Preventing mold rot (ie mildew and spoilage) is a very important issue in the packaging and transportation of goods. Commercial mold rot is produced by the action of mold, and products composed of organic substances, such as biological goods and products or articles containing biological components, are susceptible to mold and rot under normal environmental conditions, causing the quality of goods to be affected. damage. The range of mold damage is very wide. Materials other than organic matter will also be attacked by mold under certain conditions. For example, glass, metal, ceramics, etc. may be attacked by mold, which is mainly caused by mold on the organic matter adhered to it. Growth, the result of the action of its metabolites on such substances. Due to the wide variety of products, different specifications and quantities, there are opportunities for contamination by mold and microbes in various parts of circulation. As long as there are environmental conditions suitable for mold growth, mold will continuously extract nutrients from commodities and the external environment. And the discharge of waste, while a large number of growth and reproduction, the goods are gradually decomposed and destroyed, that is, the product is mildew. Therefore, in order to protect goods safely through storage, distribution, sales and other aspects, it is necessary to use mold-proof packaging technology for easy-to-make products to prevent mold damage. Anti-mold packaging technology refers to packaging technology that uses certain technical measures to prevent the growth of mold microorganisms under certain conditions, thereby extending the shelf life of the product. In summary, the commonly used anti-mold packaging technology currently has the following types. First, chemical agents anti-mold packaging The chemical anti-mold packaging technology is mainly a packaging technology that uses a mildew-proof and anti-corrosive chemical agent to properly process the articles to be packaged and the packaging materials. These chemicals are collectively referred to as mildew preservatives. There are generally two major categories, one is a mold inhibitor for industrial products, and the other is a mold inhibitor for food. Application of anti-mold agent, some are added to the raw materials to produce anti-mold packaging materials, some are directly added to a packaging process, and some are made into a solution, sprayed or applied to the surface of the product, and some liquids Soak the packaging materials and packaging containers before packaging. However, these treatments will affect the quality and appearance of some products to varying degrees. The sterilization mechanism using the anti-mold preservative is mainly to solidify, precipitate and denature the bacterial protein. Some use the anti-mold preservative and the bacterial enzyme system to affect the metabolism of the bacteria; some use the anti-mold preservative to reduce the surface tension of the bacteria, increase the permeability of the cell membrane, and the cell rupture or dissolution. When using anti-mold preservatives, choose mildew preservatives that are highly efficient, low-toxic, easy to use, inexpensive, and easy to purchase. Special attention should be paid to the use of anti-mold preservatives, especially the anti-mold packaging of daily necessities such as foods and medicines. At the same time, the anti-mold preservative is required to not affect the performance and quality of the product, has good stability, heat resistance and durability, and has no corrosive effect on packaging materials such as metal. Commonly used as a mold inhibitor, phenols (such as phenol), chlorophenols (such as pentachlorophenol), organic mercury salts (such as phenylmercuric oleate), organic copper (such as copper naphthenate), Organotin salts (such as triethyltin chloride) and inorganic salts (such as copper sulfate, mercuric chloride, sodium fluoride). There are two main types of anti-mold preservatives, one is anti-mold agents for industrial products, such as carbendazim, chlorothalonil, sterilized Dan, and the like. The other type is a fungicide for foods such as benzoic acid and its sodium salt, dehydrogenated wax acid, thiophanate, and the like. Second, gas phase anti-mold packaging The gas phase anti-mastic packaging uses the volatile gas of the gas phase anti-mold agent to directly contact the mold rot fungus, killing these microorganisms or inhibiting the growth thereof, so as to achieve the anti-mold effect of the commodity. Gas phase anti-mold is a gas phase molecule directly acting on a commodity, which does not adversely affect the appearance and quality of the product, but requires packaging materials and packaging containers to have a small gas ratio and good sealing performance. Commonly used gas phase anti-mold agents are anti-mold agents such as paraformaldehyde and cyclohexane. Paraformaldehyde is a polymer of formaldehyde. It can be sublimed at room temperature to depolymerize into a gas with formaldehyde odor, which can solidify the bacterial proteins to kill or inhibit the mold and microorganisms. When it is used, it is packaged into small packets or compressed into tablets, and placed in a packaging container together with the product to be sealed, so that it naturally sublimates and spreads. However, the formaldehyde gas sublimated by paraformaldehyde may combine with water vapor of air to form formic acid under high temperature