What are the storage methods of oranges?

In recent years, with the development of citrus production and the increasingly fierce market competition, postharvest storage and commercial treatment have become an important link to improve the commercial characters and economic benefits of citrus fruits. Let's take a look at the storage methods of citrus.

Cellar storage

Cellar storage is a widely used storage method of sweet orange, which is simple, low-cost and suitable for fruit growers to store separately. The humidity in the cellar is generally 95%-98%, the temperature is stable at about 12-18 ℃, and the concentration of carbon dioxide in the gas in the cellar is very high, which can reach 4%-6%. This storage environment is very beneficial to maintain the moisture of the fruit, make the stored fruit fresh and full, and the natural weight loss rate is low, and the storage period can be from May to July of the following year.

The cellar is generally built inside and outside houses with high terrain and low water table. Nanchong cellar is built into a "triangle cellar" with a narrow upper mouth and a wide "triangle cellar". The diameter of the top mouth of the cellar is about 50 cm, the diameter of the bottom of the cellar is generally 2-2.5 meters, and the depth of the cellar is about 1.8 meters. the mouth of the pit is covered with a slate 3-5 cm thick. Usually every 7~l0 days open the cover to breathe, and pick up rotten fruit.

Ventilation storage

Ventilation storage belongs to the category of room temperature storage, which is the most commonly used method for citrus storage in southern China. Ventilation storage has the advantages of more fruit storage, convenient operation and low cost, so it is suitable for large-scale commercial storage.

1. Preparation before entering the warehouse: disinfect the warehouse 15 days before entering the warehouse. The common disinfection method is to fumigate with sulfur, the amount of sulfur is 109 / m3, the sulfur is powdered and mixed with a little sawdust, divided into several piles according to the size of the warehouse, closed fumigation, or sprayed with 1% formalin solution, sealed for 24 hours and ventilated for 2 to 3 days, until the storehouse is completely odorless, close the door and set aside.

2. Storage management: ventilation management is carried out according to the changes of temperature and humidity inside and outside the store. when the external temperature is high, it is appropriate to ventilate at night to reduce the temperature of the reservoir. When the external temperature is close to 0 ℃, the ventilation window should be closed to prevent the citrus from freezing, and it can only be ventilated at noon on a sunny day, such as the outside is cloudy and rainy and the humidity outside the reservoir is too high, it is not suitable for ventilation, and the emphasis of storage management is different in different storage periods.

The initial stage of ① storage: generally in late November, the air temperature is high, the fruit breathing is exuberant, resulting in a large amount of respiratory heat, resulting in an increase in the temperature of the store. at this time, the main measure is to reduce the temperature in the reservoir. Except for rainy and foggy days, the ventilation equipment in the warehouse must be turned on day and night to strengthen ventilation and heat dissipation.

② mid-storage period: generally from December to the Spring Festival of the following year, when the temperature is the lowest in the whole year, therefore, we should pay attention to cold protection and keep warm, generally every 3-4 days in sunny noon ventilation.

In the later stage of ③ storage: after the Spring Festival, the air temperature gradually picked up, the temperature in the storage began to rise gradually, and the fruit decay rate increased, then the temperature should be reduced. On a sunny night, turn on the ventilation to attract the cold air at night. During the day, turn off the ventilation equipment to adjust the temperature in the warehouse to keep it below 10 ℃ as far as possible. At this stage, the fruit decay aggravates, so we should strengthen the inspection and pick out the rotten fruit, brown spot fruit and dried fruit in time, which has a good effect on reducing the pedicel rot and low water disease in the later stage of fruit storage.

There is a common problem of low humidity in ventilation storage. generally, the relative humidity in the storage is about 80% and 85%, so the fruit is prone to wilting and high light consumption. In general, sweet oranges are stored for 5 months, the fruit weight loss is 15% to 20%, and oranges are stored for 2 months, the weight loss is 5% to 10%. The storage of fruit wrapped with plastic film can increase the relative humidity around the fruit, which is an effective measure to reduce light consumption in the process of ventilated storage.

Spontaneous controlled atmosphere storage

China began to study the use of plastic film sealed rice A storage method for citrus storage 30 years ago. First put the citrus in plastic film tent (bag), and then put it in ordinary houses, ventilated warehouses, soil caves and other storage places. Plastic film account is generally selected for the thickness of 0.2~0.25ra meters, pressing the growth cube account, the volume is determined according to the storage capacity, generally 500-1000 kg. As the concentration of carbon dioxide suitable for storage of citrus fruits is 2%-4%, in order to prevent carbon dioxide poisoning, hydrated lime is usually removed from the gap at the bottom of the account to absorb carbon dioxide, or the account door is opened regularly for ventilation.

Spontaneous controlled atmosphere storage can also pack oranges with plastic film bags, and then tighten the mouth of the bag to achieve the purpose of controlled atmosphere. The film bags are mostly made of thin polyethylene film. The gas composition in the bag automatically reaches a balanced concentration by the respiration of the product itself and the permeability of the film itself.

Mechanical cold storage

Through artificial adjustment, the temperature, humidity, ventilation and ventilation in the mechanical cold storage can be strictly controlled, which can significantly prolong the storage life of citrus and effectively keep the fruit fresh. The key to the management of low temperature storage is to control the appropriate low temperature and humidity, and pay attention to ventilation.

When the citrus was stored at suitable temperature and humidity for 4 months, the flavor was normal, and the contents of soluble solids, acid and vitamin C had no significant change. It should be noted that citrus fruits can not tolerate too low temperature and are prone to low temperature injury. During cold storage, it is necessary to choose a suitable low temperature according to the characteristics of different species and varieties. Sweet oranges are generally 1-3 ℃, while wide-skinned citrus fruits are poor in low temperature tolerance, which should be controlled above 7-12 ℃. When storing oranges in mechanical cold storage, you should also pay attention to changing air every day, replenishing oxygen and removing excessive carbon dioxide, usually not more than 1% of carbon dioxide and not less than 17% of oxygen.