Quite often, when you are new to homebrewing, you can underestimate the importance of the yeast you add to your beer for fermentation.
Most beginning homebrewers, and many more advanced brewers, don’t pitch enough healthy yeast.
The kits many of us start out with come with just a sachet of generic yeast which we are told to sprinkle over the top of our wort.
Sometimes it won’t be enough yeast, especially for larger batches, and the yeast may not be as active as it should be or it may not have enough active yeast cells.
The results can be a stuck fermentation, the low pitching rate causing an infection that spoils the batch of beer causing it to have a higher final gravity than you expected.
In some cases, too low a pitch rate of active yeast may cause off-flavors as a result of excess byproducts such as sulphur compounds, those dreaded diacetyls, fusel alcohols, and fruity esters during fermentation.
Making a yeast starter is one of the most efficient and easy ways of improving the quality of your homebrew.
A yeast starter can help you grow much higher active cell counts for a faster fermentation where the yeast will out-compete all the other organisms in the fermentation stage.
Yet many homebrewers overlook this stage, both beginners and the more expert homebrewers, arguing they simply don’t have time.
Hey, we’re busy guys, and the brew day is already long enough without adding an extra task!
Enter the stir plate, a simple device that can help minimize the work involved in making a yeast starter while optimizing the effectiveness of your yeast during fermentation, and it can save you money too!
Not only that, a good healthy pitch of yeast will lower the risk of infections, make better-tasting beer, and increase the speed of the fermentation process to completion.
What Is a Stir Plate?
Basically, a stir plate is a magnetic stirrer device that is used for stirring liquids constantly.
You may have previously come across one in High School Chemistry lessons, but we are not talking complicated chemistry experiments, just a simple motion that can make a more efficient yeast starter for home brewing.
A stir plate has an electromagnet at its base which spins on a small cylinder at various stirring speeds and is ideal for continuous stirring for longer periods.
A stir bar goes inside your flask of yeast starter which, once the electromagnet is activated, stirs the liquid without any need for further manual intervention.
A good stir plate will help aerate the yeast and force out any excess CO2. The extra oxygen will help to aerate your wort which is vital for healthy yeast propagation.
Many homebrewers would argue that a stir plate isn’t an essential piece of brewing equipment and that they have had decent results by stirring a yeast starter by hand and then shaking in a one-gallon carboy method every five minutes or so or whenever passing by.
The Benefits of a Stir Plate?
It doesn’t matter whether you are using the freshest yeast possible or a favorite strain you have recovered from a previous brew via a yeast-washing process – if the yeast stagnates your starter simply will not work.
To get the most from a yeast starter you need to keep the yeast moving to oxygenate it and build up a healthy population of yeast cells.
The ceramic-coated bar of magnetic metal which is called the stir bar or stirrer spins inside the liquid flask in response to the electromagnet of the stir plate base and causes an active vortex that keeps the yeast in suspension.
It is a continuous operation of stirring that you can simply set to spin and forget about, as opposed to a shake of the starter container every hour or two.
The continuous vortex dramatically improves the aeration and pushes out more of the unwanted CO2. Having more oxygen to use as fuel, the yeast cells will ramp up their reproduction.
It saves you time, as the cells will reproduce much quicker, but the stir plate can also save you money as you will only need smaller yeast starters due to the fact that the cell count will be significantly higher.
Also, many liquid yeast packets sold don’t contain enough cells for an average batch of beer and it is recommended to use at least two packets in a 2-liter starter of most yeasts.
The extra reproduction of yeast cells caused by a stir plate can mean you only need one package of yeast on most occasions, saving you money over the long term.
Stir plates are available from most homebrew stores or online retailers and don’t need to cost the earth.
Although there are some industrial models out there, there are also plenty of budget-friendly options and entry-level models which come in at around $3 – you’ll get that money back on just the first few brews.
And your beer will hopefully taste much better.
If you’re feeling brave, and I know a lot of us homebrewers are also keen DIYers, you could even make your own stir plate using easy-to-find bits and pieces like an old hard drive from a PC, a cooling fan from a computer or similar device, and some magnets.
They are very simple to make. The only skill you really need is to be able to solder. I found a pretty good video on youtube which will give you the confidence you need to build your own stir plate.
Buying a Stir Plate – What To Consider
If you should decide to go down the route of buying a stir plate for homebrewing, there are endless options on the market.
It’s not always about money, but narrowing it down to the best stir plate for making a yeast starter can be a difficult task.
Here are a few hints about what you should look for:
Volume Capacity
All stir plates you can purchase will be rated for the volume of liquid they can efficiently stir. The maximum liters of liquid volume you will need is dependent on how much beer you brew at once.
Try to go for a larger capacity than you need ready for when you upscale your beer production.
Ideally, you only want to buy a stir plate once, as many of these functional units will last a lifetime with the proper use and maintenance. As a very minimum, choose a stir plate with a 1000ml capacity.
Also, when choosing a stir plate, ensure the magnetic stir bar is the correct size for your beaker so it doesn’t touch the sides of the liquid container.
Most magnetic stirrers are designed to be used with a vessel such as a 2-liter Erlenmeyer flask but, if your container is smaller, choose a smaller stir bar.
- Their uniform wall thickness provides the proper balance between mechanical strength and thermal shock resistance
Speed Control
Generally speaking, the faster a yeast starter spins the better with a more rapid growth of a healthy cell count. An adjustable speed control dial or digital speed adjustment can help you to reach speeds for a healthy fermentation.
A more powerful motor along with precise speed control can help adjust the speed according to the volume of liquid you need to mix.
An adjustable stirring speed also means you can experiment with a variety of speeds and achieve better results once you find the sweet spot.
