Off-flavors After Bottle Conditioning

I'm relatively new to brewing, but I'm at my wits' end with the transformation of my last 4 beers from delicious to bad. This seems to happen after being bottle conditioned past 7 days. When tasting the beer prior to priming, it's fantastic. Same goes for the bottles I test @ 5-6 days. After 7 days, the beer starts picking up this off-flavor. I've even let some condition to 3 months, and still detect the flavor.

The flavor and aroma I detect is cidery (maybe acetaldehyde?), but I'm no expert. I took a bottle of each of the 4 beers to my local homebrew shop, where none of the employees seemed to identify this flavor. Two thought they may have picked up some diacetyl in one of the beers, but not enough to be certain. They were actually complimentary of 3 of the beers. Meanwhile, I can't stand to finish any of them.

I've been priming with cane sugar, and I've been basing the amount of sugar off of John Palmer's priming nomograph. The two suggestions from the homebrew shop were: 1) use corn sugar vs. cane sugar. They said cane sugar can, on occasion, cause cidery flavors. 2) improve the water chemistry. They suspect there may be some phenols from the water I'm using.

Additional info:

• All 4 beers used WLP001, with pitch rate determined by using http://www.yeastcalculator.com/
• Attenuation of the beers has been good - confirmed by hydrometer readings.
• Fermentation temperatures have had some fluctuation between 68-71*, but stay between 69-70* for the most part
• I break down equipment as necessary and clean all equipment thoroughly with PBW and sanitize with StarSan

Would love additional suggestions/input on this. Happy to share more details as needed. Cheers!

 

Thanks for the input, @VikeMan. Will give this a go.

I've been leaving the beer on the primary for ~7 days (depends on gravity readings). On the last beer, the gravity was within 2 points of the estimated FG while in the primary, so I moved to secondary for dry hopping for another 7 days.

 

Thanks for the reply.

I think I do a good job with the bottles, but maybe not. Will soak pre-rinsed bottles in PBW for 45min. Rinse again. Put in tub of StarSan for a few mins, and then put them on a sanitized drying rack just before bottling.

I try to be very careful and detailed with every part of the process, which is what's driving me crazy here. Would love any additional input re: what I may be doing wrong prebottling. Thanks again.

 

One more piece of info -- I'm doing a partial mash for each of these using LME. In my research, I've read that old/stale LME may cause "cidery" flavors. Can anyone speak to whether or not this is true?

I feel like the shop i get the LME from has good turnover, so I'd be surprised if it's stale. But it would be good to know if this is possible. Thanks!

 

Guess it's time to learn all-grain. Thanks again for the input.

 

Will give this a go for sure on the next batch. Cheers!

 

Should I solely rely on hydrometer readings for determining when to move to secondary for dry hopping? Guess I just don't know how else to determine when it's been on the primary for long enough.

 

@RogelioRodriguez:
Yep - buying from the big drums. This may be wishful thinking, but since this is the only hombebrew shop in a large city (Dallas), I'd like to think they go through these quickly. The shop is busy every time I'm in there.

Yeast should be okay -- Was packaged within a week of pitching on the last two occasions (can't recall the former two).

Best way i can describe the taste is like apple cider, but not sour. Smells more like apple cider vinegar maybe? This has driven me to the point of ordering a Sensory Kit from the Siebel institute to taste against... hoping that will help inform me.

 

Just read something from White Labs that supports the consensus here (provided that diacetyl is the culprit):

"It is important to provide sufficient maturation time for diacetyl reduction, commonly known as a "diacetyl rest". Diacetyl reduction is slower at colder temperatures, so it is essential to incorporate the diacetyl rest when making cold fermented lagers. The process is simply to raise the fermentation temperature from lager temperatures (50-55F) to 65-68F for a two day period near the close of the fermentation. Usually the diacetyl rest is begun when the beer is 2 to 5 specific gravity points away from the target terminal gravity. The temperature is then lowered to conditioning temperature following diacetyl reduction. For ale production, the fermentation temperature is usually 65-70F, so temperature modification is not necessary. But the fermentation should still be "rested" at this temperature for two days to ensure proper diacetyl reduction. Many brewers make the mistake to quickly crash the fermentation temperature following terminal gravity. Why not? The beer is done, people are thirsty, and there is no taste of diacetyl in the beer. Even though the diacetyl can't be tasted, however, the beer may contain high levels of the precursor, acetolactate, which can be converted to diacetyl. Once the yeast is removed, there is no way to get rid of the diacetyl."​

Will certainly apply this recommendation on this coming weekend's beer. Thanks again for the input and suggestions, guys.

 

I feel confident that we aren't dealing with contamination, but certainly won't rule it out completely. You did hit on a big point though (and one that should have been obvious to me): Oxidation. I came across this article just a few moments ago: http://www.picobrewery.com/askarchive/acetaldehyde.html.

I had WAY too much headspace in my secondary for each of these, and I'm relatively certain that some of the bottles I've filled were not purged all the way. On top of this, I noticed the autosiphon bubbling periodically during racking - most likely due to a poor seal between the siphon and the vinyl tubing.

I'm sending the bottles to a commercial brewer I met, who offered to give them a taste and share his feedback. Will share his $.02 when I hear back. In the meantime, thanks for all the input!