A heat wave is defined by prolonged periods of high temperatures, exceeding normal climatic values. According to the Meteorological Office of Chile, typical summers under the El Niño phenomenon tend to present high temperatures.
The temperature increases expected for this summer season in central Chile are part of the consequences caused by climate change, which is already a reality, which is why we must be prepared to face it and our post-harvest of fruits as well.
The first thing we must bear in mind when post-harvesting cherries in this adverse climate scenario is that we must worry about controlling metabolism and dehydration. This objective is effectively achieved through control of ambient temperature, control of relative ambient humidity, control of pulp temperature and control of process times.
Our “Humidity Chain” presents an effective solution for the 6 points of post-harvest dehydration of cherries:
1.- Harvest: In this first stage of post-harvest we recommend harvesting at 6:00 am (at this time there is no dehydration and the pulp temperature does not rise at increasing rates), using a double 95% Raschell mesh cover over the bin to be harvested, the use of wet sponges on the totes is essential to stop solar radiation, the bin harvest time cannot exceed 30 minutes, and that the transfer time from harvest to storage does not exceed 10 minutes.
2.- Gathering: The idea of this point is to build a humidified storage area in an appropriate manner and with the necessary materials, mainly with a double Raschell 95% mesh and slatted doors. Our objective with this point is to achieve a relative humidity inside the storage center greater than 85%, with this we will achieve a drop in ambient temperature of around 10° C, and prevent the pulp temperature from rising. In extreme conditions of pulps of more than 30° within our humidification systems we have managed to reduce the pulp temperature by up to 20° in two and a half hours. This point is a very good contingency measure if the truck is delayed or the plant is very overloaded with fruit, this allows us to keep the fruit in good condition and wait a prudent amount of time in the storage area without damaging it.
One of the characteristics of what happens within the collection is that dehydration decreases by 94%, by maintaining pulp temperatures of around 20°, we ensure that the metabolism does not increase since if we have fruit at more than 30° the metabolism multiplies by three times.
3.- Transport to the Plant: The most advisable way to transport fruit is to use a thermal truck because it controls the temperature of the pulp, eliminates the wind, and is a powerful contingency measure in the event of a possible traffic jam on the road or in front of the plant.
4.- Reception on the Floor: For logistical reasons, we know what time the truck arrives, but we do not know the time of unloading, nor the time of the hydrocooling process. This waiting time can be from 20 minutes to 4 hours or more, ideally causing the least damage to the fruit in terms of metabolism and dehydration. This is effectively achieved by using humidification systems at reception.
5.- Raw Material Chamber: At this stage, dehydration occurs and begins from the third or fourth day onwards, when dehydration increases at increasing rates. This occurs because the water in the hydrocooler adheres to the surface of the cherry, protecting it from dehydration. Once this water evaporates, it begins to dehydrate the fruit, which is why it is necessary to have humidification systems in the raw material chambers when we are not sure how long it will be stored.
6.- Maritime Transport: The more we reduce the time, the less damage, which is why the “Cherry Express” that can reduce the damage by up to 10 days becomes more relevant.
All of these tips are very practical and efficient to use in the current cherry harvest, which is in a complex situation regarding the deterioration of the fruit due to solar radiation.
