During the industrial coffee grinding process—also known as milling—coffee beans are processed into smaller particles to make the brewing process faster, easier and tastier. The taste of the coffee depends on how fine the coffee is ground. Additionally, the fineness of the ground will also dictate the method of brewing.
Coarse Coffee Grounds versus Fine Coffee Grounds
For example, any brewing methods that involve exposing the grounds of coffee to heated or hot water for a longer period of time will require a coarser grind so that full flavor extraction can take place before the coffee becomes too small. For faster brewing methods, a finer ground is preferable since the flavor extraction process occurs at a faster rate than exposure reduction. If a coffee bean is too finely ground for a particular brewing method, there will be too much surface area exposed to the hot water which results in a bitter and harsh tasting coffee known as “over-extracted.”
On the other hand, if the grind is too coarse, unless an abundance of coffee is used, the result will be lackluster, weak-tasting coffee. As such, with both extremes producing undesirable results, the best option for industrial coffee grinding machines is to produce a uniform grind that is consistent with the brewing method to be used.
Some other things to note:
- Shorter brewing time for finely ground coffee is acceptable during brewing methods where the exposure of the grind to the hot water is adjustable
- Blade grinders are not used often in industrial coffee grinding because they cause a heat buildup due to friction
- Fine grinds provide the most effective extraction method but can also slow down the screening and filtration process
The Four Major Types of Industrial Coffee Grinding
There are four major methods of industrial coffee grinding: burr-grinding, chopping, pounding, and roller grinding. Depending on which type of industrial coffee grinding machine you use, it will affect the way that you have to brew the coffee as well as the final product (i.e. flavor, yield, strength, etc.).
1. Burr-grinding. An industrial burr mill grinder will use two wheels or conical grinding elements to crush the coffee beans. These abrasive grinders tear the coffee beans apart with little to no frictional heating. During this process, the coffee bean’s oils are released meaning that they are easier to extract during the infusion process. This makes for a richer and smoother tasting coffee. Burr-grinding machines typically produce a uniform grind which is adjustable depending on how far apart the abrasive wheels or cones are placed. This uniform grind results in better extraction during brewing while avoiding filter clogging from fine particles. Burr-grinding machines are excellent for producing grinds that can be used in a number of different brewing processes such as percolators, French press, drip, espresso, etc.
Generally speaking, most conical burr grinding machines have steel burrs that can be effective at low RPMs (500 RPMs) in order to preserve the most aroma in the bean thanks to lower frictional heating. These conical burr grinders are also quieter and are less likely to get clogged with coffee ground than disc grinders. Disc grinders also rotate faster than conical burr-grinding machines, producing more frictional heating and less aroma. Of course, disc grinding machines are cheaper than conical grinders, but aren’t recommended for high-output industrial coffee grinding operations.
2. Chopping. Chopping coffee bean machines are operated by a high-speed blade or propeller grinder that runs at around 20,000 to 30,000 RPM. While these types of coffee grinding machines are cheaper than burr-grinding machines, they don’t produce a uniform grind. This leaves with a wide variety of coffee ground size particles, making it harder to get a good brew. Generally speaking, the industrial coffee grinding process is made far more difficult with chopping-type coffee grinders, though it will be cheaper. Plus, since the coffee grind is heated with friction, it makes the final product even lower quality. For industrial coffee grinding processes that are looking to lower costs without worrying about clogging up brewers or producing an inferior cup of coffee, this is the method—needless to say, this isn’t a good thing.
3. Pounding. There are some types of coffee, mainly Arabic and Turkish coffee—that require a fine powder type of ground. This type of grind is unattainable by most burr-grinding industrial coffee machines, and must then be pounded by mortar and pestle to create the fineness needed. There are a few options for how to achieve this, though an industrial coffee grinding process will have to take the costs into account.
4. Roller Grinding. Roller grinding during industrial coffee grinding simply involves passing the coffee beans through a pair of corrugated rollers. While their size and cost make them attractive for industrial grinding operations, the result is a wide size difference in grind as well as higher frictional heating. To avoid this, some industrial coffee grinding processes turn to water-cooled roller grinders.
To find the right industrial coffee grinding process for your exact needs, visit http://www.mpechicago.com/coffee/ right now.
This article is contributed by Max Weber who writes for Modern Process Equipment Corporation. Founded in 1957 with worldwide headquarters in Chicago, MPE is the undisputed leader in the design and manufacturing of coffee grinding and related processing equipment. You can reach them using their Contact Us page.
Featured image by David Dewitt