Reiterated Mashing Notes

[explosivebeer]

Chris Colby from Brew Your Own magazine wrote an article in the December 2007 issue about his new technique for reiterated mashing. It's a method to get high-gravity beers without excessively boiling down your wort or causing it to turn dark from the caramelization that occurs during a long boil. Basically, you do a primary mash, feed that wort into a fresh set of grains, and repeat if you want an even higher-gravity brew.

Anyway, I recently listened to him talk about his method on a Basic Brewing Podcast with James Spencer. I took some notes and thought I'd post them here as a reference for anyone who was curious about this method.

Reiterated Mashing w/ Chris Colby from BYO with James Spencer/Basic Brewing Podcast


The general idea is that you're using wort as mash liquor and concentrating the wort in mash tun instead of kettle.

3 typical ways to get high gravity (drawbacks in parenthesis)
1) add extract (cost)
2) add a lot of grain to the mash tun and boil down (time to boil, darkens color)
3) add a ton of grain and only take first runnings (bad efficiency)

Reiterative mashing gets a light-colored high-gravity beer, but is not very efficient.

Forming the recipe

Plan on 2-3 mashes with each mash size the same.

Decide on your target pre-boil kettle volume and work backwards.

About 10 lbs of grain for 6 gallons of wort is about right for a typical batch for most homebrewers. So do 10 lbs of grain for each mash and only take 1st runnings.

For a very high gravity brew, think about decreasing caramel and specialty malts since they tend to yield some unfermentable sugars and raise the final gravity. Big beers usually have enough unfermentable sugars.

You could add some flaked maize to keep alcohol level high but gravity lower.

After first mash (~20 minutes), transfer wort to second grain bed. Stir occasionally and give it time. It takes more time to mash with wort than with water. About an hour for wort mashing is right, stirring every 10-15 minutes or so.

Use a refractometer to see the increase in gravity. It should be nearly double after the second batch.

Actually put the grains in the kettle and scoop out after mashing? Pour back into mash tun and filter?

1st mash ~ 150 degrees
2nd mash ~ 140 degrees (with second batch of grains)
(if 2nd is final mash, leave low to get more fermentables; if it's the 2nd of 3, take it back up to 150)

In mashes leading up to the final mash, you don't need to worry about conversion, just dissolving and extracting.

Mash out and do a full recirculation.

A little bit of sparge water is added each time to account for grain absorbtion.

With this method it is possible to get a golden or even a straw color with high gravity.

Two mashes takes about three hours. Three mashes takes about 4.25 hours. (plus boil, cleanup, etc.)

Ultimately it probably takes about the same amount of time as boiling down a high gravity beer.

Make sure you have enough yeast (use a high-gravity full yeast cake if possible).

Aerate well, possibly multiple times.

Think about using yeast nutrients. The maximum amount recommended is the starting point.

Save 10% of wort (unaerated), add fresh yeast, then add to the mostly fermented batch to kick-start it.

Get close to the upper-range of yeast temperature to ensure maximum conversion.

Assuming 65% extraction efficiency and 75% attenuation, you'll end up with 9-10% ABV for 2 mashes, and 13-14% for 3 mashes.

You COULD think about using a champagne yeast towards the end, but it never seems to yield good results and is definitely not recommended. Beer yeast is more geared towards the types of fermentables in wort.

Chris experimented with this process by doing 3-gallon batches. That may be a good option for people who don't have a bigger mash tun or kettle.

The article gives two recipes for big lagers. (I don't actually have the article but someone else may be able to help with that.)

-------------------------------------

Anyway, it sounds like a very interesting process. I did a parti-gyle session last weekend and will probably try this the next time, using all the first runnings for a big, clear beer, and the seconds for another lighter option.

If you want to listen to the podcast, go here and scroll down to November 22nd, 2007: http://www.basicbrewing.com/index.php?page=radio

 

[FlyGuy]

This is an interesting idea that hasn't seen much discussion here at HBT (although it is undergoing considerable debate on other boards). It would be good to generate some discussion here, especially if people like Kaiser can chime in after all his research on the sparging optimization.

