Australia's very own Crema Coffee Garage is back! The team has provided us with a guest blog in partnership with the University of Newcastle. Together, they studied how much caffeine & dissolved solids (sugars, oils & acids) are extracted in an espresso shot to better understand how to make a ristretto. And once again, the KRUVE Sifter was used to ensure consistent and accurate grind sizes and extractions!
The term ‘ristretto’ has become quite the coffee buzzword over the years, but what is a ristretto?
There are quite a few opinions on the definition and method of a ristretto circulating in coffee society; however, following extensive research we found only one definition can really be agreed upon:
A ristretto is an espresso that has been restricted or limited in some way.
There are many ways to do this, but through our research we have narrowed down the ristretto methods that are most commonly used to just three and – thanks to our latest coffee experiments – show the science on how much of all the good stuff ends up in your cup.
We call them the Cut-Off Ristretto, the Selective Ristretto and the Syrupy Ristretto.
Crema Coffee Garage has had the continued privilege of working with the University of Newcastle’s Chemistry Department and members of the scientific community to analyse the rate of caffeine and Total Dissolved Solids (TDS%; includes sugars, oils and acids) extracted over time in a 60mL double espresso. We also used 3 different origins from 3 different continents (Sumatra, Colombia and Ethiopia) to complete the experiment to ensure the rate of extraction was consistent – no matter the bean. This study allows us to better understand whether the methods used to produce a ristretto are creating the drink intended by the barista or customer.
Our results show the TDS percentages found in the double espresso shot over time extracted in similar intervals as the caffeine content across all three origins, indicating that the sugars, acids and oil in espresso drop in similar proportions as the caffeine, with the highest concentrations at the very beginning and tapering off steadily towards the end.
For example, if you are making a Selective Ristretto by selecting only the middle part of the espresso shot (10-25 seconds) you will have less caffeine and sugars/acids in your ristretto then if you had kept the first part of the espresso shot and cut the shot off early – a Cut-Off Ristretto. (See infographic attached)
As for the Syrupy Ristretto, this is not a commercial method of making ristretto, unlike the Selective and Cut-Off methods. Instead it is more individualised method and can include changes to grind setting, tamp pressure, grams of coffee in the basket or even shot time. Because of this we were unable to study this method – see more information about the Syrupy Ristretto in our guide.
Our study provides baristas and coffee drinkers with a verified choice of methods to get exactly the coffee they desire. For details on the different types of ristretto and what sort of bang-for-buck you’re getting with each method, follow the link to the full article: https://cremacoffeegarage.com.au/ristretto-guide