Cold storage project for Chinese winter jujube and jujube storage tips.
March 3, 2014
Here is the jujube storage we did in Shandong province, one of the main place of Chinse winter jujube. So here we shall take this opportunity to introduce how jujube is harvested and storaged here in China.
1. The picking and packaging. During the process of winter jujube harvest, logistic and picking and commercialization treatment, we must try our best to prevent any mechanical damage, including scratching, stabing damage or even crush injury. Those injury will not only increase the breathing pace and make the apperance look bad, it will also become a main way of growing germ and bacteria. So, throughout the whole process of operation, must be very careful during loading, transportation, etc.
a. Normally for long term storage, we should pick those jujubes who are slightly red, half red fruit.
b. Better hand pick jujubes, do not use sticks to hit the tree or shake the tree to make the jujube fall on the ground, do not use ethephon assistant fruit droping to pick the jujubes. Prevent any chance causing phasical fruit damage or accelerating the ripening of the fruit.
c. Take out tree leaves, damaged jujubes, too small ones and maturity degree younger than half red fruit.
d. For storage period within 2 months, we can shoose fully red, 3/4 red and half red 3 mature degree and younger than half red. For medium and long term storage which is more than 2 months, should pick those are half red, and under: half red, a quoter red, slightly red and white.
2. Preparation for storage.
a. Disinfection and cleaning. Before sotraging, must clean the cold room completely, including ground, shelf, plastic cases, etc.
b. CT high effeciency disinfectant. It is in powder shape, can cover a large area, have very little impact on metal. When using, fully mix the two small bags, light it up, seal the cold room and have it smoked for more than 4 hours. Position the smoke spot 5 gram per cubic meter.
c. Bleaching powder solution. Spay 4% concentration bleaching powder solution on the storage area.
d. Pre-cooling. Pre-cooling can remove the heat from newly picked jujubes, drop the temperature to a proper temperature for logistic and storage, so that it can remain the hardness and freshness maximumly and enlarge the storage period.
Usually there are these types of pre-cooling:
a) Ventilating pre-cooling. 2 days before putting into storage room, drop the storage temeprature to -2 to 5 centigrade, load the jujubes into the storage quickly. When the jujube temperature and cold room temperature are same, then they are ready to be packaged to plastic wrap or depressure vessels. The pre-cooling process shouldn't be too long, or the jujubes will lose water.
b) Ice water and fresh-keeping agent processing. Build a 2 meter long, 0.5 meter wide, 0.8 meter high water tank, the ratio of water to ice is 1 to 0.3. At this moment, the water temperature is around 2~5 centigrade, add jujube special purpose fresh keeping agent, the ratio of water to fresh keeping agent is 50 to 1. Soak the jujube into water ice mixture for 0.5~1 minute, take out the jujube, when they are dry, when the cold room temprature is in accordence with the jujube, put the jujube into plastic wrap or depressure vessel.
c) Fresh keeping agent processing. Low temperature have obvious inhibition to bacteria growth, but cannot kill all germs completely, on the other hand, some pathogenic bacteria still can grow and reproduce under 0 centigrade and cause harm to the storaged food, so using fresh keeping agent is necessary.
When storaging, can use CT series and CT2 series fresh keeping agent from the national fresh keeping research centre, the performence is good.
3. Storage temperature and humidity.
a. Temperature. A proper low temperature can effectively reduce the fruit breathing, reduce the nutrition consumption, rise the fruit anti germ ability. The recommended temperature is -2士5 centigrade
b. Humidity. Usually the fresh fruit contains 85~90% water, when the water loss is more than 5%, the fruit will shrink obviously. For Chinese winter jujube, the storage relative humidity should keep above 95%.
c. Gas. The recommended storage gas environment is: Oxygen 4~6%. If carbon dioxide is too much, it will make the fruit turn brown, some may have brown spot and have shrink spot, till it gets rotten.