Espresso is a brewing method that takes place when pressurised water passes through finely ground coffee. This style of brewing has the potential to achieve higher levels of flavour concentration and body than other methods.
The goal of espresso brewing is to express the inherent characteristics of the coffee. As discussed previously, the five key elements to consider when analysing an espresso are the First Impression, Concentration of Flavour, Sweetness, Balance and Clarity. If you missed it, you can read the full article here: 5 Tips For Analysing Your Espresso
The aim is to create the optimal level of resistance to a specific amount of pressurised water. The resistance is created through the extraction variables of coffee coarseness and coffee weight. This is sometimes referred to as the ‘brew ratio’. The brew ratio may vary depending on the type of green bean and its roast degree.
The espresso environment is very sensitive and subtle changes can impact greatly on the outcome. There is a small window of opportunity to realise a coffee’s full potential and it’s important to have an understanding of the variables that impact upon this.
- The use of fresh filtered water is essential
- The ideal water temperature is 92 ° C (± 0.5)
- The ideal water pressure is 9 bar
There are two variables that impact on the creation of resistance to the pressurised water.
- Coarseness of the coffee grind – a coarser grind setting will create less resistance, while a finer particle size will increase resistance.
- Weight of the coffee – an increase in the weight of the coffee will increase resistance, while a decrease in weight will reduce resistance.
PAUL’S EXTRACTION TIPS
Coffee should be freshly ground for each espresso extraction.
Firm tamping pressure and polishing of the surface of the coffee should remain consistent.
The shot length, inclusive of crema, should be 30 mls (± 5mls)
Extraction time should be 25 seconds (± 5 sec)
Over-extraction occurs when there is too much resistance to the pressurised water, leading to increased water contact time and an over-concentration of coffee.
Under-extraction occurs when there is too little resistance to the pressurised water, leading to reduced water contact time and reduced concentration of coffee.
Optimal extraction occurs when the relationship between a coffee’s coarseness and mass is in balance and the desired sensory outcome is achieved.
Thanks for joining us on our coffee journey. We hope this overview has given you an insight into the possibilities that exist in creating an exceptional espresso experience. Stay tuned for an upcoming in-depth video of Paul’s approach to espresso extraction.