Innovation: Fermenting made easy!


iSanta comes early this year, and he brings loads of innovations! In the coming weeks we’ll inform you on what we  have concocted to disrupt the distilling industry some more. In the coming weeks we’ll be introducing new technology that will make your life as a craft distiller easier.

Last week, we kicked of with the new iStill Mashers. Please see the following link for more information: Today, let’s take a look one step downstream, at what may well be the most important part in the alcohol production process: fermenting.

Spoiler alert! We are not just going to talk about fermenting, but we are also introducing the all new iStill Fermenter! You know what? Let’s start with a picture of this amazing new machine …


In this Blog post let’s first look at what fermentation is al about. Then, as a next step, we can draw up specifications on what constitutes a well-designed fermentation vessel. Last, let’s take a closer look at the all new iStill Fermenter.

What is fermenting?

Where mashing is about turning starch into fermentable sugars, fermentation is about yeast consuming those sugars and turning them into alcohol. Right? No, not really. Even though most distillers would answer the question “What is fermenting?”with a focus on the alcohol production process, that is only half of the answer.

Yes, of course, fermenting is the step where the actual alcohol is produced. And, no, that is not the most important role fermentation plays in the craft spirits production process. So what is? Flavor production! Fermentation is where 80 – 100% of your flavors develop. And that is key! Not the quantity of alcohol produced, but the quality. You are competing with Big Alcohol on taste levels, not on production levels. Craft distilling is conquering the market one glass, one bottle at a time.

The key to your craft distillery becoming successful at producing top shelf product is fermentation. Fermentation is where flavor is created. Fermentation is where you can make the difference … but only if you have perfect control over the alcohol and flavor production processes. So … alcohol production and flavor production, how does that work?

Fermentation as alcohol production process

The more sugar-rich the mash is, the higher the expected alcohol percentage at the end of the fermentation. Yeast consumes the sugars and turns it into alcohol. More sugars result in a bigger alcohol yield.

If we want to control the alcohol production part of fermentation, we need insight. Insight in the (remaining) sugar content AKA specific gravity of the fermentation. When we know specific gravity (SG), we know where we are in the alcohol production process and when the alcohol production process will finish. A drop in specific gravity (SG) means part of the sugar is already consumed and turned into alcohol. When the SG reaches zero on remaining sugar content, we know fermentation (as an alcohol production process) is done.

Of course, during the alcohol production phase a lot of CO2 is also produced. This gives you an indication that there is still fermentation activity going on, but it does not tell you where in the process the fermentation is or what kind of fermentation stopping emergencies you may have run into.

Fermentation as flavor production process

Over 80% of the flavor of your drink (or new make spirit AKA white dog) is made during fermentation. Basically, we can group the flavors in three factions:

  1. Base substrate flavors (e.g. grainy flavors in whiskey, molasse flavors in rum);
  2. Fruity flavors;
  3. Root-like and nutty flavors.

Base substrate flavors can be highlighted by a prolonged fermentation. Longer fermentation (even though bad for yield per production day) creates more flavors overall.

Fruity flavors can be highlighted via warmer fermentations. A warmer fermentation creates more fruity flavors.

Root-like and nutty flavors are underlined by more sour fermentations. A very sour fermentation creates more root-like and nutty flavors than a more neutral pH ferment.

Every drink has a specific flavor profile, with an emphasis on taste intensity, fruity flavors, and more root-like, nutty flavors. For instance, fruit brandy has a strong emphasis on fruity flavors. Single malt whisky and pot distilled rum have an emphasis on root-like and nutty flavors. Do you start to see why fermentation is so important?

What’s important in a fermenter?

Given the above, what does the (informed) craft distiller look for in a fermenter? Given the above, an IBC or tote may not be optimal, sure, you got that. But what is?

Fermenting fosters two processes. Alcohol production and (most importantly) flavor production. It therefore makes sense to expect any fermenter to give you information on time, temperature, pH, and SG. Insight in these parameters allows you perfect control over the alcohol and flavor production processes. Perfect control for spirits that have amazing, intense, and correct flavor profiles.

Specific Gravity or SG tells you where your fermentation is at from an alcohol production point of view. pH tells you how sour your fermentation is running, which in term helps you manage root-like and nutty flavors. Temperature management allows you to create more or less fruity flavors. And if you let your ferments take longer, you will highlight more of the substrate the spirit is made from.

