A new method of fresh-keeping packaging for the ho

2022-08-15
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New methods for fresh-keeping packaging of vegetables and fruits

with the development of economic DuPont will create high-performance materials and the improvement of living standards, people's dietary life has changed from the past single type of food and clothing to the current diversified nutritional type. The demand for vegetables and fruits is increasing, and the requirement for their freshness is also increasing. At present, a variety of fresh-keeping technologies and materials have been developed

unlike other foods, vegetables and fruits do not die after picking, but still remain? Life. Traditional fruit and vegetable packaging, whether corrugated boxes or eye bags, woven bags and fresh-keeping film, can not achieve the effect of fresh-keeping. At present, a variety of functional fresh-keeping films, new corrugated boxes and functional fresh-keeping agents have been developed, and some technologies and materials have been applied. Because these fresh-keeping materials and technologies often have a single function, in order to achieve the best fresh-keeping effect, sometimes a variety of fresh-keeping technologies and materials are required to be used at the same time

functional fresh-keeping film

although the traditional film can play the role of packaging and has a certain fresh-keeping effect, it has obviously failed to meet the fresh-keeping needs of the modern market. Therefore, a large number of new fresh-keeping films have been developed. These functional fresh-keeping films not only have the effect of preventing water evaporation and simply controlling gas, but also further improve the freshness of vegetables and fruits

ethylene adsorption film

ethylene adsorption film is to remove harmful ethylene gas by mixing gas adsorbable porous substances, such as tuff and zeolite, clay minerals, stone powder and other micro powders, into plastic films (especially LDPE). Most of them can absorb ethylene or block far-infrared radiation. The mechanism of adsorbing ethylene is that the pores on the surface of porous inorganic matter can capture ethylene, and even in the case of high moisture, the water molecules existing in the pores can be replaced with ethylene. However, the addition amount of gas adsorbent is 3%-5%, because the adsorption capacity of ethylene gas is limited

anti dew film

when the fresh-keeping pressure of vegetables and fruits is large, the film is generally made of low-density polyethylene, polypropylene, polybutadiene, polystyrene, ethylene vinyl acetate copolymer and polyvinyl chloride with high gas permeability. However, when the water vapor produced by the vegetables and fruits packed with these films condenses on the inner surface of the film, it not only makes its transparency worse, but also makes the water droplets gather, which makes the bacteria proliferate quickly and causes the vegetables and fruits to rot. What can solve this problem is the anti dew film. The anti dew film is used to treat the inner surface of the above-mentioned polyethylene, polypropylene, polystyrene and other materials with surfactants, which can absorb excess water and appropriately maintain the humidity in the package, so as to achieve the purpose of fresh preservation

antibacterial film

antibacterial film is the mixture of antibacterial silver zeolite into the film. Silver zeolite is the mixture of antibacterial silver and sodium ion in zeolite crystal structure or silver ion and loose zeolite synthesized from aluminum and silicon. PE, PP and PS are mainly used as base materials. This film can inhibit the proliferation of bacteria to a certain extent and play a role in keeping fresh

selective permeation film

if there is no oxygen in the package, the respiration of fruits and vegetables will stop, and fruits and vegetables will rot and deteriorate; If there is too much oxygen, the respiration rate of fruits and vegetables will speed up, which will also accelerate the withering of fruits and vegetables. Therefore, controlling the oxygen and carbon dioxide transmittance in packaging is a very effective technology, which can be used in conjunction with modified atmosphere technology. In the past, silicon windows were mostly added to ordinary packaging bags to achieve the purpose of selective permeation films. At present, the more advanced way is to add silicone materials to synthetic resins to directly produce permeable film products

fresh-keeping corrugated boxes

corrugated boxes are currently mainly used for the transportation of goods between consumption and production. Some functional corrugated boxes can be used in the preservation of vegetables and fruits, which has attracted great attention

corrugated boxes with heat insulation function

under low temperature, not only the respiration of vegetables and fruits is weakened, but also the activity of bacteria is greatly reduced. Therefore, low temperature storage is the most effective means and the development direction of maintaining food freshness

corrugated boxes with heat insulation function have good preservation function. This kind of corrugated box is lined with composite resin and aluminum evaporation film on the inner and outer packages of traditional cartons, or foam resin is added to the paper core. The corrugated box has excellent heat insulation and can prevent the temperature rise of vegetables and fruits during circulation

corrugated box with gas control function

adjusting the gas composition, humidity and other conditions of storage will also achieve a certain fresh-keeping effect, which is an important aspect of fresh-keeping technology

the corrugated box with the function of controlling gas is to insert fresh-keeping film into the inner lining and outer lining of the box or mix porous powder that can adsorb ethylene gas in the papermaking stage. This kind of corrugated box has gas barrier property, preventing the water evaporation of vegetables and fruits, and achieving the effect of controlling the gas content, so as to maintain the freshness of vegetables and fruits

fresh-keeping sheet, preservative and cryostat

in order to enhance the fresh-keeping effect of vegetables and fruits, substances with specific functions can be added while using the above packaging materials, such as fresh-keeping sheet, preservative and cryostat

fresh-keeping sheet

the single package of vegetables and fruits mostly uses the composite products of plastic shallow plate and film, so the functional sheet placed on the shallow plate body or above has the fresh-keeping function. These sheets have one or more functions, such as humidity regulation, dew proof, ethylene gas absorption, antibacterial, etc. Among them, humidity control and water absorption is a multi-layer structure composed of super absorbent resin, non-woven fabric, tissue paper and water absorbent polymer; Absorption of ethylene gas is mostly based on the porosity of activated carbon; Antibacterial property is due to the addition of inorganic substances with antibacterial properties such as silver zeolite or antibacterial ingredients extracted from plants to the sheet

preservative

because the absorption of functional films that absorb ethylene gas is limited by the amount, preservatives that absorb ethylene gas are widely used. Packaging vegetables and fruits together with preservatives can achieve a certain purpose of inhibiting ethylene gas. At present, oxidants such as potassium permanganate, gas adsorbents such as activated carbon and mineral powder, and palladium catalysts are often used as preservatives

cold storage agent

because the preservation of vegetables and fruits at low temperature is conducive to maintaining their freshness, the use of cold storage materials has become an important means of fresh-keeping technology. The elastic gel like material with ultra-high molecular weight sodium polyacrylate or its grafted polymer as the main component is a kind of high-performance cold storage material. The energy can be released slowly after freezing. If it is used together with the heat insulation box, it can achieve a good cooling effect

other fresh-keeping methods and technologies

new fresh-keeping trays

fresh-keeping trays are made of thermoplastic plates through vacuum molding and stamping molding. In addition to preventing fresh food from being damaged, the tray also has a certain degree of heat insulation. The so-called new tray is to add functional film or long fiber non poly (4-fluoroethylene) PTFE spinning cloth into thermoplastic plates? Molded from. On the basis of the original function, this tray has the functions of adjusting humidity, controlling gas content and preventing mold propagation, so it can maintain the freshness of vegetables and fruits

radioactive sterilization

in order to reduce the impact of pathogenic microorganisms on the freshness of vegetables and fruits during storage and transportation, vegetables and fruits can be sterilized after picking with radioactive but stress cracking, and then packaged and transported. At present, the United States, South Africa and other countries adopt the radiation treatment of certain varieties of vegetables and fruits under a certain intensity of radiation

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