Fruits and vegetables are natural products to maintain the vitamins needed by the human body, and they are also carrying out complex life activities. Under the catalysis of various enzymes in aerobic environment, sugars in fruits and vegetables can be completely oxidized and decomposed, and the decomposition products are carbon dioxide and water, which will release a lot of energy in the process. This process will lead to a series of changes in the taste, quality, color, shape and nutritional value of fruits and vegetables, and rot and deteriorate. one

Generally speaking, fruits and vegetables contain 90%~95% water, and the loss of internal water will directly lead to the increase of internal enzyme activity and accelerate the decay of fruits and vegetables. In order to prolong the storage time of fruits and vegetables, it is necessary to prevent microorganisms from destroying fruits and vegetables. Considering the above factors comprehensively, a kind of fresh-keeping film was developed, which not only has fresh-keeping effect, but also does not pollute fruits and vegetables. It can preserve vegetables such as cucumber, eggplant and carrot, and also fruits such as grapes, bayberry and pears. Carrots were selected to verify the fresh-keeping effect of plastic wrap, and the conclusion was summarized.

1 experimental part

1. 1 During the experiment, the experiment was divided into two groups, and each group was given the same amount of carrot pieces. The carrots in one group are packed with plastic wrap, and the carrots in the other group do not need to be packed. Their original weights are weighed and recorded electronically. After that, weigh 1 time every 1 d, and calculate the water loss of the two groups of carrots after15 d.

1.2 experimental results According to the shape and color of carrots, carrots packed with plastic wrap are much fresher than carrots packed without plastic wrap, and carrots packed without plastic wrap will wither and lose their use value. According to the data analysis, carrots packed with plastic wrap only lost a small amount of water.

1.3 experimental analysis The raw material of fruit and vegetable preservative film is protein, which is a new type of selective permeable film. Using plastic wrap to keep fruits and vegetables fresh can isolate the contact between fruits and vegetables and oxygen, balance the internal and external permeation of fruit cells, effectively control the metabolism and respiration rate of fruit and vegetable cells, and prevent tissues from being destroyed during long-term storage, thus effectively preventing cells from losing water and achieving the effect of preventing fruits and vegetables from rotting.

2. Fruit and vegetable plastic wrap insurance institutions

Although the picked fruit and vegetable leaves the plant, it is still a living organism, and its interior is constantly carrying out normal physiological activities. In the process of breathing, fruits and vegetables will release a lot of energy and produce respiratory heat. The gradual accumulation of respiratory heat of fruits and vegetables will lead to the increase of temperature of fruits and vegetables and the increase of material consumption rate in the body. Secondly, fruits and vegetables will produce a certain amount of ethylene after ripening, which will accelerate the ripening and aging of fruits and vegetables. To sum up, only by controlling the respiration of fruits and vegetables and reducing the water loss of fruits and vegetables and the ethylene content in the environment can the storage time be prolonged. When the content of oxygen and carbon dioxide changes beyond the tolerance range of fruits and vegetables, it will lead to anaerobic respiration or carbon dioxide poisoning of fruits and vegetables in anaerobic environment, thus accelerating the consumption of nutrients in fruits and vegetables, accumulating toxic and harmful substances in their tissues, inhibiting the activity of enzymes and causing abnormal physiological activities of fruits and vegetables. Therefore, when using plastic wrap to keep fresh, the oxygen concentration around fruits and vegetables should be controlled in the range of 2%~4% to achieve the best preservation effect. In order to eliminate the ethylene produced during the storage of fruits and vegetables and reduce the water loss, the plastic wrap for fruits and vegetables must have the following basic characteristics: 1) moisture permeability. Fruit and vegetable plastic wrap must have different moisture permeability according to the variety of fruit, and generally should not be too high. 2) Choose air permeability. The plastic wrap for fruits and vegetables must be conducive to the release of carbon dioxide produced during respiration and ethylene produced during ripening of fruits and vegetables, and also ensure a certain amount of oxygen to enter. Generally speaking, the permeability of plastic wrap to carbon dioxide is greater than that of oxygen. 3) Non-toxic and sanitary. Plastic wrap should control the breeding of toxic and harmful substances in fruits and vegetables.

3 abstract

With the continuous innovation of science and technology and the rapid development of agricultural economy in China, people's demand for fruits has greatly increased. The opening of fruit market has gradually increased the number of fruits transported, and all departments attach great importance to fruit preservation. In order to ensure the supply of fresh and high-quality fruits in the market, fruit suppliers must make good storage of fruits and vegetables, study the physiological characteristics of different fruits by high-tech means, and make fresh-keeping films combined with their fresh-keeping standards to ensure the supply of high-quality fruits. Today's plastic wrap can not only prolong the storage time of fruits and vegetables, but also maintain their original texture, appearance, flavor and nutritional value during transportation, effectively preventing microbial pathogens from damaging fruit tissues, thus ensuring the excellent quality of fruits and vegetables to the greatest extent.

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