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Flow control is the latest trend in espresso. It’s a tool to help you get more out of your coffee by extracting specific flavors, aromas, and nuances out of your favorite coffee and now it’s more accessible on prosumer-level home espresso machines from manufacturers including Profitec and ECM, as well as high-end home and commercial machines like Dalla Corte’s Mina. If you’ve been looking for more details on how to determine your flow rate on an E61 group machine, you’ve come to the right place. We’ll be using the ECM Synchronika and the Dalla Corte Mina to discuss how we determined our flow rate using really fresh coffee on these machines, but first, let’s give you a quick rundown on what you can do with flow control.
Flow control allows you to use the flow rate of water to adjust the flavor and aromas of your coffee. If you have a very fresh coffee, you can use flow control to allow the COz to off-gas and control the brightness of your coffee. If you have an old coffee, you might want to start off with a high flow in the beginning and gradually reduce the flow to improve mouthfeel and prevent extracting stale and oxidized compounds. You can also use flow profiling and adjust the flow rate to cater to a particular roast level. For example, you can do a gentle pre-infusion for a light roast coffee and a more aggressive pre-infusion for a dark roast coffee. Another impressive feature is the ability to replicate extraction characteristics of manual lever and pressure profiling machines, and if you like the occasional filter coffee, you can grind coarse and use a low flow to turn your machine into a single-serve filter coffeemaker. As you can see, flow control opens up a new world of possibilities and can brew your favorite coffee exactly how you like it with the right variables.
Now that you’ve got a better understanding of flow control, let’s talk about flow rate and how we can adjust it during extraction to find the sweet spot. Take the Mina for example, it’s easily programmable through on the Mina app based on the digital flow rate and timing in 5 steps. From there, the digital flow meter in the machine takes care of the rest. However, if you’re using an E61 flow control device, here’s how you can determine the flow rate.
Measure the output over 20 seconds with the flow control set in six different positions. Measure at one-eighth of a turn open, one-quarter, one-half, three-quarters, one full turn and then one and a quarter turns. For this measurement, we used a weight scale for accuracy and it’s simpler to use for calculations, but if you don’t have a scale you can measure the liquid volume of the coffee. From there, let the brew water run for 20 seconds in each position and then divide your total weight in grams by 20, if you’re using volume use milliliters, to get your flow rate in grams per second for each position.
The results from our measurement ranged from 1.5 grams per second at an eighth of a turn up to about 11 grams per second at one and a quarter turns open. By calculating these measurements and following this formula, you’ll know how far to open your flow control knob to get your desired flow rate.
If you’re working with a really fresh coffee, here’s an example of what you can do to get the best results out of your coffee. This profile comes from World Barista Championship judge Danilo Lodi, who used the Dalla Corte Mina to pull some incredible shots with fresh coffee. We recently spent some time with Danil at George Howell Coffee in Boston where he pulled some impressive shots on the Mina using one of George’s Kenyan coffees. Here’s how to do it. One the Mina, program the profile and the flow meter and let the machine take care of the rest. If you’re using an E61 group machine, you can do the same thing now that you’ve figured out the positions to get your desired flow rate. For our flow rate, we calculated 60 seconds at a quarter turn and then five seconds at just under half a turn. We then reduced the flow to finished the extraction a little over a quarter of a turn. We used an ECM Synchronika which has an automatic shot timer, so getting accurate timing what simple and convenient and only required us to keep an eye on the timer.
This profile works wonders with super fresh coffee because the gentle start allows the CO2 to off-gas and decrease the bitterness compared to what you’d get with a full rate extraction of a really fresh coffee. By keeping the flow gentle and finishing off where it started, this helps to extract the sugars and flavors of the coffee and really build a sweeter aftertaste.
This is just one example of how you can use flow control to improve extraction and how to calculate the measurements to achieve your desired flow rate. There’s a lot more to the conversation on flow control and flow profiling, so keep an eye out for more blogs and videos for more details on flow control including profile graphs with different brewing methods. Until then, check out our entire collection of machines with flow control ranging from the ECM Classic single boiler machine, heat exchange and dual boiler machines, and of course the Dalla Corte Mina.