told of this ring effect. Please help...

Answer
If you truly re-sanitized well, and the yeast got going again in the "tertiary" fermentation then I think you're fine.

The sediment in the carboy doesn't worry me: if the yeast was as active as you indicated, it meant there was excess sugar in solution.  The yeast that was left ate their fill and settled out of the wort--so that ring is likely the remnants of spent yeast and a little bit of grain.  

If you're worried, just taste a small amount of the wort, my guess is that it will taste fine.