New Improved Malt Kiln for Diastatic Brown Malt

So you want to dry your malt with a wood fire (because it’s awesome) but you live in a townhouse, what to do?

I recently received some questions about diastatic brown malt from Ryan Pfeifle at Farm Power Malt in Montana who is experimenting with making it on a larger scale. His interest inspired me to give it another go. It’s been a while since my last experiments and I’ve learned a lot since then. I also figured it was about time I fix this darn barrel kiln sitting in my garage. My next post will be about brown malt and the beer I’ve made with it, this one will just focus on the kiln which is working really well. The “air on” temperature sits solidly at 225F with one large gassifier. I’ll be tweeking this perhaps with some venting to make it more adjustable. The malt temperature did not go higher than 206F which is great, it’s where I want it, hot enough for colour but low enough to preserve the enzymes.

So this is more like how I imagined it in the first place. The top of the original barrel acts as the heat disperser and the new half barrel sits perfectly inside the outer rim. I placed 4 bolts 9 inches up from the bottom of the half barrel to hold the Webber grill which is a good width to fit in a barrel. You can buy these at the Home Depot, they’re a little pricey for what it is at $30 but since I didn’t have any other ideas for the “grain basket” I had to buy it. I placed the thermometer just under the grain bed to measure my “air-on” temperature and I’ll use my probe thermometer for the malt temp.

The insulation was also a little pricey, there are probably other options for insulation. The stuff I bought is called Fiberfax which I bought at Greenbarn. For the inch thick blanket it’s about $8.50 a linear foot (comes in 2′ wide rolls) For the 1/2 inch it’s about $5 per foot. It’s rated to 2400F so it’s definitely good enough for this application. I bought 6 ft. of the 1″ thickness but I would have been fine with the 1/2 inch stuff. Beware though that this stuff is seriously toxic, you can see the fine silica particles in the air when you handle it. I wore a respirator and goggles when I worked with it. I originally glued the insulation to the inside of the barrel with something called sodium silicate which worked but I wanted to protect the insulation and I wanted to protect my malt from any particulate matter that the insulation might impart so I bought some steel sheet metal thin enough to bend into a circle to cover it. The sheet metal is just sitting on three 2″ bolts.

Once I make or find a proper basket for the grain I’ll be really happy with this kiln. There are times in my life when I feel like Richard Dreyfuss in Close Encounters with the Third Kind, the part where’s he’s obsessed with constructing Devil’s Tower in his living room.  “Well I guess you’ve noticed something a little strange with Dad” That’s when I know I’m doing something worthwhile, at least that’s what I tell myself.

 

 

Old book review

Here’s an interesting book pointed out to me from a reader, thank’s Peter! It’s called The Theory and Practice of Malting and Brewing. By a Practical Brewer by William Creech  You can read it here. The great thing about it is that it was published in 1793, a time that predates the use of Black Patent malt in 1817 (which would eventually replace diastatic brown malt) and it’s also a time where thermometers were used to record temperatures in Farenheit. The Farenheit scale was first introduced in 1724 so it is between these two dates that we can find books published about brewing that include temperatures used in the process of making malt and beer in a more pre-industrial era and by that I mean this predates the mechanization and increased scale of malting.  So we get some very useful descriptions of malting and brewing practices that serve as a window into the past. What’s amazing about this book is all of the unique descriptions about brewing practices, things like adding the hops before the boil pg. 37 for a perceptible improvement in flavour. Hmmm gotta try that. Here’s a link to an article on first wort hopping.

There is also mention of using fresh hops for small beer on page 66. But more importantly, this is the first time I’ve seen mention of different colours of brown malt. They are referred to as Brown, Middling Brown, and High Brown. What?! This suggests that malt colour and therefore beer was not as inconsistent as one (being me) might have assumed. And if you’re into brewing historical beers check out the recipes included on page 60-72.

 

 

Blown vs. Brown malt

Blown malt left, Brown #1 on right

Diastatic brown malt is a dark malt kilned over a fire fueled with coal, wood or straw which has enough diastatic power to convert itself. Made during a time before the widespread use of thermometers and hydrometers the colours and level of diastatic power would have varied between maltsters. An essential source of information on malts of this time comes from the London and Country Brewer by William Ellis published in 1736.

