Different coffees suit different brewing techniques and this is largely based on how they are roasted and how soluble they are.
Once we have chosen whether we are roasting our coffees for filter or espresso, it is then our baristas job to choose a brew technique that is best suited to that coffee. Coffees that are roasted for espresso (more soluble) are better suited to a short contact time between the coffee and water, as well as a finer grind size in order for the aromas and flavours to be optimally extracted. Other variables that will then play a role in the coffee’s flavour is water quality and temperature, pressure and brew ratio (dry to wet coffee ratio).
For our 19grams cafes, when a new espresso arrives it is our quality managements and our baristas job to find the perfect recipe for that coffee.
Our coffee machines are always set to 9 bar with water temperature at 92° Celsius.
The first step of the barista is to work out the best brew ratio for the coffee, that is, the ratio between dry and wet, or dose and yield. As our basket size is 18g we tend to start with this as our dose. Based on the solubility of the espresso we choose our yield. The more soluble the coffee the smaller the brew ratio and therefore the smaller the yield. We tend to roast to a brew ratio of 1:2, thus our yield will begin at 36g. Once we have determined the best brew ratio, we move onto contact time, or the length of time the espresso is extracting. For our baristas we find this to be between 30 and 35 seconds. Now we have worked out our espresso recipe we are able to produce consistently great coffees for our customers.
In contrast to this, coffees that are roasted for filter (less soluble) are better suited to a longer contact time between coffee and water, as well as a coarser grind size in order for the aromas and flavours to be extracted optimally. Like espresso, there are a lot of other variables that can affect a coffee's taste. However, with brewing, these variables are a lot easier to alter and so it is important to only play around with one variable at a time when creating a recipe.
For example brew ratio, similar to espresso, needs to be determined. As a general rule we start with a brew ratio of 1:16. Then you must think about the flavours and characteristics you want to bring out of the coffee. A higher temperature, a longer brew time, and a finer grind size will extract the flavours and aromas faster and an increase in pressure will create a bigger body and vice versa. It’s good to start with a bit of information about the coffee before getting started. This can be found on our retail bags and on our online store. As always, more information can be supplied by our baristas if required!