Retention management and purging

What is Retention?

• Definition: Coffee grounds that remain trapped inside a grinder after grinding.
• Types:
• Exchange Retention: Old grounds mixed with new dose.
• True Retention: Grounds stuck inside grinder, only exiting after purge.
• Impact: Retained grounds can stale quickly and contaminate flavor in subsequent shots.

Retention Management Strategies

• Single Dosing:
• Weigh beans before grinding, grind all at once.
• Minimizes retention but requires efficient grinder design.
• Purging:
• Run grinder briefly after adjustment or idle period to clear old grounds.
• Typical purge: 1–3 g depending on grinder.
• Low-Retention Grinders:
• Modern designs (short chutes, vertical burrs) reduce retention.
• Workflow Adjustments:
• Keep grind chamber clean with brushes or bellows.
• Establish purge protocols for opening shifts, grind adjustments, and after grinder sits idle.

Purging Guidelines

• When Changing Grind Size: Purge 2–3 g to ensure new setting consistency.
• At Start of Shift: Purge retained grounds from overnight.
• After Idle Time (>5–10 min): Purge to avoid using stale grounds.

Benefits of Good Retention Management

• Accurate dosing and beverage yield.
• Cleaner flavor without contamination from stale fines.
• More predictable dialing-in process.

Summary

Retention and purging management is essential for consistency in espresso. By adopting single dosing, using low-retention grinders, and following purge protocols, baristas can ensure accurate dosing, fresh flavor, and reproducible shots.

• Tags:
• Grind Size
• Coffee Grounds
• Single Dosing
• Beverage Yield
• Old Grounds
• Management Strategies
• Cleaner Flavor
• Run Grinder