Times for kilning malts is described as being either 4, 6 or 12 hours with the “pale sort” requiring “more leisure and less fire than the amber or brown sorts”  But is it really that simple?

In my previous attempts to make diastatic brown malt a couple of years ago I didn’t think I was successful in answering the question that has been bugging me since the first time I read the London and Country Brewer and that is; how was malt dried in 4 hours with high heat, able to maintain some diastatic power, since enzymes are destroyed very rapidly over 221°F.

Modern brown malt is kilned at a high temperature, 350°F from it’s green stage, right after germination. It will not have any diastatic power.

We do know that brown malt did not have the same diastatic power as pale from the description of kilning brown malt.   “…is often crusted and burnt, that the farinous part losses a great deal of it’s essential Salts and vital Property, which frequently deceives it’s ignorant brewer, that hopes to draw as much Drink from a quarter of this, as he does from pale or amber sorts” (pg.14). What we don’t know are the kilning temperatures.

Some 70 years after this publication a study of brewing industry practices was carried out to determine if Bere barley grown in Scotland should be taxed at the same rate as English barley. The Scotch Bigg Report (Thomas, Coventry and Hope)  presented to the British Parliament in 1806 contains some of the earliest empirical data on brewing and malting collected on a large scale and includes kilning temperatures. This report also pre-dates the development of Black Patent malt (1817). Malts were still referred to at this time as either pale, amber and brown. What I found very surprising in this report is that a temperature of 170°F is given for brown malt which is the same curing temperature for pale malt.  “Malt may be made brown at a lower temperature for it is not so much the temperature, as the suddenness with which it raised, while the malt is still moist, which alters the colour.” Pg. 33 However, they also recorded some maltsters kilning at temperatures of 186°F and suspected some kilned as high as 212°F.

So how does it get dark?   With Munich malt temperatures are raised while there is 20-25% moisture in the malt causing a partial caramelization and it is more highly modified which encourages melanoidin formation upon kilning making a darker malt. It’s also kilned at a higher temperature as well but even Aromatic malt is not as dark as I would imagine a porter being at the time. In my experiments trying to make brumalt I somewhat accidentally achieved a very dark malt by stewing the malt in the proteolytic temperature range of 44-59°C or 113-138°F. So I looked for some clues to see if there was something in the older methods of malting that would promote more Maillard reactions, perhaps if using traditional methods the malt would darken to a greater degree.

One major difference between malting today and back then is the use of continuous un-aerated steeping. In another blog post I tested the theory of un-aerated steeping and it’s effect on slowing the growth of barley and it certainly does, The reason germination times were so long is because of this and to some degree the cooler temperatures. Aerated steeping is a relatively new development (150 years) in the malting industry and was utilized successfully or more consistently due to the development of pneumatic malting. This subject is probably worthy of a book so I’ll stop right here. So in order to mimic the old malting methods I would need to use a continuous steep. There is a theory that because a continuous steep delays chitting that the barley absorbs water more consistently. With aerated steeps the grain usually starts to chit before the last steep. This may cause water to absorb faster at the embryo end as opposed to along the entire length of the endosperm, so the same amount of water may be absorbed but with one end being slightly drier and therefore may affect modification. Chitting during steeping can also cause over steeping which can lead to uncontrolled growth and high malting loss. (Briggs Malts and Malting p.123)

One clue to another difference is in the London and Country Brewer with the mention of a couching phase at the end of germination; “When it is at this degree and fit for the Kiln, (wilted or when “the Root begins to be dead”) it is often practised to put it into a Heap and let it lye twelve Hours before it is turned, to heat and mellow, which will much improve the malt if it is done with moderation and after that time it must be turned every 6 hours during twenty-four.” This is actually very similar to the method used to make Brumalt or Melanoidin malt. The malt is covered and allowed to heat up to 50°C 122°F for 36 hours, only it is not turned and the carbon dioxide eventually stops the growth, but the effect is the formation of reducing sugars and amino acids. Interestingly I found this description in Brewing and Distillation by Thomas and Stewart 1848 “It was formerly the custom in Scotland to pile up the whole grain into a pretty thick heap, and allow it to remain for some time. The consequence is the evolution of a very considerable heat, while at the same time the malt becomes exceedingly sweet.” They go on to say that this is no longer practiced because of malting loss and that “the very same change takes place afterwards in the mash tun, without any loss whatsoever.” 

