STiR coffee and tea magazine

60 STiR coffee and tea / Issue 5, 2018 (October / November) The graph above clearly shows the overall challenge(s) of single- serve grinding Comparing the brew time of a pour over or bottle brewer against that of a capsule, one can see a 90% or greater reduction in the brew time and yet, it is necessary to achieve the same soluble solids (not more, not less) as shown above. All grinding is essential for proper brewing, but the margin of error, and the technical consideration of capsule grinding is critical for not only brew strength but also for time. Time vs. grind, grind vs. time After achieving the ideal grind size for a given capsule con- figuration, there is an added requirement, which is controlling the time of brew through the grind. This may seem confusing alongside the concept of optimizing the grind size to the brewer; however, it may make more sense if broken-out as this: 1) Think about an espresso brewer, and precisely how the particle distribution can affect the time it takes to brew the espresso. 2) Similarly, with capsule grinding, there is a further need to "tweak" the grind so that it brews in the given amount of time (depicted in the graph above). 3) This is especially the case with espresso style capsules; wherein there is a combination of particle sizes, which, on the one hand, provide the ideal extraction and, on the other hand, provide the "mortar" between the other particles. Densification of ground coffee Densification can be characterized as the fluffiness (or con- versely, the non-fluffiness) of the coffee so that it can fit ef- ficiently into a capsule manufactured at rates of up to 1,600 cap- sules per minute. The chart that follows compares two capsules and the amount of coffee packed into each. In each case, the volume is the same, but the quantity of coffee is different. The differ- ence is the density, or "compactness", of the coffee, which is achieved at the grinder, for each ground coffee product, with the Vortex densifier/normalizer. The first technical achievement in normalization, as repre- sented by the Vortex normalizer, allows more ground coffee to fit into a defined space such as a capsule. Since coffee is an or- ganic product that has different density characteristics depend- ing on its origin and is roasted to various degrees, the density, or fit, of the coffee into the capsule must be a dynamic process to meet the specific density requirement. The second critical element in normalization is the density control system, which must provide unparalleled consistency in density over time, thereby providing a "set it and forget it" confidence. If the art is contained in the development of the op- timal (taste and strength) parameter control adjustment, the sci- ence is provided by the ability of that control system to ensure consistency and repeatability over an extended period. Grinding of coffee for single-serve has several significant considerations: 1) The particle size and distribution must be correct for the specific type of single-serve capsule. 2) The granulometry distribution of the ground coffee must first be optimized to meet the design of the single-serve capsule (mean particle size) as well as minimize the ground coffee par- ticles that fall outside that range. 3) The coffee grinder must be capable of producing a grind that can control the brew time of the capsule through the granu- lometry design. 4) Control of the density of the coffee is critical so that the optimal amount of coffee will not only fit into the capsule but also do so under high-speed packaging conditions. 5) All of the above must be achieved while the process op- erates in a water-cooled (temperature-controlled) environment. Having to control these variables, simultaneously, is virtually impossible manually, and, accordingly, programmable logic con- trols (PLC) controls with recipe(s) for each parameter selection is a crucial part of a single-serve grinding system. With this greater knowledge on grinding, it is hoped readers will gain an elevated level of appreciation for what is required to make a daily single-serve cup of coffee. Daniel Ephraim is president of Chicago-based Modern Process Equipment Corporation. He has been active in the development and design of coffee grinding and other related processing equipment for more than 40 years. He has presented at numerous coffee conferences and symposiums and conducted hundreds of coffee grinding seminars worldwide.

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