[Kaiser]

gee Kai,  spoken like an imperial brewing geek

that is one of those topics I tend to chime in all the time since there seems to be so much confusion about it and it is oftentimes uses as a justification for thick mashes. For some reason home brewers are afraid of loosing mouthfeel in their beers.

Kai

[crabber]

Geez, to think I've been brewing 2 1/2 years and never gave mash thickness a second thought. 

[Kaiser]

I just did some digging in the literature on this and this is what I found:

Briggs "Brewing Science and Practice" : At high mash temperatures thicker mashes yield more fermentable worts while at normal mast temps thin mashes yield more fermentable worts

Narziss "Abriss der Bierbrauerei": the wort fermentability of well modified malt mashes shows little sensitivity to mash thickness.

Kunze "Technologie Brauer Maelzer": thicker mashes give more fermentable worts.

If 3 of the most respected brewing authors can't agree on this subject, how should we?

In the end, pick a mash thickness that works for a given beer and adjust the fermentability through the starch conversion rest(s).

Kai

[denny]

We're gonna have to get him a T shirt that says that on it!

[Steverino]

I just did some digging in the literature on this and this is what I found:

Briggs "Brewing Science and Practice" : At high mash temperatures thicker mashes yield more fermentable worts while at normal mast temps thin mashes yield more fermentable worts

Narziss "Abriss der Bierbrauerei": the wort fermentability of well modified malt mashes shows little sensitivity to mash thickness.

Kunze "Technologie Brauer Maelzer": thicker mashes give more fermentable worts.

If 3 of the most respected brewing authors can't agree on this subject, how should we?

In the end, pick a mash thickness that works for a given beer and adjust the fermentability through the starch conversion rest(s).

Kai

I just want to chime in to say thanks for this discussion. I guess I've been under a rock since the millennium, because I've been using 1.25 to 1.5 forever. (And I've got the worn out rotator cuffs to prove it.) I learned the 1.5-per-quart and the thicker-favors-enzyme-activity lore and until tonight, never questioned it. My great thanks to jcsbeer and Kai.

[Kaiser]

You're welcome. That's what we are here for.

I just had to brew a doppelbock at 1.3 qt/lb b/c I have only a 5 gal MLT. That reminded me how much more I like my 2 qt/lb standard mash thickness.

Kai

[stout_fan]

Kai,
I presume this is a 5 gal batch size?
thanx

[Kaiser]

I presume this is a 5 gal batch size?
thanx

Yes, I updated the caption for that chart. But that only matters for the grist weight numbers that are given.

Kai

[mtbrewer]

What a great topic! I have been struggling on this subject for a couple of days now. I am going to make an IPA ,10 gallon batch, using 25.5 pounds of grain. I only have a 10 gallon MLT, I figure using 1.15 Qt. per pound I can fit it in. I have never mashed so thick before and have been wondering if it would have any effect. Thanks for the great info!

[Hydro]

I am looking at expanding my brewing to 26 gallon batches.  This topic in conjunction with John Palmers website:

Appendix D - Building a Mash/Lauter Tun

D.3 Sizing the Tun

 http://www.howtobrew.com/appendices/appendixD-3.html 

have given me the confidence to go ahead and purchase the 120 qt cooler.

http://www.walmart.com/ip/Coleman-Xtreme-120-Quart-Cooler/14574678?findingMethod=rr

I kept second guessing about using such a large Lauter Tun, although I feel better now.

[oscarvan]

Excellent topic! As one who is about to do his inaugural AG batch I have been plowing through the literature and finding some broad ranges of answers on the subject.

So after all this I have come to the following conclusion:

Marginal differences may or may not be achieved by micro managing the ratio, but major losses WILL be incurred with clumping lumping and channeling. When in doubt, go thinner.

This may be over simplified and crude, but as a noob I have to keep it simple. When I reach master status and get bored down the line I'll start using a pipet. 

[bluesman]

Kai...I interperet your runoff chart to show that equal runoffs produce the best efficiency. right?

The other interesting thing I am thinking about is fermentability. I have always understood that the mash temp was the determining factor in fermentability but there are some great minds that believe otherwise as Kai had quoted several posts back. Thicker vs. thinner mashes may also be a factor. I wonder what mechanism can cause this?

From a pratical standpoint, I have been targeting 1.25-1.5qt/lb and equal runoffs between the first runnings and the sparge. Using this practice I have found my efficency to trend upwards.

[Kaiser]

Kai...I interperet your runoff chart to show that equal runoffs produce the best efficiency. right?

Yes, that is correct.

The other interesting thing I am thinking about is fermentability. I have always understood that the mash temp was the determining factor in fermentability but there are some great minds that believe otherwise as Kai had quoted several posts back. Thicker vs. thinner mashes may also be a factor. I wonder what mechanism can cause this?

This should answer this question. Here is the paragraph that matters:

The amylase enzymes are more stable in thicker mashes (Figure . Which is especially important to the more heat liable β-amylase and as a result thicker mashes give more fermentable worts than thinner mashes when mashing at high mashing temperatures [Briggs, 2004]. But while thick mashes offer better protection for the enzymes, they also inhibit the enzymatic activity through the reduced availability of free water and the sugars acting as competitive inhibitors [Briggs, 2004]. In addition to that the gelatinization of starch is also slower and happens at higher temperatures in thick mashes and as a result thinner mashes are known to give more fermentable worts at normal mashing temperatures.

Kai

[gmwren]

Does a large false bottom space in a mash tun affect the grain to water ratio and lauter efficiency? I use a HERMS system, but typically don't start my pump until the mash is well underway - if not complete. I use the old 1.25 qt/lb ratio, but my dead space (1.2 gal) is large enough that my strike temp calculations assume a 1.5 qt/lb ratio.

[tom]

Kai...I interperet your runoff chart to show that equal runoffs produce the best efficiency. right?

But anything between 30-70% batch sparge ratio gives only 1% less efficiency. Not anything to worry abuot.