I don’t like vacuum distillation. The process of vacuum distillation is cumbersome, the yield is low, and the costs are high. And the benefits? Do they weigh up to the downsides? Let’s dive in deeper. And hold on to your seats: in this post I am going to trash vacuum distillation, because the only fate it deserves is that it stops playing ANY role in craft distilling AT ALL. Why? Allow me to elaborate …
The way vacuum distillation works
In the process of vacuum distillation, one lowers the air pressure inside the distillation system in order to distill at lower temperatures. Lower air pressure equals an earlier boil. An earlier boil equals a lower boiling point. The bigger the vacuum induced, the lower the boiling point at which the distillation run takes place.
Vacuum distillation takes place in a glass set-up with an “Au Bain, Marie!’ oil bath for heating, cold water for cooling, and a vacuum pump to lower the air pressure. The system is both complex, often with extensive automated controls, and fragile.
The vacuum still is a complex assembly of fragile glass parts …
A cumbersome process
As the air pressure drops, and the vacuum builds, the resistance in the vapor path drops. As a result, two processes take place that make vacuum distillation hard to do in a consistent manner.
Firstly, lower air resistance, and lower overall boiling points, result in heads, hearts, and tails factions (and their associated flavors) smearing into one another. This limits the use of a vacuum distillation protocol to mostly single ingredient distillation.
Secondly, the lower resistance “sucks” over fluid from the boiler into the distillate. This is called “bumping” and it is even worse than the smearing discussed in the paragraph above. Why? Well, it means not all of your distillate is actually distilled. Part of it is easily contaminated with stillage.
Since vacuum distillation takes place in a glass set-up, and since glass blowers can only blow to a certain size, these units are small. One, two, maybe five liters. The commercial ones can be 20, 30, or 50 liters. But that’s it.
Processing a maximum net boiler filling of – say – 20 liters in a 50 liter glass boiler (you want to underfill instead of overfill in order to prevent “bumping” as much as possible), results in maybe 10 liters of product. That’s not much. It might be enough for a boutique distillery experience, but not for a craft distillery that aims to produce commercially viable amounts.
A commercially sized 20, 30, or 50 liter vacuum distillation set-up easily costs you EUR 500.000,-. Yes, you read that correctly: 500 grand. Five hundred grand!!! Half a million Euro’s … to fancily make maybe 10 liters of essence or extract per run!
“Commercial” grade vacuum distillation set-up …
The acclaimed benefits of vacuum distillation? Well, boiling at lower temperatures, or distilling at lower temperatures, limits the chance of overcooking the ingredient in question. And as some ingredients are more prone to overcooking than others, some ingredients benefit more from lower temperature flavor extraction. What comes to the rescue? Vacuum distillation! Well, sort of.
How iStill helps
iStill makes distilling easier. Via the dispersion of our knowledge and ground-breaking technologies, we empower the craft distilling industry. We do so, one step at a time.
One of the first things, for instance, that annoyed me, was the practice that most manufacturers use, of selling multiple stills to one customer. A still for stripping and another one for finishing. One still for gin, another one for vodka. Nice business model for that manufacturer, but how does overselling empower your customers, the craft distillers? Right, it doesn’t. It is (was) a self-serving practice instead of an industry-serving approach to business. What iStill did? We designed a still that can make any product to perfection. A still that can strip and finish, even in one run, in order to help save you time and money.
Another practice we exposed was mandatory spare parts purchasing. Traditional suppliers intentionally manufacture their stills in such a way that – usually within a few years – parts need to be replaced. As mr. Mueller told me at the first London Craft Distilling Expo, now some 7 years ago: “That’s how you make money! You make customers come back to buy new parts!” He added to that, that – since iStill produces machines that are over-engineered and do not break down – we would never become a competitor of them. Stills that are designed to run forever do not result in returning customers, he felt.
Mandatory spare parts purchasing … how’s that for a business model, right? Is it self-serving or industry-serving? If I inform you that we have grown to over twice the size of Mueller, the answer of what business model YOU prefer becomes evident.
Now onwards to vacuum distillation, and its manufacturers that try to make money at your expense as well. How do we help there? We help by providing you with the distilling industry’s best cold extraction device: the iStill Extractor.
The iStill Extractor doesn’t just offer low boiling point extraction, no, instead it offers NO BOIL cold extraction. No cooking means no risk of overcooking an ingredient. No risk at all. And more use cases: the iStill Extractor can make essences, extracts, tinctures, and liqueurs. It’s not a one trick pony, like a vacuum distillation device. What the iStill Extractor also offsets are the negatives associated with vacuum distillation.
So it offers all the benefits and more, and it corrects the wrongs? Yes, and here’s how:
The way the iStill Extractor works
The iStill produces alcohol at a specific strength. That alcohol is directed towards the extraction chamber. The herbs, fruits, berries, etc. sit in the extraction chamber. The alcohol extracts the flavors and colors from the ingredients and automatically syphons the resulting Extract back to the boiler. The iStill can be used to either extract a new batch, or to process the Extract into a distilled Essence.
Here’s the iStill 500 (left) with Extractor (right) …
An easy process
Since the iStill Extractor works at normal atmospheric conditions, it is not only safer, but also easier to operate. No smearing. No bumping. It can be used to process one ingredient or a complete batch of various (for instance) gin or spiced rum ingredients.
Where the “traditional” vacuum distillation set-up yields 10 liters of essence or extract from a 50 liter boiler, our technology has much higher yields. Even our smallest commercial iStill Extractor has a net capacity of 25 liters. That’s bigger than the 20 liter net capacity of the biggest vacuum distillation devices.
But there is more. With the 25 liter iStill Extractor, one can produce up to 100 liter of Extract and 50 liters of Essence. That’s 10x to 5x more yield! A five to ten times higher yield on our SMALLEST Extractor! Please note we also make iStill Extractors in 100 and 500 liter sizes, pushing output into the hundreds and thousands of liters per run. Thousands of liters instead of maybe 10 liters …
The best process is no process. The best part is no part. The best solution to any problem is usually the simplest solution. First principles thinking allows us to invent solutions that are simple and effective.
Simple designs improve longevity and slash development and production costs, where complex designs compromise longevity while adding costs. The iStill Extractor is a fine example of how that philosophy plays out in real life craft distilling.
Our 25 liter Extractor costs EUR 5.000,-. That’s 1% of the price of a “commercial” vacuum still. Up to 10 times the yield for 1% of the costs. How’s that for a game changer?
Vacuum distillation sucks. Our Extractor technology is designed to replace it.
At your service,
On behalf of the iStill Team,
Dr. H.E.J. (Odin) van Eijk, MScBA, etc.
Founder & CEO of iStill.
I’m fairly confident that vacuum distillation requires a round bottom flask attached to a distillation head and condensor with a receiving flask. What you have described seems to be referred to colloquially as “rotovapping” in literature you may see “solvent was removed under reduced pressure” or “product was concentrated under reduced pressure”. It is not best to use this device to distill your desired compounds, but rather remove solvent from pure solutions or dissolved/suspended mixtures.