Summary? Long story short? If you put fermentation center stage (as you should!) your fermenters better offer control over the alcohol and flavor production parameters, so you can create the best possible spirits!

Control has a secondary benefit and that’s ease of use. Knowing what’s going on lets you know what needs to be done. Ease of use is further enhanced by designs that make filling and emptying easy. You shouldn’t have to take care of your fermenter. Instead, your fermenter should take care of you. And of making the best possible distillers wines and beers in the world.

Efficiency is important too. Ferments create a lot of heat. The more efficient the cooling is, the less money you loose on cooling water.

Longevity, last but not least, is another topic on which fermenters should score high. If (controlled) fermenting sits at the center of successful spirits production, the craft distiller better makes sure he invests in equipment that does not break down and is build to last.

What technology is currently available?

Looking around at what’s available, fermenter-wise, is disappointing. Let me share our findings:

  1. Control. Existing fermenter technology offers either no control or (poor) temperature control. Time control, pH control, SG control are absent;
  2. Ease of use. Filling is often only possible through the top manhole, meaning one has to climb up. Fermenters in general discharge close to the ground, creating bottle necks during clean-out. Insight, computers, automated fermentation programs are not available;
  3. Efficiency. Most units use double boilers for cooling. Indirect cooling is inefficient, a waste of money and water.
  4. Longevity. Our research shows that most fermenters are made of 0.7 to 1.7 mm thick stainless steel. That is thin, way too thin! We understand that thinner sheeting makes a fermenter cheaper, but our material expertise lets us conclude it is a trade-off you don’t want to make.

So, understanding what makes for successful ferments, and what a good fermenter should offer, made looking at what was available in the market space a very disappointing experience. Our thoughts? Let’s make things better. Let fermentation take its place center stage. As the distiller’s most important access to flavor creation and spirit expression, fermentation deserves that spot. And as a (wannabe) successful craft distiller, you deserve the equipment to help get you there.

The iStill Fermenter

With the goal of making fermenting top shelf spirits easier, iStill now introduces next generation fermenters. In 5,000 and 2,000 liter net capacity. Here is a picture of the 5,000 liter model:


And here’s what makes our new iStill Fermenters nextgen and unique. Using the same coatrack applied when judging current fermentation technology, we can differentiate between:

  1. Control;
  2. Ease of operation;
  3. Efficiency;
  4. Longevity.


The nextgen iStill Fermenters offer:

  • Time control, that allows you to dial in how long and in how many steps you want to ferment. Important for substrate flavor control;
  • Temperature control (0.1 degree accuracy), both with automated cooling and heating, for control over fruity flavors;
  • pH control (0.1 pH accuracy) for the expression of root-like and nutty flavors;
  • SG control for insight in the alcohol production part of the fermentation process.

Ease of operation

The iStill Fermenters can be ordered fully automated. After you dial in your fermentation procedure, you just press “Start” and the machine does the whole fermentation process for you.

The iStill Fermenters are connected to the internet. This way you can remotely supervise and control your ferment. It also allows us to upload new software or perform remote checks, future-proofing your distillery.

The iFermenters come with push messaging, whenever certain parameters (like temperature, time or pH) run out of their pre-set values.

Our Fermenter comes with automated programs for Brandy, Bourbon, Fruit Brandy, Rum, Vodka, and Whisky. Each program helps create those flavors you are looking for, given the specific spirit category you want to make.

The iStill Fermenter comes with two big manholes. One at the top (for filling) and one near the bottom (for easy access). The PLC is operated via a touch screen or via your smartphone or computer.

Another unique feature the new iStill Fermenter has, is the Easy Discharge Center. The unit sits, as it were, on stalks. This creates a high and easy access discharge exit. You can easily forklift a receiver/container under the actual boiler for easy cleaning and grain handling. Lastly, it has Easy Filling Connect. Just connect a hose to the connect and you can start filling your Fermenter with either water or mash.

Easy Discharge Center …



Due to its compact design, unique indirect heater, insulation, and direct cooling, the all new iStill Fermenter is the most efficient fermenter in the world.

