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Lowering Diacetyl Levels


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Hi guys.

 

As mentioned in a couple of my previous posts, I'm currently brewing my first properly brewed lager.

 

The brew is about to enter it's third week of primary fermentation, & I was wondering what the best time point & best temperature to increase the brew to from it's current 11\xb0C to lower diacetyl levels before bottling.

 

For those unfamiliar with the term, "Diacetyl", it is a buttery/butterscotch like flavour left behind by the yeast after fermentation. In some styles of beer it can be a wanted characteristic, but in a lager it is generally considered an unwanted flavour.

 

Would increasing the FV temperature to an ale brew temperature of say 18\xb0C in the last 2-3 days be advisable?

 

Anthony.

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Im about to put my Helles into a diacetyl rest after lastnights tasting, Im also going to brew a nut brown ale during this time due to the increace in temp.

Its been in primary over 2 weeks now and is nearly finished and has a slight trace in there, remember its not always necissary and certain yeasts wont give of any noticable amounts.

 

I will rest mine for the amount of time it takes to brew the brown ale as there in the same freezer, I will ten transfer it into secondary to get it off the trub and lager it for approx 12 weeks which is the key for a nice clean tasting lager.

 

Good luck and keep us posted

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Hi guys.

 

As mentioned in a couple of my previous posts, I'm currently brewing my first properly brewed lager.

 

The brew is about to enter it's third week of primary fermentation, & I was wondering what the best time point & best temperature to increase the brew to from it's current 11\xb0C to lower diacetyl levels before bottling.

 

For those unfamiliar with the term, "Diacetyl", it is a buttery/butterscotch like flavour left behind by the yeast after fermentation. In some styles of beer it can be a wanted characteristic, but in a lager it is generally considered an unwanted flavour.

 

Would increasing the FV temperature to an ale brew temperature of say 18\xb0C in the last 2-3 days be advisable?

 

Anthony.

 

I'd make it 4 days if I was going to do it, but I stress I'm not a lager expert.

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I'd make it 4 days if I was going to do it, but I stress I'm not a lager expert.

 

You want to be at about 1.020 which is unlikely for a beer at day 4 fermented at 11\xb0c with lager yeast, that being said that grav could vary depending on how big a lager you are brewing

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I'd make it 4 days if I was going to do it, but I stress I'm not a lager expert.

 

You want to be at about 1.020 which is unlikely for a beer at day 4 fermented at 11\xb0c with lager yeast, that being said that grav could vary depending on how big a lager you are brewing

I think Damien meant to conduct the rest for 4 days, not at 4 days.

 

I could be wrong though [unsure]

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Hi Graham & Damien. Thanks for your input.

 

I'd make it 4 days if I was going to do it, but I stress I'm not a lager expert.

 

You want to be at about 1.020 which is unlikely for a beer at day 4 fermented at 11\xb0c with lager yeast, that being said that grav could vary depending on how big a lager you are brewing

Graham, to be fair to Damien, I think he means with 4 days left of primary, not 4 days into primary.

 

The 1.020 is probably about what I should hope for at that junction, but I'll have to take a SG reading with an expected 4-5 days left of primary ferment to see where it's actually at.

 

The lager recipe I put down can be found >> HERE << Post #17.

 

Anthony.

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Generally, secondary fermentation mops up diacetyl. So if you plan to secondary ferment the brew, a diac rest in the FV is not required.

 

Also, have a smell of a sample from the FV - if it doesn't smell like butter/butterscotch, no diac rest required [cool]

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I'd make it 4 days if I was going to do it, but I stress I'm not a lager expert.

 

You want to be at about 1.020 which is unlikely for a beer at day 4 fermented at 11\xb0c with lager yeast, that being said that grav could vary depending on how big a lager you are brewing

I think Damien meant to conduct the rest for 4 days, not at 4 days.

 

I could be wrong though [unsure]

 

What he said. Last 4 days.

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Hi PB2. [happy]

 

Generally, secondary fermentation mops up diacetyl. So if you plan to secondary ferment the brew, a diac rest in the FV is not required.

 

Also, have a smell of a sample from the FV - if it doesn't smell like butter/butterscotch, no diac rest required [cool]

Excuse my "noobness", I was always of the belief that secondary fermentation was purely for carbonation purposes? So there are other things going on besides carbonation? [unsure]

 

Also curious as to why it is that diacetyl levels are pin-pointed & that certain steps should be adhered to when brewing lagers & other lower controlled temp brews if indeed secondary ferment "mops up diacetyl" satisfactorily?

 

I'm finding this a very interesting subject. [cool]

 

Anthony.

 

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Yep, secondary fermentation will clean up diac'. [cool]

 

A diacetyl rest is normal procedure for commercial breweries because the majority of lager produced in the world is force carbonated. So, any diacetyl, hanging around, needs to be mopped up by the yeast prior to lagering.

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Hi PB2.

 

Yep' date=' secondary fermentation will clean up diac'. [cool']

 

A diacetyl rest is normal procedure for commercial breweries because the majority of lager produced in the world is force carbonated. So, any diacetyl, hanging around, needs to be mopped up by the yeast prior to lagering.

So if I'm understanding this correctly, if I was kegging the beer & force carbonating, a diacetyl rest for a lager is a good idea, but due to the fact I am bottling, there is NO need for the diacetyl rest?

 

Anthony.

 

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So if I'm understanding this correctly, if I was kegging the beer & force carbonating, a diacetyl rest for a lager is a good idea, but due to the fact I am bottling, there is NO need for the diacetyl rest?

Anthony.

Hey Anthony

That's the way I'm reading it. In fact my first Lager will definitely be for the bottle and not the keg.

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