Aseptic packaging of the hottest food

2022-09-23
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Aseptic packaging of food

according to the characteristics of aseptic packaged food, the selected materials can be made into a form suitable for the packaging of the product, mainly including: (1) aseptic paper packaging: the paper packaging material used for aseptic packaging is actually a composite material, which is made of paper/polyethylene/aluminum foil/sarin resin and other multilayer composite paperboard. Among them, paper is the structural material, polyethylene is the bonding material, sarin resin is the heat sealing material, and aluminum foil is the high barrier material. There are two forms of sterile paper packaging: roof bags and brick bags

(2) sterile Cup Packaging: the material used in sterile cup packaging is multi-layer co extruded sterile packaging sheet, and its structure is PP/PE/ADH/PVDC or evoii/ADH/PS. Among them, PP is a peelable sterile packaging protective film, PVDC and EVOH are high barrier materials, and PS is a structural material. Before entering the sterile room, the roll of sterile packaging sheet is stripped of the PP film, and the sterile PE surface is exposed in the sterile room, and then formed, filled, sealed in the sterile room, and then labeled. The cover material used for aseptic packaging is Al/PE/Pet multilayer composite material, in which pet is a peelable layer

(3) aseptic aluminum/plastic bag packaging: this packaging method is similar to aseptic paper packaging, but the material used is aluminum/plastic composite film, and the packaging form is bag packaging

(4) bag in box: for large capacity packaging, the form of bag in box can be adopted. The sterilized food is poured into pre sterilized sealed multi-layer plastic bags, and the filled bags are packed in outer packing boxes or steel drums made of wood or cardboard, mainly packed with thick slurry or base materials. At present, this form of packaging has basically replaced the method of preserving food by using iron or plastic barrels as packaging and adding preservatives to food

(5) bottles: mainly glass bottles and plastic bottles. Aseptic packaging of glass bottles was developed as early as 1942, but large-scale industrial production has not been formed. In recent years, with the development of glass bottle manufacturing technology, light-weight reinforced glass bottles have emerged. The heat resistance and impact resistance of glass bottles have been greatly improved, and even if the internal and external temperature difference is above 800 degrees Celsius, they will not break, thus enhancing their application in sterile food packaging and expanding the application field of sterile packaging technology. Plastic bottles can be sterilized at the time of molding and filled immediately, or sterilized before filling. Sterilized bottles are filled and capped in a sterile room. General bottles cannot be reused. Bottles made of high-grade polycarbonate vinegar with a molding temperature of 290 ℃ (3) 50 ℃ can be reused. But the market share of this kind of bottle is still relatively low

(6) metal cans: metal cans are one of the earliest packaging forms used in aseptic packaging, mainly divided into tin cans and aluminum cans. At present, the most advanced typical representative of aseptic packaging of metal cans in the world is Dole aseptic canning system in the United States. The sterilization method of metal cans used by Dorr system is dry heat sterilization, that is, high-temperature superheated steam is used for sterilization. When the empty tank passes through the sterilization chamber on the conveying chain, the superheated steam is sprayed from top to bottom for 45 seconds. At this time, the tank temperature rises to 221 ℃ ~ 224 ℃, and the tank cover is also sterilized with superheated steam of 287 ℃ ~ 316 ℃ for 75 ~ 90 seconds. Such a high temperature is enough to kill all heat-resistant bacteria. Because all containers and equipment are sterilized by superheated steam, the sterility is high, the residual air in the top gap of the can is very little, and it is in a high vacuum state, and the quality of the product is safe and reliable

(7) composite tank: composite tank is a three piece tank composed of more than two materials, namely, the bottom and cover are made of metal, and the tank body is made of aluminum foil, cardboard or polypropylene. The printing and decoration effect of the composite tank is good, the cost is low, the quality is light, and the treatment is convenient without causing public hazards. However, the air tightness and heat resistance of the composite tank are worse than those of the metal tank, so it is used as a sterile packaging container for frozen concentrated fruit juice in Europe, America and Japan. Due to the poor heat resistance of the composite tank, it is generally sterilized with hot air at about 127 ℃, and the fruit juice is cooled to 80 ℃ after sterilization above 93 ℃ for hot filling. Sterile air is used in filling and sealing areas to maintain positive pressure to prevent bacterial contamination. However, it is difficult to kill heat-resistant bacterial spores, so the compound tank is only limited to filling high acid fruit juice. Under the conditions of low temperature and high acidity, these residual bacterial spores will not reproduce and grow, so the hygiene index of food can be guaranteed

(8) paper based composite containers: paper based composite containers are composed of paper, polyethylene, aluminum foil and other materials. These containers are widely used in aseptic packaging in Western European countries, especially the aseptic brick boxes and diamond bags produced by Tetra Pak packaging company in Sweden

this composite material with a thickness of about 0.35mm is composed of eight layers of materials, which has excellent barrier to oxygen and water vapor. Moreover, the printing and decoration effect is also very good. It is convenient to drink, and the shelf life of the product is long. It is also one of the ideal materials for aseptic packaging of beverages. The sterilization of paper containers adopts the method of combining hydrogen peroxide (hydrogen peroxide) with heating. First, the packaging materials are subjected to hydrogen peroxide water bath, and then when filling, tubular heating elements are used at the feed pipe to make the air temperature between them very high, which promotes the hydrogen peroxide liquid film on the inner surface of the paper to quickly decompose into water and new ecological oxygen. This oxygen has strong sterilization ability, making the container meet the requirements of sterility. High concentration hydrogen peroxide solution is also used to sterilize the packaging materials for 8 ~ 9 seconds at a temperature of about 80 ℃

