Strawberry storage in a controlled atmosphere
Storage conditions strawberries:
Maturity: strawberries are harvested at different stages of development, depending on the variety and market preference. The maturity of strawberries is best indexed by the color of the outer surface and the firmness of the fruit. Fruits of most varieties intended for consumption should be harvested whenthe surface of the fruit is completely red, but fruits of less hard varieties should be harvested when they have a lighter color. Less hard varieties include Senga Sengana, Polka and Honoeye.Stronger varieties, such as Selva and Camarosa, should be harvested when they have a deep red color. The Aroma of all varieties of strawberries is more sought after and sweeter if the fruits are allowed to ripen entirely on the plant. Strawberry fruits no longer ripen after harvest.
Temperature: the storage temperature of strawberries in the refrigerated state is within the range (0 / +1)°C.
Humidity: relative humidity should be maintained between 90 – 98%. If the relative humidity drops below the level of 90% the strawberries will dry out and present wrinkles on the surface.
Lighting: strawberries must be stored in total and constant darkness.
Ventilation: it must be ensured at a minimum level, to avoid dehydration, but sufficient to eliminate the excess CO2 generated during storage.
STORAGE SYSTEMS:
1. Refrigerated storage:
– it is recommended that after harvesting the fruit be subjected to the rapid cooling process (pre – cooling) at a temperature as close as possible to the storage temperature (0 / +1)°C.
– considering the relatively large air currents that are involved in the rapid cooling process, it is recommended to use constant pressure chambers or a protective curtain on the surface of the upper flasks.
– during rapid cooling, two factors are mainly pursued: reducing weight loss (water loss) and extending the storage term.
– storage condition refrigerated is directly dependent on the type and mixture of the fruits during the harvest , the quantity of CO2 (15 to 20% could be prevented successfully, the extension of Botrytis and other fungi), the possibility of the removal of ethylene during the storage, and the quality of the water used to provide and maintain the humidity required.
– the storage term in pre-drying conditions, controlled temperature and humidity is about 2 weeks.
2. Refrigerated storage in CA / UA conditions-refrigerated warehouses.
– it is recommended that after harvesting the fruits go through exactly the same steps as in the case of storage under controlled temperature and humidity conditions.
– after the completion of the loading of the Fruit Warehouse, proceed to its sealing and proceed to ensure the conditions as in the storage room. Generic storage conditions are included in the parameters: 3% O2 and 10% CO2 / (-0.5 / 0)°c / 90-95% rH.
– in these conditions the storage periods increase up to 7 – 8 weeks depending on the condition of the fruits at the date of picking.
3. Refrigerated storage in CA / UA conditions – palletized system.
– fruit storage in CA / ULO cold stores is done individually under O2 and CO2 conditions determined according to the nature of the fruit.
– pallets with sant fruit covered with a gas-tight plastic system. Dimensions of the system sant 1200 x 1000 x 4500 max (Lxwxh) (mm). The system thus created is connected to the plant as / ULO there is the possibility of creating specific conditions for a variety of fruits inside the same cold storage.
– advantages: different settings O2 and CO 2, it is impossible to migrate fungi / spores and flavors from one fruit time to another, the impossibility of CO2 loss in cases of accidental decoupling.
– the system allows simultaneous use of mínimum 10 pallets and máximum 300 pallets.
Post-harvest diseases:
Post-harvest degradation is a major cause of the existence of poor quality, unsold fruits. Several different fungal diseases are responsible for the vast majority of post-harvest decay problems. The main disease after harvesting strawberries is gray rot – Botrytis. Diseases of lesser importance are soft rot and Rhizopus skin rot.
Strawberry diseases involve complex interactions between the causative agents, the host plant and the environment. The development of a disease is influenced by the strawberry variety, the stage of maturity of the fruit, physical degradation, when the fruit is infected, post-harvest temperature and surface humidity.
A combination of control methods should be used to minimize the incidence and severity of post-harvest diseases. These control methods include field hygiene, appropriate crop practices, the use of crop protection factors, care during picking and handling, the use of protective packaging, rapid cooling after harvesting and maintaining the cooling chain during transport and distribution to the market. There are no post-harvest fungicides available for use on strawberries.
In late February or early March, dead leaves and stolons of last season should be removed. Dead plant material is a major source of gray mold spores.
Manual removal of this source of inoculation before a new growth begins will significantly contribute to Disease Control. Fungicides applied before harvest are available for use on strawberries, allowing protection against post-harvest diseases.
The use of appropriate fungicide (s) in a timely manner and in accordance with the instructions of pesticide manufacturers will help protect strawberry fruit from disease. Problems with post-harvest diseases also increase when plantings are too dense, which makes the leaves and fruits dry hard after rains and make it more difficult to spray properly.
