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Bacterial DMS source? [Maybe gas equipment? Solved?]

[Solved? Originally I was thinking “old ingredients”. Now, seems more likely bad cleaning & sanitation… see post at end]

[color=#C0C0C0]I’m trying to deduce the origin of a “vegetable” off-flavor in a beer I produced. Sanitation is possible, but unlikely. Boiled with the lid off, of course. Yeast was pitched in accordance with numbers recommended by YeastCalc.com / MrMalty. And fermentation temperatures were kept cool & controlled to the nearest 0.5 degrees F using a thermowell. So, process-related off-flavors are unlikely, IMHO.

This leads me to the note on “aged, stale, or old ingredients” on the “Vegetable” off-flavor list from BJCP: http://www.bjcp.org/docs/Beer_faults.pdf

As of the date of this post, almost all of my specialty grains were purchased over 6 months ago, and it’s very likely that some were purchased over 18 months ago. The likelihood that I used grains that old for the beer in question is possible, though not more than 5-10% of the total grist. I store all my specialty grains in ziplock bags inside another large (but not airtight) container. They’re stored in the garage in the winter (and so are practically refrigerated), and stored inside in the summer (and so are always <80 F, usually <74 F).

Some of my hops may have been purchased as long as 18 months ago, though most are likely in the 6-12 month range. Some of my hops are partial bags, having been re-sealed using a vacuum sealer (though occasionally the hop bag material is too stiff to actually suck out the air before the bag is re-sealed). All of my hops are stored in the freezer and always the freezer, except on brew day.

So, when talking about “old ingredients” contributing to off flavors, how “old” are we talking about? None of the my ingredients, hops or grains, are likely to have been purchased more than 36 months ago. I’m looking to brew again soon, and I’d really hate to have an off flavor in this new batch due to old ingredients.

Cheers.[/color]

Not saying it can’t be the grain, but I usually associate veg. offlavors with hops. Sometimes water.

I do sometimes use grain that is in the age range you are describing - and in large quantity. Not saying it has no impact, but I’ve never picked out any major flaws like that.

I know older grain is not ideal, but in my experience it has not lead to noticable off flavors.

[quote=“Brew Meister Smith”]Not saying it can’t be the grain, but I usually associate veg. offlavors with hops. Sometimes water.

I do sometimes use grain that is in the age range you are describing - and in large quantity. Not saying it has no impact, but I’ve never picked out any major flaws like that.

I know older grain is not ideal, but in my experience it has not lead to noticable off flavors.[/quote]

Good point, I’ll edit the OP to be more generic.

On that point, I also have hops that have been stored in the freezer for about year. Always in the freezer, though.

Oxidation can lead to a “vegetable” taste. Is this a possibility?

Other than that things are pointing more towards the hops. Thy can easily give off these flavors if improperly stored.

My vote is it’s either from:

A) Old, perhaps freezer burned, hops, or

B) Your boil wasn’t vigorous enough so you got some DMS in there. Do you have a nice simmering boil, or is the wort practically leaping out of the kettle? In my experience, the latter type boil produces superior beer.

[quote=“Silentknyght”][quote=“Brew Meister Smith”]Not saying it can’t be the grain, but I usually associate veg. offlavors with hops. Sometimes water.

I do sometimes use grain that is in the age range you are describing - and in large quantity. Not saying it has no impact, but I’ve never picked out any major flaws like that.

I know older grain is not ideal, but in my experience it has not lead to noticable off flavors.[/quote]

Good point, I’ll edit the OP to be more generic.

On that point, I also have hops that have been stored in the freezer for about year. Always in the freezer, though.[/quote]

Why change the OP? Muddling the issue IMO.

I’ve had grain in my possession for 2 years. Add to that, the grain was harvested the year before. Possibly the year before that to include the maltster.

At a minimum your grain is close to 1yr old when you get it.

Been thinking a lot about this, and aside from a one-off situation, the only thing that could be the cause oxidation is the extended aging in the carboy. I’d never before aged a beer for 3+ months in secondary. I suppose the CO2 could have become disrupted and left the carboy when I used a thief to collect beer for checking gravity. I’ve got a barleywine aging in a carboy right now; when I keg it in october, I can sample it for the vegetable off-flavor. It had none when I transferred it from primary to secondary…

There could be some “freshness” flavor lost in older grain. But with out seeing the label on the bag of grain, you have no idea when it was harvested/malted.

If you plan to transfer these beers to kegs, do it now. Then you know they will not be in contact with oxygen.

I don’t have an educated comment on the hops.

I have grains over a year old and sometimes pellet hops as old.
I don’t think its a hop issues more like oxidation.
Just my $.02 cents.

