Issue link: https://read.dmtmag.com/i/491374
52 STiR tea & coffee industry international sistency that resembles flour. The ideal diameter for K-Cups doubles again, to approximately 850 µm. "If you don't have consistent particle sizes, every cup will taste different and the customer will not be satisfied, said Bezjian. Consistency is why K-Cup and pour over single cup brewing have taken off so rapidly," "At MPE, we customize our grinders for each customer to optimize the internals and deliver the best grind size and density for each coffee capsule application, and we offer different designs for various K-Cup capsules and European-style capsules in the marketplace," said MPE's Will. "Faster brew times translate to optimized grind sizes with minimal margin for grind errors," he said. "The flavor of your coffee depends on the coffee grind size and profile, which is controlled by the grinder, as well as the amount of coffee used, which is related to the densifier. By altering the grinder vari- ables, you can change the taste and intensity of the coffee," according to Will. It is important not to make the grains impermeable, explains Karl Schmidt, president of Probat Burns in Chicago. Visualized on a Gauss curve, a small percentage of the grounds should be slightly larger and above the curve to facilitate flow and a small percentage should be finer to enhance extraction, he explains. This is critical with espresso machine capsules with brewers that exert 10+ bars of pressure. "You want to control "overs" and "fines" but not eliminate them," ex- plains Schmidt, citing a text on coffee quality by Andrea Illy. Due to the high pressure necessary to extract espresso you need a certain amount of larger particles to allow the water through. "The trick is to crush the coffee cells and then get the water in and out," said Schmidt. Grinders There are two phases to grinding, a crushing phase where the convolute structure of the brittle beans are broken into fragments, typically about one mil- limeter in size; and a second phase, properly called grinding in which the fragments are sheared. Dry-process grinders are either "impact" de- signs that shatter coffee into irregular particles or the much preferred "gap" design in which cof- fee is dropped through a shear gap between the notched surfaces of cutting tools (conical grinders, cutting rollers, or flat grinders). "You have to be perfect in your execution in grinding. You're dealing with exact brewing times and very small amounts of coffee in a fixed vol- ume at high density. Everything has to line up per- fectly," explains MPE's Will. Grinders must contend with many sources of disturbances which cause the equipment to per- form irregularly. Coffee beans not only come from different botanical varieties and producing coun- tries, they vary by season and climate. Blends of- ten include beans processed by diverse methods. Beans that are fresh contain more moisture than beans stored for many months in a warehouse. Neuhaus Neotec sales and project manager Ralf Torenz said that Neuhaus recently introduced roll grinders with a capacity of 150 to 1,000 kilos per hour specifically designed for capsule and pod coffee. Flexibility is a key attribute in dealing with what amounts to daily disturbances, he explains. "The motor and each roller motor have their own frequency converters. As a result, each roller can be driven at its own speed. The grinding pres- sure can also be individually adjusted to new prod- uct specifications when changing between types of coffee. These parameters can be saved as a recipe for quick adjustment when changing between cof- fees," he said. During a presentation at COTECA 2014 in Hamburg, Germany, Torenz described the chal- lenges roasters face due to high capacity production. The most fundamental is defeating heat build-up (which imparts a 'burnt', bitter taste from over- An industrial laser burns details onto a carton of coffee capsules Nested capsules are grouped by eight and stacked 3 rows deep. Typical Grinds Application Grind microns (µm) Turkish Coffee 100 µm Commercial Espresso 300 µm Pour Over 500 µm Filter Coffee 600 µm K-Cups 850 µm Course Grind 850-1,000 µm French Press 1,000 µm Cold Brew 1,180 µm Source: Ditting USA, Inc.