Mash Temp Versus Mash Time

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mew

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I've heard that doing a 90 minute mash improves efficiency, especially for a weak crush, because the enzymes have more time to access starches. But beta amylase will also keep working during that time and make my wort more fermentable.
Say I have a beer I like mashed at 154 for 60 mins. If I want to do a 90 min mash and have the same beer as the 60 min mash, would I up the temperature by a degree? two degrees, maybe? Anyone have experience with this?
 
Why would you want to go 90 minutes if you're looking for the same beer you get at 60?

I have heard of people getting a more fermentable wort out of a 90-minute mash, but not more efficiency. If 90 gives you more efficiency, it means you weren't fully converted at 60.
 
I think there are two situations where a 90 minute mash could possibly improve your efficiency over a 60 minute mash.
1. When mashing at very low temperatures when the alpha amylase is not so active.
2. When you have a poor grain crush, and the enzymes cannot get to the starches to be converted.

As Bike N Brew said, if it does increase efficiency, then it would only be because conversion was not complete at 60 minutes.
According to Papazian, beta amylase will be deactivated within 40 - 60 minutes at 149F, so doing a 90 minute mash at higher temperatures would not have the desired effect.
However, using a thicker mash at a slightly lower temperature could produce the desired results. The thicker mash increases the enzyme concentration, which speeds up the process, and the lower temperature prolongs the beta amylase activity. I mash with 1 qt per lb, and find that mashing at 151 - 152F produces a more dextrinous wort than mashing at 154 - 155F with 1.25 qts per lb.

-a.
 
Why would you want to go 90 minutes if you're looking for the same beer you get at 60?

I have heard of people getting a more fermentable wort out of a 90-minute mash, but not more efficiency. If 90 gives you more efficiency, it means you weren't fully converted at 60.

John Palmer and Jamil have stated that a 90 minute mash will increase efficiency on several podcasts. It is not that the mash is unconverted, but there are little bits of starch left in tiny crevasses in the husks. Even with a 90 minute mash, some of these starches are left unconverted. The longer the mash, the more of the difficult to reach starches are converted.

I think this played a large role in my 60 % efficiency on my last batch, because I switched LHBSs and their mill didn't crush the grains much. I was hoping to improve my mash efficiency on my next batch, though it will still be crushed in the same way.
 
I do 80 Minute Mashes, I have not had any gain in eff. I still get a steady 65% but with the longer mash I get better attenuation.
 
I like to mash at 149 for 75 min. My understanding is that lower mash temps make for a more fermentable wort, but mashing must be longer. Higher mash temps make for a less fermentable wort and can be mashed for less time. Of course your grain to water ratio can create other variables.

Eastside.
 
Isn't it much easier for you to just adjust your crush? or change your water/grain ratio.
 
Along with longer mash times I think that short sparge times are the reason a lot of new brewers don't get all the sugars they have converted from the starches out of the husks. I also have found that a modified fly sparge is the most efficient. I just keep the sparge water 1 to 2 inches above the grain while draining at 1 quart per minute for a 14 gallon preboil volume (12 gallon batch). It takes just under 1 hour to sparge but as BierMuncher says, "It acts like a squeegee to rince all the sugars from the grains". Try it out.
 
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