Extended mash times

Has anyone experimented with mash times in excess of 60 minutes? I've read some material indicating a slightly increased efficiency numbers with 90 minute mashes. Any thought?

How about - it depends.

If you have 100% conversion at 60 minutes, you can't get any increase in efficiency.


If you are less than 100% conversion, then you'll continue to convert as long as you hold the temp. The crush at my local homebrew shop hits the low 90's in 60 minutes and will be 99% at 90.

I usually do a 75 or 90 minute mash on beers that I either want to finish really dry or where I am using a less attenuative yeast. I am not sure how much it affects efficiency, but it does seem to help lower my final gravity.

billl said:

How about - it depends.

If you have 100% conversion at 60 minutes, you can't get any increase in efficiency.


If you are less than 100% conversion, then you'll continue to convert as long as you hold the temp. The crush at my local homebrew shop hits the low 90's in 60 minutes and will be 99% at 90.

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99% efficiency? That is amazing if it is true.

I am new to all grain (I've got 2 batches under my belt). My efficiency is in the 65-70% range. I'd like it to be more like 75-80%. I think the screen I use in my mash tun may be at least part of the problem. I've seen different recipes call for 60 min mashes and others 90 minutes. I guess I wasn't sure what the pros/cons were.

Effiency is potential SG vs what's in your fermenter. Conversion can be 100% (I don't know that it is) and you still have sparge and equipment losses to lower efficiency.

I biab and use a longer mash time (90 m) to ensure the amylase(s) have time to chew the carbs in the dilute environment of full volume biab.

"99% efficiency? That is amazing if it is true."

Just to clarify, that is 99% conversion efficiency. Anyone with a good crush is getting 99% efficiency in under 60 minutes. Anyone with a mediocre crush generally isn't. That is why people report such large brewhouse efficiency jumps when they start milling finer. If you only start out with 90% conversion, that would change an 80% brewhouse down to a 70%.

In terms of fermentability, that is highly temp dependant. If you are mashing in a temp where Beta is working well (under 152), that will continue to break down the larger sugars as well as the starch. If you are at a much higher temp, Beta slows way down and alpha dominates. A long rest at alpha temps won't necessarily produce a much more fermentable wort.

The diastatic power of your intended base malt, other fermentables in the grist, and targeted mash temp(s) also comes into play here. I suggest reading up on this more if you want to improve efficiency (in select cases) with an extended mash time.

http://byo.com/all-grain-brewing/item/1497-the-science-of-step-mashing

I mash longer than 60 minutes because it makes my brew day easier. After dinner I heat my strike water and mash in, usually by 7:00. Then I get the kids ready for bed and read books with them. By the time I get back to the garage it's usually 8-8:15. But it means I'll be boiling by 9 and done by 10:30 instead of midnight

This isn't an issue of efficiency- 90% of homebrewers are getting full conversion, and most of those in teh first 20m of the mash. Mashing for longer will give you a more fermentable wort as the amylases continue to work on the already converted sugars in the mash, breaking them down into smaller and more easily fermentable sugars.

daksin said:

Mashing for longer will give you a more fermentable wort as the amylases continue to work on the already converted sugars in the mash, breaking them down into smaller and more easily fermentable sugars.

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this^^^^

"this isn't an issue of efficiency- 90% of homebrewers are getting full conversion, and most of those in teh first 20m of the mash. Mashing for longer will give you a more fermentable wort as the amylases continue to work on the already converted sugars in the mash, breaking them down into smaller and more easily fermentable sugars."

This is most definitely NOT true. 90% of homebrewers who mill their own grain might be getting full conversion in 60 minutes. Everyone who is relying on the big online shops or LHBS? Tossup. At 20 minutes with an average LHBS mill? Not likely. I've tested several shops and was around 70% at 20 minutes and 150 degrees. Conversion time and efficiency are incredibly dependant on the quality of the crush.

billl said:

"this isn't an issue of efficiency- 90% of homebrewers are getting full conversion, and most of those in teh first 20m of the mash. Mashing for longer will give you a more fermentable wort as the amylases continue to work on the already converted sugars in the mash, breaking them down into smaller and more easily fermentable sugars."

This is most definitely NOT true. 90% of homebrewers who mill their own grain might be getting full conversion in 60 minutes. Everyone who is relying on the big online shops or LHBS? Tossup. At 20 minutes with an average LHBS mill? Not likely. I've tested several shops and was around 70% at 20 minutes and 150 degrees. Conversion time and efficiency are incredibly dependant on the quality of the crush.

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I've never owned a mill and buy from multiple shops and online retailers- I've tested for conversion frequently and have always been totally converted at the 20m mark. Lower mash temps are an exception, but at the 152-160 range, conversion happens quickly if you've thoroughly stirred up your mash.

How are you testing for conversion? Iodine? What formula are you using to show you are at 100% conversion?

And big picture, how do you explain the tons and tons of posters who report a significant jump in efficiency when they improve their crush? If they were already getting 100% conversion from the LHBS crush, they should see zero increase, right?

daksin said:

This isn't an issue of efficiency- 90% of homebrewers are getting full conversion, and most of those in teh first 20m of the mash. Mashing for longer will give you a more fermentable wort as the amylases continue to work on the already converted sugars in the mash, breaking them down into smaller and more easily fermentable sugars.

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So I assume you're an advocate of longer mash times. Are you typically mashing for 90 minutes, then?

JBeuchs said:

So I assume you're an advocate of longer mash times. Are you typically mashing for 90 minutes, then?

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I personally am, in the event that you want a very very fermentable wort. My best results have been at ~153F for 90-120 minutes for super super dry beers, but only when that's what I'm going for.

I started doing a 90 minute mash when I started mashing at < 150F. I found that I was not getting complete conversion at 60 minutes (via an iodine test).
Nowadays, I always mash for 90 minutes as it takes me nearly that long to heat my sparge water.

-a.