Progress in aseptic filling technology and equipme

2022-08-09
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Progress of aseptic filling technology and equipment for liquid food

overview

since the world's first Tetra Pak aseptic filling machine sterilized with hydrogen peroxide came out in 1961, aseptic filling technology has developed to an increasingly perfect level. It has become a high-end technology integrating electromechanical integration technology, modern chemistry, physics, microbiology, automatic control, computer communication and other high-tech [1], And with the continuous development of modern technology. As far as paper plastic aseptic packaging machines are concerned, there are vertical and horizontal, shaped cartons and preformed cartons. The packaging form has also developed from the earliest polyhedral packaging to brick carton packaging and roof packaging with different capacities. The style is more novel and the application life is as long as possible, which is suitable for the psychology of consumers. PET bottles have developed rapidly because of their light weight, transparency, non shattering and recyclability. The development from hot filling to aseptic filling has brought the advantages of PET bottles into full play. The application of aseptic filling technology has reduced the cost of bottle makers and diversified bottle types. It can realize the direct bottle making and aseptic filling from PET raw materials, further reducing the overall cost. The progress of these technologies is closely related to the continuous improvement of microbial fence system, and is more based on safety, reliability and environmental protection

the continuous innovation and improvement of liquid food sterilization technology is an important part of the rapid development of sterile filling technology and equipment. The application of fluid control system enables the sterilization time and temperature of liquid food to be accurately and effectively controlled, thus ensuring the stability and safety of product quality. With the pursuit of food nutrition and color, aroma and taste, people hope that the liquid food, fruit juice, beverage and milk sold on the market are closer to the original flavor and nutrition of food. For many years, scientists have been exploring and seeking more advanced sterilization methods. In addition to the classic HTST and UHT using steam as the heating medium, microwave sterilization, resistance heating technology, high-voltage killing 411.9 bacteria, high-voltage pulsed electric field, radio wave, excited ultraviolet light pulse sterilization technology and other physical methods of sterilization technology are being studied in depth, and some have been commercialized

wall type UHT system with saturated steam as heat source

ultra high temperature sterilization system (UHT) is composed of a group of tubular or plate heat exchangers, material tanks, maintenance tubes, superheated water preparation system and CIP device [2]. These equipment are connected into an organic whole through pipelines and valves with different performances. The whole system is controlled by PLC to realize automatic program operation and automatic adjustment of process parameters. The type of sterilizer depends on the type of liquid food. Usually, plate heat exchangers are used as sterilization coolers for products with good fluidity. Most of the products with higher viscosity use tubular heat exchangers, and the products with higher viscosity use scraped surface heat exchangers. There are two types of tubular sterilizers: multi sleeve and multi tube. The former is composed of a group of concentric sleeves with different diameters and corrugations. According to needs, it can be made into a sleeve. The heat exchange of thermal medium and materials can be carried out through one or two heat transfer surfaces, which can realize reverse flow operation. In fact, the multi tube sterilizer can be regarded as a heat exchange device with 180 ° elbow connecting multiple shell and tube heat exchangers. It is installed in a pipe with a larger diameter (mm) φ Mm straight tube, with a length of M, can realize multi-path flow operation, which is the type of tubular sterilizer used more at present

according to the introduction of SIG Manzini company in Italy, the company cooperated with the University of Parma to study the heat transfer of the tubular sterilizer with corrugated pipe and smooth pipe structure. It is believed that for liquid food with low viscosity, such as milk or fruit juice, when the fluid is in turbulent flow or turbulent flow, the total heat transfer coefficient of the fluid when the corrugated pipe and smooth pipe are heated or cooled is relatively close, and the pressure drop of the fluid in the corrugated pipe is significantly higher than that in the smooth pipe. For the heating and cooling of viscous materials, when the fluid is in the transition flow, the total heat transfer coefficient and pressure drop of the bellows are significantly greater than that of the smooth tube

radio wave sterilization technology

according to sig Manzini, the company has cooperated with the University of Milan in Italy to put radio waves into practical use as an industrial device for heating liquid food. Art30 device has been used for sterilization of milk and fruit juice respectively. Its production capacity is 3300l/h, sterilization temperature is 140 ℃, installation power of radio wave is 100kW, and the maximum thermal power used is 75kW (65000kcal/h). The structure of the whole device is similar to the traditional UHT system. The materials in the material tank are first pumped into the heat recovery device, and then heated to the set sterilization temperature in the radio wave heating unit. The high-temperature materials are sent to the sterile filling machine for filling after being cooled to the filling temperature through the maintenance tube and the heat recovery device

the frequency of the radio wave used in this device is 27.12MHz. The liquid food being processed is heated up due to the high-frequency vibration of polar molecules caused by the magnetic field, and its heating time is only 1/100 of that of the traditional superheated water heating method. Materials in contact with food are made of polytetrafluoroethylene. The advantage of using radio wave sterilization is that the food is evenly heated and will not produce dirt on the pipe wall due to overheating, and the flavor of the product is closer to the raw material itself. Radio wave sterilization technology can be used for fruit and vegetable juice, jam, milk and dairy products with lumpy materials, as well as fruit juice and pulp sensitive to heat

microwave sterilization

microwave refers to the electromagnetic wave with the frequency of 300MHz ~ 300GHZ. The microwave frequencies used in the food industry are 915MHz and 2450MHz. The heating of liquid food with polar molecules by microwave is the result of the conversion of microwave energy into heat energy by the material itself. Microwave sterilization is not only due to the conversion of energy absorbed by organisms into thermal effect, but also by virtue of its non thermal effect. The non thermal effect of microwave refers to that although organisms do not produce obvious temperature rise under the action of electromagnetic waves, they can disturb and destroy the normal metabolic function of microbial cells, inhibit their growth, or even stop growing or dying. Microwave can also reduce the water activity of microbial cells and destroy their living environment. The application of microwave can kill microorganisms in materials at a lower temperature than traditional heating methods [3]

