Deciding on the perfect coffee brew ratio to achieve the texture you prefer...
Texture is overwhelmingly important to me when I consume food and drink. I love veal glace, King Island cream, pre-phylloxera 1878 muscat (only tasted once almost a quarter of a century ago), a well-made boscaiola sauce… all have in common an unctuous, more-than-coating-the-back-of-a-spoon texture which lingers on your tongue and saturates your taste buds. I’ve also described some of these liquids as having the viscosity of sump oil (and no I have never tasted sump oil). Texture is an important part of why I roast the way I roast. In a previous message I discussed the impact of roasting decisions on various dimensions of coffee such as acidity, aroma, body and bitterness. Texture is also a significant driver of the way I make coffee every morning for myself and my family.
I tend to extract our espresso at the very short end of the spectrum. Let me introduce the concept of brew ratio, it’s a simple fraction with weight of ground coffee being the numerator and weight of extracted coffee as the denominator. If I were to use 18 g of ground coffee and extract 36 g of coffee then the brew ratio would be 18/36 or 50%. The higher the brew ratio the shorter the coffee, conversely the lower the brew ratio the longer the coffee. Standard brew ratios are in the order of ristretto at 100%, normal espresso at 50% and a lingo at 33%. My tendency has been to extract our coffees at brew ratios close to 100%.
But if texture is your main concern then why don’t you just extract coffee at high brew ratios? Perhaps even higher than 100%? Well there’s the tricky issue of optimising extraction yield. Everything in coffee (and in life I suppose) is a compromise. The compromise with exceedingly high brew ratios is that it is extremely difficult to extract enough out of the coffee for it to taste great given so little water has gone through the coffee puck. If you imagine your coffee puck having a proportion of material that is soluble, some that is insoluble but can pass through the holes of your portafilter, and some that just won’t move or dissolve at all, then it’s easy to visualise that the proportion of solubles and moveable insoluble components that goes into your coffee will increase as more water is pushed through the ground coffee. The longer your coffee the higher the extraction yield. There’s a sweet spot for extraction yield which produces the best taste for your preferences. Where you sit on the spectrum of optimal extraction yield is personal… and the relationship between extraction yield and tasting pleasure is non-linear.
The elements which impact extraction yield can be the source material for an enormous volume of writing - grinder, burr geometry, tamper geometry, management of turbidity - I’ll likely cover most if not all of these topics in future newsletters. I’ll also break out my refractometer to provide some quantitative evidence for some of my pseudo-scientific assertions!
The short version of the above is that I’ve been experimenting with pulling longer shots… more like 66% brew ratio… and I’ve been enjoying it. If you end up trialling different brew ratios please let me know what you discover!
To read about a coffee extraction experiment click here
To learn about an experimental coffee club click here