Step Mashing and Attenuation

[Natebriscoe]

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.

[Techbrau]

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.

[Weizenberg]

[Techbrau]

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.

[Weizenberg]

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.

[Natebriscoe]

[Natebriscoe]

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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[Weizenberg]

[Natebriscoe]

[Natebriscoe]