Coffee Processing

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Below is an article I wrote about roasting coffee. Before the coffee can be roasted it must be picked, pulped, cleaned, dried and then hulled. At this stage you have green bean. The process is not too difficult as long as you have the machines!

Green bean can be kept with little trouble or preparation for years. In fact, the green bean, like wine, changes with age and becomes more complex as it ages! This is not the case for roasted beans. Whole roasted beans will deteriorate noticeably within two weeks irrespective of how they are stored. There is much debate over how to store roasted beans, we don't, so we don't have a storage problem. Ground roasted beans will start to deteriorate noticeably within a day! In days gone by, every country house would roast their own beans on a daily basis with small hand cranked wood fired roasters. Small urban roasters operated in urban areas to service neighbourhoods. It was only for the second world war that mass produced instant coffee was prepared to keep the troops happy. This led to the decline in the standard of coffee as a drink overall.

There is a whole story in itself on the roasting side of the preparation. First crack, second crack and where to stop the roast. Cinnamon, City or Viennese are the names of these roasts. Then there is blending or not, and the differences in taste between the beans themselves...perhaps not this article. We roast our own with a lovely machine that allows you to see the beans darkening and to hear the cracks of the beans to determine the stage of roast. Lots of fun and you can experiment and blend and vary the roasts and get very technical and really impress your guests as you demonstrate the art of roasting. It certainly is a talking point.

Once roasted we tip the beans into our grinder and only grind as we need to. The grinder has a hopper on top and a "dosser" to drop a measured amount into the cup/strainer in the handle of the group head (the heated mass of metal that the handle attaches to). At this stage the important issue is to get a consistent measure of coffee into the cup/strainer so that the rate at which heated water (at 95 degrees C) passes through the group head is perfect. The resistance to the pressure of the water should be such that in less than 30 seconds you get 30ml of expressed coffee. Sounds easy you say....well it can be once everything is set up, here are some of the things that affect the porosity of the ground coffee: the bean type, roast, grind fineness, moisture content of the ground coffee, amount of ground coffee in the cup/strainer, the pressure at which the coffee is pressed into the cup/strainer, the pressure of the heated water that passes through the handle, the type of strainer etc. The main aim is consistency so you should try to keep as much constant as possible and vary just a few of the variables so that you get a consistent 30ml in 30 seconds. We adjust the fineness of the grind (easily adjusted on a good grinder) and keep everything else constant, that is until we decide I want to try some different roasts. We stopped using a double spout handle because it was so different to the single spout handle (quantity of coffee in the cup/strainer and the resistance of the sieve itself) that we needed two different grind sizes...a pity but we get consistent coffee doing it the way we do.

Finally, the milk should be heated to no more than 60 degrees otherwise is gets scalded and it tastes well, scalded. We use a thermometer, but at a pinch we could use our finger on the metal jug as we heat it up. Thermometers are cheap and easy to use.

We have invested in a manual coffee espresso machine that is robust, does NOT use a thermo block heating element and has a good steam and separate hot water (95 degrees ) outlet for tea or heating our cups. From our research and experience, fully automatic machines are a good way to show off to your friends that you have no idea about good coffee; manual machines are the way to go.

We love our coffee. We grow it, pick it, pulp it, dry it, hull it, roast it, grind it, espress it and finally drink it. It is a journey and like all good journeys it is about the experience, but after this long experience, it is nice to relax with a great coffee.

Trees in flower look as if they are heavy with snow The coffee blossom is very fragrant, and lasts a day The bush/tree showing both green (unripe) and ripe fruit Pulping the flesh off the beans Drying the beans before hulling The hulling machine Cleaned grean beans ejected into bucket Close up of the ejected beans Grean beans Grean beans ready for roasting Roasted beans cooling in roaster tray Roaster Grinder Espresso Machine