To brew coffee well, extraction is an important concept to understand. When we begin to brew a coffee, the natural acids present in the coffee will extract most easily, followed by sugars, and then heavier bitter compounds towards the end of the brew. This means controlling how much we extract from a coffee will control the balance of flavour in your cup. Extract too little, and we have a sour coffee, too much acid from the beginning of the brew, and not enough sweetness to create balance. Extract too much, and we will extract too much bitterness from later in the brew, resulting in an overall bitter and drying cup.
There are two main ways we can control extraction, in ANY method of brewing coffee. Grind Size, and Brewing Time. The table below shows a guide to controlling extraction when brewing.
|Coffee Tastes||Too Bitter/Dry||Too Sour|
DOSE 19-20 g for a double espresso
BREW WEIGHT 38-40 g
EXTRACTION TIME 26-30 seconds
GRIND Very fine - adjust to brew time
FILTER BASKET 18 g or 20 g VST Basket
WATER TEMPERATURE 93°C
WATER PRESSURE 7 bars
STEP 1 Use a scale to measure your dose of coffee and brewed liquid.
STEP 2 Distribute the coffee evenly to ensure the bed of coffee is flat.
STEP 3 Tamp down the bed of coffee with tamper. Be sure to tamp evenly. This is more important than the pressure.
STEP 4 Adjust your grind size to have the full beverage weight in approximately 27 seconds. Extraction time is controlled by the grind setting, so it is worth experimenting with this. As you grind finer, you increase extraction time.
STEP 5 For a more balanced cup, we like to give the espresso a quick stir to mix the layers before drinking. Enjoy!