Case 1 of the most fiery controlled atmosphere sto

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Detailed case of controlled atmosphere storage (I)

IV. case

(I) apple

1. Storage characteristics are as mentioned above, the differences in storage resistance between different apple varieties are extremely obvious. Late maturing varieties (mature after October), such as Fuji, Qin Guan, Beidou, Xiushui, Shengli, xiaoguoguang, etc., have a lot of substance accumulation, low respiratory level, late ethylene occurrence and low level, so they generally have the characteristics of good flavor, crisp meat and storage resistance. Apples are typical respiratory climacteric fruits, and ethylene production is large at maturity, which can generally reach 200 ~ 800 at the peak of respiration μ L/l, which leads to more ethylene accumulation in the storage environment. During storage, the occurrence of respiratory jump can be delayed and the storage period can be prolonged by cooling and adjusting the gas composition. Apples are highly sensitive to ethylene. Ventilation or removal technology can be used to reduce ethylene in storage environment. In addition, harvesting maturity has a great impact on apple storage. Apples that are planned to be stored for a long time should be harvested before the start of respiratory jump

2. Storage conditions the suitable storage temperature of most apple varieties is -1 ~ 0 ℃. Varieties sensitive to low temperature, such as ruby and Xu, are prone to physiological disorders when stored at 0 ℃, so the recommended storage temperature is 2 ~ 4 ℃. High humidity storage should be adopted under low temperature, so that relatively new products in the warehouse can enter the market, and the humidity should be maintained at 90% - 95%. If it is stored in the normal temperature warehouse or MA storage mode, the relative humidity in the warehouse can be slightly lower and kept at 85% - 90% to reduce the decay loss. For most apple varieties, 2% - 5% O2 and 3% - 5% CO2 are relatively suitable gas combinations. Individual CO2 sensitive varieties, such as red Fuji, should control CO2 below 3%. C2H4 is controlled at 10 μ Below l/l

3. Storage technology. The harvest, post harvest treatment, warehousing and stacking, and warehouse out management of Apple controlled atmosphere storage are basically the same as those of mechanical refrigeration. Controlled atmosphere storage mainly includes the following ways

(1) plastic film bags are stored in Apple boxes lined with 0.04 ~ 0.07mm thick low-density PE or PVC film bags, loaded into apples, sealed and placed in the warehouse. In 2017, the development of new materials industry will start a new journey, and each bag will form a sealed storage unit. The initial CO2 concentration is high, and then gradually decreases. Within 2 weeks of storage, the upper limit of CO2 concentration of 7% is relatively safe, but the CO2 of Fuji Apple should not be higher than 3%

(2) store the plastic film tent in the cold storage, and use 0.1 ~ 0.2mm thick high-pressure PVC film to stick it into a rectangular tent to close the apple storage stack, and the capacity can be determined according to needs. Use molecular sieve nitrogen charging machine to flush nitrogen into the account to reduce oxygen, take the gas in the account to measure the concentration of O2 and CO2, so as to accurately control the gas composition in the account. During storage, take gas every day to analyze the concentration of O2 and CO2 in the account. When the concentration of O2 is too low, add air to the account; When the CO2 concentration is too high, CO2 can be removed by CO2 remover or hydrated lime. The e-commerce market of plastic and hardware industry is about to burst. The amount of hydrated lime is 0.5 ~ 1 kg per 100 kg apple

pasting silicone rubber diffusion windows in the middle and lower parts of the large account wall can naturally adjust the gas composition in the account. It is more recommended that export enterprises build a safety assurance system focusing on "raw material procurement - raw material account management - factory safety and health control". The area of silicon window is determined by experiment and calculation according to the storage capacity and the required gas ratio. For example, when storing 1 ton of Golden Delicious apples, in order to maintain O2 at 2% - 3% and CO23% - 5%, the silicon window area is 0.6m at about 5 ℃ × 0.6m is suitable. The fruit should be fully cooled and kept at a stable low temperature before covering the tent to reduce the condensation water in the tent

(3) controlled atmosphere storage: controlled atmosphere storage is the best way to store apples on a large scale. During storage, appropriate storage conditions should be determined according to the storage characteristics of different varieties, and the gas composition required in the warehouse and the accurate control of temperature and humidity should be ensured through gas regulation

4. Disease control in Apple controlled atmosphere storage, in addition to the above, the main diseases are CO2 Poisoning and hypoxia damage. CO2 poisoning is caused by the inhibition of succinate peroxidase system in Apple mitochondria by high concentration CO2. Hypoxia injury is caused by low O2 concentration in the storage environment and long-term hypoxia respiratory poisoning of fruits. There are two kinds of CO2 Poisoning: external injury and internal injury. External injury occurred in the early stage of storage, and the pathological tissue was well-defined, yellowish brown, sunken and wrinkled; There are small brown plaques in the local tissue of the internal damaged pulp and core. Finally, the affected part of the pulp loses water and becomes a dry brown cavity. Eating it has a bitter taste, the whole fruit flavor becomes weak, accompanied by a slight fermentation taste. The same thing between the two is that the hardness of the affected fruit does not decrease. Hypoxia damages the cork of the peel, necrosis of the pulp to the core tissue, and has a strong fermentation flavor. During storage, the concentration changes of O2 and CO2 in the storage environment should be checked frequently and adjusted in time to prevent injury


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