Lastly, I recently bought a copy of La Practique du Maltage Lucien Levy 1898 and there is a kilning schedule for “Malt Anglais” which states. “It rises as fast as possible to 50 ° (malt temperature and not air). We stay there for about twelve hours.” (Translated from French) It then goes up to 60 for another 12 hours. Interesting! lots of time for proteolytic enzyme activity here especially if it raised to 50° with a high moisture content. However this is not mentioned in the Scotch Bigg report but it does say that kilning takes anywhere from 40-80 hours and that the starting temperature is usually the same as body temperature which is 37°C. With such long kilnings it wouldn’t surprise me that the malt would spend a considerable amount of that time leading up to 50°C and that there would be a lot of enzyme activity during this initial kilning.

I suspected a “hot couch” and some stewing at 50-60°C would definitely add some colour but would it be enough at a kilning temperature under 212°F This will be malt #1

Just to be sure I also planned to make a traditional malt with the hot couch but without the proteolytic stew and just go straight to 205°F for 4 hours. I know with such a high moisture content going this high right away would be bad for the diastatic power but I was more curious to see what effect this would have on colour. This will be malt #2

Blown malt, malt #3

Blown malt on the left, brown on right

In the London and Country Brewer of 1736 a distinction is made between malt that is “blown” and brown malt.

 On the subject of frames, or the materials used for the kiln floor it states “the Iron and Tyled one, were chiefly Invented for drying of brown Malts and saving of Fuel, for these when they come to be thorough hot will make the Corns crack and jump by the Fierceness of their Heat, so that they will be roasted or scorch’d in a little time, and after they are off the Kiln, to plump the Body of the Corn and make it take the Eye, [ What I believe “take the eye” means is that it will simply look better by increasing in volume. In Wigneys 1823 Philosophical Treatise of Malting and Brewing he describes the effect of  sprinkling as “giving to the malt a plump, fair appearance to the eye…” ] Some will sprinkle Water over it that it may meet with better Market. (Malt was sold by volume) But if such malt is not used quickly, it will slacken and lose it’s Spirits to a great Degree, and perhaps in half a year or less may be taken by the Whools (a small insect) and spoiled: Such hasty dryings or scorchings are also apt to bitter the Malt by burning it’s skin, and therefore these Kilns are not so much used now as formerly” This is a criticism of surfaces that conduct or retain too much heat. What he is describing is “blown malt” although he does not refer to it as such. Corns that “crack and jump” and expand in size will occur when temperatures are high and the moisture inside the grain cannot escape fast enough. 

Most recipes for Blown malt after Black Patent malt comes into use refer to it as simply Brown or Porter malt. All the recipes I’ve read dry the malt  to a certain degree first. In Brewing and Distillation by Thomas Thompson and William Stewart (1848)  “Brown or Porter malt is dried by applying the same heat at first as to pale malt, and after it is half dried, by blowing it (as it is termed) on the kiln. This is done by raising the heat as high as the men who turn it on the kiln can possibly stand. This may be stated at 200° for the first turning, and higher afterwards.”  The same thing is stated 50 years later in La Practique Du Maltage: The brown malt or blown is obtained as follows: We take malt half kilned and we carry it in a second kiln heated with a large fire of oak or beech it is installed in layers of 3-4 centimeters.

What also encourages this popping effect is the shrinkage of the pores of the husk which occurs after the “free drying” stage of kilning which happens at around 23% moisture. So if the temperature is raised very rapidly at this point the steam formed will not be able to escape fast enough and the kernel will pop. I suspect the sprinkling of water can increase the malt temperature faster by adding steam to the malt bed. I decided not to try sprinkling water on mine. This time I just wanted to try drying the malt down below 30% and subjecting it to a high heat, above 212°F. I put it in the oven at 350°F which may have been overkill but it sure popped! It sounded sort of like popcorn when it really got going after 20 minutes at this temperature.

