First lager - german pilsner

I brewed my first lager, a German pilsner from a recipe in my zymurgy magazine. Here is the recipe:

7.1 lb pilsner malt
0.4 lb Vienna malt
0.4 lb wheat malt
1.75 oz hallertauer 60 min
1.65 oz hallertauer 30 min
0.55 oz hallertauer 5 min
2 packages of safale S-23

Brewed on 3/29/15, fermented at 54 degrees. Raised temp to 65 for a diacetyl rest on 4/8/15 for two days. Kegged and lagered for 4 weeks. Before I kegged the sample tasted great. I tapped the keg today and the beer has what I think is a strong diacetyl, butter flavor to it. Why would the it taste fine before lagering and weird now?

zach976 said:

I brewed my first lager, a German pilsner from a recipe in my zymurgy magazine. Here is the recipe:

7.1 lb pilsner malt
0.4 lb Vienna malt
0.4 lb wheat malt
1.75 oz hallertauer 60 min
1.65 oz hallertauer 30 min
0.55 oz hallertauer 5 min
2 packages of safale S-23

Brewed on 3/29/15, fermented at 54 degrees. Raised temp to 65 for a diacetyl rest on 4/8/15 for two days. Kegged and lagered for 4 weeks. Before I kegged the sample tasted great. I tapped the keg today and the beer has what I think is a strong diacetyl, butter flavor to it. Why would the it taste fine before lagering and weird now?

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Diacetyl flavors get worse with time. It's possible that while it tasted "fine" before kegging that the flavor was not as prominent as it is now. Generally, in low amounts diacetyl presents as a "slick" or oily feeling on the tongue or teeth. In larger amounts, it can taste a bit like butter. In huge amounts, it can scream "BUTTERSCOTCH" or even 'buttered popcorn'.

Diacetyl doesn't lessen with time, and actually gets worse with time, so maybe you had a wee bit of diaceytl earlier and didn't pick it up.

The other consideration is that contamination (pediococcus) can cause diacetyl and diacetyl flavors, so it could be in the lines of the keg.

Thanks for the reply. Definitely doesn't taste like butterscotch. Has a smell and little butter flavor to it. I cleaned and sanitized the lines and faucet before I tapped it. Can I get rid of the diacetyl or just drink it as is?

Take it off the gas and bleed off the pressure until it de-gasses.

Then natural carb it with sugar or malt extract in the keg.

I've had the extra burst of yeast clean up beers for me before.

Unfortunately, for your first lager you chose a style that is the worst about revealing any off-flavors and brewing issues. The toughest to get really right.

Magnus314 said:

Take it off the gas and bleed off the pressure until it de-gasses.

Then natural carb it with sugar or malt extract in the keg.

I've had the extra burst of yeast clean up beers for me before.

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How much sugar should I put in the keg?

I ended up putting 3 oz of priming sugar and it's sitting in my laundry room. I guess we'll see in a few weeks if it cleans up.

3 oz is probably good. I was going to say I usually use 2.5 oz or a little less, but use extra for the extra head space... 3 oz would be right on

I had this exact issue with pilsner once. I made a 1 liter starter and pitched it when it was most active. It cleaned that beer right up. If adding the sugar doesn't work I'd give that a shot.

Thanks for the help. It's definitely appreciated.

you probably missed the opportunity for diacytl rest as the beer was likely fully attenuated by the time you raised the temp.

I begin raising the temp a few degrees per day on day 3, and by day 7 generally my lagers are fully attenuated. on day 7 i free rise to room temperature (usually 60-70 degrees (depending on season). i leave it at room temp for another 7 days, then bring it down to 32* for a day or two and package.