All tests will follow a standard format that conforms to the good brewing practices outlined in this manual. In summary, ECBC will ensure all tests use:
- Fresh, cold water with a temperature of 15ºC that contains between 100 and 200 parts per million (ppm) dissolved minerals.
- The proper grind for the required brewing time of the coffee-brewing device.
- 50-60 grams of coffee per litre of water (or 7 grams of coffee for each 125 ml of water) (Ten (10) grams for 6 fluid ounces for American standard brewers).
- The water contact temperature is measured in the centre of the filter unit on the surface of the coffee.
- The voltage used during the test will be adjusted to obtain the given wattage of the coffee maker.
- All equipment is tested at full capacity.
If a brewing device is designed to operate at varying capacities and has passed the full-capacity performance test, it will then be tested for the other rated capacities. It must achieve the same performance rating at this level as at full capacity. No unit will be tested at less than two-thirds capacity, unless it has been specifically designed for this operation.
The first part of the performance test will use the coffee maker at full capacity. After the beverage has been prepared, the solubles yield will be measured and a sample taken for a measurement of the solubles concentration. Solubles concentration, or dissolved coffee flavouring material, can be measured by a coffee conductivity meter, a coffee hydrometer, oven-dehydration, or a variety of other methods that measure solubles concentration. Because oven dehydration has proven more precise and subject to less error, ECBC will use it for measuring soluble solids.
This measurement can provide information about the strength of the beverage prepared and the extent of extraction from the grounds. If the brewing process is repeated several times, the measurement also determines the uniformity with which the brewer operates. In the case of manually operated equipment, solubles concentration measurements help evaluate a person’s ability to use the equipment with consistent results.