and high humidity conditions, which is corrosive to metals, and therefore cannot be packaged in metal. In addition, formaldehyde gas has a stimulating effect on the human eye and mucous membranes, and it is harmful to the eyes, so the operator should pay attention to the protection. As an anti-fungal agent, ethylene oxide can combine with the bacterial protein, the carboxyl group of the phenol molecule, the amino group, and the free hydrogen atom in the hydroxyl group to form a hydroxyethyl group, which causes the metabolic function of the bacteria to be impaired and died. Ethylene oxide molecular penetration is larger than formaldehyde, so the bactericidal power is stronger than formaldehyde. Ethylene oxide can be used at low temperature, which is more suitable for anti-corrosion packaging of products that are afraid of heat and moisture. However, ethylene oxide can liquefy protein, which will destroy vitamins and amino acids in food, and will also leave the toxic substance chlorohydrin. Therefore, it should not be used as anti-mold for food and food. It can only be used for the prevention of industrial products. Mildew. Third, air conditioning anti-mold packaging The air-conditioning and anti-mild packaging is to replace the air in the package with different protective gases to achieve anti-mold effect. Air-conditioning and mildew-proof packaging is mainly used for the preservation of various foods to extend the shelf life of food and enhance the value of food. Gases commonly used in gas-proof and mildew-proof packaging include carbon dioxide, nitrogen, and oxygen. Carbon dioxide has the effect of inhibiting the growth and reproduction of most spoiled bacteria and molds. Nitrogen is an ideal inert gas. It generally does not chemically interact with foods and is not absorbed by foods. However, it can reduce the oxygen content in the package, greatly inhibit the growth and reproduction of bacteria, molds and other microorganisms, and slow down the oxidative deterioration of foods. And corruption. Oxygen has the effect of inhibiting the growth and reproduction of most anaerobic spoilage bacteria and maintaining the respiratory metabolism of fresh fruits and vegetables. Gas-proof mildew is one of the forms of ecological anti-mold. The respiratory metabolism of mold and microbes and biological products are inseparable from the three factors of air, moisture and temperature. 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, a low-oxygen environment is artificially created, and the growth and reproduction of the mold and microorganisms and the breathing of the biological products themselves are controlled. Air-conditioning and mildew-proof packaging is to replace the air in the box or bag under the condition of sealed packaging, change the external environment of the food in the box (bag), inhibit the growth and reproduction of bacteria (microorganisms), and slow down the metabolism of fresh fruits and vegetables. The speed of the food thus extends the shelf life or shelf life of the food. For example, by changing the air composition in the package to reduce the concentration of oxygen, causing a low-oxygen environment to inhibit the life activities of the microbes and the respiratory intensity of the biological products, thereby achieving the purpose of preventing mildew of the packaged goods. The air-conditioning and mildew-proof packaging is filled with a gas that is non-toxic to the human body and has an inhibitory effect on the mold and microorganisms. At present, it is mainly charged with carbon dioxide and nitrogen for oxygen reduction. The normal content of carbon dioxide in the air is 0.03%. A small amount of carbon dioxide has a stimulating effect on microorganisms; when the concentration of carbon dioxide in the air reaches 10% to 14%, it has an inhibitory effect on microorganisms; if the concentration of carbon dioxide in the air exceeds 40%, the microorganisms are obviously inhibited and killed. effect. For oxygen-reducing and mildew-proof packaging, the packaging container can be vacuumed to a certain extent and then filled with nitrogen or carbon dioxide. Deoxidizer can also be added to the packaging container to consume oxygen in the package, thereby reducing the oxygen concentration. However, in any case, the packaging material must use a gas-tight material that is resistant to gas or water vapor to maintain the gas concentration in the package. The key to air-conditioning and mildew-proof packaging technology is sealing and oxygen reduction. The sealing of packaging containers is the key to ensuring gas-proof and mildew resistance. Oxygen reduction is an important part of gas-proof and mildew prevention. At present, the methods of artificial oxygen reduction mainly include mechanical oxygen reduction and chemical oxygen reduction. Mechanical oxygen reduction mainly includes vacuum nitrogen filling method and carbon dioxide filling method. Chemical oxygen reduction uses a deoxidizer to reduce the concentration of oxygen in the package. Atmospheric packaging materials are mostly low barrier materials with greater gas permeability. Therefore, in order to make a modified atmosphere package, it is necessary to make a reasonable choice of the permeability of the packaging material according to the characteristics of the product. Most packaging materials for modified atmosphere packaging require a high-barrier composite packaging material to maintain the protective