There is not a lot of info to go on but, I would say more of a process issue, dms, or oxidation.

You can use your old stuff and go buy new stuff and do a side by side if you think that it the case.

[quote=“Loopie Beer”]Oxidation can lead to a “vegetable” taste. Is this a possibility?

Other than that things are pointing more towards the hops. Thy can easily give off these flavors if improperly stored.[/quote]

Quite a few years ago when amarillo hops first hit the market they were hard to find and I bought a large (for me) amount. This was before I had a vacuum sealer. I very carefully packaged them in two ounce bundles and the last bundle was used five years later and made a good pale ale.

I have not peesonally experienced vegetal flavors from old ingredients. I have stored frozen, properly sealed (vacuum sealed) hops for more than two years with no issue. Sometimes I feel that a high percentage of low alpha acid hops can contribute to some vegetal flavor…like bittering with low AA hops. I also feel that dry hopping can taste somewhat grassy or vegetal soon after dry hopping is done. It also depends on the variety used though.

I don’t see the “old” grain being the issue unless perhaps they are noticeably stale. I am not sure staleness would contribute to a vegetal flavor though.

How long is your boil?

[quote=“roffenburger”]
How long is your boil?[/quote]

For the beer in question, a RIS, it was a 60 minute boil. I think I used 2 oz of Admiral as the bittering addition.

[quote=“Silentknyght”][quote=“roffenburger”]
How long is your boil?[/quote]

For the beer in question, a RIS, it was a 60 minute boil. I think I used 2 oz of Admiral as the bittering addition.[/quote]

you see issues on normal gravity beers?
How did the issue come about?

[quote=“grainbelt”][quote=“Silentknyght”][quote=“roffenburger”]
How long is your boil?[/quote]

For the beer in question, a RIS, it was a 60 minute boil. I think I used 2 oz of Admiral as the bittering addition.[/quote]

you see issues on normal gravity beers?
How did the issue come about?[/quote]

Honestly, I don’t think I’ve ever had this issue before. My best current thought is some contamination in a gas line, liquid line, or a keg.

Honestly, I don’t think I’ve ever had this issue before. My best current thought is some contamination in a gas line, liquid line, or a keg.[/quote][/quote]

I doubt that, but that isnt what I asked

[quote=“grainbelt”]
I doubt that, but that isnt what I asked[/quote]

I answered it indirectly; you asked:

[quote]you see issues on normal gravity beers?
How did the issue come about?[/quote]

assume by “issues”, you meant the vegetable off-flavor discussed in this thread. I’ve never seen it before. For clarity:

No, I haven’t seen this issue on normal gravity beers; I’ve never experienced it before.

I speculate that it (the vegetable off flavor) came from the keg, or related equipment; but, I’m really guessing and don’t really know how it came about, as I’ve never experienced it before.

Apologies.

[quote=“Silentknyght”][quote=“grainbelt”]
I doubt that, but that isnt what I asked[/quote]

I answered it indirectly; you asked:

[quote]you see issues on normal gravity beers?
How did the issue come about?[/quote]

assume by “issues”, you meant the vegetable off-flavor discussed in this thread. I’ve never seen it before. For clarity:

No, I haven’t seen this issue on normal gravity beers; I’ve never experienced it before.

I speculate that it (the vegetable off flavor) came from the keg, or related equipment; but, I’m really guessing and don’t really know how it came about, as I’ve never experienced it before.

Apologies.[/quote]

Just sounds like someone told you it was an off flavor from you initial post.
Sounds like a process issue and could be many different things , not contaminated equipment.

Hard to imagine the flavor is caused by old grain. If stored so that moisture can’t get at it, grain will stay good almost indefinitely. Five years is definitely not a problem. If exposed to moisture, the off flavor would be “stale” not “vegetable”. And by the way, staling can happen very fast.

Hops are a possible source, but if the vegetable flavor comes from the hops it is likely not because they are old, but rather they are a bad batch. Hop flavor fades with time, but unless there was a strong vegetable component already present which was being masked by other stronger flavors when fresh, I doubt it would suddenly develop that way.

I second the suggestion for process. Perhaps the propane tank was low and the boil vigor wasn’t what you thought it was for some significant portion of the boil?

[quote=“rebuiltcellars”]
I second the suggestion for process. Perhaps the propane tank was low and the boil vigor wasn’t what you thought it was for some significant portion of the boil?[/quote]

That’s not what I remember, but it’s entirely possible. It was late November in Minnesota, and we had a bunch of people over for pre-Thanksgiving festivities, so it’s entirely physically possible that the boil was weak and I was distracted enough then not to remember it properly now…

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