Step Mashing and Attenuation

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Natebriscoe
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Step Mashing and Attenuation

Postby Natebriscoe » Thu Jan 05, 2017 2:26 pm

OK, so knowing everyone's system and process are different and no one can say exactly. I am trying to get a baseline for a Hochkurz stepped mash schedule for time vs attenuation. I have done a few batches, but am not getting very close to my target yet.
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Re: Step Mashing and Attenuation

Postby Techbrau » Thu Jan 05, 2017 4:46 pm

I believe that it's quite a complicated issue. Agitation or circulation will massively speed things up and make your mash more consistent. To be honest, with a recirculated Hochkurz mash every single one of my beers in the 11.5-12.5p OG range ends up with an attention limit around 2p, regardless of how long my rests are. 15 minutes at 64c + 30 minutes at 72c will give me the same limit as spending an hour at each temperature.

If you're not recirculating or agitating the mash then rest time may be a more significant variable.
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Weizenberg
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Re: Step Mashing and Attenuation

Postby Weizenberg » Thu Jan 05, 2017 7:52 pm

Those interested should read the dissertation of Dr-Ing F.A. Schüll from the TU-Munich (aka Weihenstephan).

Assuming that one doesn't sabotage one's brew with poor water composition, ingredients or fermentation practices, people have reportedly achieved an EVG/Vsend of 85,5% with the following schedule using this year's malts (source: Oliver Weiss)

  • 15 min bei 61-62°C
  • 20 min bei 64-65°C
  • 25 min bei 66-67°C
  • 10 min bei 68-69°C
  • proceed as usual

Measuring Vsend is also a hairy affair. A specialist gauge in the range of 0-7% would be advisable (some are calibrated at 5 Celsius).

High gelatinisation temperatures make mashing a rather tricky affair if a high attenuation is desired. The schedule above is for malt where the temp is 64,4 (2016 crop).
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Techbrau
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Re: Step Mashing and Attenuation

Postby Techbrau » Thu Jan 05, 2017 11:41 pm

To get a very high attenuation (84-90% apparent), I think the trick is to spend a good amount of time in a temperature range where both alpha and beta amylase are appreciably active at the same time and working in concert. That would be 65-69c. Beta amylase can't work too close to amylopectin branching points, but if alpha is allowed to break the starch into smaller bits, more ends are exposed for beta to convert. A textbook Hochkurz mash only allows beta and alpha to work separately. I typically see 82% EVG as the most often quoted figure in the textbooks for ~12p lagers that were Hochkurz mashed, and that's pretty consistent with my own results. For my own brewing, I'm quite happy if I'm able to consistently get 82%, but then again I mostly brew helles and pils anyway.
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Weizenberg
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Re: Step Mashing and Attenuation

Postby Weizenberg » Sat Jan 07, 2017 3:02 am

The dissertation has a nice graph showing how beta amylase activity declines at temperatures above 62C. That's why stepping the maltose conversion is important.

At 64,4 it's already high enough to give people problems, unless the maltster hasn't already taken some necessary steps.

What's interesting is that a standard double decoction mash is ideal to deal with malts whose gelatinisation temp is unduly high. The paper mentions a year where this temp had effectively been 67C!

On the other hand this begs the question whether a beer with such high attenuation is desirable, but it's good to bear this study in mind as the weather become inscreasingly capricious.
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Natebriscoe
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Re: RE: Re: Step Mashing and Attenuation

Postby Natebriscoe » Sat Jan 07, 2017 10:40 am

Weizenberg wrote:The dissertation has a nice graph showing how beta amylase activity declines at temperatures above 62C. That's why stepping the maltose conversion is important.

At 64,4 it's already high enough to give people problems, unless the maltster hasn't already taken some necessary steps.

What's interesting is that a standard double decoction mash is ideal to deal with malts whose gelatinisation temp is unduly high. The paper mentions a year where this temp had effectively been 67C!

On the other hand this begs the question whether a beer with such high attenuation is desirable, but it's good to bear this study in mind as the weather become inscreasingly capricious.

A higher gravity beer would be the only reason I could think of to up the fermentability. At 12p it seems about perfect.
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Re: Step Mashing and Attenuation

Postby Natebriscoe » Sat Jan 07, 2017 10:47 am

I wonder if my issue is splitting the enzymes between 2 kettles? One kettle at the rest temp one a few degrees lower. I feel like I am messing with the fan levels by the way my fermentations are acting lately, (take off ferment like mad and all but stall at 1.02, but finish slowly)

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Re: RE: Re: Step Mashing and Attenuation

Postby Weizenberg » Sun Jan 08, 2017 6:02 am

Natebriscoe wrote:At 12p it seems about perfect.


What confuses me now is that you started this thread stating that you were "not on your target yet". What did you mean?
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Re: RE: Re: RE: Re: Step Mashing and Attenuation

Postby Natebriscoe » Sun Jan 08, 2017 6:16 am

Weizenberg wrote:
Natebriscoe wrote:At 12p it seems about perfect.


What confuses me now is that you started this thread stating that you were "not on your target yet". What did you mean?

Not my results, everyone else's.
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Re: RE: Re: RE: Re: Step Mashing and Attenuation

Postby Natebriscoe » Sun Jan 08, 2017 6:35 am

Weizenberg wrote:
Natebriscoe wrote:At 12p it seems about perfect.


What confuses me now is that you started this thread stating that you were "not on your target yet". What did you mean?

My fermentations before working on step mashing would take off at a healthy pace and run right to fg. After starting stepping they take off, ferment like crazy (more so than before) and all but stall at 1.02 then slowly drop a few more pts, still finishing high. I am questioning weather my mash tun temp is dropping back down to the 130s and changing my fan levels. I had noticed this behavior in the past, doing an infusion mash with ferulic rest and wheat yeast.

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