gas composition of the package. If the shelf life does not have to be long, the general barrier PA/PE or PET/PE can be satisfied. It is best to use a high barrier PVDC or EVOH composite packaging material for long shelf life requirements. The packaging film of fresh fruits and vegetables acts as a gas exchange membrane, and the gas components in the package are maintained by gas exchange between the film and the atmosphere. Commonly used gas-permeable PE, PP, PVC film, but this film can not meet the packaging requirements of tropical fruits, mushrooms, etc. with high breathing rate, and requires a highly breathable film. Therefore, we must pay attention to research and development of new air-conditioning and mildew-proof packaging materials. For example, the carbon dioxide plastic packaging material developed in the United States uses a special catalyst to mix carbon dioxide and ethylene oxide (or propylene oxide) in equal amounts to make a new plastic packaging material with glass-like transparency. And non-ventilating; similar to polycarbonate and polyamide resin; does not completely decompose into gas at 240 ° C; has biodegradability, does not pollute the environment and soil. China has also successfully used nanotechnology to efficiently catalyze the synthesis of degradable plastics from carbon dioxide. That is, the catalyst obtained by using carbon dioxide to obtain plastic is pulverized to the nanometer level to realize polymerization of catalytic molecules and carbon dioxide, so that about 130 g of carbon dioxide is catalyzed per gram of the catalyst, and a new packaging material containing 42% of carbon dioxide is synthesized. Fourth, low temperature anti-mold packaging The low-temperature anti-mold packaging technology controls the temperature of the commodity itself by a certain technology, so that it is lower than the minimum limit of the growth and reproduction of the microorganism, thereby inhibiting the respiratory and metabolic decomposition of the product, and also inhibiting the metabolism and growth of the microorganism. Thereby achieving the purpose of anti-mold. The temperature and time required for cryopreservation and mildew resistance should be determined according to the specific commodity. In low temperature environment, the activity of mold will not only be greatly inhibited or even died. Therefore, in general, the lower the ambient temperature, the longer the duration, the higher the mortality of mold and microbes, and the better the anti-mold effect. According to the level of refrigerating temperature and the length of time, low temperature anti-mold can be divided into two types: cold storage and freezing. Refrigerated and mildew-proof packaging typically has a temperature of 3 degrees Celsius to 5 degrees Celsius. At this temperature, the enzymes of the mold and microbes almost lost their activity, and various physiological and biochemical reactions of metabolism were slow or even stopped, so the growth and reproduction of the mold was greatly suppressed, but it did not die. Refrigeration is generally suitable for perishable goods with large water content and not resistant to freezing, such as fruits, vegetables, and fresh eggs. Freezing is a perishable commodity that is suitable for freezing to a large moisture content. The temperature is usually controlled at a freezing storage below -12 degrees Celsius. At this temperature, most of the molds die. During the freezing period, the quality of the product is not substantially damaged, and the moldy microorganisms on the commodity become dehydrated with the intracellular water, and the ice crystal water damages the plasma membrane of the cell and causes death and injury. Freezing is generally suitable for anti-mold packaging of meat, fish, etc., but low-temperature frozen mildew packaging should pay attention to the use of low-temperature packaging materials. Five, dry (low humidity) anti-mold packaging Moisture is a necessary condition for mold growth. The lack of water in the microbial living environment causes dryness. In the dry conditions without suitable water, the mold grows and reproduces in a special way, and the product does not rot. The dry anti-mold packaging technology achieves the anti-mold effect by reducing the moisture content in the sealed package and the moisture content of the product itself, so that the mildew microorganism can not obtain the moisture required for growth and reproduction. Therefore, controlling the moisture in the product and the package can effectively inhibit the growth and reproduction of the mold, because the drying can denature the microbial cell protein and increase the salt concentration, thereby suppressing or promoting the death of the microorganism. Generally, the relative temperature inside the package is below 60%, which can effectively prevent mold rot. The mycelial anti-drying ability is very weak, especially the young strain has weak resistance to drying. The moisture content of the package can be absorbed by placing a certain amount of desiccant in the sealed package to reduce the moisture content of the contents to below the allowable water content. Generally, high-speed water loss is not easy to cause microbial death, slow drying of mold fungus deaths, and the fastest death in the early stage of drying. The bacteria are not easy to die under low temperature drying, and are most likely to die when exposed to room temperature after drying. Therefore, when