Storage and fresh-keeping Technology of Golden Pear

1. Key points of storage technology.

1.1 timely harvest of golden pears in North China is from September 20 to 30. At this time, the fruit has matured, the nutrients are fully accumulated, and the storability is the best. Early harvest (September 10) the decay rate of pear fruit was high during the whole storage period, and the pericarp was easily browned. When harvested too late (early October), brown scald occurred seriously during storage (18.94%). Special attention should be paid to avoid bruising in the process of harvesting.

1.2 the purpose of grading fruit crystal classification is to standardize the commodity. The grading standards of pears in China are divided into four types: national standards, industry standards, local standards and enterprise standards. At present, the classification of golden pear is mainly selected by hand according to its weight, and it has not been classified by large-scale fruit selecting machine and other equipment.

1.3 Packaging can be divided into outer packaging and inner packaging. Production are packed in cartons, each carton 15~20kg, cartons require scientific, strong, economic, moisture-proof, exquisite, light. The inner packaging is to pack the fruit with packaging materials (such as fresh-keeping paper, fresh-keeping bags, etc.). The experimental results show that the single fruit sealed packaging with 0.013mm thick polyethylene film bag has low natural loss rate and decay rate, and the fresh-keeping effect is good. Although the film bag is too thick to reduce the natural loss rate, it is easy to cause physiological diseases such as black heart disease. Therefore, it is advocated that the postharvest golden pear fruit should be sealed and packed with 0.013mm thick market plastic film bag, and then boxed.

1.4 the air temperature and storage temperature of pre-cooled golden pear are higher when harvested, such as using natural cooling storage (cellar), golden pear can not be directly into the storage, but should be fully precooled to quickly dissipate the heat in the field. Therefore, we should try our best to use low temperature for pre-cooling, and pay attention to prevent the sun and rain. The results showed that the fruit of golden pear could adapt to rapid precooling after harvest. Therefore, the postharvest fruit can be put directly into low-temperature cold storage for pre-cooling.

1.5 Storage management

1.5.1 disinfection in storage and rodent control play a positive role in reducing microbial infection and fruit decay during storage of golden pear, and it is also an important link in management measures. The storage of golden pears should be cleaned and disinfected one month before the storage (and after the end of storage). The frequently used agents are sulfur, formaldehyde, bleach and sodium hypochlorite. In addition, attention should be paid to the prevention and control of rodent damage and plugging holes. Rat traps and poisonous ear traps can be used to prevent and cure the fruits after they are stored.

1.5.2 after the stacked golden pear fruit is transported to the cold storage, the stacking in the storage should be neatly arranged and firmly arranged, which is conducive to ventilation and management, and can make full use of the space. The bottom of the stack is padded with sleepers, and there should be a proper gap between the fruit boxes (general 2~5cm). The stacking height is determined by the compression strength of the box, but generally there is a gap between the upper part of the stack and the top of the reservoir with 60cm. Stack away from the walls, air holes and other places to leave a gap (generally 30cm around), and leave access to the roadway. Stacking can be in the form of "product glyph", "well zigzag" and so on.

1.5.3 temperature in order to better grasp the temperature of various parts of the library, thermometers should be placed in different representative places. During storage, the storage temperature should be kept stable and the temperature fluctuation should be reduced greatly. The suitable storage temperature of golden pear is 0 ~ 2 ℃.

1.5.4 humidity Golden Pear during storage, the relative humidity should be kept at 85%-90%. When the humidity in the warehouse is too high, you can dry sawdust or quicklime; when the humidity is low, you can properly sprinkle water, lay wet sawdust or wet grass curtains, etc.

1.5.5 when gas components are stored in controlled atmosphere, attention must be paid to controlling carbon dioxide and carbon dioxide concentration. The use of 0.01~0.02mm thick polyethylene film bag single fruit airtight packaging, will not occur black skin and carbon dioxide poisoning, has a very ideal storage effect.

1.5.6 properly ventilated Golden Pear should have adequate ventilation during storage. Ventilation can take away the heat load in the reservoir, eliminate harmful gases such as ethylene, ethanol and carbon dioxide produced in the process of fruit physiological metabolism, supplement appropriate oxygen, and prevent uneven temperature in the reservoir. In order to prevent the temperature in the reservoir from fluctuating greatly, the ventilation should be carried out at the minimum temperature difference between the inside and outside of the reservoir.

2. Main storage diseases and their control.

2.1 Golden pear fruits with high carbon dioxide damage and low carbon dioxide damage have more water content, exuberant physiological activity and sensitive to carbon dioxide. When the pear fruit is stored in high carbon dioxide and low carbon dioxide environment for a long time, high carbon dioxide injury and low carbon dioxide injury will occur. The sensitivity of golden pear fruit to carbon dioxide injury is closely related to its fruit maturity. Unsuitable low temperature can also increase the incidence of carbon dioxide injury.

The way to control high carbon dioxide injury and low oxygen injury is to strictly control the gas concentration in the storage environment, with carbon dioxide concentration below 3% and carbon dioxide between 5% and 8%.

2.2 the experimental study on chilling injury and freezing injury showed that the freezing point of Golden Pear was-2.9 ℃ 3.1 ℃ and could withstand 0 ℃ low temperature during storage. if the temperature was lower or lower than-5 ℃ during transportation, the moisture in the fruit would freeze gradually. Sharp cooling during storage is easy to cause black heart of the fruit, which is also a kind of chilling injury.

2.3.The pericarp of browning golden pear is thin and brittle, and the content of phenols and the activity of polyphenol oxidase (PPO) are higher than those of other parts. During the storage and transportation of golden pear, the browning at the fruit point gradually deepened and expanded, and the increase of tissue membrane permeability and the destruction of regional distribution caused by pericarp water loss and membrane lipid peroxidation were the main causes of pericarp browning of golden pear.

To control the pericarp browning of golden pear, we should pay attention to the following points: ① should be harvested late to improve fruit maturity; ② low temperature storage can reduce pericarp water loss: ③ pre-harvest calcium spraying or postharvest calcium immersion, ④ pre-harvest field bagging, postharvest single fruit packaging film bag storage; ⑤ to avoid branch and leaf abrasion, bag abrasion, mechanical injury.