Between-Batch Protocol (BBP): How to Achieve Back-to-Back Roast Consistency

The exact step-by-step between-batch protocol used by production head roasters to reset drum thermal energy and match curves with ±0.5°C repeatability.

Why Batch #2 Always Roasts Faster Than Batch #1

The most frequent complaint among commercial coffee roasters is profile drift across consecutive production batches. You drop your first morning batch of washed Ethiopian at 11:30 with perfect flavor, but the second batch reaches First Crack 45 seconds earlier, resulting in a hollow, baked cup profile.

The cause is residual drum latent heat. During a roast, the heavy cast iron front plate, drum bearings, and dual-wall carbon steel walls absorb thermal energy. Unless you execute a disciplined Between-Batch Protocol (BBP), your roaster enters batch 2 with significantly higher conductive energy than batch 1.

The 4-Phase RC-Tech Between-Batch Protocol

To achieve ±0.5°C repeatability on RC-Tech CAST and IS roaster series, follow this standardized 4-minute protocol between consecutive charges:

1. Phase 1: The Quench & Discharge Flush (0:00 - 0:30) - Immediately after dropping the roasted batch into the cooling tray, keep the drum door closed. - Boost exhaust airflow to 80% with zero gas input for 30 seconds to flush all remaining smoke, carbon particulates, and residual chaff from the drum cavity.

2. Phase 2: Thermal Equilibrium Soak (0:30 - 2:00) - Set the premix gas burner to a calibrated idling level (typically 15% to 20% on CAST-15). - Set airflow to 40%. Allow the Environmental Temperature (ET) and Drum Face Temperature to converge toward your target charge temperature.

3. Phase 3: Charge Stabilization (2:00 - 3:30) - When the Bean Temperature probe reaches 5°C above your target charge temperature, hold the burner steady. - Never charge on a steep rising curve or a falling curve. The temperature slope must be flat (RoR between 0°C/min and +1.5°C/min).

4. Phase 4: Green Bean Charge (3:30 - 4:00) - Verify green coffee hopper weight and temperature. - Open the hopper gate cleanly. Set burner and airflow to your pre-programmed profile recipe.

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