In the process of circulation of commodities, not only the types, specifications, and quantities, but also many links. There is an opportunity for contamination with moldy and tainted microorganisms at all stages of commodity circulation. If there are suitable environmental conditions around the product, the product will develop mildew. Therefore, in order to protect the goods safely through storage, distribution, sales and other links, it is necessary to carry out mold-repellent packaging for products susceptible to mildew. Anti-mold packaging technology currently has the following main types. First, chemical agents anti-mold rot packaging technology Chemicals anti-mold rot packaging technology is mainly the use of anti-mold and anti-corrosion chemical agents to be packaged items, packaging materials for proper treatment of packaging technology. Some add the anti-mholeosal agent directly to a certain process; some spray or smear it on the surface of the product, and some need to soak the packaging material and then pack it. However, these treatments will affect the quality and appearance of some products to varying degrees. The use of anti-mildew preservatives for the sterilization mechanism is mainly to coagulate, precipitate, and denature bacterial proteins; some use antifungal and antiseptic agents in combination with the microbial enzyme system to affect bacterial metabolism; some use anti-mildew antiseptics to reduce the surface tension of bacterial cells. Increases the permeability of the cell membrane and breaks or dissolves the cells. When using anti-mold antiseptics, anti-mildew antiseptics that are highly efficient, low-toxic, easy to use, cheap, and easy to purchase should be selected. At the same time, it is also required that the anti-mildew antiseptic does not affect the performance and quality of the commodity, has no corrosion effect on the metal, and requires the anti-mold antiseptic itself to have good stability, heat resistance and durability. Phenolics (such as phenol), chlorophenols (such as pentachlorophenol), organic mercury salts (such as phenyl mercury oleate), and organic coppers (such as copper naphthenate soap) are commonly used as anti-mushroom agents. Organic tin salts (such as triethyltin chloride) and inorganic salts (such as copper sulfate, mercuric chloride, sodium fluoride). Anti-mold and antiseptic agents have two major categories. One is anti-mold agents for industrial products, such as carbendazim, chlorothalonil, and sterilized Dan. The other type is a mildew-repellent agent for foods, such as benzoic acid and its sodium salt, dehydrogenated wax acid, thiophanate, and the like. Second, gas phase anti-mold rot packaging technology gas phase anti-mold rot packaging technology is the use of volatile anti-mold antiseptic, the use of its volatile gases directly contact with moldy microorganisms, killing these microorganisms or inhibit their growth to achieve the goods Anti-mold rot purpose. Moreover, since the gas phase anti-mold rot is a gas phase molecule directly acting on the commodity, it does not have an adverse effect on its appearance and quality. However, packaging materials and packaging containers are required to have characteristics of low gas rate and good sealing performance. Vapor-phase anti-mould rot has paraformaldehyde anti-mould agent. Paraformaldehyde is a polymer of formaldehyde that slowly sublimes to depolymerize at room temperature into a gas with a stimulating odor of formaldehyde, which can cause the bacterial protein to coagulate to kill or suppress the moldy rot microbes. When used, it is packaged into small packets or compressed into tablets. The agent, together with the product, is placed in a packaging container and sealed to allow it to sublimate and diffuse naturally. However, the formaldehyde gas sublimated from paraformaldehyde may combine with the water vapor of air to form formic acid under the condition of high temperature and high humidity, and it has corrosive effect on the metal. Therefore, products with metal accessories cannot be used. In addition, formaldehyde gas has a stimulating effect on human eye mucous membranes, so operators should do a good job of protection. There is also an ethylene oxide anti-male agent. Ethylene oxide can bind to free hydrogen atoms in the carboxyl, amino, and hydroxyl groups of bacterial proteins, phenolic molecules, and generate hydroxyethyl groups, which can cause bacterial metabolism to die and die. Ethylene oxide molecular penetration greater than formaldehyde. Therefore, the bactericidal power is also stronger than that of formaldehyde, and it can also exert bactericidal action under low temperature and low humidity. Therefore, it is preferable to apply bactericidal and mildewproof rot to a product that cannot be heated and fear moisture. However, ethylene oxide can liquefy proteins, and can destroy vitamins and amino acids in foods, and it also leaves toxic chlorohydrins. Therefore, ethylene oxide can only be used for the anti-mold rot of daily-use industrial products, and should not be used as anti-mold rot for food and food. Third, the modified