Antibacterial technology and its application progr

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Antibacterial technology and its application progress in the flexible packaging industry (Part I)

the World Health Organization (who) of the United Nations proposed that the global theme of the 21st century is "health and environment", and 60% of everyone's life and health are in their own hands. In other words, in addition to the factors that cannot be changed in genetics, the environment of individuals plays an important role in life and health. Pathogenic microorganisms such as bacteria and viruses are one of the main killers of human health. According to the statistics of who magazine in 1996, there were 17million deaths caused by bacterial infection in the world in 1995, accounting for about 1/3 of the death population. In 1997, E. coli 0-157 was prevalent in Japan. In 2000, Japan, South Korea, Mongolia and other countries started foot-and-mouth disease and the spread of SARS in China in 2003. This series of flat experiments: events similar to the ring stiffness experiment have caused global panic. Therefore, in recent years, how to control and eliminate the infectious diseases caused by bacteria and virus transmission (such as malaria, cholera, tuberculosis, hepatitis, pneumonia, etc.) has been put on the agenda. Because antibacterial products can fundamentally eliminate the bacterial cross infection between people, people and things, and things and things, they are widely welcomed all over the world. In Japan and developed countries in Europe and the United States, antibacterial materials have been widely used in the packaging of vegetables, fruits, dairy products, cosmetics, medicine and other aspects

the concept of "antibacterial" in a broad sense is very broad, including sterilization, bacteriostasis, disinfection, bacteria prevention and other meanings. The antibacterial objects are bacteria, actinomycetes, fungi and viruses in the protozoa. The target microorganisms are mainly pathogenic bacteria. Antibacterial material refers to the material with antibacterial function after antibacterial treatment. Antibacterial properties are achieved by adding antibacterial agents. In practical application, antibacterial materials are generally not required to quickly kill harmful microorganisms, but focus on inhibiting their growth and reproduction in the long-term use process, so as to achieve the purpose of environmental protection

with the continuous development of science and technology and economy in the world, people pay more and more attention to their own health and environmental protection, so there are higher requirements for the packaging of products (daily necessities, food, industrial products). High performance and functional plastic packaging materials have become the development hotspot of many countries. Such materials include high barrier, multi-functional freshness preservation, selective permeability, heat resistance Sterile ncm111 and ncm622 account for 13% and 10% respectively (antibacterial) and plastic packaging materials such as rust prevention, deodorization, shape memory, resealability, and easy unsealing. Nowadays, antibacterial packaging materials are developing most rapidly and will become the focus of development at the beginning of the 21st century

at present, the methods of preparing antibacterial packaging materials include compounding method, molecular assembly method, grafting method, surface spraying method, etc. Among them, the compound method is the most simple and effective, so it is widely used in the research and production of various antibacterial products. In recent years, molecular assembly antibacterial technology has also made great progress, and began to be put into practical application. Based on the classification of antibacterial technology and antibacterial agents, this paper focuses on the development status of the technology and application of food antibacterial packaging materials

1. Composite method

composite method is to blend antibacterial agents or preservatives into polymer materials. Antibacterial agents or preservatives are evenly distributed in the materials. By slowly releasing antibacterial or preservative components to the surface of the materials, microbial growth is limited or prevented, so that the materials have long-term antibacterial ability. These materials can be used in plastic liquid film, fresh-keeping film, paper plastic composite materials and other packaging materials. Because the concentration of antibacterial or antiseptic ingredients added is very low, it generally will not affect human health

1.1 natural antibacterial agent electromagnetic directional valve 1 is always in the energized state

natural antibacterial agent is an antibacterial agent manufactured and used by using the unique antibacterial properties of various natural substances. The ancients all know that many acidic and alkaline substances, spices, mustard, ginger flower, castor oil, Chinese toon oil, edible oil and other oils, mengzongzhu, horseradish and other plants have the function of preserving food. Until today, people still use natural antibacterial agents to preserve food, clothing and daily necessities when they are included in an integrated production line to prevent bacteria, mold and other hazards

there are many kinds of natural antibacterial agents, and the sterilization principle is also different. For example, acid and alkaline substances destroy the cell wall and cell membrane of microorganisms, and then solidify the cell protein to achieve sterilization; Alcohols denature cell proteins, interfere with cell metabolism, and complete sterilization; The sterilization principle of chitosan is that it contains amino acids and belongs to cations, while the microbial cell wall is composed of acids and phospholipid anions. The combination of the two hinders the development and reproduction of microorganisms

the advantage of natural antibacterial agents is that they are non chemical products extracted from natural food and plants or used directly, and generally do not pollute humans, animals and the environment, so they are favored. However, its antibacterial function is limited, there is no long-term broad-spectrum antibacterial property, and after use, it will cause peculiar smell or discoloration of food and supplies, and the scope of application is limited

natural antibacterial agents used in food packaging materials mainly include chitosan, protamine, cinnamon oil and arhat tar, which are refined from driven plants and have the advantages of excellent weather resistance, low toxicity and safe use, but their heat resistance is poor and the duration of efficacy is short. Among them, chitosan is more studied, especially its application in food industry has attracted special attention [1]

ginopakku company, which manufactures food containers, and fudokarucha food additive development company jointly developed a new packaging material with antibacterial and acid proof effects, and the freshness retention period of food is 4 times higher than that of the original packaging material. This material is made by fusing the extract from natural salt as an antibacterial component with plastic [2]. In addition, Japan also extracts essential oil from taro due to antibacterial fresh-keeping packaging film materials

in recent years, people have paid attention to the environmental pollution caused by packaging materials. Therefore, the research on it tends to be edible coatings or film materials. Edible coatings and films have many advantages, such as biodegradability, edible, good-looking appearance, blocking oxygen and physical pressure. In addition, they can also be used as the carrier of edible preservatives. Padgeu t et al. Mixed lysozyme and nisin into corn protein or soybean protein respectively to make edible packaging films, and found that both of them could well inhibit the Gram-positive bacterium Lactobacillus plantarum (ncdo1752). After adding EDTA, these films increased the effect of inhibiting the Gram-negative bacterium Li [3]

edible antibacterial film is a film with porous complex structure formed by the interaction between different molecules with natural edible substances (such as proteins, polysaccharides, cellulose based derivatives, mixed with a small amount of food additives such as emulsifiers, plasticizers, antioxidants, food pigments, spices and antibacterial agents) as raw materials. The practical performance of edible packaging film is the same as that of synthetic plastic packaging film, and it has more advantages than synthetic plastic. It has obvious water resistance and can delay the migration and diffusion of water, oil and other components in food; It has optional permeability and anti permeability, which can prevent the volatilization of flavor substances in food; It has good physical and mechanical properties, which can improve the mechanical strength of food surface and make it easy to process; It can be used as the carrier of food color, aroma, taste, nutrition enhancement, antioxidant and antibacterial substances; It can be eaten together with the packaged food and has no pollution to the food and environment, as shown in Table 1. Therefore, it has broad application prospects in the food industry [4]

table 1 Some edible antibacterial films

edible film food function

cmc hard cheese, hard sausage inhibit mold

alginate meat products inhibit microbial growth

gelatin meat products preservative carrier

pectin food fungicide, antioxidant carrier

carrageenan medium humidity cheese reduces the growth of surface microorganisms

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