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-   -   Very strange fermentation (http://www.homebrewtalk.com/f163/very-strange-fermentation-212005/)

BenS 12-15-2010 11:41 PM

Very strange fermentation
 
I brewed up a hefeweizen a couple weeks ago and fermented at 62F. I made a 1L yeast starter but the yeast was old from my LHBS, like 9 months old. Because of this, it took over a day for fermentation to take off. This is the first time it's ever taken that long for me to see active fermentation using a starter. 10 days later fermentation seemed to subside, so I racked to my bottling bucket and prepared to bottle. I drained a sample to test gravity and have a taste. The gravity was at 1.020 (guess I racked to early), then I tasted it. This is what really got me going, the mouthfeel was slick like vegetable oil, disgusting really. The taste and aroma were right on but it was undrinkable because of the mouthfeel. I poured the sample down the drain and it was so viscous, it even poured like oil. This was not a slick on the top of the beer as i've seen sometimes, it was the entire volume of liquid. It's been sitting in the bottling bucket for a few days and the gravity is down to 1.010 now but it still has the oily mouthfeel.
The only thing that I can think this came from is my pot. I use a turkey fryer to brew and like many people, decided to fry a turkey for thanksgiving. Knowing that I use the same pot for brewing, I scrubbed and scoured that pot with dishsoap (surfactant) after the oil from the turkey was removed and left it over night with bleach water sitting in it. The next day (brew day) there were no signs of oil floating on the surface of the water so I figured I was good to go.
I the brew day went fine, transfered to fermenter and pulled a sample to test gravity and taste. The wort tasted perfectly fine and the sample was at room temp so it should have been just as viscous then as it is now.
In conclusion, I don't know what the f*ck happened to my hefeweizen. Anybody have any ideas?

BenS 12-15-2010 11:43 PM

Recipe was simple. 6 lbs wheat malt, 3 lbs 2row, wyeast hefeweizen, and .5 oz mt. hood @60min.

Yooper 12-15-2010 11:48 PM

Sounds like a big dose of diacetyl. In bigger amounts, it's said to taste like butter or butterscotch or even butter popcorn. In smaller amounts, it's more like a slickness or oiliness on the tongue or in the mouthfeel.

A couple of things cause excessive diacetyl- stressed yeast, inadequate time in the primary, and pedio infection. It wouldn't be present going in the fermenter until after fermentation, as it's a byproduct of the yeast (or again, from infection).

Because the SG was 1.020, I'm leaning toward the "racked too early" theory. What happens with yeast is that diacetyl is created as a by-product of fermentation. After the fermentable sugars are gone, the yeast will go back and start to digest other foodstuffs, including their own waste products like diactetyl. Racking too early halted this part of the process, and the result is diacetyl left in the finished beer.

hoppymonkey 12-15-2010 11:50 PM

Don't have a clue. Just posting so I can follow this craziness.

BenS 12-16-2010 12:01 PM

Yooper, thanks for the feedback. I also considered diacetyl but had never heard of it being produced in such large amounts that it actually changed the viscosity of the liquid. I rubbed a small amount between my fingers the other day while taking a sample and it had the consistency of olive oil.

Brewham 12-16-2010 12:16 PM

I'll bet the turkey oil was absorbed into the metal of the pot and released when it was heated again. No amount of scrubbing could get the oil out of the metal matrix. I'm no chemist but I do know cookware can be seasoned with oil and not appear to be slick or greasy. The most volatile components of the oil evaporated so there is no slick on the wort surface but the heavier molecules stayed behind to leave the oily taste and feel. It wouldn't take much. That and a some diacetyl from the old yeast could be the issue.

kanzimonson 12-16-2010 01:21 PM

If it's animal fat, then it would pool at the top, and if refrigerated it would solidify.

motobrewer 12-16-2010 01:31 PM

Quote:

Originally Posted by Brewham (Post 2480684)
I'll bet the turkey oil was absorbed into the metal of the pot and released when it was heated again. No amount of scrubbing could get the oil out of the metal matrix.

uh, what!?

BenS 12-17-2010 03:47 AM

Quote:

I'll bet the turkey oil was absorbed into the metal of the pot and released when it was heated again. No amount of scrubbing could get the oil out of the metal matrix.
While I have to agree that there might have been some oil still in the pot, I would have to see some sort of literature saying that fat molecules "soak" into metal. I do appreciate the feedback, and you could be right, it just seems a little far fetched.

Hermit 12-17-2010 01:31 PM

Quote:

Originally Posted by hoppymonkey (Post 2479837)
Don't have a clue. Just posting so I can follow this craziness.

You don't have to post a comment to a thread to subscribe. Simply go up to "thread tools" and subscribe. Not too many folks on this forum seem to know this.


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