atmosphere anti-mold rot packaging technology is one of the forms of ecological anti-mold rot. The three factors of air, moisture, and temperature are all related to the respiratory metabolism of moldy rot microbes and biological products. As long as one of the factors is effectively controlled, the purpose of preventing the occurrence of mildew in the commodity can be achieved. For example, as long as the concentration of oxygen in the air is controlled and regulated, artificially creating a low-oxygen environment, the growth and reproduction of moldy and rot microbes and the breathing of biological products themselves. Will be controlled. Air-conditioned mildew-repellent packaging is to reduce the concentration of oxygen in the package under the conditions of sealed packaging, to reduce the concentration of oxygen, resulting in a low-oxygen environment to inhibit the life activity of microbial humic microorganisms and the respiratory intensity of biological products, so as to achieve The purpose of preventing moldy rot on packaged goods. This is also the principle of the modified tone mold. Air-conditioning anti-mold and rot-proof packaging is a gas that is non-toxic to human body and has an inhibitory effect on moldy rot microbes. At present, carbon dioxide and nitrogen are mainly charged. The normal content of carbon dioxide in the air is 0.03%. Trace amounts of carbon dioxide have a stimulating effect on the growth of microorganisms; when the concentration of carbon dioxide in the air reaches 10% to 14%, it has an inhibitory effect on microorganisms, and if the concentration of carbon dioxide in the air exceeds 40%, the microorganisms are significantly suppressed and killed. effect. The packaging material must use gas-tight materials that have a certain resistance to gas or water vapor in order to maintain the gas concentration in the package. The key to the air-conditioning, mold-repellent and rot-proof packaging technology is sealing and oxygen reduction, and the sealing of the packaging container is the key to ensure the air-conditioning and mold-removal protection. Oxygen reduction is an important part of the air conditioning and anti-mold rot. At present, the methods of artificial oxygen reduction mainly include mechanical oxygen reduction and chemical oxygen reduction. Mechanical oxygen reduction is mainly vacuum nitrogen filling method and carbon dioxide method. Chemical oxygen reduction uses a deoxidizer to reduce the concentration of oxygen in the package. Fourth, low-temperature refrigeration and anti-mold rot packaging technology low-temperature refrigeration anti-mold rot packaging technology is controlled by the temperature of the commodity itself, so that it is lower than the minimum limit of growth and reproduction of moldy humic microorganisms, control of enzyme activity. On the one hand, it inhibits the respiratory oxidation process of biological products, causing their own decomposition to be obstructed. Once the temperature is restored, it can still maintain its original quality; on the other hand, it inhibits the metabolism and growth and reproduction of moldy rot microorganisms to achieve anti-corruption. purpose. The temperature and time required for cold storage and mildew prevention should be based on the specific commodity. In general, the lower the temperature and the longer the duration, the higher the mortality of moldy rot microbes. According to the level of refrigeration temperature and the length of time, it can be divided into cold storage and frozen storage. The refrigerated anti-mold and rot-proof packaging is suitable for perishable goods with large water content and impermeability to freezing, and is stored at a temperature of about 0° C. for a short time, such as vegetables, fruits, and fresh eggs. During the cold storage, the enzymes of the moldy microorganisms almost lost their activity. The various physiological and biochemical reactions of the metabolism were slow and even stopped. The growth and reproduction were inhibited, but they did not die. Frozen storage is suitable for freeze-tolerant perishable products with high moisture content and is stored for a long time at about -16--18°C, such as meat and fish. During the frozen storage period, the quality of the product is basically not impaired, and the moldy rot microbes and the intracellular water become ice crystals dehydrated. The ice crystal water damages the plasma membrane and causes death and injury. Low-temperature storage and mildew packaging should be made of low-temperature-resistant packaging materials. Fifth, dry anti-mold rot packaging technology Microbiological living environment lack of moisture that causes dry, in the dry conditions, mold can not reproduce, the product will not rot. Dry and mold-repellent packaging technology is to reduce the moisture in the sealed package and the water content of the product itself, so that the mold and rot microorganisms can not obtain the water needed for growth and reproduction to achieve the purpose of preventing mold and rot. Because drying can denature microbial cell proteins and increase the