# Optimal temperature for low DP mash?

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#### mashdar

##### Supporting Member
HBT Supporter
I'm preparing to mash 4 lbs of MO with a DP of 62L. I'm planning to mash with 1lb flaked oats and 1lb chocolate wheat. This will result in an average DP of ~41L.

This got me thinking: is there much literature on optimal mash conditions for to maximize enzyme activity?

I could see doing a long beta/LD rest, followed by another alpha rest. I imagine it depends on the solubility of starches, too.

Does anyone have any thoughts/experience/backup? I imagine there are some relevant munich-base recipes?

Distillers probably have the most experience in pushing borderline DP (like in the high 30s apparently) to high conversion levels and from what I've read a significant strategy centers on a prolonged sacc' rest at 148°F. I'd start with that plus a solid crush...

Cheers!

Or you could cheat, and throw in a little extra alpha amylase.

Brew on

Found this nugget:
(edit: post by user Lyrebird_Cycles at Aussie Home Brewer)
The thermal decay of each enzyme is given in Muller J Inst Brewing 1991 "The effects of Mashing Temperature and Mash Thickness on Carbohydrate Composition" with the activity being governed by the equation A = Ao e^-kt. The given values of k are 0.0163 for alpha and 0.0434 for beta, both at 65 oC. Use t 1/2 = k/ln(2), we can derive half lives of about 42 minutes and about 16 minutes, again both at 65 oC, which correspond reasonably well with the data in Fig 1 of the paper.
The data in figs 2a to 2d aren't nearly as neat: according to the results given the degradation of beta after 10 min at 75 oC is somehow less than at 65 oC, which is simply not possible.
We can, however, get some useful insight by looking at the changes in activity between temperatures, which shows that the degradation rate of alpha roughly doubles for each 10 oC whilst that of beta roughly triples. Using this to estimate new values of k using the equations
k = 0.0163 * e ^ (0.07* (t-65)) for alpha and k = 0.0434 * e ^ (0.1* (t-65)) for beta and converting this value to a half life as before:
Temperature:....65...70...75...80...85...90
Half life Alpha....42...30...21...15...10...7
Half life Beta.....16...10.....6....3.5...2....1.5

Using piecewise linear approximation and integration, this says that mashing at 68 and allowing to cool to 64 over two hours will give beta activity equivalent to about 24 minutes at 65 degrees.

You could mash just the flaked oats together with the MO. That keeps your grist's average DP higher, at around 50.
Maybe do an Iodine test at the end to verify complete conversion.

Then steep the chocolate wheat by itself in hot water, and add the black potion at the end of the boil.

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You could add the flaked oats to the mash. That keeps your grist's average DP higher

Doesn't flaked oats have 0 DP?

Doesn't flaked oats have 0 DP?
Yeah, but they need to be mashed. The chocolate wheat doesn't.
Average grist DP with the flaked oats, but without the choc wheat:
4 x 62 / 5 = 248 / 5 = ~50 °L

A minimum DP of 35°L is recommended, and may need extra time for full conversion.
A DP of 50 gives some needed leeway.

P.S. Rephrased my original reply, for clarity...

It will just take a bit longer. You can speed it up by slowly ramping the mash temp upwards a couple degrees every 10 minutes after about 45 minutes if you have the ability.

41 Lintner isn't crazy low. I've mashed at about 25 Lintner (coincidentally with Maris Otter base malts and flaked oats in the grist) without problems. Single infusions in the low/mid 150s, 1.5 qts per pound mash thickness. The worts were not highly fermentable, but that was planned and expected. OGs were also what I expected, so no noticeable issues getting full conversion, though it may have been on the hairy edge.

Yeah, I ended up doing a pretty generous double mill & threw it all in at 148F. I was little worried at pH of 5.5 (I guess chocolate wheat doesn't drop it as much as roasted barley?), but by 60 minutes I wasn't seeing any starch with iodine.

Slowly raisng temperature for good measure in case there's still some chunks of starch, but 41L definitely seems to have acted pretty much normally, at least at low mash temps.

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I was little worried at pH of 5.5 (I guess chocolate wheat doesn't drop it as much as roasted barley?)

Wheat doesn't contribute as much acidity as barley. You can pretty much figure this will be the case for any "equivalent" malts, such as White Wheat Malt vs Pilsner Malt, or Chocolate Wheat vs. Chocolate (Barley) Malt.

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