The four mechanisms in barrel aging:
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1. Exchange
During barrel aging, a natural exchange occurs between the spirit and the wood. The spirit soaks into the wood, drawing out flavors like vanilla, caramel, and tannins, while the wood absorbs harsh or unwanted notes, leaving the spirit smoother and more refined. Our tiles are carefully toasted and charred, just like the wooden planks, called staves, that make up the sides of a traditional barrel. This process ensures your spirit develops the same complex and balanced flavors as it would in a full-sized barrel.
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2. Digestion
Wood interacts with alcohol and water through digestion, where natural wood components—like cellulose, hemicellulose, and tannins—dissolve into the liquid. Cellulose, a structural plant fiber, adds texture, while hemicellulose, a sugar-like material, breaks down to release sweet, caramelized flavors. This process enhances the liquid, creating a smooth, velvety mouthfeel barrel-aged beverage fans love.
The MOBA Glass Cask’s high-surface-area tiles increase digestion, developing rich, complex flavors more efficiently than traditional barrels.
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3. Oxidation
Oak barrels naturally allow small amounts of oxygen to pass through their walls, effectively allowing the spirit to 'breathe.' This slow oxygen exchange is essential to maturation, so we’ve ensured the MOBA Glass Cask can breathe too. Oxygen enters the liquid by dissolving into the liquid from the headspace of the barrel. This dissolved oxygen initiates oxidation reactions, gradually transforming alcohols and organic molecules into carboxylic acids, which contribute to the rich flavors and aromas of barrel-aged spirits.
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4. Esterification
Acids formed during barrel aging react with alcohol through esterification, creating a family of molecules called esters. Different acids contribute unique flavors and aromas: acetic acid produces fruity, tangy notes like ripe apples or pears, while lactic acid adds creamy, buttery richness. These reactions are essential to developing the complex choreography of fruity, floral, and nutty flavors and aromas that one can only find in the finest barrel-aged spirits. The balance of acids during aging determines the complexity and depth of your creation.
History
If you've come this far, we happily share some of the experiences of the team over a roughly 9 year period:
Team
The team that created the electric modern barrel, MOBA, consisted of (left to right) Jeffrey Williams, Adam Thomas, and Zachary Detweiler.
Early days
Heavy chemistry
100% of the zero day team had graduate degrees in chemistry. 0% of the team had any experience in the production of distilled spirits. We set up a makeshift lab in Zach's 1 bedroom apartment (we'd hide it for fire inspections). We learned quickly using Design of Experiments tools we had access through our day jobs. The first results were so over oaked that they were literally undrinkable - they would pull any moisture off the pallette immediately. We quickly dialed in the wood to spirit ratio, and over the course of 700 experimental samples dialed in around 20 recipes that we enjoyed across a number of sirits.
0 to 1
Hardware is hard
With new distilleries opening every day, and miniature barrels popping up everywhere, we opted to solve the problems those barrels presented and radically reduce the time needed to barrel age distilled spirits. At the time, we had no experience in electronics, so we brought on a prototyping contractor. The process was a mess, and the development stalled at software. A flier post in a public slack channel led us to Jeffrey, who fixed the software, and the initial MOBA prototype came to life.
Going for it
Time to build
We conducted surveys supporting the notion that the product was interesting and raised a small round of financing from family and friends. Since the first prototype was unmanufacturable without substantial tooling, we redesigned it and replaced the Raspberry Pi with a properly designed and outfitted PCB. Even this design had a flaw though: the fittings did not seal well enough to prevent the release of critical flavor elements during the high temperature portion of the processing cycles.
maybe too much magic?
The last bullet
We sold several dozen of the electric barrels, all at a loss, even without factoring in build / ship labor. Several dozen needed to be at least several hundred or even several thousand to represent a market signal that we could build on. One theory is that we asked for too much belief from the customer, and at a high price point -- making spirits fast, and in a miniature barrel, and for $400 MSRP -- required exceptional levels of trust paired with expendable income income that was rapidly drying up during the pandemic. So we took one last concept off the shelf and introduced what we called MOBA Zero (later renamed the Glass Cask by ChatGPT). It solved for cost (cost < $20 to make, MSRP $40), and was not electronic so took a long time just like regular barrels.
That's a wrap
Leaving a mark
Since marketing costs outweighed revenue of the MOBA Glass Cask, we decided to roll up the business but to also publish the trade secrets developed by the company over 9 years.
They are below.
Cheers and enjoy.
Tricks of the trade secrets
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Wood processing - tannin
Boil the wood in water to pull out tannin. We chose to do this three times before further processing any wood. The notion was that there were surface area reactions that benefited from having more wood tiles but that the volume of the wood dictated that we remove tannin ahead of time.
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Toasting and charring
While it may be obvious to anyone who has looked into this, toasting adds a lot of great sweetness, vanilla, and baked goods character to the spirits. We would bake the cut and soaked tiles in the oven at 400-450F. This made our homes smell outstanding. Char would add smokiness and seemed to clean up some of harshness.
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Wood - less is more
Shown above, its easy to over wood the spirit. For one 750mL bottle of spirits, we used 7x American White Oak tiles 1.0" x 0.5" x 1/4" in dimension. They were actual barrel staves that we chopped with a chop saw. We experimented with other woods, but American White Oak seemed easier to market so we did most of our work with that.
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Controlling heat
We targeted roughly 60C for processing. This is lower than the ethanol boiling point and clearly had a massive impact on wood dissolution rates and character development. It's also lower than the boiling point of ethyl acetate (one of the primary flavors in mature spirits) but both alcohol and other mature flavors will leave the system if it's heated without a good closure.
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Vinegar
Acetic acid formation takes place as wood breaks down when oxidized in the place of ethanol, turns to ethyl acetate -- this is one of the rate limiting steps for maturation. Other carboxylic acids turn to other flavors the same way. We never sold anything treated with acetic acid but we thought it tasted better. If you want to accelerate the process turn this lever. 10mL of vinegar per 750mL of spirit.
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Let it breathe
In order for spirits to mature they need dissolved oxygen in them. The way to maximize this is to sparge the liquid with oxygen or air at cold temperatures. Of course, this will then heat up and some oxygen reacts and other oxygen will evaporate from the liquid. Repeat this often enough in the presence of properly treated wood, and you'll get an awesome outcome.