An Adaptive Espresso Profile is a modern espresso extraction method that automatically adjusts the water flow rate to maintain a consistent flow after a peak pressure is achieved.
Thus the machine tries to adapt to variations in grind size and puck consistency to produce a balanced, flavorful shot with good crema and mouthfeel.
It uses a strategy of pre-infusing the coffee puck, then building to a specific peak pressure and flow rate within the first few seconds, after which it allows the pressure to decrease while holding the flow rate steady to compensate for changes in puck resistance.
This formula is impt:
Pressure = flow x puck resistance.
They are linked.
The early (analog) lever machines naturally understood this relationship.
You pulled on a spring (loaded at 6 or 9 bar).
My Elektra is loaded at 6 bar.
As the lever went up the pressure slowly decreased from max pressure.
During this time, the flow naturally would also decrease.
And this would compensate for the degradation of the puck over time.
Today, pumped machines keep the pressure at 9 bar even though the puck is degrading.
The result is a increase in flow rate towards the end of the shot with a much more diluted finish.
I think lever machines had it right from the beginning. When you pulled the lever down (in the case of a spring lever) the puck was saturated instantly
(at boiler pressure) reducing the chance of puck unseating, and then a pressure to flow relationship was maintained during the shot pull.
With my E61 machine I'm getting about 7g/sec flow.
It will continue to deliver water to the coffee puck at that rate until it hits 9 bar.
At that point, the OPV will kick in.
Usually the 9 bar level is reached pretty early .. usually at the end of pre-infusion.
The flow rate is probably not 7g/sec. Instead, it will be whatever it needs to be to stay at 9 bar.
This is one of the settings on my Gaggiuino.
Flow is very hard to control.
Resistance is related to the type of grinder, the grind size, roast level, puck integrity, grind solubility, tamp force, distribution, etc
I think that above 10bar, coffee doesn't taste great, so if your focus is on flow
and you accidently touch 10 bar, you risk the coffee failing.
The adaptive setting is very interesting.
Its designed to prioritize the flow rate .... moving it up or down
& adapt it to the chosen grind and dose size..... keeping everything below the peak pressure.
Note that preinfusion is mostly about flow (as there is usually very low pressure).
When discussing flow we usually are focused on the post infusion stage.
So basically, the adaptive profile allows the machine to dynamically adjust the pressure and flow rate during the extraction process.
The machine monitors the resistance of the coffee puck (how easily water flows through it) and adjusts the pressure to maintain a desired flow rate or to reach a target pressure within a specific timeframe.
This means that if the grind is a little too fine and the resistance is high, the machine might lower the pressure to prevent channeling or over-extraction. Conversely, if the grind is too coarse, it might increase the pressure to ensure proper saturation and extraction.
By adapting to the coffee's resistance, adaptive flow profiles can help compensate for variations in grind size, dose, and tamping, leading to more consistent and repeatable results.
How it works
Pre-infusion: The group head fills with water, saturating the puck to ensure even extraction and reduce the risk of puck unseating.
Pressure Peak: The water then ramps up to a high pressure, and the machine finds the optimal flow rate at this peak pressure.
Pressure Drop & Flow Maintenance: After reaching the peak, the profile aims to hold this flow rate constant, even as the machine's pressure decreases due to the puck degrading. This is a key difference from traditional 9-bar profiles, which can lead to increased flow and dilution.
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My Gaggimate also has flow control capabilities.
The GaggiMate controls flow by taking direct command of the espresso machine's pump, using a Solid-State Relay (SSR) to regulate its power, thus controlling the flow.
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