1. Storage technology of leafy vegetables (spinach, scallion, cabbage) (1) Storage characteristics of spinach 1: Frozen storage method is mainly used for storage of spinach, and warm storage may also be used. The frozen storage of spinach requires quick freezing after the pit, and it is always frozen. After the pit is suddenly frozen or frozen, or not frozen for a long time, or frozen too much, it is easy to cause major losses. Proper harvest is one of the keys to success in obtaining frozen storage. Early harvest, high outside temperature, can not be stored in the ditch, heat inside the spinach heap, leaves turn yellow, increase rot loss; harvest too late, easy to make spinach frozen in the field can not be returned. Generally frozen on the ground in the morning and evening, it can be opened at noon, that is, the ground has just frozen and unfrozen in real time, the best harvest. After harvesting, the yellow dead leaves should be removed and bundled in place, then placed on the north side of the wind barrier or in other shaded areas for pre-storage, with a little coverage; it can also be directly frozen in the ditch. 2 storage methods: frozen storage method. Frozen spinach is similar to the general one, except that the storage temperature is different. The specific operating methods vary from place to place. The main difference is whether or not to set up shadow barriers and furrows. It is generally within the shading range on the north side of the shadow barrier, dug or parallel to the shadow barrier in parallel or vertically to the trenches. Narrow grooves (25 to 30 cm) do not have air passages; wide grooves (1 to 2 meters) must be excavated at the bottom of the trench with 1 to 3 air passages, and both ends of the air passages are exposed to the ground. The depth of the frozen ditch is about the same as or slightly shallower than the height of the dish. The spinach is bundled or erected in the ditch, and the wide ditch is first laid on the ventilation channel and the single layer of straw is horizontally spread. After the ditch is filled with vegetables, sprinkle a thin layer of sand on the surface, or cover the top of the ditch with a single layer of straw. Coverage at this time mainly acts as a windshield moisturizer, and should not be too thick so as to rapidly cool and freeze. Ventilators should be opened day and night. Afterwards, the cover soil is gradually added as the temperature drops. In order to facilitate the change of the temperature of the ditch, a temperature measuring tube may be installed in the ditch. The frozen thawed spinach is thawed three to five days before it is put on the market to restore it to a fresh state. Remove the spinach from the frozen storage ditch, place it in an empty room or shed, and slowly thaw at a low temperature of 0 to 2 degrees, then remove the yellow rot leaves, and arrange the bundles. Thawing can not be carried out under high temperature, otherwise the ice juice will not be absorbed by the cells after the ice melts. The cells will lose their turgor pressure and will not be able to return to a fresh state. The outflow of juice also promotes microbial activity and aggravates corruption. Warm storage, which maintains the low temperature near the freezing point, does not freeze the spinach significantly. This storage method can better maintain the vigor and storage of spinach, and reduce storage loss. The practice of warm storage is basically the same as that of frozen storage, except that the storage ditch is slightly wider and deeper, and the coverage is also thicker. The warm storage groove of spinach in Jinzhou and Shenyang is about 0.7 meters wide and 0.5 to 0.7 meters deep. The double ditch is parallel to the north side of the shadow barrier. The management of warm storage must be carefully and carefully, and timely adding coverage so that the temperature in the ditch does not exceed the range of 0 to 2°C. (2) Welsh onions. 1 storage characteristics: Weighing onion is very common in northern China. The onion's cold-resistance is stronger than that of onions and garlic. It can expose winters and can tolerate low temperatures below -30°C. Cells still have viability. So it is generally frozen and kept dry. 2 Storage technology: proper harvest is an important condition for the storage of green onions. When harvesting is too late, the nutrients are easily transferred to the base of the leaves, light blue becomes hollow, and the quality of food is reduced. The premature maturity of the harvest is not enough, the yield is low, and the storage loss is large. Onion needs to be given high temperature and dry after harvesting, with good ventilation conditions, which will cause the tube leaves to dry and wait for the temperature to fall so that they can be frozen. The frozen onions can be bundled in a well-ventilated shade, or naturally frozen under shade. Thaw at room temperature before eating, light blue still can return to a fresh state. However, the southern scallions from the north can not return to their original state after being frozen in the north. (3) Cabbage. 1 storage characteristics: cabbage like hi cold and humid, storage temperature is about 0 °C. Excessive temperatures are perishable, and the metabolism is strong, aging is accelerated, and the storage period is shortened. It is suitable for storage under a relative humidity of 98% to 100%. Generally can save 5 to 6 months. 2 Storage methods: Stacking: In a cool and ventilated place indoors, stack the vegetables into rectangles with a height of 70-80 cm and a width of 50-60 cm. Can also be scattered heap, but each pile should not be too large, generally 2500 kg is appropriate. Several crates or dill baskets are placed in the middle of each vegetable pile to enhance ventilation and prevent the accumulation of heat and cause rot. It can also be used as a container for storage. Cold storage: Select the ball with a solid core, flatten the root, leave some leaves properly, and put the dish in the basket. Proper stacking at the time of warehousing, ensuring ventilation, and leaving the walkway in check. The storage temperature is generally kept at 0 ~ 1 °C. Trench: Select high-lying, unobstructed drainage areas and dig trenches that are 1.5 to 2 meters wide. The depth of the trenches is generally suitable for stacking two layers. Put the roots of the vegetables down, put the roots up and then cover the soil. The thickness of the soil is about 20 cm.
