Written by  Jake Newnham, Nuffield Scholar

Improving sweet cherry fruit quality - handling at harvest

Despite growing techniques differing from orchard to orchard, harvesting generally follows a consistent model across most global commercial cherry production.

Harvest
Unlike some fruit (e.g. bananas), cherries are non-climacteric, meaning they will not continue to ripen with large increases in sugar during storage.
That is why harvest timing is important and can have one of the greatest impacts on final fruit quality.
Fruit harvested immature will never gain the sugars or colour deemed acceptable by the consumer, despite having a greater storage potential. Conversely, fruit harvested over-mature will be much sweeter but lack required firmness as well as having much reduced storage potential.
Determining optimal harvest timing will often depend on balancing several factors, quite often in conflict with each other. These can include availability of pickers, market opportunity, climatic conditions and prioritisation among cultivars or blocks.
For an individual cherry to reach its greatest potential, the optimum harvest window between under maturity and over maturity is relatively narrow.
Whilst fruit quality can vary drastically between growing seasons, orchards and cultivars, selecting an appropriate harvest window and harvesting quickly and efficiently offers producers the first practical step towards achieving an optimum result. It is critically important that fruit has the correct balance of sugar and firmness at harvest as a lack of either will greatly diminish fruit quality. Neither problem can be rectified after this point as cherry quality cannot be improved after harvest.
Global harvest model
Despite growing techniques differing from orchard to orchard, harvesting generally follows a consistent model across most global commercial cherry production.
Picking occurs early in the morning to avoid the heat of the day, in some cases commencing at midnight with pickers using personal headlamps.
Proper training of workers is crucial as cherries are very sensitive to physical damage during harvest. This damage is often not detectable for up to ten days.
Fruit must be removed from the tree either individually or in bunches and placed into a picking lug with care taken not to remove buds from the tree, or stems from the fruit.
Most compression damage or bruising found in stored fruit is caused by rough handling by pickers.
Fruit is transferred from the tree to a bin in many ways. It almost always begins with cherries being picked and placed directly into buckets or small lugs, weighing between 5kg and 8kg. From this point an orchard can utilise a no-tip, one-tip, or two-tip system, with each providing its own advantages and disadvantages.
No-tip system
With a no-tip system, the original picking lug is removed from the picker’s harness and stacked directly into a larger bin. The picker would then take another lug and repeat the process. This method provides the gentlest experience for the fruit as it is picked directly into a receptacle without further handling, with every point of tipping bringing further opportunity for physical damage.
However, this method provides the least efficient use of space in transport and in cool room storage, as the lugs take up significantly more room in bins than tipped fruit.
To keep fruit in the original lug also requires an orchard to have access to considerably more bins due to this inefficiency in storage, as well as many more lugs as a great number will be holding fruit at any given time.
This also means large numbers of lugs and bins need to be constantly ferried from the shed to the paddock. Despite the clear physical benefits to the fruit, this method is often not viable for most large producers.
Two-tip systems
Two-tip systems involve pickers picking into lugs/buckets, tipping those lugs into larger totes, and (usually) a pick-up crew tipping those totes into bins for transport.
This greatly improves the transport, storage and logistical issues encountered in a no-tip system but most growers aiming to produce a premium product would view the potential physical damage to cherries as unacceptable.
One-tip systems
One-tip systems can involve pickers picking into lugs, tipping into a larger tote (10-14kg) and stacking those totes into larger bins for transport. This system was frequently observed in Chile, where commitment to fruit quality is high (see Figure 1).
Alternatively, pickers may tip their lugs directly into a bin. This offers supervisors greater opportunity to inspect picked fruit as well as giving maximum transport and storage efficiency, although it does still require fruit to be tipped once (see Figure 2).
Plastic bins
Most modern commercial orchards across all regions visited have converted entirely from wooden fruit bins to plastic bins with the MacroBin 12-FV being the dominant choice in North America.
These bins offer many advantages over traditional wooden bins including having rounded internal corners for damage prevention, weighing 60% of a wooden bin, being much quicker and easier to stack, having forklift access to all four sides, and importantly, being non-porous allowing for greater sterilisation.
Growers choosing to keep fruit in totes generally use a plastic full bin with plastic fitted totes to give the highest storage and transport efficiency possible. While both systems are considerably more expensive than conventional systems still in use in Tasmania, the benefit to fruit quality cannot be completely ignored.
Transport to packing shed (cont next issue)

See this article in Tree Fruit July 2021

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