Sunday, December 11, 2011

Making (Diastatic) Brown Malt

It is nearly impossible to mention London Porter in any conversation about historical brewing and not say a thing or two about brown malt. They are, after all, practically one in the same. For the beer that revolutionized the brewing world and set the stage for the industrial revolution, was truly born of brown malt (to ti esti). It is also interesting to note that while the brewing world continues to celebrate porter in all its forms, brown malt has largely been forgotten by contemporary brewers. How many commercial beers can you think of that use brown malt in any discernible amount? If you are an American reading this, chances are you won't be able to think of any.

My interest in brown malt goes back a few years ago when I was doing some research on how to make historical porters. Long story short, I had plans to make a batch of (diastatic) brown malt, but I never got around to doing it - not that I had any idea of how to make it anyways. All that changed quite recently when I came across a post in HBT concerning brown porters and brett. For whatever reason, that thread reignited my interest in the subject and gave me something to work towards. My goal was to find out how to make a batch of brown malt, make the stuff, and then brew a historical porter. Luckily, there is a ton of information concerning historical brown malt on Ron's blog and I was fortunate enough to get some help from Ben, aka "fuggledog" from Jim's Beer Kit, a fellow brew-obsessed homebrewer in the UK who's already done this a number of times.

First, it is probably worth mentioning that all historical brown malts are not the same. In fact, there seems to be different types (and shades) of the stuff at various periods of time. To simplify this greatly, the earlier type (1700's) was a lighter (?), not as intensely smokey, and self converting grain that was often kilned over straw or wood for hours at a time - to be used for 100% of the fermentables. It would not have produced a beer with the same black color and roasted flavor like our modern porters. The later type of brown malt (and form I am most interested in) was produced in the 1800's and can be characterized by a darker color and burnt/smokey-type flavor that could not be used for the entire grain bill. This brown malt was often kilned over hardwood, notably hornbeam, at high temperatures for a relatively short amount of time in its later stages.

Moving on... this is how I made the brown malt. First, as many of the historical sources state that wood of choice for kilning brown malt was hornbeam, I had to find some. Luckily, this was pretty easy as American and Eastern hornbeam are common wood species here in CNY and it often sold as firewood. I knew my parents had a sizable amount of stacked firewood at their house and after spending a few hours tearing it apart, I was rewarded with a bunch of hornbeam. With my firewood in hand, I set about making the fire. I originally planned on starting a fire in a pit and letting the hornbeam burn down until I had a good amount of hot coals. From there I could transfer the coals to my BBQ smoker and add more hornbeam on top of that. I figured this method would both concentrate the heat under the grain and provide a bit of separation from the fire source. However, this wasn't to be. As the weather was total crap (28F and windy as hell) I could not maintain any sort of continued fire in the smoker. The wind would whip up and put the coals out. So instead, I rigged up a wire-mesh screen that I could use over my fire pit and kiln the grains there. As such, I let the hornbeam burn down to hot coals and when I had a continued reading of 255F on my wire-mesh, I added my malt. 

I should note that I used two types of malt. For the first batch, I used Golden Promise and the latter batch I used Thomas Fawcett Maris Otter. Not historically accurate, but where does a guy find green malt at this time of the year!? Anyways, not long after adding the malt, the grains started to 'snap' from the heat - hence the term, "snapped malt." Turning the grain over and over again, to prevent scorching, I carefully tended my grain for nearly 45 min this way, watching it slowly turn color. It was pretty cool, too, in that you could really smell the changes in the grain the longer it sat on the heat. At first the grain smelled like a toasty-popcorn (it tasted amazing like that!) and then transitioned into a toasty peanut butter, and finally to a dark toast crust type of aroma. The hornbeam wood was working out great, as it burned hot and steady and didn't produce much smoke once it got going. With about 20 minutes left, I added smaller hornbeam logs and got the fire going again - but not so much that the grain would come in contact with the fire. Stirring constantly to prevent the grain from scortching, the malt changed even further. It went from a light tan color to a shade darker in minutes, interspersed with black/charred grains. When I felt it had reached an appropriate color (the historical sources seem to indicate brown malt wouldn't have been much darker than 30L) I took it off the fire. 

The flavor of this first batch is very nice and nothing like the modern brown malt I am used to. Its flavor is mostly a toasty/dark munich/amber malt type of thing with a lot of complexity. Nothing like any grain I have ever tasted. Also, the grain has virtually no smoke flavor and the interior of the grain is intact and white colored. I would imagine this batch would be somewhat diastatic, or at least sufficiently so. With my first batch done and good, I decided to make a second batch. I was going to use more hornbeam but I wanted to experiment with a different type of wood. I had some really nice, 24 month aged dry cherry firewood on hand, so I figured I'd go with that. I am pretty sure no maltster in England ever used cherry wood for their brown malt, but I am an American and we are supposedly inventive folk. Not to mention cherry wood smoked BBQ is amazing stuff. On I went. The temperature at this point had dropped to 24F and the wind wasn't helping. Trying to get the cherry wood alight was pretty hard but after a few hours and a few beers-for-warmth, I had some nice coals. I added the Maris Otter and did the same as the previous batch. Again, after 40 minutes I added more cherry wood to the coals and got the fire going. 