Surface Dimensions
The actual size of the magnetic stir plate will affect the size of beaker or other vessels that you can use with your stir plate. A wide footprint with a larger diameter plate is essential if you are planning to make larger batches of beer at once.
Ideally, you will want all your yeast starter in one container ready to go for more consistent results.
Choosing a food-grade stir plate where the steel plate is generally covered with a ceramic will increase the stirrer’s resistance to corrosion.
Display
If you’re like me, you probably like to see clearly what’s going on at every stage of the brewing process, including making the yeast starter.
A digital display, normally found on the more expensive models, can let you know the exact speed of the stirrer and any other information you may need to know – such as the temperature of the liquid that you may need to optimize the process of making an efficient yeast starter.
At the very least the basic design should have an indicator light to let you know the equipment is powered on and running.
Timer
With our busy schedules, any automation or scheduling function a stir plate can offer will allow for fitting more activity into a shorter period of time.
Timers can help pre-set when the equipment turns on and starts operation to free up more of your time for other crucial brewing tasks.
Some stir plates even have timers that you can preset up to 48 hours in advance. Simply prepare your starter, ensure it is stored at the correct temperature, set the timer, and leave it while you prepare your mash and wort.
Favorite Homebrew Stir Plates reviewed
Best Overall – Northern Brewer Maelstorm Stir Plate
- The first industrial-grade programmable stir plate designed specifically for yeast starters
- Five distinct speeds, from 480-1440 RPM, to accommodate yeast starters up to 5 gallons
- Scheduling function for up to 48 hours
Marketed as the first industrial-grade programmable stir plate designed specifically for yeast starters, the Northern Brewer Maelstorm is a high-end stir plate for those more advanced homebrewers who don’t like to compromise on the quality of their homebrew equipment, regardless of the cost.
With a maximum capacity of up to 5 gallons, you can choose from 5 different speeds from 480 rpm to 1440 rpm, with the powerful magnets offering all the stirring power you need for effective fermentation.
Loaded with features, it has an option for scheduling programs for up to 48 hours.
You could effectively set it to operate for up to 48 hours without the need for coming back every couple of hours to restart the program, as with some less advanced cheaper units.
This compact unit has a light body with a translucent stir plate which enables you to see the functioning of the powerful magnets. A stir bar of 50mm does its job of mixing well with an almost noiseless performance by ensuring the stir bar doesn’t hit the sides of the beaker, even at higher speeds.
The surface is also seamless and can be cleaned and maintained easily. the Northern Brewer Maelstorm Stir Plate is a powerful machine that has been designed especially for homebrewers by expert brewers.
It makes making a yeast starter easy and caters to every need of the brewer.
Best Budget Stir Plate – INTLLAB Magnetic Stirrer Stainless Steel Magnetic Mix with stir bar
- ✔ HIGH QUALITY - resistant 316 stainless steel top plate
- ✔ POWERFUL - up to 3000ml capacity, ideal for home brew yeast starters
- ✔ EASY USE - stepless adjustable stirring speed, speed regulation up to 3000 rpm
Although not as advanced as the Northern Brewer Maelstrom StirPlate, this basic model from INTLLAB is the epitome of strength, durability, and performance.
It’s much easier to use too, although it doesn’t quite give you the same control.
With a powerful motor that allows you to adjust the speed from 0 RPM to 3000 RPM via a rotary speed dial on the front of the compact unit, it can handle volumes up to 3000 ml, which is ideal for most homebrewers and their yeast starters.
A stainless steel plate is easy to clean and less susceptible to corrosion than many other lab-based stirring plates, with a powerful magnet under the base which works perfectly well.
it’s a small compact unit that is lightweight and easy to use straight out of the box. There’s hardly any learning curve with this basic model, just put the 25mm stir bar in your flask and set the speed to whatever desired speed you want.
There’s no digital speed display, so some of it will be guesswork until you find that sweet spot, and at higher speeds it can be slightly unbalanced with liquid often splashing over the top of the beaker or the stir bar hitting the sides of the vessel.
Be careful how long you operate it at high speed.
All in all a great stir plate for beginner Homebrewers at a competitive price.
Best Mid-range – Stir Starter Magnetic Yeast Starter Plate
if you’re not quite ready to splash out for an all-singing, all-dancing stir plate like the Northern Brewer model but want something a bit more upmarket from the budget INTLLAB stir plate, this model from Stir Starter is a perfect compromise and only $10 or $20 more to buy.
The Stir Starter Magnetic Yeast Starter plate is specifically designed for the homebrewer rather than some of the multipurpose lab stir plates that have been repurposed for brewing.
A 12V DC motor combines with dual action knife button magnets to provide a model with decent stirring power.
Although some of the cheaper stir plates are known to throw their magnetic stir bars at higher speeds, the Stir Starter has a relatively limited max RPM which means you can use it at full power with very few problems.
What I particularly liked about this functional model was the keeper magnet, which is included in the price and locks down the stir bar so you don’t accidentally pitch it into your fermenter along with the prepared starter.
A great option for beginner to intermediate homebrewers, the Stir Starter Magnetic Yeast Starter Plate is a functional unit at a great low price.
Final Thoughts
Magnetic plate stirrers are a huge advancement from the old-fashioned mechanical hand stirrers that many homebrewers often used to employ, and are definitely a step up from the shake-it method.
Most of the magnetic plate stirrers now commercially available are whisper quiet and can be left running overnight. Some can even be preprogrammed and just left to do their work.
If you are a keen DIYer then making your own stir plate can be a fun project, but there is a wide range of magnetic stir plates on the market to suit every budget and all levels of experience.
Hopefully, now you know your yield volume and budget, you can go out and get that first plate stirrer which should last you a lifetime of brewing.
Give those tired arms a rest and be assured that you will be able to recreate a perfect yeast starter every time.
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