Packing House Design and Workflow

Post-harvest handling sets the sequence — cut, de-hand, wash, treat, drain, cool, grade, pack. This page sizes the facility that runs it: how big, how much water, how much cold room, and how the fruit moves through without doubling back. Get the flow wrong and the best steps in the world still cannot keep up.

Size it from throughput#

Everything starts with the busiest day, not the average one.

Peak day throughput (t) = annual packable tonnage ÷ harvest days per year × peak factor
Peak-hour throughput     = peak day throughput ÷ working hours

A 5 ha block selling 128 t a year over 250 harvest days averages about 0.5 t/day; with a 1.5 peak factor the packhouse must handle 0.75 t on its busiest day, about 0.15 t/h across a five-hour shift.

Throughput	Building area	Wash capacity	Cold room
< 0.5 t/day (1–2 ha)	20–40 m² shade + table	200–400 L tanks	Cool store 5–10 m³
0.5–2 t/day (2–5 ha)	40–80 m², roofed	500–1,500 L, 2 tanks	15–30 m³ forced-air
2–8 t/day (5–20 ha)	100–250 m² line	2,000–6,000 L, flow	40–120 m³, rooms
> 8 t/day	Purpose-built line	Mains supply + treatment	Multiple rooms

The flow: a one-way line#

Fruit should never meet clean fruit on its way back. Arrange zones in a U or straight line, entry and exit at opposite ends:

[ field delivery ] → [ de-hand ] → [ wash/deflux ] → [ treatment ] → [ drain ]
                                                                            ↓
[ dispatch / cold ] ← [ pack ] ← [ grade ] ← [ cool to 13–14 °C ] ←─────────┘

Zone	Purpose	Key control
Receiving	Bunch intake, shade, weigh	Cut-to-receive under 2–4 h
De-handing	Hands off the crown	Padded surface, sharp blades
Wash / deflux	Remove latex	30–35 °C, changed when milky
Treatment	Crown-rot / residue control	Label rate and contact time
Drain / cool	Surface-dry, then chill	Pulp to 13–14 °C
Grade / pack	Sort and box	Correct grades separated
Cold hold	Buffer before dispatch	13–14 °C, 90–95% RH

Slope the floor toward the wash zone so water flows away from packing, and keep all drains outside the clean side.

Route fruit one way: field-dirty at one end, clean and cold at the other, so clean fruit never meets field dirt on the way back.

Water: the volume nobody plans for#

Defluxing and washing use more water than most growers expect, and dirty water is the fastest route to crown rot.

Use	Typical volume	Notes
Deflux soak	300–600 L per tonne of fruit	Warm (30–35 °C), changed before milky
Rinse	150–300 L per tonne	Clean water, single pass
Equipment cleaning	200–500 L/day	Food-grade sanitiser, scheduled

Plan a two-tank system — a dirty (first) tank and a clean (rinse) tank — so hands are never re-contaminated by the water that just removed their latex. Budget a water reserve of at least one day's peak use in case supply drops.

Cold room capacity#

The cold room is a buffer, so size it on days of hold, not hours.

Cold room volume (m³) = peak daily tonnage × hold days
                        × 1.4 (airflow and stacking allowance)
                        ÷ 0.5 t/m³ (typical boxed product density)

For 0.75 t/day held two days: 0.75 × 2 × 1.4 ÷ 0.5 ≈ 4.2 m³ of product space, plus aisles and clearance on top. A forced-air unit cools packed boxes in 1–3 hours; passive room cooling takes 6–12 hours and risks uneven pulp temperatures.

Hold at 13–14 °C and 90–95% RH, with airflow that removes ethylene and no mixing of green fruit with ripeners.

Packaging and dispatch#

Decision	Guidance
Carton	Food-grade, ventilated, correct weight for the buyer (12 kg export typical)
Padding	Non-absorbent crown pads; nothing that can bruise fingers
Label	Block, harvest date, grade, packer — traceability is a legal requirement in most export chains
Pallet / stacking	Banded, within rated stack height; bananas are strong on corners, weak on faces
Dispatch hold	Unbroken cold chain; record pulp temperature at loading

Match carton weight to both the buyer specification and the manual-handling limit — a 12 kg box is a different ergonomic job from a 20 kg box on a hot afternoon.

Hygiene and food safety#

Route the safety system through Quality and food safety and keep the paperwork in Record-keeping templates.

Common packhouse mistakes#

Mistake	Result
Sized on the annual average	Fruit queues in the sun on peak days
Single dirty wash tank	Re-contamination; crown rot
Cold room sized in hours, not days	Bottleneck at dispatch; warm fruit loaded
Two-way flow with cross traffic	Clean fruit meets field dirt
No traceability labels	Fails audit; no way to trace a problem
Pads and rollers never cleaned	Mould inoculum reintroduced every pack

Next steps#

Follow the handling sequence step by step: Post-harvest handling.
Meet the buyer's rules: Certification and market compliance.
Measure what you keep: Pack-out and grade calculator.
Ripen to specification: Ripening.