Good coffee can be made by several methods but the two principles to be considered are:
1. The control of method in order to avoid loss of flavour substances.
2. The extraction of desirable amounts of bitter substances.
Two level measuring table spoons are added to 3/4th cup of water in making coffee. If a weaker brew is desired hot water can be added after the coffee has been made at full strength.
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Filtration:
By this method, water filters through the coffee into a lower compartment of the coffee maker. The drip pot consists of an upper compartment which is perforated and a lower compartment which is a receiver for the filtered beverage.
A small perforated device is placed on the coffee powder of the upper compartment and helps in maximum extraction.
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Vacuum coffee maker:
The upper compartment which holds the coffee has an open tube which extends to the lower compartment.
Coffee is usually prevented from passing into the lower compartment by the use of cloth covered disc placed over the tube opening.
Water is placed in the lower compartment and the pot is heated until almost most of the water rises into the upper compartment.
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When the pot is removed from the heat, a vacuum is created in the lower bowl, drawing the clear infusion down into the bottom bowl.
Percolation:
Here the heated water is forced upwards through a tube on to the coffee compartment. The grounds (regular) are kept in the perforated coffee basket. There is a dome at the lower end of the tube which extends from the top of the percolator.
The tube supports the basket. Steam exerts pressure on the surface of the water under the dome, forces the water up the tube on to the coffee. Percolation time which depends upon the speed of circulation varies from 8 to 15 minutes.
Steeping:
Water is heated and just before it reaches boiling point medium ground coffee powder is added.
Steeping time is about 6-8 minutes. The coffee is then passed through a strainer. During steeping the coffee pot should be lightly covered to prevent losses of flavouring compounds.
Espresso coffee:
This is made by a special machine which brews the beverage a cup at a time. It is derived by a brewing finely ground coffee with a mixture of steam and hot water.
Soluble coffee
Soluble coffee is spray dried strong coffee brew. Or it can be made by freeze drying. The product is inferior in taste and aroma compared to the freshly prepared brew.
Soluble coffee should be kept packaged in water and air-tight containers because they are hygroscopic and tend to absorb moisture. Aluminium foil/polyethylene laminates are suitable for packaging soluble coffee.
Decaffeinated coffee:
Caffeine is not tolerated by some or adverse physiological effects can be avoided by using de-caffeinated coffee. By a chemical process most of the caffeine can be removed from the beans to give decaffeinated coffee which has good flavour.