Both sizes, the 2000 and 5000, can be additionally equipped with the patented Jet Propulsion Agitator System (J-PAS). Together with the flush square boiler design, it helps prevent shearing, which leads to better mixing efficiency, better particle distribution, and optimal heat distribution in your ferment. The system counteracts vortex formation too, resulting in higher fill grades, easier cleaning, and no unwanted oxygen addition.


Most fermenters are made out of 0.7 to 1.7 mm thick steel. Since we feel fermenting is THE essential step in your flavor production process, we decided to beef-up design specifications.

Our fermenters use 3 to 5 mm thick stainless steel. They are build to last! The sides are insulated and the insulation is armored for heavy duty use.

The actual tank is suspended in a strong, stainless steel skid. The skid acts as an exoskeleton that protects your fermenter, and that allows for side-by-side operation of multiple mashers and/or fermenters.


iStill Fermenter 5000:

  • 5,000 liter net capacity;
  • Insulated flush square boiler design;
  • Weight: 950 kilo;
  • Sizes: 170x170x320 (wide, deep, high, in centimeters, J-PAS adds 50 to height);
  • Power: 6.75 kW;
  • iStill Boiler Radiator for direct (instead of indirect) cooling;
  • Manholes: 40/60 cm diameter, one at top, one near bottom;
  • Supports on the grain, potato or pulp fermentations;
  • Patented indirect heater system;
  • PLC system and touch screen computer (option), with:
  • Automated fermenting programs;
  • Time, pH, temp, agitator, and SG control, and with:
  • Internet connectivity, smartphone & computer management and control;
  • Easy Fill Connect and Easy Discharge Center;
  • J-PAS variable speed mixing technology (option);
  • Optional: WiFi.

iStill Fermenter 2000:

  • 2,000 liter net capacity;
  • Insulated flush square boiler design;
  • Weight: 600 kilo;
  • Sizes: 130x130x230 (wide, deep, high, in centimeters, J-PAS adds 50 to height);
  • Power: 6.75 kW;
  • iStill Boiler Radiator for direct (instead of indirect) cooling;
  • Manholes: 30/50 cm diameter, one at top, one near bottom;
  • Supports on the grain, potato or pulp fermentations;
  • Patented indirect heater system;
  • PLC system and touch screen computer (option), with:
  • Automated fermenting programs, with:
  • Time, pH, temp, agitator, and SG control, and with:
  • Internet connectivity, smartphone & computer management and control;
  • Easy Fill Connect and Easy Discharge Center;
  • J-PAS variable speed mixing technology (option);
  • Optional: WiFi.


The iStill Fermenters come in two sizes: 2000 and 5000 liter. Each size can be ordered “naked” as well as fully automated. The fully automated versions have the J-Pas mixing technology and WiFi as additional options.

The iStill Fermenter 5000 “Naked” costs EUR 20.000. The iStill Fermenter 2000 “Naked” costs EUR 15.000,-. It has screw-in ducts for heaters and controls (such as temperature), and it comes with the iStill Boiler Radiator, that can be used for both cooling and heating.

The fully automated iStill Fermenter 5000 costs EUR 25.000. The iStill Fermenter 2000, fully automated, costs EUR 20.000. The J-PAS mixing system adds EUR 7.500 to the price of the 5000 liter model and EUR 5.000 to the 2000 liter model. WiFi (instead of internet connection via a cable) adds EUR 1.000 to the bill.


The iStill Fermenter comes in the sizes 2,000 and 5,000 liters. We could probably build them smaller, but why would you want that? Pricing will only go down marginally, and in order to make a living out of producing your own alcohol … well … there is no substitute for cubic inches.

This is the second of a new line of innovations. The iStill Masher got introduced first and optimizes the first step of your alcohol production process: starch to fermentable sugar conversion. The all new nextgen fermenters perform the next step, where sugars are converted to alcohol and flavors are formed. What’s next? Well, distilling of course. Pump the beer or wine you just created into your iStill and concentrate and harvest the flavors you are looking for.

Delivery and availability

We are currently building the first iStill Fermenters. Orders or requests for information can be placed via Current lead time is 1 month for the naked-series and 3 months for the fully automated one.

Our online design center ( will be updated for the iStill Fermenter in just a week from now.

Building a new batch of iStill Fermenters as we speak …


One thought on “Innovation: Fermenting made easy!

  1. Pingback: Building New iStill Fermenters! | The iStill Blog

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