Cold Storage

Respiration — the process by which harvested produce uses up its sugars and reserves — roughly slows as temperature falls, and with it the pace of ripening, softening, and ageing. Cooling also slows the growth of most decay organisms and reduces water loss, which is what causes wilting and shrivelling. Together these effects can extend usable life from days to weeks or months, depending on the crop.

Because cooling is most valuable early, produce is often pre-cooled to remove field heat quickly — by forced air, hydro-cooling, or room cooling — before being held in cold storage. Maintaining high humidity in store limits water loss, while good air circulation keeps temperature uniform and carries away heat of respiration.

Not all produce tolerates the same temperatures. Temperate crops such as apples and many leafy vegetables store best just above freezing, while many tropical and subtropical crops — including bananas and many other warm-climate fruits and vegetables — suffer chilling injury if held too cold, showing symptoms such as pitting, discolouration, or failure to ripen. Matching the storage temperature to the commodity is therefore essential.

• Cool produce promptly after harvest to remove field heat.
• Hold each commodity near its own optimum temperature and humidity.
• Avoid temperatures that cause chilling injury in sensitive crops.
• Maintain uniform temperature and good air circulation throughout the store.
• Keep ethylene-producing and ethylene-sensitive produce apart where relevant.