Possible Off-Flavor?? or Not??

[JSager89]

So I brewed was I was intending to be an Oktoberfest earlier this year. Upon recent drinking of said beer, I discovered a sweetness/tartness (almost like an green apple, but lighter) in it. It is actually still pretty good, which is a plus, but I am still very interested in where the flavor came from, I've done a fair few All-Grain batches and this is the first of them to have a flavor like this. Recipe is as follows:

5.5 lbs Munich Malt
3 lbs Vienna Malt
2.5 German Pilsner

1.5 oz. Hallertauer hops @ 3.9% alpha

Used Wyeast 2206 (Bavarian Lager)

Fermented in my chamber for primary @ 48-50F
Gave a D-rest @ 68F for 3 days
Went back to lager @ 35F

This was all done in late March/Early April so the lagering period should have had plenty of time to mature it.

I am aware that this recipe is NOT a good example for an Oktoberfest (I realized this after brewing....sadness). So my question is: Is the "tartness" or sweet flavor a product of the relitively large amount of Munich Malt I put in? Or is it a true off-flavor?

Any feedback would be great.

Thanks!

 

[daksin]

It looks pretty Oktoberfesty to me, but I don't make them that often. Munich malt does not have any tart quality to it- it's a very bready, malty grain. Anyway, the green apple flavor is likely Acetaldehyde, which is a common off-flavor in lagers. Off flavors will not go away during lagering- the only thing that happens there is some precipitation of proteins and polyphenols to make that clean, crisp quality lagers have. If you detect an off flavor, the d-rest is the time to let it clean up. Don't start lagering until your beer tastes the way it should.

Anyway- how much yeast did you pitch? Everything else about your process looks fine, so I suspect the off flavor came from underpitching.

 

[JSager89]

Anyway- how much yeast did you pitch? Everything else about your process looks fine, so I suspect the off flavor came from underpitching.

You know I'm not sure exactly what my pitch rate was (obviously something I need to branch into paying attention to). I do know that I used a half-gallon yeast starter w/ an OG of ~1.040 and gave 3 days to get going. Would this be under-pitching?

Also, what would some good resources be for a pitching calculator. and also is Acetaldehyde something that cleans up during the rest? I gave a 3 day d-rest so I would have though it would be fine. However, I did transfer to a keg before d-rest, using the fermentation to let the beer self-carb. Would this cause anything?

 

[daksin]

I would use yeastcalc.com or http://www.mrmalty.com/calc/calc.html. If you have a stir plate, that half gallon starter is about right. If you don't have a stir plate, you definitely way underpitched.

Acetaldehyde should be cleaned up in the rest, but if you do your D-rest after all fermentation is done, nothing will happen, you need to have happy, active yeast. Typically you do it when you're 80% of the way to FG.

 

[JSager89]

I would use yeastcalc.com or http://www.mrmalty.com/calc/calc.html. If you have a stir plate, that half gallon starter is about right. If you don't have a stir plate, you definitely way underpitched.

Acetaldehyde should be cleaned up in the rest, but if you do your D-rest after all fermentation is done, nothing will happen, you need to have happy, active yeast. Typically you do it when you're 80% of the way to FG.

I'm gonna go ahead and say I under-pitched then. I definitely don't have a stir plate (looking into correcting that now) and the rest was taken at about 78-80%.

Thanks a ton for the explanation

sum-up....Do not underestimate the power of the under-pitch, that pretty much it?

 

[daksin]

Yea, pitching rate is critical for lagers.

 

[homebrewdad]

OP, according to Designing Great Beers - and to a lot of feedback here on HBT where we discussed Oktoberfest recipes - there's not a thing in the world wrong with your recipe. This style has a TON of room for interpretation, and you used very appropriate ingredients.

But yeah, I agree with daskin - you're pretty much giving a textbook description of acetaldehyde, which almost certainly came about from your underpitch of the yeast. If you brewed the same recipe again, but with an appropriate amount of yeast, you would have been much happier with the result.