Since my last installments on home roasting ( Part 1 which is an introduction and Part 2 which gets into experimentation and I make Special B ), I have been doing some more experimentation as well as research on the reactions of home roasting. The experimentation I focused on was working on comparing oven roasting to roasting the grain in a nut roaster (A drum roaster or something similar will give you the same results as my nut roaster). Each has a trade off, the nut roaster has more control and is a bit faster. The tradeoff for this is that things can quickly and very easily go beyond the point you intend. The second, is that at a specific point, the grain will start to smoke. The smoke can get very heavy very fast. I do find that the color in the nut roaster seems to be a bit more even. The oven is a much slower, but offers much better temperature control. There is also a bit less smoking. However, the roast appears to be a bit more uneven, and to keep the roast even you have to take the grain out and stir it, which will increase your roast time. You are also limited to being able to do the much deeper roasts because you need the control and high heat of a nut roaster, or other roasting vessel. Below you will see examples of several grain types for comparison in color and even texture. I must note that I did some experimentation with wheat malt and pearled (dehusked) barley and found the nut roaster to be a much better option for those types of grain.
Roasting Grain-The Reaction.
I covered this briefly in part 1 of my home roasting segment, but I will cover it a bit more in-depth here. Don’t worry, I will not be going into formulas and chemistry, I found that very boring. But understanding the reaction a bit more will help you come up with your own roasting varieties and experiments. The only process you really need to concern yourself with in home roasting malt is the Maillard reaction, which is not a single reaction but rather a grouping of complex chemical reactions between acids and carbohydrates. In short is a non-enzymatic browning by heat. During the Maillard reactions there are many different flavor compounds created, the number and type of compounds created depend on the food type being heated. For example when grilling a steak, you have the Maillard reactions taking place and while some of the aroma and flavor compounds may me the same as with grain, you are going to have some that are quite different and unique. This why you can make the connection between certain foods in flavor and aroma between beer. A classic is biscuits. A lot of beers have a biscuit flavor and aroma. That is the result of a Maillard reaction correlation between compounds in what makes the biscuit and your grains. It’s no surprise that since beer is mostly grain, we get a lot of similar flavor and aroma compounds between foods like breads, pastas, crackers, and so on in the malt profile of a beer. We even get caramelization, even though to get the caramelization in the truest sense, you have to bring the temperature of the sugar components up to 248-302 degrees F. In most cases what we get when we roast/toast grain is actually the formation of Melanoidins, which often bring a degree of caramelization-like flavors and aromas to the grain, even though it is not true caramelization of the sugars. In short, the varying degree of pH (acidity), types of amino acids and sugars, temperature, time, presence or lack of oxygen, water, and other food components all are important in this Maillard Reactions in the grain. Changing one part of the whole process will give you a new degree of flavor and aroma, which is something I have been playing around with a lot lately. Generally the only part of the reaction process we can change when roasting/toasting grain is time, temperature, food component (type of grain used), water, and sugars (if you mash the grain first, and to what degree you mash). Does that makes sense? I hope so because that’s about as simple as I can make it.
To Mist or not to mist, that is a big question.
OK so now the big question that seems to be getting asked. Do you mist the grains with water or not? The answer is not so simple. You need to consider what you are trying to do. Misting the grain will introduce a water component to your process. I generally do not mist my grains and I get good results. Others claim that misting the grains prevents burning in some cases, reduces smoking, and prevents the grain from drying out too much. Since I mostly use roasted/toasted grain for specialty malts, I don’t have an issue with drying out the grain too much. I made a beer once with all home roasted malt as the base and had some issues with conversation, so I don’t recommend making a beer with all roasted malt anyway. For specialty grains, the moisture level of the grain is meaningless, unless you are going to store it for a very long time. So I say misting the grain is up to you. When I do the grain in the oven I do not get a lot of smoke anyway. In the nut roaster, I get some smoke but by that time I’m usually at the end of the roast anyway. For chocolate or black malt, misting may be appropriate, but that would be a two-man job.
Nut Roaster or Oven?
So Below you will fin a bunch of pictures of what I am talking about in this segment, so if you want to skip this part, feel free. In a side by side comparison, I found that I was easily able to reproduce any grain in the nut roaster that I was in the oven. The key is to keep the grains moving and keep a close eye on the changes in color of the grain. Because the roasting goes so fast in a nut roaster (less than 5 minutes in most cases) it is very easy to get beyond the point you wish to get to, for example while making chocolate malt I easily went past my point and charred a few grains. I lost focus for only about 30 seconds as I stirred and watched what my son was doing for just a second. You also get a considerable about of smoke past a certain point, so if you don’t have a fan above your stove, you may be better off doing this outside. I found the best temperature to roast my grains in the nut roaster to get a decent even browning and not to over burn the grain or take forever to get to the browning point was at medium heat on my stove. I cannot stress enough that you really need to keep the grain moving. I did notice that you have 5 easily definable stages. The point you notice the grain starts to brown slightly, a slight crackled of the grain every now and again, a heavier crackle of the grain as it roasts, a light smoke, and a heavier smoking stage. The problem with using these stages though is that there is a lot of color change between each one, so you really need to mainly gauge the stage of the grain by your eye, unlike the oven where you can rely on time and temperature. I also found that the darker grains were much more even and had better flavor in the roaster than in the oven, even though it is much easier for the grain to get away from you once you hit that higher roasting stage. Below is a quick Pros and Cons of each roasting method.
Oven.
Pros: Easy Temperature control, time is easy to control, Roast/Toast is consistent with your system, easy to provide instruction to others (toast grain at 350 degrees for 30 minutes is easy instruction to pass on).
Cons: Roast can be uneven at times if you don’t stir often, stirring often can increase roast/toast time, takes a long time to achieve roast, darker roasts are near impossible.
Roaster
Pros:Faster Roast Time, Roast/Toast is more even, easy to get darker roasts not achievable in oven, visual gauging of the grain can give you a wider variety of roasts, handles dehusked or husk free grains a bit better.
Cons: Easy for the grain to get away from you (too dark or burned), grain can start to smoke, consistent roasts are hard when based solely on visual gauging, if roaster is too hot you will only brown the husk and not the starches inside.
As always, if you have any questions, feel free to email me. Below are pictures of a few recent roasts as well as Marris Otter and White Wheat experiments. Note that in each picture I included a small amount of the unroasted grain for change comparison.
Now on to the photos