concentration of salts, so that microbial growth is inhibited or prompted to die. The ability of mold mycelium to resist drying is very weak, especially young strains have a weak ability to resist drying. A certain amount of desiccant can be contained in the sealed package to absorb the moisture in the package, so that the moisture content of the contained product can be reduced below the allowable moisture content. In general, high water loss is not easy to cause the death of microorganisms; slow drying of mold cells is the most common death, and it is the fastest in the early drying period. Bacteria are not easy to die when they are dried at low temperatures, and they are most likely to die at room temperature after drying. VI, ionizing radiation anti-mold rot packaging technology energy through the space called radiation, radiation to the irradiated material to produce ionization, known as ionizing radiation. The direct effect of ionizing radiation is that when the radiation passes through the microorganisms, the internal components of the microorganism can be decomposed to induce mutation or death. Its indirect effect is to dissociate water molecules into free radicals, and radicals react with dissolved oxygen in the liquid to produce strong oxidizing groups. This group oxidizes the -SH group of the microbial enzyme protein and the enzyme loses its activity, thus making it mutagenic or death. Ionizing radiation is generally the alpha, beta, and gamma rays released by radioactive isotopes. Both of them can damage certain parts of the microbial cell structure and metabolism. Alpha rays are absorbed by air at the time of irradiation and hardly reach the target. The beta-ray penetration is weak and is limited to surface sterilization. Gamma ray penetration is strong and can be used for internal sterilization of foods. The radiation can kill insects, and the radiation will not cause the object to heat up, so it can be called cold sterilization. However, some foods may deteriorate or improve their quality after being irradiated. Ionizing radiation anti-mold rot packaging is currently used mainly for beta ray and gamma ray. After the ionized radiation is applied to the packaged goods, it completes the function of sterilizing and sterilizing. After irradiation, if it is no longer contaminated, it will cooperate with the conditions of cold storage; low dose radiation energy. Extended shelf life weeks to months. High-dose radiation can be completely sterilized and stored for long periods of time. Ultraviolet light is generally used to process packaging containers (or materials) and non-food items that are packaged. These objects to be sterilized are irradiated with ultraviolet rays for a certain period of time to kill the mold and rot microbes on the surfaces of the products and the containers. Prepackaging can extend the shelf life. Microwave microwaves are high-frequency electromagnetic waves with a frequency of 300-300000 MHz. An object that has a lot of water and fat content can easily absorb microwave energy and convert it into heat energy after absorption. The sterilization mechanism of microwaves is that microorganisms absorb microwave energy and then transform it into heat on the one hand and bactericidal. On the other hand, moisture and fat and other substances of cells are affected by microwaves, and their molecules vibrate and vibrate. The heat generated by the internal damage of the cells causes the death of the cells. The heat energy generated by the microwave is in the interior, so the utilization of heat energy is high, the heating time is short, and heating is even. Far-infrared far-infrared is an electromagnetic wave with a frequency higher than 3000000 MHz. Its function is similar to that of microwaves. Its bactericidal mechanism is mainly the radiation of far-infrared rays and the resulting high temperatures that cause the bacteria to rapidly dehydrate and dry and die. The sterilizing mechanism of high-frequency electric field high-frequency electric field is that the commodities with high moisture content and microorganisms can “absorb†the frequency energy of the electric energy into heat energy and sterilize. As long as the microorganisms on the commodities and commodities have sufficient moisture and a high-frequency electric field with a certain intensity, disinfection can be completed in an instant.
7. Ultraviolet, microwave, far-infrared and high-frequency electric fields Ultraviolet ultraviolet light is also a bactericidal effect of rays, which is the main factor in solar sterilization. The wavelength range of ultraviolet rays is 100-400nm, among them the ultraviolet ray with the wavelength of 200-300nm has bactericidal action, especially 265-266nm bactericidal force is the strongest. Ultraviolet light penetrating power is very weak, so it can only kill the humic microorganisms on the surface of the commodity. In addition, foods containing fats or proteins can cause odors or discoloration when exposed to ultraviolet light, and sterilization by ultraviolet radiation should not be used.
Commodity mold and corrosion resistant packaging technology