Essentially, I think the skeptics argue that sparging with mash runnings shouldn't work -- since your runnings are already laden with dissolved sugars, the efficiency of the mash and subsequent sparge should be really low. Yet Chris Colby reports that his efficiency was unexpectedly high.

I haven't done it yet, but I am going to try a small batch using this method to see how it works. I would be curious to hear if anyone else has had any success (or failure) with the method.

 

[ColoradoXJ13]

Essentially, I think the skeptics argue that sparging with mash runnings shouldn't work -- since your runnings are already laden with dissolved sugars, the efficiency of the mash and subsequent sparge should be really low. Yet Chris Colby reports that his efficiency was unexpectedly high.

I don't think he means sparging with mash running, he is talking about mashing with mash runnings...I listened to that podcast, personally seems like a lot of work and a long brew day...I brewed a 10% belgian golden which is still pretty light, just did a longer boil to reduce volume and added sugars (candi) to raise the SG.

 

[FlyGuy]

I don't think he means sparging with mash running, he is talking about mashing with mash runnings...I listened to that podcast, personally seems like a lot of work and a long brew day...I brewed a 10% belgian golden which is still pretty light, just did a longer boil to reduce volume and added sugars (candi) to raise the SG.

Yes, right. The terminology gets confusing once you infuse a second grist with runnings!

 

[ColoradoXJ13]

I think the confusing thing is that it really is difficult to 'saturate' water with the sugars we brew with, I would need to figure out what the main sugar in mash runnings is, but i would bet that even with very high gravity runnings, you are not even close to maxing out the solubility of these sugars. What you max out with sparges is the equilibrium of sugars that can dissolve vs. what is in the grains still. With this method, you effectively push the equilibrium with each additional mash with new grains towards higher gravity runnings. To me, this seems like a waste of time. People on this board make plenty of beers with OGs in the 1.100 and higher neighborhood, just boil low and slow and you shouldn't carmelize too much of the sugars, and we are talking mostly about the color of the beer, personally, taste is much more important, and my 1.080 belgian golden is what is says, golden and delicious.

 

[Kaiser]

I checked my notes about batch sparging efficiency. If you look at this graph

You see that with a 30lb grain-bill and a 6.5 gal pre-boil volume, your max batch sparging efficiency can be as high as 73% with 2 sparges. Your actual efficiency might be lower though, but definately in the 65 - 70% range assuming a good crush and fully converted mash.

This means that this reiterative mashing doesn't beat the batch sparging efficiency barrier, it may only be a way aound the equipment needs for handling such a large grain bill.

I'll have to listen to the pod-cast though.

Kai

 

[Kaiser]

here is another graph that would illustrate a 2nd approach to the problem:

If you were to take a 30lb grain bill and divide it into 3 mashes. For all these 3 mashes you calculate the water as if you are sparging them twice, then the 1st run-off gravity of you first run-off from a 10lb mash can be almost 1.100. Look at the thin red curve on the far left. Collect the 3 run-offs and you have a preboil volume of 6.5 gal (all these graphs are for 6.5 gal pre-boil) at a gravity of 1.100. If you don't sparge the grains again for another beer you efficiency will be ~60-65% (look at the no-sparge efficiency for 30lb grain in the graph in the previous post).

Kai

 

[Funkenjaeger]

This really makes me think of the 'cascade' system they use to fill scuba tanks.
http://www.divesports.com/cascadesys.htm

I think as ColoradoXJ13 points out, it's pretty hard to truly saturate the runnings, it's more of an equilibrium reached between sugars dissolved and what's left in the grains, and by mashing in with wort (instead of just water) you're starting at a high gravity to begin with so equilibrium will be reached at an even higher gravity with each successive iteration (within reason) - makes sense.

I know this method was described in a book I recently read (probably 'Radical Brewing') as one that was used historically.

 

[ohiobrewtus]

I've been wanting to try this since I read the article in BYO. Maybe once it warms up a bit I'll give it a try.

