While flow is often considered the most critical chemical factor in extraction, pure flow profiling is incredibly difficult to dial in. In an espresso machine, small micro-adjustments in flow rate cause massive spikes in pressure. If your grind size isn't absolutely perfect, a flow profile can easily spike past 9.5 or 10.5 bar. This high pressure forces the coffee puck into a "secondary compression," resulting in severe channeling and a highly muted, unappealing flavor profile.
Adaptive profiles—developed in collaboration with astrophysicist Jonathan Gagné—bridge the gap between pressure and flow. Instead of sticking to a rigid flow line that might cause pressure to spike dangerously, an adaptive profile dynamically moves the target flow line up or down. It actively adapts to your specific grind size and dose to ensure that your extraction always reaches your exact desired peak pressure without exceeding it.
During extraction, a coffee puck naturally dissolves and loses its resistance to water. If you use a rigid pressure profile, the water flow will rapidly accelerate and "gush" near the end of the shot as puck resistance drops. If you switch to a flow profile instead, the machine caps the flow rate so it cannot accelerate; consequently, the extraction pressure naturally declines as the puck falls apart, leading to a much slower and more controlled end to the shot.
In terms of flavor, flat to slightly increasing flow rates tend to produce the best espresso. While flat flow is acceptable, allowing the flow rate to gently increase (for example, from 1.0 ml/s to 2.0 ml/s over the course of the shot) yields a much more vibrant acidity and a more balanced cup. Conversely, a decreasing flow rate at the end of a shot consistently results in a flat, muted, and boring espresso.
The most successful profiles on the Decent combine the best of both worlds. They use flow profiling during the pre-infusion stage because the dry coffee puck is simply absorbing water, meaning pressure cannot rationally be measured. Once the puck is fully saturated, the machine transitions to a pressure-managed step to nail the optimal extraction pressure, and finally relies on an adaptive flow line to finish the shot smoothly.
If a built-in profile is not doing exactly what you want, you can easily reveal and edit its background structure by converting it into an advanced profile. To do this, navigate to your presets, hit the plus icon to create a new preset, and choose Advanced. The machine's software will automatically copy over every single step and parameter from your current profile, allowing you to fine-tune the hidden settings.
Standard profiles use a calculation that triggers the volume stop based strictly on the water poured after the pre-infusion stage finishes. Once pre-infusion ends, the coffee puck is fully saturated, meaning that any water pumped in directly equals the coffee liquid coming out. This makes the volumetric stop highly accurate.