Shot time vs flow profiling
The relationship between shot time, flow rate, and pressure profiling, and how they shape espresso extraction and flavor.
- Coffee Basics Nerds
- 2 min read
Article 6 of 12 in Espresso Fundamentals/
Shot Time
- Definition: Duration from pump start to final yield.
- Typical Range: 25–30 seconds for a normale (1:2 ratio).
- Short Shots (<20 sec): Often sour, under-extracted, thin body.
- Long Shots (>35 sec): Often bitter, hollow, over-extracted.
Flow Profiling
- Definition: Controlling the rate at which water passes through the puck during extraction.
- Methods:
- Constant Pressure (classic machines): Fixed 9 bar throughout shot.
- Pressure Profiling: Variable pressure curve (e.g., ramp up, hold, decline).
- Flow Profiling: Direct control of water flow rate instead of pressure.
Interactions
- Fast Flow: Lower contact time, lower extraction yield → sourness and lack of body.
- Slow Flow: Higher contact time, higher extraction yield → bitterness and dryness.
- Flow Profiling Benefits:
- Gentle preinfusion → reduces channeling.
- Ramp-up and tapering → balance clarity, sweetness, and body.
- Custom curves allow tailoring for light vs dark roasts.
Flavor Impacts
- Constant 9 bar / fixed flow: Consistency, but less flexibility.
- Profiled shots: Can highlight acidity, enhance sweetness, or smooth body depending on curve.
Practical Tips
- Track both shot time and yield, not just one.
- Use refractometer data to evaluate extraction yield (18–22% ideal).
- Start with standard 1:2 in 25–30 sec, then experiment with flow/pressure curves for refinement.
Summary
Shot time alone is a crude measure; flow and pressure profiling provide finer control. Together, they shape extraction dynamics, allowing baristas to highlight or balance espresso flavors with greater precision.