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Fermentation smell

so I recently made a 5 gallon all grain brew (Grandma’s Secret Stash) and it calls for adding raising to the end of the boil. I did a little tweaking to the recipe, but nothing major… mostly just adding some molasses, using a slightly more “stout” type of hops, that’s about it. The boil was a little more violent than I wanted, but no scorching seemed to occur. However, I do believe some of the raisins may have made it into the primary fermenter.

That being said, after a few weeks of fermentation, I transferred to the secondary. I made sure any and all raisins did not make it into the secondary. I took my gravity measurements, tasted my gravity sample and it was very good. The smell seemed like a rum raisin flavoring on top of a stout, the taste seemed to agree.

However, after letting it sit in the primary for about 11 days, I was supposed to add some vanilla beans and cinnamon. When I took the top off of my carboy, I noticed a sour smell coming from the beer inside. I took all the precautions I could have in terms of sanitation, so I don’t know where any bacteria could have come from. At first, I thought something could be up in terms of the raisins. They are, in fact, just grapes, and maybe some sort of wine-like fermenting had gone on. Then, I did some research online, and many people seemed to believe fermentation sometimes just smells bad even if the beer is good. I won’t be bottling for another week, and then it is about 2-3 weeks after that before I drink it.

This means I may drive myself crazy waiting for 3-4 weeks, worried that my beer has been contaminated. Like I said, I tried really hard to sanitize everything, and the smell was not present during the transfer from primary to secondary. Does anyone have any thoughts as to why this is happening? Hopefully this isn’t all too unheard of, and maybe you guys can put my mind at ease…

You’re just going to have to worry for a while. Did you sanitize the raisins in some form of drinking alcohol before adding?

Did it taste sour?

I sanitized the raisins in rum for a few days, so yes they should have been fine.

I did not taste it recently. I tasted it while transferring into the secondary and it tasted nice, but that was before the smell popped up. Since I was not moving the beer at all this time, just dry hopping some items, I did not remove any liquid to taste it.

Based on what you’re saying, I’d sanitize a turkey baster or siphon or something and have a taste. Just to put my mind at ease.


Awww yes… sampling is a must! You check gravities through out the fermentation, and send the sacrifice down the gullet … You are also training yer nose!! Sneezles61

I taste everything through out the process even unfermented wort. Some people say it’s wasting but its not really

Ok so I tasted it, using a sanitized “robber”. It didn’t taste sour, tasted super strong in alcohol. Then again my taste buds are a little fried thanks to a cigar. My mind is less worried but not outta the woods. Do super strong beers give off a weird aroma?

I think you gave a good clue in the opening paragraphs… some of the adjuncts that was added would be the culprit… If its a high alcohol brew, it will benefit from a long aging/cellaring period… Let it clear up and bottle it and put it away, thinking, In the next few years you should be able to quaff a few and do keep notes… Winter warmer? Sneezles61

The spec sheet on this beer calls for 1.065 OG. I wouldn’t expect it to have a strong alcohol taste at all. What was your OG and what’s your current gravity? If it has a hot alcohol taste that would be fusels.

It will be higher than normal because I added molasses to the end of the boil, and the raisins probably had some extra sugar on them. Plus, like I said some raisins made it into the primary.

The OG was about 1.08, gravity at the end of primary fermentation was 1.02. So it’s a decently high alcohol content but not crazy. I let it sit in the primary for an extra week, I will also let it sit in the secondary for an extra week. I will try one after the standard bottle conditioning period and then just stagger my tastes from there.

I still do wonder where the smell came from. It will bother me until I get a good tasting one from the batch… I just don’t want this to turn out poorly, my first 5 gallon all grain batch.

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