Beer changing over time...in a not so tasty way!

I recently entered my very tasty American Red Ale in a competition.
When I got the judging results, they said it had vegetal overtones and some DMS. I was really surprised, because I thought this was one of my best beers ever, but upon tasting the 2 bottles that I had left, they DID have vegetal/DMS overtones and tasted rather flat (in terms of flavor, not carb)! What happened? This beer was brewed back in Nov, aged out and bottled in early January, and kept in my pantry at around 16-18C. It has good carbonation and awesome head retention, and there were never any signs of microbial contamination (I'm going to look at the sludge under the microscope next week to be sure). It still tasted great in mid-March when I sent it off to the comp, and the competition judging started April 24, at which point it must have been off. Is this just a case of holding on to a beer a bit too long? Autolysis? Contamination? It definitely had a full wort boil and was chilled quickly with an immersion chiller, so I don't think it's a case of brewhouse practice-related DMS. Any other thoughts are greatly appreciated!
Cheers.

Can you post your ingredients and process?
OG
FG

Sure..

12.3 lbs Simpson's golden promise malt (base)
3/4 lbs. melanoidin malt
1/4 lbs. black patent malt
0.6 lbs. flaked barley

1 oz amarillo @ 60 min
1 oz cascade @ 3 min

Mashed for 1 hour at 152 F
sparged at around 165 F
Boiled 1 hour
cooled with immersion wort chiller

OG 1.046
FG 1.010

Fermented with wyeast 1099 (Whitbread) at about 68F. Pitched 1L starter.

Need anything else??
thanks.

Well for review sake, lets look at the flavors and confirm that it truely is what you are tasting and if any of the pat suggestions uncoveranything.

DMS
Cooked Corn/Cabbage per the bjcp.

Use a long, rolling, open boil. Reduce amount of pilsner malt. Cool quickly before pitching yeast. Check for infection. Make sure you use a healthy, vigorous yeast starter.​

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Vegetal Off flavors per the bjcp.

Encourage a fast, vigorous fermentation (use a healthy, active starter to reduce lag time; this is often due to bacterial contamination of wort before yeast becomes established). Check sanitation. Check for aged, stale, or old ingredients (especially old liquid malt extract). Avoid oversparging at low temperatures.​

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I don't know of any reason why Golden promise would kick off any more or less DMS then MO so I can't say that the 60 minute boil is the problem. I have no reson to suspect the Whitbread yeast.

I can only guess that if it was truly DMS, then was the bacterial type that may have taken a long time to develop in the bottle givenb the low cellaring temps.

I'll add the the OG and FG put this at the very low end of the 10b American Amber category. ~4.5% is not an ABV that is known for it's aging capacity.

My guess would be some pediococcus contamination. Pedio does well with <6% abv after about 4-6 months of age which is where you are now, especially in a bottle conditioned beer. The bacteria feed on the nutrients released by autolysed saccharomyces.

I've noticed that fresh beers are better for comps.

I made an Irish Red from Zymurgy's recipe recently and also ended up with something with vegetable broth tones - really is pretty awful stuff. In reading this thread it appears I may have failed by foregoing a starter. I just tossed the tube of white labs 004 into the fermenter after I aerated. Fermentation started within 24 hours. Anyway, lesson learned.

So today I peeked at the Red Ale dregs under the microscope (1000x) and there was definitely bacterial contamination--small cocci in singles and pairs, so likely Pediococcus, especially since everything else fits (4-5 months, below 6% ABV, DMS/vegetal).
Nice work, Saccharomyces!!!
I think from now on, I'm going to refresh my StarSan a little more religiously!!

how frequently were you refreshing it before? If I brew two weeks in a row, I'll use a 5 gallon bucket for two weeks and then mix a fresh batch after that. I don't use RO/distilled water when I make it, so it clouds up once it cools

Ok, just read a little more.. looks like I'm getting lucky if it's not infected using the cloudy version. Granted it's not totally clear, but it's not milky either. I think I'll use RO water from now on.

yeah, I was using it with my water when it was quite cloudy...even though the pH was good, I'm not sure it was the best idea. I'm also going to leave my bottles in for 1-2 minutes versus wet for 30 secs.

brewgrl said:

yeah, I was using it with my water when it was quite cloudy...even though the pH was good, I'm not sure it was the best idea. I'm also going to leave my bottles in for 1-2 minutes versus wet for 30 secs.

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I believe the starsan bottle says contact time is 1 minute.
okay, nevermind I looked at the tech sheet.. it says contact time is 1-2 minutes or for parts soak for 30 seconds and put on wet. (whatever that means).