The novelty of brewing a high gravity low SRM beer is quite intriguing to me.

 

[cheezydemon]

It sounds interesting, but since you take the same time as just going the regular route and boil off more. Doesn't that make more sense and use less grain for the same result?

Of course the second runnings from those grains would still be pretty great.

I recently took my second runnings and fortified it with some DME and hops, and actually ended up with a better brew than my AG.

 

[CBBaron]

There is some complexity in calculating expected efficiency with this system.
First the first mash step should yield you the same efficiency you would get with a normal beer as that is the wort you are producing.
For the second mash the first runnings should be very high after dissolving the additional sugars in the new grain into the already rich wort leaving behind about 1.8 gal (10# * .18gal/#) of rich wort. You then sparge this grain bed with a similar volume of water to make up for the water left in the grains. Which leaves you with 1.8 gals of wort with half the gravity of the first runnings in the grains.
For the third mash you get a similar situation only with an even higher gravity. So the inefficiencies of the system are the combination of the worts left in the 30# of grain.
If you mash 30# at one time you leave about 5.4 gal of wort at the gravity of you last runnings. For a big beer with a 60 min boil you are going to sparge 30# with 3-4 gals so the last running are going to be pretty high G.
For 3 iterations it is going to be 1.8gal at the low final runnings of the first mash + 1.8 gal at the higher final runnings of the second mash + 1.8gal of the even higher final runnings of the third mash.

I think I can use the formulas from Kaiser and estimate a best case efficiency. I'll think about doing that this evening. I'm curious if 1, 2 or 3 mashes is optimum for a 5gal beer with 30# of grain and a 6.5gal starting boil volume.

I have a interest in reiterative mashing because I have a 5gal mashtun and I'm curious if reiterative makes more sense than multiple regular mashes.
Craig

 

[Kaiser]

I think I can use the formulas from Kaiser and estimate a best case efficiency. I'll think about doing that this evening. I'm curious if 1, 2 or 3 mashes is optimum for a 5gal beer with 30# of grain and a 6.5gal starting boil volume.

I think you can go even a step further and calculate how close your actual batch sparges have come to the theoretial maximum and use that number of get an actual efficiency estimate from the theoretical maximum that you get for reiterative mashing.

Another benefit of reiterative mashing might actually be the fact that you can get better fermentability by keeping the last mash really low for a long time. This allows the beta-amylase, that has just been added, to produce lots of maltose. You will then need to step it up to convert the rest of the mash.
Kai

 

[CBBaron]

I think you can go even a step further and calculate how close your actual batch sparges have come to the theoretial maximum and use that number of get an actual efficiency estimate from the theoretical maximum that you get for reiterative mashing.

Good idea I keep that in mind.

Another benefit of reiterative mashing might actually be the fact that you can get better fermentability by keeping the last mash really low for a long time. This allows the beta-amylase, that has just been added, to produce lots of maltose. You will then need to step it up to convert the rest of the mash.
Kai

That assumes you want a more fermentable wort. I like my big beers chewy.
Well maybe not always but it is something to consider.

I also plan on running some calcs with lower volumes for the first mash which fits better with my system (I can't fit 6 gal of mash water and 10# of grain in a 5gal cooler). My gut feeling is that using a lower volume after the first mash will trade off extraction efficiency from the first mash for improved extraction (greater sparge volume) for the second mash, resulting in slightly better results because the wort gravity is higher in the second mash.
Then of course I'm going to have to experiment to show that my numbers match reality.

Craig

 

[explosivebeer]

I'm glad people seem to find this concept as interesting as I did. I'm definitely curious to see how it turns out, or hear other peoples' experiences with it.

 

[Kaiser]

I checked my notes about batch sparging efficiency. If you look at this graph

I updated this graph to make the lines stop when the water/grist ratio is less than 1 qt/lb which makes for an unrealistic sparging scenario. Given this information, only a no-sparge is realistic for a 30 lb grist and there you will get 62% max efficiency.

Kai