coffee roasting commodity study


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coffee roasting commodity study

  1. 1. Chapter 4 TECHNICAL STUDY
  2. 2. 4.1 Introduction  This chapter highlights processing steps as well as important machineries and equipments used along production line in coffee roasting .  coffee roasting process consists essentially of cleaning, roasting, cooling, grinding, and packaging operations.  main machineries and equipments along the production line are vibrating screen, blender, roaster, destoners, grinder, and the packing machine.
  3. 3. ROAST BEAN 4.2 Coffee Roasting Process description Schematic of coffee production plant
  4. 4. 4.3 Decaffeination the process of extracting caffeine from green coffee beans prior to roasting.  general decaffeination process includes soaking green coffee beans in hot water (700C -1000C) and then some sort of solvent or activated carbon is used to extract/dissolve the caffeine.  Several methods of decaffeination are used including supercritical carbon dioxide (CO 2) extraction, water extraction, and solvent extraction using oil (extracted from roasted coffee), methylene chloride, or ethyl acetate as a solvent. 
  5. 5. Decaffeination Process Green coffee beans (before roasting) are first soaked in water to make them swell and allow the scCO2 to penetrate more easily. It is also thought water may be needed to help free the caffeine from chemical complexes in the bean. ScCO2 is circulated for up to 10 hours through pre-soaked beans in a high-pressure extraction chamber. In the second vessel, water and the caffeine-rich carbon dioxide are passed in opposite directions and the caffeine dissolves in the water. The carbon dioxide is re-pressurised and re-used. Caffeine is recovered from the water as a concentrated solution using one of a range of processes, including reverse osmosis. In reverse osmosis pressure is used to make solvent pass through a semi-permeable membrane from high to low concentration of solute, rather than the other way round. This concentrates the caffeine further.
  6. 6. Decaffeination by supercritical CO2 method
  7. 7. Machineries and Equipments
  8. 8. Green Bean Separator Foreign matters in green coffee: sticks, rocks, dirt, lint, strings, leafs, fibers, metallic scraps, seed grains etc  Why cleaning needed?  To ensure a quality product,  to eliminate hazards like bits of combustible material that may cause serious fires in roasters.  Some foreign materials may also clog up conveyors and piping that lead to reduction in production efficiency.   Industrials coffee cleaning process involves different machines that sort the coffee by density of bean and by bean size.
  9. 9. Coffee Mixer/Blender Why blending needed?  to have a consistency in quality, aroma, flavor etc, Blender is hollow cylinder, mounted horizontally. Helical flanges inside blender mix different grades of coffee in few minutes. dust or chaff loosened by mixing is removed by an exhaust system. The blended coffee then goes to holding bins, to feed hoppers over roasters.
  10. 10. Roaster  Roasting determines coffee’s final taste and aroma  Roasters are horizontal rotating drums that tumble green coffee beans in current of hot combustion gases. Operating Temp: 370°C 540°C Roasting time: few minutes to about 30 minutes The more the coffee beans are roasted the darker they become and more bitter will be the final taste    11
  11. 11. Cont… Depending on heat source, roasters are classified into two categories: Electric fired Gas Fired Electric Fired Roaster  use halogen lamps  faster starts to the coffee roast cycle  more control over roast profile  Safe from dangers of fire  No CO poisoning Gas Fired Roaster  Uses natural gas/LP  lower operating temperature range  more uniform, higher quality roast.  Are two types: direct fired and
  12. 12. Typical coffee roaster Afterburner Roasting Chamber ontrol Panel Roast Pneumatic Loader Cooling Tray Destoner
  13. 13. Cooling Why needed?  to avoid beans from cooking further at higher temperatures  Some machines accomplish cooling through built in cooling fan  Other use water to quench beans  Cooling tray equipped with rotating arm and blower
  14. 14. Destoner Why needed? To remove stones, metal fragments, and other waste not removed during initial screening Working principle: airflow is regulated to lift roasted beans and leave the bits of rock and metal behind 
  15. 15. Grinder Why neded? to improve extraction efficiency & aroma retention in preparation of beverage       Grinding texture depends on the coffee-making method: fine- for the espresso coffee machine medium- for the moka pot coarse- for the filter coffee machine more coarse- for the coffee pot 16
  16. 16. coffee grind influences coffee's flavor. Grinder Types 1. Blade Grinder   economical  Grind controlled by time blade runs But difficult to get consistent granule size 2. Burr Grinder  modern upgrade to the millstone grinding method  consistent grind  Crushes rather than cutting 
  17. 17. Packaging To retain aroma Roasted coffee is packed either as whole beans or as ground coffee.  Common forms of packs :  at atmospheric pressure,  vacuum packs and  gas-filled vacuum packs 
  18. 18. List of major Machineries and Equipments S.No 1 2 Machinery and equipment Green Bean Separator Coffee Mixer (Blender) Purpose To separate green coffee beans based on bean size To mix coffee from different origins in specific proportions so as to get a consistent taste and flavor. To roast (‘cook’) green coffee beans in order to produces the characteristic 3 Coffee Roaster flavor of coffee by causing the green coffee beans to expand and to change in color, taste, smell, and density. 4 Coffee Grinder To breakdown roasted coffee beans so as to improve the extraction efficiency in the preparation of the beverage. To seal and pack roasted or ground coffee. The storage conditions of roasted 5 6 Automatic Packaging coffee must ensure hygiene and prevent contamination of the product by Machine volatile substances, such as oxygen (which can cause oxidisation) and moisture Destoner (which can increase the growth of mould). This is used to remove the foreign debris (i.e. stones, buttons, sticks, etc.) from coffee after it is roasted. The destoner is attached to the cooling bin chute, separates the coffee from the foreign debris and via an "elephant trunk" transports the roasted coffee to a holding silo.
  19. 19. 7 8 9 10 Destoner Weighfill Packaging System Loader Afterburner/Oxidizer Blending Mixer This combines the destoner and a semi-automatic packaging unit. The packaging unit allows you to take either whole bean or ground coffee, weigh and dispense the proper amount into your coffee bags. Bag filling however is a manual operation via a foot pedal to release the pre-weighed amount programmed into the scale. The Loader transports the green coffee from a loading station that is about knee/thigh height to the roaster's funnel. It also saves time between batches. Highly recommended with roasters starting at 12 kilos and virtually required on anything larger than a 45 kilo roaster. There are three different types of loaders namely, pneumatic loaders, Mechanical (bucket) feeder / loader, and screw-type (worm) loader. This is pollution abatement equipment used to treat the effluents from the coffee roaster. Its purpose is to eliminate smoke, odor, and to reduce the total amount of emissions released into the atmosphere to an acceptable level. Smoke, odor, and various chemical compounds that are natural biproducts of coffee roasting. A drum style piece of equipment that allows you to blend varietals throughout with minimal bean breakage. Typically, this is sized based upon the following: Full kilo batch size of roaster X maximum number of varietals in the blend