A recent survey of six pack houses in British Colombia, all of which were utilising in-line hydrocooling, found that the most consistent systems were producing fruit pulp temperatures of 2.1-3.2C at box filling.
Packing procedure (cont from last issue)
The same study found that pulp temperature in palletised boxes showed little to no further decrease when held in 0C cool rooms for 20 hours. In fact, only when pallets were held in very cold rooms (-1.7C) and placed directly in the path of cool air from the refrigeration coil was any serious lowering of pulp temperature observed in the first 20 hours.
This further cooling was only measured in boxes on the outside of pallets, with internally stacked boxes showing no further cooling, even under these colder conditions.
The Australian and Tasmanian cherry industries rely heavily on (relatively) cheap air freight and a developed domestic transport system to deliver fruit to international markets within days of packing.
When the cool chain is managed correctly and cherries reach the final consumer within a week of packing, fruit pulp temperatures of 2–4C on dispatch are sufficient to ensure fruit quality is maintained.
These ideal conditions are not always a reality though when many producers rely on having fruit in certain markets at specific times or when market prices are high.
Volatile relations between trading partners and the potential for unforeseeable events means having the ability to hold fruit in storage for any increased length of time could be priceless. Achieving lower fruit pulp temperatures at dispatch through current packing processes is challenging as any further reduction in temperature prior to packing will raise incidence of pitting and bruising damage.
Paired with findings that passive room cooling does not significantly cool fruit once it has been palletised, one of the most commonly utilised methods to achieve such results is forced air cooling (FA cooling).
Forced air cooling (FA)
FA cooling, also known as pressure cooling, is a post-packing process in which chilled air in a cool room is sucked through vent holes in the sides of palletised boxes.
FA cooling systems vary depending on produce being cooled, floor space, and produce packaging but the most common system found in cherry pack houses is tunnel-style.
(cont next issue)
See this article in Tree Fruit March 2022
