This article is part of a series of blogs which are aimed at helping you choose the best coffee grinder for espresso and for your specific business. So if you find this article useful, we would recommend you read the whole series of articles starting from part 1.
Function – Adjusting the grind size. Traditional Grind Ring Vs Grinding Adjustment Knob
Having the ability to adjust the size of the grind particles that your coffee grinder produces is critical to the extraction of the espresso. When we use the tamper to compact the dose of coffee, the grinds are squeezed together in the basket. But even after a firm tamp there are tiny gaps between the coffee grinds. It’s these gaps that the water is pumped through by the espresso machine, whilst it saturates the grinds and takes with it, the coffee that ends up in the cup.
Here’s the important bit. The larger the grind particles are, the bigger the gaps will be between them, after tamping.
These larger spaces allow the water to flow through the coffee faster and subsequently reduce the amount of time that the coffee is in contact with the water. This reduces the extraction because a smaller percentage of the coffee bean will be dissolved into the water. So to reduce the extraction, the contact time (extraction time) should be reduced by grinding the coffee particles larger and to increase the extraction the contact time should be increased by grinding the coffee particles finer.
Your coffee roaster can provide you with the ideal extraction time for their coffee (usually between 25-40 seconds).
If you have an espresso grinder that easily allows you to adjust the grind size you can make sure the advice is followed and your espresso is served, as intended by your coffee roaster.
Espresso extraction is another topic to discuss, something I will leave for another day! But in simple terms, Under extracted espresso is watery and sour tasting. Whilst over extracted coffee has plenty of body it is overwhelmed by bitterness. When you get the extraction just right, (assuming the coffee is good quality and roasted with care), the cup will have the perfect balance of saltiness, sourness, sweetness and bitterness. The kind of espresso that your customers will pay a premium for.
Traditional Grind Ring
The traditional grind ring is found on all of our Mazzer grinders, including the Manual and On-Demand versions.
The grind ring screws into the main body of the grinder. Upon doing so, it pushes the top burr downwards and closer to the bottom burr, reducing the gap between the burrs and reducing the grind size. To increase the grind size the grind ring is turned clockwise which moves the burrs further apart. If you keep turning the grind ring clockwise it can eventually be removed. To those of you who have noticed – Yes it is a reverse thread!
Another significant point to make is that with a Traditional grind ring, the burrs are angled horizontally, and once the coffee is ground, it is pushed out of the grinder horizontally.
Traditional Grind Ring Diagram – Based on Mazzer Super Jolly On-Demand
Positives of a Traditional Grind Ring
Price – The simple nature of the Grind ring makes freshly grinding coffee for espresso affordable for all businesses. The manual grinder is included in all of our rental packages at no extra cost. It can be upgraded to the on-demand version for the price of 2 coffee’s per week. It is a professional grinding system that has been used for decades.
Reliability – Although there is a learning curve to navigate, once your baristas have the knowledge and skills necessary, their simple design makes traditional grind rings are as reliable as any of the more recent grind adjustment solutions. There are over a million Mazzer (traditional grind ring) espresso grinders in use worldwide for good reason.
Negatives of a Traditional Grind Ring
The grind ring can become stiff to turn – Over time, coffee grinds are likely to work their way between the thread of the grind ring. This can cause the grind ring to become stiff to adjust. The grind ring stick gives the barista extra leverage, but eventually the grind ring needs to be removed and the thread cleaned out. Our engineers are available to help with this. Just give us a call using the telephone number on the grinder and we will be with you to help!
Horizontally angled burrs require more maintenance and cleaning – This is because the coffee that enters the grind chamber has to be pushed horizontally out of the chamber and throat by the following grinds. So when the grinder stops, there will always be some grinds retained in the chamber, between the burrs and in the throat of the grinder. I.e. The grinds will not simply fall out of the grind chamber.
This can lead to the following problems:
The grinder will eventually jam. The grind chamber will become clogged with compressed grinds and require cleaning. This involves completely unscrewing and removing the grind ring. The barista can then clean the chamber, burrs and thread between grind ring and chamber. This process only takes 10-15 minutes but it requires a certain level of confidence and the grind ring can tricky to reassemble.
Important – The grinder MUST be turned off AND unplugged from the power supply before removing the grind ring. The exposed burrs could cause serious injury if they are accidentally turned on during the cleaning process! Take time to explain this to your colleagues. After unplugging the grinder, follow the cable to the grinder to make sure you have disconnected the correct electrical device. If in doubt give us a call. We can send an engineer to clean out the grind chamber for you. There is no charge for this.
Large bean fragments can get stuck between the burrs. If the ring is turned clockwise until there is a large gap between the burrs, large bean fragments can fall between the burrs. These trapped bean fragments will then stop the barista from closing the gap when setting the grind size. The solution is simple. Turn the grinder on whilst closing the gap and the large fragments will be ground into smaller particles and out of the way.
The throat of the grinder will always be full of ground coffee. The throat of the Mazzer Super Jolly grinder holds approximately 2.5 grams of coffee. If the coffee is ground very fine, or has a high moisture content this is another point in the grinder that can cause a blockage and disrupt your service.
After making a grind adjustment, the new grind size needs to be tested by pulling a shot of espresso and timing the extraction. But before this, the coffee grinds that were retained in the chamber and throat need to be pushed out of the grinder and discarded. Why? Because they were ground before the adjustment was made! So if they make up part of the dose that is tested, the extraction time will be falsified and could be misleading. The Mazzer grinders hold approximately 2.5 grams in the throat, but the barista is likely to purge more than this to make sure the new grind size is coming through. The extra grounds that are discarded can add up if the baristas are making regular grind adjustments, increasing wastage and your coffee bills.
The grind size need to be re-set every time the grind ring is removed – To remove the grind ring for cleaning it needs to be continually turned clockwise, until it can be removed. This means that once the chamber is clean and the grind ring is screwed back, the grind size will need to be re-established. The best way to do this is to mark the grind ring at the front with a sharpie to remind you where it was positioned. For an alternative method check out this video on our website – beginners guide to adjusting a Mazzer on demand grinder.
Traditional grind rings are used on many different coffee grinders, in many coffee shops and businesses worldwide. They are tried, tested and approved by coffee professionals because of their reliability. Once the barista understands how to work with these professional work horses, they are an excellent addition to any coffee bar. If you are concerned about the negatives I have discussed in this article, our Full care Service may be just the ticket. We can usually get your barista back on track in a few minutes over the telephone, but when needed, an engineer will be with you within a couple of hours to help. There’s no extra charge for this, it’s all included in our Full Care Rental Service.