1. Overview & Physics
Cold Diffusion Physics
Solubility rates are directly proportional to temperature. Hot water accelerates molecular kinetic energy, dissolving acids and lipids in minutes. Cold brew relies on time instead of heat. Over 12 to 24 hours, caffeine molecules diffuse into the water, while heavy bitter acids remain unextracted, resulting in a smooth, chocolatey profile.
Extraction Time Guide
Steep cold brew for 12 hours at room temperature, or 24 hours inside a refrigerator to protect volatile aromatic compounds.
2. Practical Calibrations
Managing this requires measuring indicators in real time. Adjust grind size, water dynamics, and flow parameters incrementally. Change only one variable at a time to ensure clean results and isolate target parameters.
Barista Action Checklist
- Weigh dry grounds dry dose exactly to 0.1g.
- Calibrate water temperature using PID sensors.
- Target correct brew ratios (e.g. 1:15 for filter, 1:2 for espresso).
- Swirl or stir to ensure even saturation during extraction.
- Record extraction time and evaluate flavor notes subjectively.
Frequently Asked Questions
Why does cold brew have low acidity?
Many bright, sour fruit acids require hot water (above 90째C) to dissolve. Cold water extraction leaves these acids locked inside the grounds.
Is cold brew higher in caffeine?
Caffeine is highly soluble and eventually extracts completely over long contact times (12-24 hours), resulting in a high caffeine concentrate.
