Blueberry storage in a controlled atmosphere
MATURITY: for long-term storage, blueberries must be picked at the right time. The timing of harvesting depends on several factors:
– the color of the fruit at the time of harvest.
– sugar or antioxidant content. Blueberries are harvested when they are almost ripe, because the quality of the fruit decreases rapidly after harvest.
TEMPERATURE: refrigerated storage temperature of blueberries is in the range (-0.5 / 0) ° C.
HUMIDITY: the relative humidity must be maintained between 90 – 95%. If the relative humidity falls below the level of 90%, the blueberries will dry and will show wrinkles on the surface.
LIGHTING: blueberries should be stored in total and constant darkness.
VENTILATION: must be ensured at a minimum level, to avoid dehydration, but sufficient to eliminate the excess CO2 generated during storage.
1. Refrigerated storage:
– it is recommended that after harvest the fruits be subjected to the process of rapid cooling (pre – cooling) at a temperature as close as possible to the storage temperature.
– considering the relatively high air currents that are involved in the rapid cooling process, it is recommended to use constant pressure chambers or the protection curtain on the surface of the upper crates.
– During rapid cooling, two main factors are pursued: reducing weight loss (water loss) and extending the storage period.
– the storage term in refrigerated state is directly dependent on: the type and mixture of fruits during harvest, CO2 content (15-20% can successfully prevent the spread of Botrytis and other fungi), the possibility of removing ethylene during storage and quality water used to ensure and maintain the necessary humidity.
– the duration of the storage term in pre-cooling conditions, temperature and controlled humidity is about 2-3 weeks.
2. Refrigerated storage in CA / ULO conditions – cold storage:
– it is recommended that after harvesting the fruits go through exactly the same stages as in the case of storage in controlled temperature and humidity conditions.
– after the completion of the loading of the fruit warehouse, it is sealed and the CA conditions are ensured in the storage room. The 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 terms increase up to 7 – 8 weeks depending on the condition of the fruits at the date of harvest.
3. Refrigerated storage in AC / ULO conditions – palletized system:
– the storage of the fruits in the CA / ULO refrigerated warehouses is done individually in O2 and CO2 conditions determined according to the nature of the fruits.
– The fruit pallets are covered with a gas-tight plastic system. The dimensions of the system are 1200 x 1000 x 4500 max (LxWxH) (mm). The system thus created is connected to the CA / ULO boiler, with the possibility of creating specific conditions for a variety of fruits inside the same cold storage.
– advantages: different O2 and CO 2 settings, it is impossible to migrate mushrooms / spores and flavors from one fruit time to another, the impossibility of losing CO2 in cases of accidental decoupling.
– the system allows the simultaneous use of a minimum of 10 pallets and a maximum of 300 pallets.
For home storage, we recommend:
– they can be stored either in the refrigerator or in the freezer, but there are also options for drying and preserving them in different forms.
– if they are kept in the refrigerator, they should not be washed beforehand and should be kept in a clean and dry container, covered with a plastic foil. Do not put in this storage place the fruits that are soft or that are starting to rot, and when it is seen as one shows traces of damage, it will have to be removed from the storage space. Thus, the fruits will last up to two weeks, but it would be better to eat them as soon as possible.
– Blueberries can be put in the freezer, after they are thawed they will be just as tasty and only a little juicier than in the fresh version. do not wash them before freezing, but after they have been thawed.
– to be placed in a covered box, leaving a space of 1-2 centimeters from the fruit to the lid, to allow them to increase in volume. If you want to be consumed in the raw version, to be contained in a syrup made of four cups of water and three cups of sugar, to be sealed the box and put in the freezer. And if after thawing it is thought to be crushed, add 1-1.5 cups of sugar for each liter.
– if it is desired to be dried, to follow the following procedure: to be immersed for 15-30 seconds in boiling water, then immediately thrown in cold water. To be wiped off by traces of juice and dried in a dehydrator or in a space where they will be placed at dry – it must be well ventilated and protected from too much light and heat. It can be considered that they have dried when the juice no longer comes out when pressed.
© Frigotherm Group 2020