Though the espresso coffee grinder is an essential component of every espresso bar, its periodic maintenance is often overlooked. Generally the espresso grinder is a durable piece of equipment, but skipping the minimum amount of service it requires will not only lead to frustration on the operator's part, but to bitter coffee tastes and, ultimately, less profits for your cafe.
In this month's column, we will examine the weekly servicing of three components that, when properly performed, will keep it functioning for years to come. The five minutes that you or your employees spend each day or week can save you hours of work down the road.
The basic purpose of the espresso grinder is to provide a consistent and efficient method of grinding and dosing your coffee. Although one or two pulls of the doser handle form the extent of most people's interaction with the machine, it's actually two metal blades inside the grinder that do all the work. These two blades are essentially two metal discs with sharpened surfaces. Although they range in size depending on your grinder make and model, the purpose is ultimately to grind your coffee beans.
It's important to discuss and understand the grinding blades, or - as they are more commonly referred to - grinder burrs. As coffee beans enter through the bean hopper, they pass over the surfaces of the burrs. These burrs are usually one of two types: flat or conical. Flat burrs are the more common of the two styles and are used at most espresso bars. High-volume bars, however, will sometimes switch to the more expensive conical burr grinder.
Flat burrs are, as the name suggests, flat. They have a cutting surface on one side and are placed in opposing positions in the grinder. Generally, one burr is in a fixed position while the other is attached to the motor. The motor engages the attached burr at an average of 800-1500 revolutions per minute (RPM).
The conical grinder is shaped, also as its name suggests, like a cone. In addition to having a different burr style, the conical grinder's motor spins at a much slower speed. This is usually at about 500-700 RPMs. Regardless of the style your espresso bar uses, each grinder type requires cleaning, maintenance and burr replacement.
The cleaning and maintenance of grinder burrs can be broken down into two categories: preventative and replacement. Preventative maintenance involves removing the bean hopper and cleaning out the grinding area with a brush and soft cloth. You should also clean the threads of the adjustment collar to make it easier to adjust the grind and to avoid cross threading the collar upon replacement.
Replacing the grinder burrs is easy - it involves only some patience, a screwdriver and some new burrs from your local service representative. Grinder burrs should be replaced after grinding approximately 800 pounds of coffee beans. This is the average life of burrs, however, and not a rule of thumb. If you notice your shots becoming inconsistent and bitter, or you have difficulty maintaining a proper grind, look into a new set of burrs. Dull burrs will crush your coffee rather than grind it and will generate excessive amounts of heat. This heat damages the flavor of the ground coffee. It also forces the grinder to work overtime. All you'll be left with in the end is a bad grind and a grinder with a short lifespan.
The second component of the grinder that requires specific attention is the doser compartment. The doser compartment is where the coffee is stored after is has been ground by the burrs. The function of the doser compartment is to allow the ground coffee to be delivered consistently and efficiently. You can clean the compartment with a soft bristle brush to remove the built-up coffee grounds and coffee oils. This simple cleaning will improve the taste of your coffee and preserve the life of your grinder.