Coffee Roasting - Articles and news items

918 Coffee Co’s Coffe-Eco System attracts international recognition

Industry news  •  18 November 2015  •  Victoria White

The Coffe-Eco System roasts coffee beans using the organic waste left over from the roasting and brewing process…

The complexity of coffee processing

Issue 2 2013  •  26 April 2013  •  Moreno Faina

Coffee roasting, at first glance, appears to be a simple process: applying heat to raw coffee beans. It is important to generate and control the correct temperatures at the right time, and then stop the process when the colour of the coffee is homogenous throughout the whole bean and the aroma has fully developed so as to appeal to consumers and connoisseurs. However, on closer inspection, the dependency of the changing temperature distribution in the coffee bean on the parameters governing the process, such as roast gas temperature, fluid flow conditions and material properties of the coffee bean are all important factors. The difficulty in mastering the whole process comes from the changes in nearly all parameters involved in the process; the temperatures, the material properties and the geometry of the beans.

Progress on coffee roasting: A process control tool for a consisten roast degree – roast after roast

Issue 3 2012  •  4 July 2012  •  Chahan Yeretzian, Flurin Wieland & Alexia N. Gloess, Zurich University of Applied Science, Institute of Chemistry and Biological Chemistry and Marco Keller, Andreas Wetzel & Stefan Schenker, Bühler AG

A real-time automated process control tool for coffee roasting was developed to consistently and accurately achieve a targeted roast degree. It is based on timeresolved on-line monitoring of volatile organic compounds (VOC) in the off-gas of a drum roaster, using Proton-Transfer-Reaction Time-of-Flight Mass-Spectrometry (PTR-TOF-MS). These experiments provide a detailed, real-time picture of the evolution of the roasting process with the aim of controlling the process and consistently achieving a targeted roast degree.

The flavour of a freshly prepared cup of coffee is the final expression and perceptible result of a long chain of transformations which link the seed to the cup. These include agricultural factors such the variety of the plant, the chemistry of the soil, the weather and the alti – tude at which the coffee is grown. Combined with the way the cherries are picked, further processed and stored, a green bean is obtained that contains all the ingredients necessary for the later development of the typical coffee aroma. Yet, the green beans give no clue as to what they might become once roasted. They have neither the characteristic smell nor the taste of a good cup of coffee. To reveal the typical coffee flavour, coffee has to be roasted.

From a scientist’s point of view, roasting is the collection of a large number of heat induced time and temperature dependent physical and chemical transformations. It turns a hard, spongy to bite, green / grassy smelling bean into an intensely fragrant, brittle, and extractable dark brown bean.


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