Very old Extract kit ... turns into a clean but sour beer.

[EagleDude]

I was visiting a buddy in San Diego this last week who brewed an extract batch that he had been holding for quite a long time. As he was brewing, he knew that something was not right during the entire boil. Just didn't look right, wouldn't foam, and never came close to boiling over. He still followed through and bottled the beer which ended up being a really clear beer with a very strong but clean sour flavor. The beer didn't taste bad, just very sour (smell and taste).

Any ideas what caused the sour flavor?

Thanks,

[headcase.brewing]

What type of yeast? It may also be due to some small bug in the wort that had time to regenerate and sour the beer. Good news though that it is still drinkable. I had a wheat beer that I used belgian yeast on and it took a turn for the sour side. I was going to dump it, but ended up ok. It had a high ABV and had a good sour taste.

[EagleDude]

It was a dry yeast ale packett ... he is using plastic so I figured his next beers would turn out sour if it was a bug issue, but they were fine. I am guessing that the malt itself went sour with age and poor storage, but don't know if that is possible. It tasted like a good clean sour beer that was a bit on the watery side. I haven't brewed a sour beer yet, but I would assume that they need to be a bit more malty to help balance the flavour.

Thanks,

[headcase.brewing]

You can sour your beer prior to fermentation. If you are doing all grain you can start a mash and throw a few bugs in it. Let it sit for a few days in a warm place, then taste. Once you get the desired flavor mash out and start your boil. The boil will kill all of the bugs and you will retain the sour flavor. I have not tried this method yet, but will next year during our 110 + F summers

[EagleDude]

It was an extract batch ... so the grains weren't soured but maybe heat soured the liquid and/or dry (used both) malt in a similar manner. Otherwise, maybe it was a wild yeast contamination ... although he has had good batches since, he did clorox the shit out of his equiptment after that batch.

[headcase.brewing]

I had an extract kit go sour, but just let it condition for a little longer. I was about to dump the whole batch, but bottled it anyway. Wouldn't you know my dad drank half the batch. Now I have to make it again.