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Why does protein rest affect saccharification times?

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Shawn Hargreaves

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When I look at the kind of mash schedules people are typically using, I mostly see single infusion mashes at 154 degrees taking around 60 minutes.

But when people include a protein rest, the saccrification step usually goes down to just 45 or even 30 minutes. For instance I see a lot of schedules like:

- 20 min @122
- 45 min @154
- 10 min @168

I'm curious what is the rationale for reducing the time spent at the saccrification temperature? My understanding was that the protein rest doesn't actually involve any sugar conversion, so I'm curious why this affects how long is needed at the higher temperature?
 

Kaiser

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There is starch conversion happening during the protein rest and a wort prepared with a protein rest and then rested at a given sacc temp for a given time will have a higher fermentability than a wort prepared w/o the protein rest but rested at the same sacc temp for the same time. To what extend, I don’t know. This has to do with the amylase activity that you already get at protein rest temps. But that activity is much less than it will be at the sacc rest b/c the starch has not gelatinized yet.

But I never shortened the sacc rest when I did a protein rest.

Kai
 

steelerguy

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I noticed that also and figured it was a combination of two things. The first being the that beta amylase is active at the protein rest temp so you are getting some starch conversion. Secondly, people didn't want to wait all day to do their mash and when you raise the temp to 154 things are happening pretty fast.
 

thebikingengineer

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I'd imagine a lot of the recipes you see like that have a reduced saccarification time just to save time. If you're using fully modified malt you shouldn't need more than about 30 minutes to get full conversion. I've dropped my mash times down into the 20-25 minute range and I'm seeing high 80s for my brewhouse efficiency.
 

Kaiser

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If you would be able to sterilize malt w/o killing the enzymes and then make a mash at room temp and let it stand for a long time, you will end up with a solution of glucose, amino acids and other basic building blocks. All the enzymes will be active but at a much slower rate than they are when higher temperatures are present.

But malt is far from sterile and we need to mash it within less than 12 hrs (I’m guessing here) otherwise it would turn sour. And while we strive for maximum starch conversion we do not strive for converting all starch into fermentable sugars. That’s why we seek to control mashing.

Once you better understand how mashing is controlled by controlling the enzyme life time and their activity you’ll be much more relaxed about over/undershooting temps and temp drops during mashing. To some extend all these things can be compensated for. If for example your mash always looses a few degrees over the mashing time, you can compensate for that by aiming for a slightly higher initial heat.

Kai
 
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