Malt #1 Hot couch and 21 hr. stew+ 4 hours at 205-210F

• Malt #1 Continuous steep until 44% changed water twice
• 8 day germination. Malt temp. between 11-13°C 52-55°F
• Hot couch 36 hours in an open cooler to mimic a larger amount of malt. Temp. reached 39°C Turned after 12 hours then every 6.
• 21 hours kilned lightly covered, closed vents, no fan at around 50°C
• Moisture now at 28%
• Kilned for 2 hours at 205*F
• 2 hours at 210°F

 

• Malt #2 Continuous steep until 44%
• 8 day germination 11-13°C 52-55°F
• Hot couch 36 hours temp. reached 39°C 102°F
• kilned for 4 hours at 205°F moisture at 14%
• kilned another hour and a half  at 205°F moisture down to 6% Colour was light!
• kilned another 2 and a half hours at 210°F (8 hours total kilning) Colour now at around 30L

Malt #2 Hot couch, no stew and 8 hrs. at 205-210.

• Malt #3 Blown Malt Same steep
  

  Blown malt #3

• same germination
• same hot couch
• same limited stewing at 50°C 122°F as malt #1
• Moisture at 28%
• Kilned for 40 minutes at 350°F
• Moisture below 5%

Blown malt #3

 

 

Observations: When comparing the Blown malt to malt #1 the colour is almost the same. I was really excited to see how dark #1 got. Much darker than my previous attempts at Brown malt. Because malt #2 remained light, even after 8 hours kilning,  it’s safe to attribute the darkness in colour in malt #1 to the limited stewing phase at 50°C. I ran them all through a mini-mash at 152°F pH adjusted to 5.2 (or as close as possible with a little baking soda or some acid malt) for one hour. I was not using the standardized congress mash, instead, I was using a scaled down version as if I were brewing a 5 gallon batch with 10lb of malt only I was using 4 oz of malt. The math may have gone a little sideways but as long as it was the same for each I thought it would make an interesting comparison.  Of course #1 had the highest brix at 9° and the blown had the lowest at 7°. I was pretty surprised to see that Malt #2 had some diastatic power at 8°. As a control I made another mini-mash the same way with a pale malt and it also scored a 9°.

Mash #2 which did not have the initial lower temperature kilning remained a gloopy mass and the mash did not separate from the wort. This was not surprising as the beta glucans had not been broken down which may show the importance of the enzyme activity during kilning below 50°C 122°F or more specifically in the 37-45°C 98-113°F range .

Malt #2 after mashing notice the lack of separation of wort.

Malt #2 after 5 1/2 hours kilning at 205°F and still light.

 

The flavour of the Blown was bitter and slightly charry like a roasted malt. The interior of some of the kernals was charred while the exterior looked a nice light brown with some darker areas. Malt #1 tasted great nice and malty. As for volume the malt was divided by weight before kilning. After kilning Malt #1 measured 4 1/2 cups. The Blown was 5 cups, a difference of 10% Perhaps it would have been more had I sprayed some water on it during kilning.

 

I know I’ll get a lot of people questioning my methods here they’re not the most scientific, but I think it answered some questions in my mind about the effects of using a proteolytic stewing (or a slow kilning) phase. Also I think it’s safe to say that by omitting any initial drying or even withering phase the London and Country Brewer article has an oversimplified version of the kilning process. That may have been obvious to a lot of people but I know it has caused a lot of debate amongst others.

What I’d like to try is kilning at a lower temperature and raising the temperature when the moisture content is lower around 20%. I’ also like to try making a blown malt at 200-250°F which is where I observed some popping happening during my first attempts at brown malt as I think this may be more historically accurate. But first I think I’ll make a much larger batch for a more historically accurate porter and perhaps this time I’ll get to play with some fire!

Many thanks to Melanie and Andrew at McInnes Farms for supplying me with a big sack of Newdale barley grown 10 minutes away from where I live. These experiments and many more to come will be done with this barley.