pulse microwave sterilization mainly uses non thermal effects. Its methods are as follows: 1. Using pulse microwave sterilization technology with instantaneous high-power pulse microwave energy and low average power, the object is irradiated by high-energy microwave in a very short time, and bacteria and other microorganisms lose their viability under the action of extremely high electromagnetic field, so as to achieve the purpose of sterilization. 2. The continuous wave microwave power is cut off periodically with millisecond continuous and stop time, so that the cell body is subjected to periodic continuous action, resulting in a resonant state, resulting in bacterial cell membrane rupture and bacterial death

high pressure sterilization technology

high pressure technology is to put food in liquid medium and process it under MPa pressure. During the processing process, high molecular substances such as enzymes, proteins and starch in food lose activity, denaturation and gelatinization, and destroy the cell membrane of microorganisms to achieve the purpose of sterilization [4]. Using high-pressure technology to sterilize food avoids a series of processing defects caused by heat treatment sterilization. It will not destroy vitamins, pigments, flavors and nutrients, will not produce heat odor, and can effectively save energy. Therefore, since the Research Report on the application of high-pressure technology in food was put forward by Lin limaru of Tokyo Metropolitan University in 1986, it has immediately attracted the attention of some developed countries and made some progress. In 1990, jam produced by high-pressure technology in Japan was first sold in supermarkets. Its processing technology is to pressurize jam to MPa at room temperature and keep it for min. Pokka and Wakayama companies in Japan use semi continuous high-pressure devices to sterilize orange juice. FMC of the United States and Kjeldahl foods and beverages of the United Kingdom have also established sterilization devices for fruit juice and soymilk [5]. Some universities and industrial production departments in China are still in the experimental stage of the application of high-pressure technology in the food industry, and there are no reports of commercial applications so far. The 52 Research Institute of ordnance industry group carried out a high-pressure sterilization test on watermelon juice containing pulp, and the product is valid for 6 months under normal temperature. Pan Jian, et al. Of Hefei University of technology carried out a high-pressure sterilization test on strawberry juice sealed in double-layer polyethylene plastic bags. The results showed that when the touch was very soft, the pressure was 350Mpa, and the strawberry juice at 29 ℃ was pressurized for 3min, the coliform group could be completely killed; Mold and yeast can be completely killed at 350Mpa after 10min [6]

continuous high-pressure sterilization is to pump the liquid food directly into the pressure vessel. An isolation baffle separates the pressure medium from the liquid food. The medium pressure is transmitted to the product through the diaphragm, and the processed product is pumped into the sterile tank. In order to prevent pollution, sterile water is used as the pressure medium to realize the continuous operation of high-pressure sterilization and sterile packaging system [4]

aseptic filling machine

it has been nearly 40 years since Guangdong cannery introduced the first Tetra Pak aseptic filling machine to produce chrysanthemum tea and guava juice in 1976. Now more than 400 aseptic filling machines packaged with paper plastic composites are in operation in China. In addition, there are large bag aseptic filling machines filled with concentrated fruit and vegetable juice or puree and aseptic filling machines packed with composite plastic film in operation. In 2001, Beijing Huiyuan Juice and Tianjin Dingxin group took the lead in introducing five PET bottle aseptic filling production lines. Since then, a total of 17 such production lines have been introduced across the country. The introduction of these aseptic filling production technology and equipment has promoted the promotion and development of China's beverage industry, and made the production technology and equipment of China's beverage industry enter the international advanced ranks

the form of aseptic filling machine depends on the packaging materials. In terms of the key technology to realize aseptic filling, a complete aseptic filling machine should include devices for sterilization of packaging materials, transportation of aseptic liquid food, filling and sealing in a sterile atmosphere, as well as CIP and sip conditions. There are many ways to sterilize paper plastic packaging materials. Tetra Pak's paper plastic packaging materials are immersed in a hot hydrogen peroxide solution with a concentration of 35%, and then form a cylindrical drum. Under high temperature conditions, the O3 decomposed by H2O2 sterilizes the materials, and completes the filling and sealing of materials in the drum filled with O3. Pkl's Kangmei bag fully sprays atomized H2O2 inside and outside the carton in the formed carton, and then uses hot air to decompose H2O2 to produce O3 to sterilize the carton. At the same time, it also creates O3 atmosphere in the small environment, which is filled and sealed here. As a large aseptic filling bag, the multi-layer film composite bag uses a plug similar to a plunger to pre seal the filling port, and then irradiates with a sufficient dose of Co60 to kill the microorganisms in the packaging bag, and disinfects, decaps, fills and seals the filling port in the aseptic room of the filling machine. In the early days, the sterile room was disinfected with halogens or peroxides and other chemical agents, but now most of them have been sterilized with saturated steam, and the volume of the sterile room is less than 0.01m3

the disadvantage of paper plastic packaging materials is that they are difficult to recycle. If they are not specially recycled, the pollution to the environment is self-evident. In recent years, the application of pet (polyethylene terephthalate) bottles in the beverage industry has developed rapidly. In addition to the convenience of consumption, it can also realize the efficient production of bottle making and filling, and the materials can be recycled. The key technologies to realize the aseptic filling of PET bottles are mainly the sterilization of bottles and caps, the maintenance of aseptic atmosphere in the filling sealing area, and the filling machine itself should meet the aseptic filling

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