(9) plastic containers: plastic is the fastest-growing and most widely used material in aseptic packaging. It has low cost, diverse shapes and strong mechanical adaptability. Especially in recent years, the continuous development of plastic film coextrusion and container molding technology has promoted the development of plastic in the field of aseptic packaging materials. The requirements for plastic packaging materials are mainly to have the protection and preservation of food, the mechanical strength to adapt to circulation, the adaptability of packaging machines and merchantability, especially to have a high barrier to oxygen and water vapor. Therefore, at present, the sterile plastics used in countries all over the world are mainly composite films. At present, the vast majority of plastic film production enterprises in China have not yet produced such sterile packaging materials, and they also lack domestic materials with good barrier properties such as polyvinylidene chloride; In terms of manufacturing sterile packaging containers, there is a lack of strict clean room conditions and various sterilization measures. Therefore, in order to develop aseptic packaging in China, the manufacturing of packaging materials is a very important link. Due to the poor heat resistance of plastics, the current sterilization methods for plastic packaging materials are usually hydrogen peroxide sterilization, and the technology of combining low concentration hydrogen peroxide solution with ultraviolet light and sterile hot air is also used. It is reported that these methods have good sterilization effects. In order to prevent the diffusion of hydrogen peroxide in the operating environment, it is advantageous to use low concentration hydrogen peroxide

in addition to the packaging containers and materials listed above, there are also some special materials involved in aseptic packaging, such as metal composite materials and containers, paper and metal composite containers, etc. Moreover, with the improvement of people's requirements for food quality and the needs of the sustainable development of human living environment, packaging materials and containers are gradually moving towards environmental protection and green, especially in the food packaging of people's daily consumption, it is more necessary to pay attention to the electronic universal experimental machine, which means health and green. Therefore, the development of aseptic packaging containers will be an important issue to be solved in the wide application of aseptic packaging technology, and its development will take health, non-toxic, green environmental protection, economic and practical as the main goal and direction

in the use of packaging materials, attention should be paid to the sterilization of packaging materials (containers). Common sterilization methods include: Pharmaceutical sterilization (such as hydrogen peroxide, ethanol, etc.), superheated steam sterilization, ultraviolet sterilization, etc. Different sterilization methods have different defects, and appropriate sterilization methods should be selected according to different materials. To a great extent, the structure type, complexity and stability of the sterile packaging system are determined by the packaging material and its corresponding sterilization method. Generally speaking, paper plastic packaging containers can be sterilized by UV, hydrogen peroxide, ethanol, hydrogen peroxide + UV, ethanol + UV and other methods. For heat sensitive plastic bottles, composite films and paper containers, they can also be sterilized by radiation, while metal, glass packaging containers, metal can covers and so on are generally sterilized by thermal methods, superheated steam, hydrogen peroxide + thermal methods. The sterilization of packaging materials and containers should be carried out according to the reliable sterilization form determined by strict tests. Since most sterile packaging containers use soft composite bags, it should be considered to minimize the impact of long-term high temperature on the quality of materials, which is an important link of sterile packaging and the key to the success or failure of sterile packaging Pay attention to the sterilization of packaging machinery and operation work

packaging environment (i.e. packaging production line) includes equipment and working environment. Aseptic packaging equipment is the general name of a unit, which is mainly composed of sterilization cooling and aseptic filling equipment. The unit must be equipped with an appropriate material conveying system, a completely reliable self (1) experimental machine, a 2-year dynamic control system guaranteed by the company, an automatic cleaning system, and special packaging materials. The supply of water, electricity, steam and compressed air must be completely reliable during work. The system through which the food passes must be sterile, and the space environment through which the food is filled into the packaging container must be sterile. In addition, aseptic packaging generally requires large-scale equipment, especially food sterilization machines and aseptic packaging machines, which have large investment and high cost; The hygiene requirements of operation and management are strict and difficult. Once polluted, it will be scrapped in batches, causing waste and great losses, and all links from beginning to end must be re sterilized; The specificity of equipment and products is strong, which is not suitable for the production of small batch and multiple varieties of products, and the universality is poor; Aseptic packaging is difficult to apply to high viscosity food and solid food, and is generally only used for food with good liquidity

aseptic packaging requires to prevent the invasion and pollution of external microorganisms in the whole process from food sterilization to aseptic filling to package sealing. All connecting parts of food flow should be reliably sealed to prevent food from being polluted by microorganisms from outside the system. In the process of aseptic packaging, full attention should be paid to the secondary pollution of microorganisms, and the time of direct contact between sterilized food and packaging containers with air should be shortened as far as possible. Before food packaging, the packaging machinery and operating environment should be sterilized first. Packaging machinery can be washed with hot alkaline water, neutralized with dilute hydrochloric acid, washed with hot water, and then sterilized with high-temperature steam. The operating environment can be sterilized by both chemical sterilization and physical sterilization. Generally, the sterile room is equipped with air filtration device and ultraviolet sterilization device to maintain the regular sterile state of the sterile room. Ultraviolet irradiation can be carried out regularly to kill microorganisms free in the air. Ensure that the cleanliness, temperature and humidity of the sterile room should meet the specified standards (the temperature is generally controlled at about 18 degrees Celsius and the humidity is generally about 55%). Sterilization of operating environment is to prevent bacteria and other dirt from entering the operating environment. Sterilization is mainly achieved by filtration and dust removal. Generally, the air in sterile operation space needs to be disinfected, secondary filtration and heating disinfection to produce sterile overpressure

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