Oak Smoked Single Malt

[Fills Jars Slowly]

Cold smoking malt with oak smoke makes for a single malt that brings some American character to an Islay style smokey malt whisky. It is different than peat, but more like it than the campfire or BBQ you might expect. There are phenolic, earthy, smoky notes and when 100% of the grain bill is smoked malt, the character is every bit as assertive as a Laphroaig or Ardbeg. However, a batch of unsmoked malt whiskey that is otherwise identically made can be used to blend with for a more subtle effect.

Although the smoked single malt is of Scottish style, fermentation and distillation are both done on the grain in a plated column still without separating the liquid wort from the grain, like they do in bourbon country. This whiskey is also aged on newly charred once used oak, which is kind of a hybrid of Scottish and American styles. If you are not set up for indirect heat (steam) distillation, you can lauter the wort out like a beer and go off the grain like they do in Scotland.

Smoking the Malt

The malt is cold smoked and then rested for a week or longer prior to mashing. Here is the setup I built to perform this operation:

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It is simply a plywood box with a hole cut for the smoke inlet, some smaller holes on the other side to vent the smoke, and a rack inside to hold a layer of grain. The rack was constructed by putting a 2”x4” wood lip around the inside of the box. A sheet of expanded metal sits on that lip, and a window screen sits on top of that to hold the grain. The smoke enters below the screen and the vent holes are above the screen. The lid is just a sheet of plywood that sits on top. It can be held down with a brick or something similar if desired. I also reinforced the box with some boards around the top that can be seen in the photo showing the inside of the box.

The outlet vent on the charcoal smoker is piped to the cold smoker box with flexible dryer vent hose. A dryer vent flange attaches the hose to the cold smoker, and the other end has a flange attached to a cardboard square. I tape the cardboard square over the smoker outlet vent with duct tape.

To prepare the malt, spread a thin layer of about ½” on the window screen placed in the cold smoker and spray it with a spray bottle of clean water until it is slightly damp. Keep adding layers and dampening each with a spray bottle. You can stack the grain 4” or 5” high.

To prepare the fire, light about 10 charcoal briquettes and place several fist sized chunks of smoke wood on them. I use Central Texas live oak, but you can choose a different wood if desired. Close up the smoker and shut the inlet vents almost all the way so you get a lot of smoke, but not too much heat. I have used a thermometer sticking in through one of the vent holes to ensure that it doesn’t get above 100F or so in the box so as not to deactivate enzymes in the malt. Unless you have built too large of a fire, the box stays near ambient temperatures throughout smoking.

You can experiment with smoking times, but I do between 1 and 2 hours, or until the grain is dry again. Turn the grain with a scoop or your hands every half hour or so while smoking to promote even drying and smoke exposure. You can leave the grain out in a dry place to dry out if it is still damp when you are done smoking. Let it rest for a week or longer prior to mashing (in a bag or storage bin is fine) and it will mellow a bit and make a better product.

Mashing, Fermenting, and Distilling

This recipe is scaled to a 20 gallon batch to give back to back 10 gallon runs in a beer keg boiler.

1. Mill 40 lbs of malt. Use a very fine crush if you are not lautering and it will increase efficiency.
2. Add 15 gallons of strike water to the mash tun and heat to 153F.
3. Adjust the strike water to pH 5.3 prior to mash in, add 7g CaCL, 5g gypsum, and a Campden tablet.
4. Add the grain and perform a round trip step mash cycling from 145 to 140 degrees F, then up to 149 and back to 145 over a 2 hour period to maximize fermentability. If you don’t have the ability to step the temperature, it is fine to do a standard mash at about 145-147.
5. Cool to < 90F with an immersion chiller or your method of choice and top up to 20 gallons with 2 gallons of cold water.
6. Pitch a healthy quantity (2 tablespoons) of DADY yeast to get the fermentation going quickly and strongly.
7. Ferment 3-5 days at 80F-85F until finished. Cooler is OK, but it may take longer to finish.
8. Distill on the grain through a steam injected 4 plate flute and make whiskey cuts.
9. Age on charred white oak bourbon barrel staves for 4-12+ months at about 65% abv.

OG = 1.077, FG = 1.000, ABV = 10.2%

[*UPDATE* - After further discussion based on the observation that the OG of 1.077 seems high, I am adding this note. I used pale ale malt with an extract potential of about 83% by weight, or 38 ppg. I also crushed the grain very finely and followed the other mash protocols listed above, resulting in very high conversion and extraction efficiency near 100%. If you use a malt with lower potential or a coarser crush or different mashing procedures, you might get a lower OG. For example a malt with 36 ppg potential (78% sugar) and 85% efficiency would achieve a gravity of about 1.063, and a malt with 32 ppg potential (70% sugar) at 85% efficiency would have a gravity of 1.056.]

With plain water in the steam boiler this yields about 1.75 gallons of total still output with about 1 gallon kept as hearts. Feints from prior runs can be added to the steam boiler up to a 3-4% ABV 10 gallon steam charge. This increases total yield to 2.5 gallons or so with 1.5 gallons kept.

You can repeat this recipe exactly with unsmoked malt and then try different ratios of blending the two together to get the precise amount of smoke you desire. If you find a ratio that you want to stick with, you can then try a mash with the smoked and unsmoked grains together in that proportion.

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