The six-day box fermentation protocol

Fermentation converts the sugary pulp around fresh beans into heat, alcohol and acids that kill the seed and develop chocolate flavour precursors. Done well it takes six days. Done poorly it cannot be fixed later - no roaster can rescue slaty beans.

The protocol

• Day 0: Break pods within 5 days of harvest. Discard black, germinated and damaged beans. Fill wooden boxes 60-90 cm deep, cover with banana leaves and sacks.
• Day 3: First turn - move the mass into a second box, outside-in. Temperature should reach 45-48 °C.
• Day 5: Second turn. The smell shifts from sharp alcohol to vinegar.
• Day 6: Cut test - slice 20 beans lengthwise. Stop when at least 17 show brown centres with cracked, ring-patterned cotyledons.

The three failures

Too shallow (under 50 kg) never heats. Unturned ferments unevenly - vinegar outside, purple inside. Overlong (8+ days) smells of ammonia and hams the flavour. A thermometer and a knife are the only instruments needed.

Members can book slots at cluster fermentaries through the services directory instead of building their own boxes.