Quality criteria for a good coffee
What are the most important quality criteria for a good coffee? There are three main criteria to apply when assessing the quality of a cup of coffee or espresso:
- Aroma: Aroma is a complex sensation which includes two senses – tasting and smelling. Taste is always a one-dimensional characteristic and is sweet, sour, salty or bitter. Aroma brings the subtle differences such as “flowery” . Aroma is always judged in a freshly brewed cup of coffee.
- Acidity: A certain acidity is a valuable characteristic of coffee. It describes the tingling sensation in coffee, similar to lightly carbonated water. It is the sensation of slight dryness on the edge of the tongue and the back of the mouth. Acidity gives to coffee what aroma gives to wine. It gives a lively, bright taste, without which coffee would taste flat. Light acidity should not be confused with a sour taste, which is considered a negative characteristic of coffee.
- Body: Body describes the sensation of weight of coffee on your tongue and in your mouth (we experience milk as being more full bodies than water). The body of a coffee depends on the oils and particles extracted during brewing.
In addition to the type of coffee machine, it is important to use good quality water, and to correctly set pump pressure, water temperature, grind and portion size to get an ideal result in the cup. Even slight deviations from a perfect setting can seriously impair the quality of coffee.
The quality and temperature of water
- Coffee contains 98 % of water.
- Ideal water hardness for coffee brewing is 6° to 8.°
- Coffee machines using very hard water require an additional lime deposit remover.
- Too soft water prevents tanning agents, essential oils and aromas from being released.
- The recommended boiler temperature is 90 to 95 °C, otherwise the coffee tastes sour and watery and crema turns out light and flat.
- The recommended coffee temperature in the cup should be 82 °C to 84 °C. Lower temperatures will prevent the aroma and flavor from being extracted properly. Higher temperatures (above 90 °C) will cause the coffee to taste bitter and burnt.
Pump pressure and extraction duration
- A pressure of 9 bars is perfect for coffee making.
- Lower pressure forces water through ground coffee too slowly causing tannic acids andbitter substances to be released.
- With higher pump pressure, important aromatic substances fail to be extracted andthe coffee tastes too watery.
- Duration of extraction is crucial for the quality of coffee and differs according to recipes.
- The recommended extraction time is 28 seconds for large black coffee and 18 – 23 seconds for espresso.
Coffee grind setting
To make fine aromatic coffee, it is important to use the right grind setting for your coffee machine.
- Too fine grind: longer extraction time, undesirable elements such as cellulose, tannic acid and bitter substances are extracted. Coffee crema is very dark and foamy. The filter may be blocked slightly. The water ends up in a cup around the filter and does not come into contact with the coffee.
- Too coarse grind: shorter extraction time, some desirable ingredients are not extracted, coffee has no flavor (watery and flat) and aroma, crema is light and flat.
Serving Size
The ratio of coffee to water is crucial for the strength and flavor of coffee. The correct ratio of coffee and water requires good ground coffee management. The recommended dosage is 6 to 8 grams of ground coffee per cup. If the dosage is too high or too low, the quality of coffee may be compromised.
- Too high dosage: coffee tastes bitter, harsh and burnt.
- Too low dosage: coffee tastes sour and watery and has no crema.
