I know there is a substantial amount of debate regarding whether to use DME or corn sugar or table sugar to bottle prime, but I wanted to ask the question if priming with simple glucose, can perceivable off-flavors be introduced?

I tasted a bit of an IPA I made prior to priming, and i was a clean, neutral, hop-forward with some malt flavor. Then I bottle-primed and noticed something very similar to other beers I have made. Its almost a cidery/green apple flavor that other people can't necessarily notice but is unmistakeable to me, and was NOT present prior to me bottling.

The only other possibility is, I will often (and did in this case), add my dissolved sugar syrup to the bottlin bucket AFTER I rack the entire batch to my bottling bucket. I pour the sugar solution VERY slowly down the side of the bottling bucket to minimize oxidation (but maybe still get some?). I do this because all of my fermenters/secondaries aren't marked for volume, and I want to be precise in calculating the weight of the priming sugar. I know that oxidation typically tastes like cardboard though, and not acetaldehyde.

The firkin specialist at a local brewery told me to NEVER prime with corn sugar, and always prime with DME. He says the former "just gives it that homebrew flavor". However, I've heard that DME can be incredibly imprecise when used for priming.

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    Interesting question. A cask ale specialist I spoke with said something similar, that he only uses fresh krausen to prime his kegs (I think that's called gyleing). The cidery flavors could well be coming from the sugars, but it'd be hard to prove. – JoeFish Mar 7 '12 at 20:56
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    I think this one is two broad for the SE format. There is no question being asked, and the first line states "looking for opinions". Should be a wiki or closed all together if not edited to an answerable question. – brewchez Mar 8 '12 at 3:13

I do believe you when you say it tastes different, but... I'm sure you know it's not a good idea to draw conclusions based on one occurrence! - It could be the sugar, or the process, or something else.

If the beer has been in the bottle less than a week then it could be actelaldehyde from fermentation, so you can simply leave it and that will be metabolized by the yeast when the sugars are done, if the temperature is still appropriate for the yeast strain. Although note that "old" yeast have a harder time absorbing it - it gets stuck in the cell, so that at the end of fermentation inside:outside concentration is 10:1. That's why pitching fresh fermenting yeast can clean up the aldehyde much better.

You mention oxidization, but didn't think it's that because of the taste. Acetalaldehyde, aka ethanal, is oxidized ethanol, so if you did oxidize the beer, or at least, the alcohol in the beer, then that's a possible outcome.

If you wanted to be more certain it was the corn sugar, next time, bottle half the batch with corn sugar, and the other half with DME and see if there is a difference then. Ideally, do this over several brews, and see if a pattern emerges, while also trying to ensure the process is as equivalent as possible.

On a theoretical level, it's hard to see there would be a difference. The metabolic pathway for yeast fermenting maltose has only one extra step compared with fermenting glucose/corn sugar - the application of the maltase enzyme to hydrolize the disaccaride into two glucose units. Apart from that, the rest of the pathway (glycosis) is the same.

It could be that after a big ferment, the yeast were unable to absorb the acetaldehyde produced by the priming sugar, something that could happen regardless of what type of priming sugar you use.


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    I don't understand this site sometimes. When is there ever a DEFINITIVE answer in homebrewing? Unless you want the site to be limited to "should I sanitize my fermenters", there are going to be open-ended and sometimes outright rhetorical questions. I understand that it is not supposed to be discusson forum, but aren't we splitting heirs here? Is there not room on the server? Mosher, Daniels, and Jamil get on podcasts regularly and debate whether secondaries make any sense. Upvoted and accepted MDMA's excellent answer, which is what I was looking for. – Pietro Mar 8 '12 at 14:40
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    Yes, it seems harsh as there are many other questions that are useful even if there is no definitive answer. Maybe you would have had more success if you phrased the question,"What causes off flavors when priming with corn sugar?" At least then there is a question. While the rationale for closing this question can be contested (as I do), I do agree that it's important to have a clear question, even if, as in this case, it's easy to imply what question is being asked. – mdma Mar 8 '12 at 17:19
  • For these reasons I am growing more to dislike this format. You can have these types of discussions on a traditional forum site. – brewchez Mar 11 '12 at 0:26
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    not to be pedantic, but I don't think the problem is with the format itself, but with the way its managed. In this case, the poster should be given a chance to edit the question, change it to add focus, remove the request for opinions and actually ask a question. Then the question should be fit to be reopened. – mdma Mar 11 '12 at 6:24

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