drying and anti-mastic packaging, it is necessary to use a packing material with good air tightness and low moisture permeability for sealing packaging, and place an appropriate amount of desiccant (such as silica gel) and humidity indicating paper in it to absorb moisture and Indicates relative humidity. Sixth, ionizing radiation anti-mold packaging technology Ionizing radiation means that energy is transmitted through space and irradiated onto a substance, and the radiation causes ionization of the substance to be irradiated. The direct effect of ionizing radiation is to cause the internal components of the microorganism to decompose and cause mutagenesis or death when the radiation passes through the microorganism. Its indirect effect is to dissociate water molecules into free radicals, which 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 is inactivated, thereby causing mutagenesis or death. Radiation can cause pests, eggs, proteins, nucleic acids and enzymes that promote biochemical reactions to be destroyed and lose vitality, thereby terminating the process of erosion and growth and aging of foods, and maintaining quality stability. Ionizing radiation is generally alpha, beta, and gamma rays emitted by radioisotopes, which can damage certain aspects of microbial cell structure and metabolism. The alpha ray is absorbed by the air upon irradiation and hardly reaches the object. The β-ray penetration is weak and is limited to the surface sterilization of the object. The gamma ray has a strong penetrating effect and can be used for internal sterilization of food. The radiation can be sterilized and insecticidal, and does not cause the object to heat up, so it can be called cold sterilization. However, some foods may deteriorate or be improved after exposure. Ionizing radiation and mildew resistant packaging currently mainly use beta rays and gamma rays. The radiation used for radiation packaging has the characteristics of strong penetrating power and high lethality. Through the radiation of such rays, pathogenic bacteria, microorganisms and insects parasitic in food are killed. At the same time, after the food is irradiated, the food itself can be inhibited from undergoing metabolic processes, thereby preventing deterioration and mildew of the food. After the packaged goods have been ionized, the disinfection and disinfection effect is completed. After the irradiation, if the pollution is no longer contaminated, and the conditions of refrigeration are combined, the small dose of radiation can extend the storage period for several weeks to several months, and the large dose of radiation can be thoroughly Sterilize and store for a long time. However, it should be noted that too much radiation dose may accelerate the aging and decomposition of the packaging material, so also pay attention to control the dose. Seven, microwave radiation anti-mold packaging Microwave refers to an electromagnetic wave having a wavelength of 0.001 m to 1 m (frequency of 300 to 300,000 MHz). The microwave frequency used for sterilization is generally 2450 MHz. Microwave energy advances forward at the speed of light, and encounters object blocking, which can cause reflection, penetration, absorption and the like. The microwave can cause the water molecules in the material to vibrate, rub and heat, so that the microorganisms are killed by heat to sterilize. Microwave sterilization mainly has two factors: thermal effect and non-thermal effect. After the microwave absorbs microwave energy under the action of high-frequency electromagnetic field, it is converted into heat to increase temperature and sterilize. On the other hand, the water and fat of the bacteria Under the action of microwaves, polar molecules in the organism produce a strong rotation effect in the microwave field. This intense rotation inactivates the vegetative cells of the microorganism or destroys the enzyme system within the microbial cells, causing the death of the microorganisms. The heat generated by the microwave is internal, so the microwave heat energy utilization rate is high, the heating time is short, and the heating is uniform. Microwave fire fungus has strong penetrating power, energy saving, fast sterilization, high efficiency, simple operation, wide application range, microwave sterilization for easy control, uniform heating, food nutrients and color, aroma and taste after sterilization. Still close to the natural quality of food, it can be used for the sterilization of liquid and solid objects. The packaged items are placed in the microwave field and the sterilization process can be completed in a very short time. However, care should be taken to prevent microwave leakage during use. At present, microwave sterilization is mainly used for sterilization of meat, fish, soy products, milk, fruits and beer. Eight, far infrared radiation anti-mold packaging Far-infrared rays are electromagnetic waves with a frequency higher than 3 million MHz. The mechanism of sterilization is similar to that of microwaves. The main purpose is to use the far-infrared light radiation and the high temperature to cause the bacteria to dehydrate quickly and die. The far-infrared rays can be used to directly illuminate the food, or the food can be sterilized by far-infrared rays after being placed in a plastic bag. The use of infrared light began in the 20th century. In 1935, Groveny of Ford Motor Company of the United States first obtained