Retention mapping and mods

What is Retention?

• Retention = coffee that stays inside the grinder after a dose is ground.
• Includes:
• Exchange retention: Old grounds mixing with fresh.
• Total retention: Coffee trapped in burr chamber, chute, or declumper.
• Leads to inconsistent dosing, stale flavors, and recipe inaccuracy.

Mapping Retention

1. Weigh In vs Out Test:

• Dose a known weight of beans.
• Grind fully, weigh output.
• Difference = total retention.

2. Purge Tracking:

• Grind again and weigh the first output.
• Shows how much old coffee remains in grinder (exchange retention).

3. Repeat Over Multiple Doses:

• Build a profile of retention behavior across several grinds.

Typical Retention Levels

• Large commercial grinders: 3–6 g or more.
• Single-dose grinders: <1 g.
• High-retention grinders require purging before critical brews.

Mods and Solutions

• Declumper Mods: Replace or trim rubber flaps to reduce coffee buildup.
• Bellows/Puffers: Attach silicone bellows to blow out retained grounds.
• Anti-Retention Chutes: Aftermarket metal or 3D-printed parts improve flow.
• Single-Dose Hoppers: Reduce beans sitting in grinder and minimize exchange retention.

Best Practices

• Map retention when first calibrating a grinder.
• Document expected purge amount for consistency.
• In cafés, incorporate purge grams into recipe SOPs.
• At home, consider mods if retention exceeds 1–2 g and impacts flavor.

Summary

Retention mapping reveals how much coffee remains in your grinder between doses, directly affecting freshness and accuracy. With tools like declumper mods, bellows, and single-dosing setups, baristas can minimize retention, ensuring cleaner flavor and precise recipes.

• Tags:
• Best Practices
• Single Dosing
• Burr Chamber
• Old Grounds
• Cleaner Flavor
• Leads Inconsistent