When is the right time to harvest jujube fruit

The ripening period of jujube fruit can be divided into three stages: White ripening stage, fragile ripening stage and full ripening stage. The harvest time of jujube fruit depends on the use of jujube fruit.

The main results are as follows: (1) in the white ripening stage, the pericarp green fades, showing green-white or milky white. The fruit has soft flesh, less fruit juice and low sugar content. When used for processing jujube, it should be harvested in the white ripe period.

(2) during the brittle ripening stage, from the stem depression, the fruit shoulder turned red to the full red fruit, the texture became crisp, the juice increased and the sugar content increased sharply. Jujube used for fresh food and processing should be harvested during this period.

(3) during the mature stage, the pericarp became red and dark, slightly wrinkled, the pulp was yellowish brown near the core, and the texture became soft. The fruit of this period has been fully ripe, and the dried varieties have been harvested in this period, with high drying rate, strong color, thick pulp, elasticity and good quality. How to make dried dates?

The drying method of jujube in most jujube producing areas in China is adopted. This method is simple and easy, with less investment and large amount of processing. The specific method of drying fruit is to choose a flat sunny place where there is no stagnant water, and use bricks and bamboo slices to support the straw foil 15 cm away from the ground. Spread the jujube evenly on the foil, 6-10 cm thick, expose to the sun for 3-4 days, turn once every 1 hour in the process of exposure, pile up the jujube in the middle of the foil at night to form a ridge, cover with a mat. After 3-4 days of exposure, the jujube is spread out to dry every morning, the jujube is piled up at 11:00 in the morning, and then spread out to dry after 2 o'clock in the afternoon. after a stage of drying, the pericarp appears fine wrinkles and the hand is elastic. at this time, the jujube foil can be piled up, sealed with a mat, and ventilated for 3-4 hours every few days. In the process of drying jujube, we should pay attention to the following problems:

The main results are as follows: (1) due to the different maturity and water content of jujube, the duration of drying is also different. Therefore, the jujube should be classified according to the maturity of the jujube before drying, so that the dry humidity of the jujube is the same. Pick out insects, rotten, injured and diseased fruits when sorting.

(2) pay attention to turning frequently during exposure, if the time of jujube violence is too long, it is easy to appear "oil head" jujube.

(3) during the drying period, the dates with different water content should be selected and classified according to the water content, and the dates with different water content should be separated and dried.

At present, the fresh jujube storage technology is not very good, can not be preserved for a long time, generally can only be preserved for 2 months to 3 months. There are many factors affecting jujube fruit preservation, such as varieties, harvest maturity, chemical types, storage conditions (such as temperature, humidity, gas composition) and so on. The main results are as follows: (1) the corresponding storage-tolerant varieties are Dongzao, Xifengshan jujube, Xifengshan Xiaoya jujube, Tuanzao jujube, toad jujube, Jian jujube, wooden jujube, October red and so on.

(2) timely harvest, the lower the maturity, the more resistant to storage, but the harvest is too early, the sugar content is low, the flavor is poor, the nutrition accumulation is less, but the respiratory metabolism is exuberant, the consumption of substrate is large, and the development of protective tissue on the surface of jujube fruit is not sound enough, water retention is poor, easy to lose water; too late harvest, low fruit vitality, poor resistance to external adverse conditions, not resistant to storage. Therefore, it is appropriate for fresh edible varieties to be harvested in the semi-red period.

(3) the method of picking fruit is generally picked by hand, picked and placed gently to avoid bruising, and pay attention to keeping the stalk intact.

(4) pre-cooling is generally carried out by spraying or soaking in water, in order to avoid bringing a large amount of heat into the field, weaken respiration and prolong the storage period.

(5) the storage period can be prolonged by soaking the fruit with calcium chloride or spraying calcium chloride, gibberellin or methyl topiramate before harvest. Calcium can change the ratio of water-soluble and insoluble pectin in jujube fruit, making most of the pectin insoluble; secondly, calcium fixation on the exchange point of protoplast surface and cell wall reduces its permeability and weakens respiration. Generally, the concentration of calcium chloride is 0.2% Mel 2% and soak for half an hour. But the effect of chemical treatment is related to the variety. For example, Xifengshan jujube and Po jujube were sprayed with 0.2% calcium chloride half a month before harvest, and after 45 days of storage, the good fruit rate of the former increased by 13.8%, while the effect of the latter was not obvious. Therefore, the appropriate type and concentration of agents should be selected in application.

(6) bagging can reduce water evaporation, properly inhibit breathing, and put it in perforated plastic bags or plastic film bags, which can keep low temperature without accumulating too much carbon dioxide. 2-4 kg jujube fruits are packed in each bag, sealed and placed in layers.

(7) during storage, the storage temperature is stabilized at 0 ±1 ℃ (or slightly higher than the freezing point temperature of the variety), the relative humidity in the bag is stable at 90% rel 95%, the carbon dioxide concentration is less than 5%, and the fruit changes are regularly sampled and left the warehouse as early as possible if necessary.