Function of compound fresh-keeping paper bag for h

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The role of fruit composite fresh-keeping paper bags

and tensile strength are measured

the theoretical basis of fruit preservation is to control the activities of microorganisms, slow down their normal life activities, and maintain their natural storage resistance and disease resistance. Controlled atmosphere storage is a commonly used gas preservation technology, but it is difficult to promote because of its large investment and high cost

the fresh-keeping paper bag made of paper has a good fresh-keeping and antiseptic effect on fruits. Its manufacturing method is simple and low-cost compared with traditional fresh-keeping methods, especially suitable for long-distance transportation of fruits

basic principle of fruit preservation paper bag

the basic principle of manufacturing composite preservation paper bag is that there is a certain amount of preservative between the kraft paper bag and polyethylene plastic film. When the fruit is loaded into the paper bag, the preservative can evenly release a certain amount of carbon dioxide or sorbic acid gas in a closed paper container to maintain the fresh taste of the fruit

reasons for fruit flavor change

under normal respiration, fruit absorbs oxygen from the air, oxidizes sugars and other substances, and decomposes carbon dioxide and water. After picking, the nutrients are gradually consumed, making the fruit gradually aging and withering. At the same time, if fruits are damaged during harvesting and transportation, ethylene will be released, which can stimulate plant respiration, accelerate metabolism, and promote fruit ripening and aging. Therefore, inhibiting the respiration of fruits and preventing the production of ethylene are the key to the preservation of fruits

the role of preservatives

so2 is an ancient preservative. One of the preservatives used in fruit preservation paper is the salts that can produce SO2, such as potassium pyrosulfite, sodium pyrosulfite, etc. These salt storm countries have guided the graphene industry to establish the strategic alliance for technological innovation of China's graphene industry. Exposed in the air, it can release SO2 gas, which is easily soluble in water. It is a preservative that can release hydrogen ions in aqueous solution

The antibacterial effect of SO2 is to interfere with various forms of enzymes in the fruit cell structure, inhibit the enzyme transfer chain of their chemical reaction terminal products or intermediate products, and make the enzyme lose its activity. If SO2 is released too quickly, it is easy to cause excessive local fumigation of fruits, which will bleach, fade and produce peculiar smell; The release is too slow, and the antiseptic and antibacterial effect is not obvious, so it cannot play an antibacterial role. In order to control the release of SO2, a certain amount of slow-release agent (increase the effective supply of alkaline) can be used to control the release rate of SO2, because with the increase of pH value, the anti-corrosion and antibacterial ability of SO2 decreases. The proportion and dosage of preservative and slow-release agent are very important for the preservation of fruits

British fixtures, etc. meet the standards of many countries

it should be pointed out that sorbic acid can also be used as a preservative in the test. The antibacterial effect of the preservative is based on its inhibition of various enzymes in microorganisms, such as enzymes of carbohydrate metabolism. Its biggest feature is that it can penetrate the cell wall and play a role in microbial cells. Mixed with SO2, due to its synergistic or synergistic effect, the anti-corrosion effect is better. However, because sorbic acid is easy to volatilize, the storage time of the fresh-keeping paper should not be too long

role of paper bag substrate

paper bag is the simplest and most efficient ordinary packaging, which is widely used in transportation packaging and sales packaging. It can effectively prevent the invasion of harmful substances such as pests and dust on fruits. At the same time, as the carrier of preservative, paper bag prevents the preservative from contacting fruits directly. The high permeability of the paper ensures that SO2 and sorbic acid gas released by the preservative can diffuse to the surface of the fruit through the pores of the paper. In order to improve the moisture resistance of paper bags and prevent the dissolution of preservatives, AKD should be used for internal sizing of paper bags

the role of plastic film

due to the permeability of plastic film, such as low-density polyethylene, the water vapor transmission rate is relatively small, and the gas transmission rate is relatively large, making the oxygen outside the paper bag penetrate into the bag, ensuring the normal breathing of fruits, while carbon dioxide and ethylene penetrate into the thin film. Water and SO2 molecules have polarity and poor permeability, so they cannot penetrate outside the film, stay in the paper bag for a long time, and the preservative can play a lasting role

when plastic film is combined with paper bag paper, the selection of adhesive is very important. In the test, water-soluble adhesives, such as oxidized starch, polyvinyl alcohol, carboxymethyl cellulose, etc., can also be used to mix according to a certain proportion

the fruit fresh-keeping paper bag made of SO2 and sorbic acid as fresh-keeping agent has obvious fresh-keeping effect on fruits, especially for long-distance transportation of fruits. Compared with traditional fresh-keeping technology, it has less investment, simplicity and convenience

(text: Jinwang Hubei)

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