Mini mashing

Mini sparge

 

1804 Porter taste test

This is the Porter based on the Barclay Perkins Porter from 1804 with Brown malt and Pale malt. I shouldn’t call this a taste test because that would imply that I haven’t tried any when in fact it’s almost all gone. But hey, can you blame me? It was the perfect beer for the Christmas holidays. After all the food, desserts, and chocolate it was nice to finish the evenings with something not sweet but full of dry roasted flavours. Dark toast and coffee dominate, the smoke is almost non-existent. It’s so subtle it’s  presence could be mistaken for a slight sourness but I recognize the flavour from my other pecan wood  brown malt porter. The hops are very low which doesn’t surprise me. These were the hops I picked on River Rd. just outside of Fort Langley. I have no idea what kind they are but I’m guessing the alpha acid level is around 3% so I could have used a lot more. The colour is gorgeous, no complaints there and it’s got a full mouth feel. The head doesn’t stick around for very long, but considering the disastrous brew day and the stuck sparge I’m extremely happy it turned out so well.

 

 

1804 Porter

What a disaster. This beer was loosely based on the 1804 Barclay Perkins TT recipe from Ron Pattinsons book The Home brewer’s Guide to Vintage Beers. I didn’t think I was going to use the whole batch of brown malt in one recipe but this gave me a perfect excuse to do just that. So 4lb of non-diastatic brown, 2 lbs of my diastatic brown malt samples in place of the Amber malt in the recipe and 6lb of pale malt. I also added 1 lb of pilsner malt just because I had some and to help with conversion. Everything was going great until I tried to sparge. This mash got stuck and I mean really really stuck. With brown malt being roasted it is very friable, the husk breaks down in to very small pieces and the inside is a fine dusty powder which turned into cement at the bottom of my mash tun and completely plugged the false bottom. A larger mash tun would have helped and definitely more rice hulls, a lot more, I would suggest one pound minimum. I tried giving it a stir – nothing, I tried blowing some air through it – still nothing. I finally ended up ladling it out into a bucket and throwing all the sparge water in, sort of a batch sparge and then just pouring it through a strainer, what a mess. I’d be very surprised if this turns out. I ended up with 4.5 gallons of a decent looking dark beer with an O.G. of 1.064.  It’s been bubbling away nicely and has just started to slow down, my fingers are crossed. I thought this post might at least be useful for anyone else trying to make this recipe,  Cheers!

 

New malt kiln

Still on the quest for a more authentic diastatic brown malt. I was pretty disappointed with the soot that appeared on my last batch and I wanted to play around with using higher temperatures so a new kiln was in order. Unfortunately I live in a townhouse, otherwise I would have built one by now using cinder blocks or anything I could get my hands on. Instead I had to settle for something on a more portable scale. I had originally thought of using a barrel so that I could take it to a campsite close by and put it over a fire pit, that way I could try using straw as a fuel. Then I figured why not use the gassifiers in the barrel, it’s clean, very safe, and I get one hour of burn time for each load of pellets. Every time I try burning straw it burns faster than paper, I still don’t get how this was used in the early malt kilns.

As I mention in the video I just didn’t have the time to perfect the design and my malt was at 10% moisture level after air drying for two days, it was more than ready to be kilned. The temperature crept up to 250 by the end of the first hour, there was still steam coming off at this point. During the second hour the temperature rose to 275 and then to 300 during the third. I knew this would probably be too hot for the malt to have any diastatic power left to convert itself but I wanted to see how a faster and hotter kilning would affect the colour.  My results were most likely inaccurate because even though my oven thermometer read these temperatures the heat coming out of the small holes in the barrel was much higher. The 4 oz. test batch came up with a 1.020 original gravity after an 8 hour mash.

Well at least now I know I can make a pretty descent blown malt, check out the snapping action in the video. As well this would be a great way to roast your grain outside, you could easily do 7 pounds at a time this way.

 

This barley’s looking good in brown

My brown malt

One malt that has a unique procedure is brown malt. Historically used in porters this malt differs from other roasted malts in that it has a higher initial kilning temperature. Whereas chocolate and black malts start out as pale malts which are then roasted, brown malt is kilned at a higher temperature from the green stage. Procedures vary but here’s what I did:

From the green stage I kilned it at 212 F for 5 hours

Cured at 350 F for 40 minutes

I can’t wait to compare the flavour of brown malt to the other roasted malts I make with the same barley.