Coffee Knowledge

The coffee plant

Coffee is a cherry. It is the seed of a tropical plant of the Rubiaceae family. It grows at an altitude between 400 and 2000 metres and at a temperature between 20° and 25° C. About 60 species of coffee are grown but the most commonly used all over the world are Arabica and Robusta. Once mature, a coffee plant produces an average of 1 kilo of raw “green” coffee beans per year. These coffees are the subjects of a lot of misinformation, often perpetuated by coffee companies. Arabica is the most valued for its aroma whereas Robusta gives body to the coffee. The Arabica beans are flat and elongated while Robusta’s are small and rounder. A coffee plant can grow up to eight metres high. It produces a cherry-like fruit, which turns bright red when it is ripe. It contains two seeds covered with a thin silvery membrane; which are the coffee beans. The arabica beans are usually regarded as the premium variety. Many roasters will make much of the “100% arabica” content of their roasts. These beans tend to be grown in more mountainous regions, over 800 meters above sea level, where disease is less prevalent. As such, harvesting is more labour-intensive. For this reason arabica beans command a higher value on the market. The robusta beans, as their name suggest, are less susceptible to disease and can be grown at lower altitude, from sea level upwards. They tend to cost less as they can often be harvested by machine. That arabica is always superior to robusta is complete nonsense. There are some downright lousy arabicas on the market, as well as some truly exceptional robustas. Lots of the top espresso blends contain a small amount of the best robustas. The berries are harvested either by hand or mechanically. The beans are harvested by machine (in flatter areas, for lower quality beans) or by band (in sloping areas, for higher quality beans) and are usually exported to coffee roasters in their green state. Harvesting by hand will gather only the ripe berries, while mechanical picking will gather all berries thus producing unevenly mixed batches. The berries are treated with two different processes: dry and wet, in both cases the beans are separated from the pulp and impurities. The coffee beans are the packed in 60-kilo bags and sold all over the world.


Roasting differs from country to country. In European countries the beans are usually roasted to a «monk’s cowl» brown. Each roaster uses it’s own blend, usually made up of three to eight types of green coffee. The beans are roasted at a temperature of 200°-220 °C, the process taking from ten to fifteen minutes. During this phase internal gasses swell the beans, and cause an increase of volume of about 60% with a weight loss of 20%. There are about 800 volatile aromas in one coffee bean.

The chemical composition of unroasted coffee is as follows:

  • Water 12%
  • Nitrogenous substance 12%
  • Sugar and dextrin 10%
  • Cellulose24%
  • Non-nitrogenous extractive substances 18%
  • Ash 4%
  • Caffettannin acid 6.7%
  • Caffeine 1.2%
  • Essentialoils 0.1%

After roasting there is a substantial decrease in the water percentage, which is the principle cause of weight loss. The roasted coffee must not be exposed to air for too long because the fatty substances turn rancid resulting in an «off-taste» in the cup. Volatile substances trapped inside the bean, so the methods of grinding and preserving the coffee are fundamental in obtaining a good cup of espresso coffee create coffee’s aroma.

How to clean an Espresso Machine

Daily cleaning procedure

A minimum of 3 times per day use your blank filter and black flush each group head. The goal of this exercise is to remove any loose coffee rounds that have built-up between the screen and brewing head during the day use. Because the blank will not allow water to pass through, this water is forced back up through the screen and brewing head and the loose grounds are dislodged into the blank.

Reinigung einer Espressomaschine

  1. Replace the normal filter with the „blind“ filter (It has no wholes)
  2. Place 1/2 teaspoon (3g) of detergant onto the „blind“ filter
  3. With the portafilter attached to the group, backflush by pressing the start button for 15 seconds
  4. Remove the portabilter, discard leftovers and run the group. Use a brush to get rid of oils and loose grinds
  5. With the „blind“ portafilter attached, backfush the machine for 15 seconds
  6. Remove the „blind“ portafilter and run the group to thoroughly rinse clean
  7. Remove the „blind“ filter and replace it with the normal filter
  8. Pull and discard two test shots before serving coffee

Remove the metal drip tray to a sink and clean. Clean the drain. Before you return the drip tray to the machine, you will see a round, lack, drain. This drain is designed to catch any loose grounds before they get a chance to lock the mains. Coffee grounds can dry like concrete in a drainpipe. Remove the grounds with a teaspoon and flush 2-3 cups of water down the drainpipe to ensure you have flushed away any loose grounds. Replace clean drip tray.

Every night

  • Remove the handles, separate the baskets, and clean all parts with a green scrubby.
  • Back flush the group heads with hot water following the procedure in the manual.
  • Remove both parts of the drip tray and scrub well with hot water.
  • Pour a large jug of hot water down the drain of the espresso machine to ensure all old coffee grounds are flushed away.
  • Replace all pieces back into the machine.
  • Clean steam wands – you may have to soak them in hot water for 10 – 15 minutes. (Do not soak overnight-if the machine is turned off it creates a vacuum and foul water can be sucked back into the boiler.) Scrub away any built-up milk residue.
  • Clean the bean hopper on the grinder
  • Block the hopper and remove from the grinder.
  • Pour any remaining beans into a bowl (remember the freshness rule – don’t have any more beans in the hopper than you con use for this shift).
  • Use a damp cloth (no soap please – only hot water), clean any built-up coffee oils. Dry the hopper, return to the grinder and pour back the beans.
  • Use a paintbrush to dust away any stale coffee grounds around the grinder.

Cleaning single/double handle

  • You need to clean the handles at least twice per day, shift change is the ideal time
  • Using a spoon, pry the filter basket away from the handle.
  • Using a green scouring pad, scrub away the built-up black residue inside the handle and on the inside of the filter.
  • Rinse and re-assemble.

Note: Make sure you get the single filter back onto the single handle.

Weekly cleaning procedure

Note: Brewed espresso leaves a substantial residue on all brewing surfaces. These coffee tars give a bitter, stale flavour to espresso drinks. Also, this residue can damage your equipment by clogging the screen, valves, brewing passages and water jets.

Regular black flushing with a neutral detergent loosens these coffee tars and flushes them away. Neutral detergent leaves no toxic residue when used and rinsed according to directions.

One day each week drop a teaspoon of neutral detergent into your blank and proceed with back flushing Steps Three and Four outlined in the Daily cleaning procedures. For the detergent to be effective, allow the water to run for 20 second, as opposed to the 8 – 10 seconds stated in Step Four of the Daily cleaning procedures. Again, repeat the above step four times or until the water runs clear. Run fresh water through the group head to rinse.

  • Repeat this procedure for each group head.
  • Every week rinse the bean hopper of the grinder with cold water.
  • Clean the doser with a dry paintbrush.
  • Once a week at closing, in addition to your normal cleaning, you need to back flush with espresso detergent. Follow the steps in the manual.
  • Soak basket and ground handles in espresso detergent for an hour or overnight.
  • Do not submerge plastic handles.
  • Steamer tips can also be removed and holes cleaned with a pin, then soaked in espresso detergent.
  • Always rinse items soaked in detergent well.
  • On the same day you choose to do the above, also de-scale the filter machine using one sachet of de-scale powder.