The cherry wood produced more smoke than the hornbeam, but the smells coming off the grain were very much the same. Within 15 minutes of stirring, I had reached a similar color and flavor as the previous batch. I took half of the batch off the fire and left the remaining grain on the fire to continue to roast. I wanted to try and get a really dark, brown malt similar to our modern version. Interestingly, the longer I left the grain over the fire, you could slowly see the grain start to 'caramelize.' The outside husk would turn a deep brown color, then turn black as if it was completely burnt, and then on to an almost oily-shiny look. These grains were completely hollow and tasted exactly like a really caramelized/burnt sugar- liquorice candy. This made me very happy. After a while the grain stopped changing color and it only began to burn. I sat over the fire turning this last batch for another hour before I was ready to give up. The fire was going out and my pint glasses had partially frozen. What I had started at 10am was finally done at 7pm. Not to mention it was cold as heck. I got my stuff together and went home to air out the malt out on cookie sheets. 

The flavor of the cherry wood brown malt is pretty unique. The malt I took off the fire at the same time as the hornbeam batch is very similar tasting, although the cherry wood imparted a very nice, sweet, subtle smokey character. The last batch, the darkest stuff, tastes bloody amazing. I really can't believe how good it tastes - it has a really nice (slightly bitter) coffee-chocolate flavor (not unlike pale chocolate malt) with that same slightly sweet light smoke character as the other cherry kilned batch. Whether or not this type of malt is even remotely historical, I really don't care. Best grain I've ever made and sure to be repeated in the spring. In fact, I think I'll be brewing two batches of my "historical porter," one with the regular hornbeam kilned brown malt and another one with my dark-roasted cherry wood malt. 

As of now I am still looking for recipes (anyone got any good historical ones?) but in the mean time I'm thinking something from the early 1830's would be nice - a recipe like 72% pale, 15% brown, and 3% black malt. O.G: 1.060,  and 30 ibu worth of fuggles. Both batches will get some brett c in the secondary/barrel. 

The final product
In review, I am happy with how my experiment went and look forward to testing the grain for its diastatic potential and brewing with it. Changes for next time are to build a more suitable malt kiln and keep the grain farther away from the heat source. I also need to read up more on how they would have constructed their brown malt kilns, as to the replicate the process better. Specifics would also help, like how long they kilned the malt, at what temperatures, and so on. Lastly, if any of you are even remotely interested in kilning your own brown malt, do it! Though wait until you have good weather. I'd love to be able to swap some brown malt with other people.. or even drum up some interest in the stuff.

Part II is here.


  1. Great post! Congrats on pulling this off. I definitely want to try this.

    I would look at the Durden Park Beer Circle for recipes. They have two porter recipes online from 1750 and 1850 that call for pale, brown, and black malt, but in their "Old British Beers" book they have several recipes for porter made with all brown malt:

    I brewed their 1850 Whitbread porter in June and it is amazingly good and keeps getting better. I just brewed a similar recipe from 1870 this weekend and can't wait to try it.

    Ron Pattinson has an 1834 porter recipe that sounds like what you are looking for:

    I wrote to you a little while ago about a brown ale (also from the Durden Park book) made with brown malt and diastatic pale amber, both of which I roasted myself in the oven. I was way below the OG (probably wasn't as diastatic as it could have been) and it didn't properly attenuate (I let it get too cold and couldn't restart it), but when I bottled it on Saturday it tasted awaesome.

    I think you are going to love the beers you make with this malt!

  2. Brian,

    Thanks for links and the comment! I am half-ashamed to say I had never came across the Durden Park website and the lets brew 1834 recipe too. I'll give the recipes a full look tonight and pick one out to brew on sunday.

    Also, I'm glad to hear that your brown ale came out well. I wonder how diastatic my brown malt really is... it would probably be best to test it before I brew the beer.

  3. Fascinating - I look forward to reading about the results.

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  5. Will,

    I finally had a chance to look at the Durden Park "Old British Beers" book and they have one recipe from 1743 for an all brown malt porter (4.75 lbs for 1 Imperial gallon, plus 3/4 oz. of fuggles--OG 1.081) with a note that use of an amylase enzyme will be needed with modern brown malt. I've never tried that, but I have seen it in my local homebrew shop.

    (edited to correct the amount of brown malt)

  6. I've made home made brown malt in my wood burning stove indoors recently. It worked well, but stirring the malt to prevent charring was a bit of a problem. I heard recently of burning (wall)nut shells in a bread oven for flavour- I wonder if it would influence the malt flavour in the same way as bread?
    Anyway, I used the wood fired malt in a whitbread-esque porter and it was lovely!



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