Time is one of the main factors in the deterioration of cherries during post-harvest. Controlling the times of the processes will be key if we seek to improve the condition of the arrival of cherries at their destination, and we must set it as one of the main objectives in the planning of the following season.
As we know, post-harvest is a process that is made up of different stages and in each of them the fruit is exposed to different environmental conditions and different waiting times. Thus, in each stage the fruit is exposed to different levels of deterioration, mainly due to metabolic activity and dehydration. To implement improvements in the post-harvest process, then, we must first identify what these stages are, then characterize them and finally make decisions focused on adopting management or modifications that allow minimizing the deterioration of the fruit in each of them.
We have already identified the stages that are part of the post-harvest process. In each of them, the fruit is subject to variable waiting times, which depend on the reality of each field, each processing plant, and in some cases also on the date and time, since the bottlenecks that occur in some stages of this process are generated by the high load of fruit to be processed that occurs at the time. peak of the harvest. The average waiting times per stage are:
(1) Harvest: 1 – 2 hours
(2) Field storage: 3 – 6 hours
(3) Land transportation (from field to processing plant): 1 – 3 hours
(4) Reception at processing plant: 1 – 3 hours
(5) Raw material chamber (waiting for processing): 2 – 5 days
(6) Maritime transport (to export destination): 30 days
To demonstrate the importance of time as a determining factor in fruit deterioration during post-harvest, we conducted a trial in which the post-harvest time was kept to a minimum, from harvest to packing of the cherries. The fruit was then stored in cold storage for 30 days, simulating a trip to the destination, as shown in Figure 1. This trial was conducted with 4 varieties of cherries (Bing, Lapins, Santina and Sweetheart), and with fruit harvested at two different times: AM (harvest at 8:30) and PM (harvest at 12:30).
Figure 1. Stages of the post-harvest process of cherries. For the test, the first five stages (harvest, field collection, transport to the processing plant, reception at the plant and storage in the raw material chamber) were carried out in just 1 hour and then a trip to the destination was simulated by storing the fruit for 30 days in a cold chamber.
After 30 days of cold storage, the fruit was subjected to evaluations in which the total weight loss and the condition of the pedicel were determined.
Regarding the weight loss of cherries, the results (Figure 2) showed a very low total weight loss in all cases, fluctuating between 0.02% and 0.17%. Additionally, differences were observed between varieties, with greater weight losses identified in Santina and lesser in Bing. Similarly, a lower weight loss was observed in the fruit harvested in the morning compared to the fruit harvested at midday.
For evaluations of pedicel condition at box opening, cherries were classified into four categories according to the level of pedicel dehydration: healthy pedicels (less than 25% of their surface browned), pedicel with moderate dehydration (pedicel browning between 25% and 75%), completely browned pedicel (browning surface greater than 75%), and fruit without pedicels. The results (Figure 3) showed a high percentage of completely green pedicels, ranging from 50% of the total for the Bing variety to 100% of green pedicels for Santina. Between 0 and 40% of pedicels with moderate dehydration were observed (depending on the variety) and less than 1% of pedicels with severe dehydration.
The results of this trial show how valuable time is and how important it is to control the periods during which the fruit is subjected to waiting during post-harvest. If waiting times are reduced to a minimum, dehydration of the cherry will also be minimal and the condition upon arrival at destination will be optimal.
Figure 2. Weight loss from harvest to opening of boxes after 30 days of cold storage following minimum time in the pre-harvest stages of Bing, Lapins, Santina and Sweetheart cherries harvested at 8:30 a.m. (AM) and 12:30 p.m. (PM).
Figure 3. Pedicel condition after 30 days of cold storage of Bing, Lapins, Santina and Sweetheart cherries harvested at 8:30 a.m. (AM) and 12:30 p.m. (PM), after minimal time in the previous stages of post-harvest.