This is just a picture of the nut roaster. You could probably use a drum roaster, clean wok, or even a clean pat if you can keep the grain moving.

Golden Malt, in the oven (300 Degrees for 25-30 Min)

Deep Amber in the Oven (375 Degrees for 40-45 Min)

Brown Malt (400 degrees for 45-50 Min depending on you oven)

White Wheat in the oven (400 degrees for 15 Minutes) You need to remember that grains without husks will brown the starches faster and more direct.

White Wheat in the Nut Roaster till the grain starts to crackle.

Marris Otter in the Oven, amber Roast (350 degrees for 25-30 Minutes)

Marris Otter in the Nut Roaster till the grain crackles heavy.

Here is a pale chocolate roast of dehusked barley. I did this in the nut roaster until the grain got this dark color. Be careful because it will smoke.

I call this a stout roast. It's beyond brown malt and quite black. It was too bad a some of the grains got charred, You need to be careful to avoid charring too many grains.

This was a fun experiment. I have started mashing in a pot instead of soaking the grains and then mashing in the oven. It is easier to control the mash temps and it seems a bit easier. You don't have to worry about the grains at the top drying out. But this time around I also did a decoction style boil after the mash. This will help develop the melanoidin character in the grain. This was the result. A very caramel-like and sweet grain. The drying and post roasting process remains the same as it has in past posts.

Mashing in a small pot. Easier to control the mash temp of the grain.

Here I am boiling the grains in a thin decoction style mash. This helps develop true caramelization and melanoidin character.