Attention lager brewers: No need for a diacetyl rest ever again.....

[Goose]

Assuming you can get your hands on some of this.

Supposedly this works by converting the alpha-acetolactate (AAS) that is produced by yeasts in the normal course of fermentation directly to acetoin by skipping the intermediary step of diacetyl formation.

Normally, this is the purpose of the diacetyl rest which I have learned is not just to get the yeast to absorb the diacetyl and metabolise it to acetoin, but also to first encourage the AAS -> diacetyl conversion.

As mentioned elsewhere, AAS is not detectable by taste but will transform to evil diacetyl in time.. such length of time is dependent on temperature. So just because you cant detect diacetyl post fermentation, it doesnt meant it wont emerge later in lagering by which time the residual yeast have settled and become dormant.

Instead dont bother, just add a few drops of this stuff .. I wonder if comemrcial breweries use it because I have never seen it available anywhere at least not on a hombrew level...


EXALASE is produced by fermentation of a selected strain of Bacillus subtilis and contains alpha-acetolactate decarboxylase activity. In classical lager fermentations without the use of EXALASE, alpha-acetolactate is slowly converted to diacetyl by rising the temperature at the end of main fermentation and diacetyl is reduced by yeast to acetoin during the maturation period. EXALASE can be used to catalyze the decarboxylation of alpha-acetolactate directly to acetoin since the beginning of excretion of alpha-acetolactate by yeast. The maturation period could be eliminated as far as diacetyl is concerned.





TEMPERATURE


The optimal temperature for this enzyme is around 30-40°C and at the normal lager fermentation temperature the enzyme works at 25% of its maximal activity, but as the fermentation is a long process (several days) the enzyme can eliminate all the alpha-acetolactate.






pH EFFECT


Optimum pH between 5.5 and 6. At pH 5 the enzyme works at 50% of its maximal activity, and at pH 4 at 25% . The same remark as for optimal temperature can be made.






DOSAGE


1-2 ml per Hl of beer.






ACTIVITY


2000 ADU/ml. One ADU is the amount of enzyme which under standard conditions produces 1µmol of acetoin by decarboxylation of alpha-acetolactate.






FOOD GRADE


This product complies with FAO/WHO JECFA and FCC recommended specifications for food grade enzymes, supplemented with maximum limits of 5 x 104/g for total viable count and 102/g for moulds; the product is GRAS.






AVAILABILITY


EXALASE is avalaible in liquid form in polyethylene drums of 1-5-25 liters.






STORAGE


EXALASE will maintain the declared activity for at least 6 months when stored at 5°C.

 

[Thefatdoghead]

Isn't it easier and cheaper to just turn the fridge up? Whats the big deal about a D-rest?

 

[Florian]

The 'big deal' is time and certainty I guess.

If I could add that stuff for 50c a batch then I would.

 

[Fatgodzilla]

TEMPERATURE The optimal temperature for this enzyme is around 30-40°C

DOSAGE 1-2 ml per Hl of beer.

EXALASE is avalaible in liquid form in polyethylene drums of 1-5-25 liters.

EXALASE will maintain the declared activity for at least 6 months when stored at 5°C.

Pretty much makes this product pretty bloody useless to home brewers.

That said, it was good information (which I will pretty much forget as I am (almost) exclusively an ale yeast brewer.

Thanks anyway Goose.

 

[Goose]

Pretty much makes this product pretty bloody useless to home brewers.

That said, it was good information (which I will pretty much forget as I am (almost) exclusively an ale yeast brewer.

Thanks anyway Goose.

LOL sorry to waste bandwidth, but maybe inetresting to some.

dosage is 1-2 ml per 100 litres of brew. So yeah 1 litre last you longer than 6 month shelf life indeed.

Isn't it easier and cheaper to just turn the fridge up? Whats the big deal about a D-rest?

Sometimes a d rest dont work.... in my experience anyway. But that precursor remains.

 

[drsmurto]

Can you expand on your comment that 'sometimes a d rest dont work'? Could it be that you are raising the temperature too late and the yeast is already inactive? Yeast health? Yeast generation? Are you adding yeast nutrient?

The other point you may also need to consider is the possibility that diacetyl appearing post fermentation/lagering is a possible sign of an infection. Lagering with too much headspace in the lagering vessel is one of the main causes as the bacteria involved need oxygen. I have had a few beers throw massive amounts of diacetyl after exposure to oxygen. Making sure your lagering vessel has as little headspace in it as possible minimises this potential risk.

Not having a go, just thought I would throw that information in to the discussion (before it turns into the current AHB trend - see the rehydration thread for a perfect example).

 

[Goose]

Not having a go, just thought I would throw that information in to the discussion

LOL is ok, though the original post did seem to piss a few off with the implication of irrelevance, but come and get me baby

Can you expand on your comment that 'sometimes a d rest dont work'? Could it be that you are raising the temperature too late and the yeast is already inactive? Yeast health? Yeast generation? Are you adding yeast nutrient?

Just saying I've had several cases where I have done the d-rest and still had diacetyl form on me post racking. It could well be any of the above reasons. The reason I posted the link onthe enzyme is that if I had some it might solve the problem where for reasons you have mentioned, a diacetyl rest might not.

 

[Droopy]

I'm doing a diacetyl rest right now... Just saying,

 

[manticle]

@droopy - What exactly are you saying?

@goose - interesting idea regardless of availabilty to HB.
I'm mainly an ale brewer but I do a couple of lagers each year. The first this year had large notes of diacetyl and 2-3 pentadione which I reduced with fresh yeast. This one was simply warmed up towards the end of fermentation. Second one I took a lot more care and warmed slowly about 2/3 the way, held, then dropped slowly back. This seemed much more successful although no doubt you've heard of and tried this method.
.Slightly different recipes but same yeast in both (starter for second batch made from the slurry of the first)

 

[Goose]

@goose - interesting idea regardless of availabilty to HB.
I'm mainly an ale brewer but I do a couple of lagers each year. The first this year had large notes of diacetyl and 2-3 pentadione which I reduced with fresh yeast. This one was simply warmed up towards the end of fermentation. Second one I took a lot more care and warmed slowly about 2/3 the way, held, then dropped slowly back. This seemed much more successful although no doubt you've heard of and tried this method.
.Slightly different recipes but same yeast in both (starter for second batch made from the slurry of the first)

G'day Fella. Ignore the troll, look at the post history of smart arse one liners and you will see what I am talking about. ^_^

Yes fresh yeast does also solve the problem, however administering it into the keg requires exposure to air which although minimal I try my darndest to avoid. My transfer from boiler to fermenter to keg is fully closed system so to open to air to pitch fresh yeast is the last thing I want to do, but agreed worth a go and compared to the alternative of binning 40 litres of hard work...

On the temperature control side, I've always waited for fermentation to complete then raise to 18 for the rest because every batch seems to run at a different rate, hard to know when 2/3 is done unless SG is measured religiously by day which maybe I should start doing..

 

[manticle]

Even just a rough idea. Essentially my process was to pitch cold (4ish), rise to about 7, hold for 2-3 days then take a sample. I don't think the 2/3rds thing needs to be precise - it's more about warming slowly while there is plenty of active yeast.

 

[///]

The simplest answer is good yeast management, cost you nothing but a bit of effort.

Definitely the 'get right first' principle i was taught.