a patent for heating and drying infrared rays. Many components and microorganisms in foods have strong absorption in the far infrared region of 3 μm to 10 μm. Far-infrared heat sterilization does not require media, and heat penetrates directly from the surface of the object to the inside. Therefore, it can be used not only for the sterilization of general powdery and blocky foods, but also for sterilization and mildew of nut foods such as coffee beans, peanuts and grains, and direct sterilization of bagged foods. Nine, ultraviolet radiation anti-mold packaging Ultraviolet light is also a bactericidal radiation, which is a major factor in the sterilization of sunlight. The bactericidal mechanism is that ultraviolet radiation can cause changes in the molecular structure of the microbial cell core protein to cause death. The wavelength of the ultraviolet ray is from 100 nm to 400 mn, and the ultraviolet ray having a wavelength of from 200 nm to 300 nm has a bactericidal action, and the wavelength with the strongest bactericidal power is from 250 nm to 260 nm, so that the wavelength of ultraviolet sterilizing is mostly 253.7 nm. UV sterilization is an easy-to-use sterilization method with no drug residue, high efficiency, high speed, and can be reflected by different surfaces. However, due to the weak UV penetration, it can only kill the mold on the surface of the product. Rot microorganisms. In addition, foods containing fat or protein may cause odor or discoloration after being irradiated with ultraviolet rays, and therefore these products are not suitable for ultraviolet sterilization. Ultraviolet light is generally used for the sterilization of packaging materials and containers, working environments, and non-food packaging products, as well as sterilization of liquid materials (such as beverages, milk, etc.) that are more suitable for ultraviolet sterilization. When used, the liquid material can be passed through the ultraviolet irradiation zone in a thin layer to kill the mold microbes on the surface of the article and the surface of the container. However, it should be noted that the ultraviolet rays must be irradiated to the product to be sterilized, and the irradiation cannot be sterilized. The ultraviolet light is linearly propagated, and its intensity is weakened in proportion to the square of the distance. The sterilization effect is related to the irradiation intensity, time, distance, and air temperature. Therefore, it is necessary to determine the irradiation distance and time according to the power of the ultraviolet lamp. In addition, UV sterilization is also related to the surface state of the material. For the smooth and dust-free packaging materials, ultraviolet rays can kill the bacteria on the surface; for the convex aluminum foil surface, the sterilization time is 3 times longer than the smooth surface; On the surface of a regular-shaped packaging container, the sterilization exposure time is 5 times longer than the plane. At the same time, the characteristics of the material should be considered when using ultraviolet sterilization, especially the inner layer of the composite material, such as PVC, PVDC, LDPE and the like, which will reduce the heat seal strength by about 50% after being irradiated by ultraviolet rays. Ten, high voltage electric field pulse anti-mold packaging High-voltage electric field pulse sterilization is to place food in an instantaneous high-voltage electric field generated between two electrodes. High-voltage electric pulse (HEEP) can destroy the cell membrane of bacteria and change its permeability, thereby killing cells. There are two methods for obtaining a high voltage pulsed electric field. One is to use the principle of LC oscillating circuit to charge a group of capacitors with a high-voltage power supply, and connect the capacitor to an inductor coil and the electrode of the processing chamber. The high-frequency exponential pulse attenuation wave generated when the capacitor is discharged is added to the two electrodes. A high voltage pulsed electric field is formed thereon. Since the LC circuit discharges the electrode quickly, the electric field energy can be released within tens to hundreds of microseconds, and the LC oscillator circuit can be continuously charged and discharged by using an automatic control device, which can be completed in several tens of milliseconds. Bacterial process. The other is to use a specific high-frequency high-voltage transformer to obtain a continuous high-voltage pulsed electric field. The high-voltage pulsed electric field for sterilization is generally 15 kV/cm to 100 kV/cm, the pulse frequency is 1 kHz to 100 kHz, and the discharge frequency is 1 kHz to 20 kHz. High-voltage electric field pulse sterilization is generally carried out at room temperature, and the processing time is several tens of milliseconds. This method has two characteristics: First, due to the short sterilization time, the energy consumption during the treatment is much smaller than the heat treatment method. Second, because it is carried out under normal temperature and normal pressure, the processed food has little change in physical properties, chemical properties and nutrients compared with fresh food, and there is no difference in flavor and taste. Moreover, the sterilization effect is obvious, and the requirements for commercial sterility can be achieved, and it is especially suitable for heat sensitive foods.