Application of the hottest polyvinylidene chloride

2022-08-13
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Application of polyvinylidene chloride in chilled meat packaging

in many places in China, chilled meat is also known as "assured meat", and China is vigorously promoting the "assured meat" project Some experts assert that chilled meat has become the mainstream of Chinese meat consumption in the new century

in recent years, with the rapid development of China's economy and the acceleration of internationalization, China's meat consumption structure has also changed significantly. Raw meat shows a development trend from hot fresh meat to frozen meat, and then from frozen meat to cooled meat

chilled meat, also known as cold fresh meat and assured meat, refers to fresh meat that is slaughtered in strict accordance with the requirements of the quarantine and inspection system, which is rapidly cooled and reduced to 0 ℃ - 4 ℃ within 24 hours, and is always maintained in the range of 0 ℃ - 4 ℃ in the subsequent processing, circulation and sales process

although the cold chain in China has tended to be perfect and standardized, chilled meat can not completely inhibit the growth and reproduction of some psychrophilic microorganisms in the range of 0 ℃ ~ 4 ℃ used for cold storage. Therefore, the shelf life of chilled meat is short, and the surface browning and juice loss are serious. The storage period is generally 3-7 days, which cannot fully meet the needs of market circulation. In addition, China's traditional consumption habits have affected the promotion of chilled meat in China

how to prolong the fresh-keeping period of chilled meat is the key to the development of chilled meat. For this reason, food experts at home and abroad have carried out a lot of scientific research, and many new meat preservation technologies such as preservative preservation, radiation preservation, low water activity preservation and other research results have been published frequently. The new packaging technology is also crucial to prolong the fresh-keeping effect of chilled meat. According to authoritative information, the variety and quality of meat products in China are far behind the world's advanced level, mainly due to the lagging development of meat packaging technology. The author believes that choosing appropriate packaging materials and packaging technology can play a very significant role in prolonging the fresh-keeping period of chilled meat and ensuring the hygiene and quality of meat

foreign fresh meat packaging technology

1. Modified atmosphere packaging technology, also known as gas replacement packaging, uses appropriate gas composition to replace the gas environment in the packaging, so as to change the atmosphere in the packaging, so as to inhibit the growth and reproduction of microorganisms and extend the packaging of fresh-keeping period. Among them, high oxygen packaging (also known as red meat packaging) and anaerobic packaging are mainly used for meat segmentation, and low oxygen packaging is mainly used for carcass. In developed countries in Europe and the United States, three different gases, Co:, N:, O: are mainly used in different proportions. Co: it mainly inhibits the growth of bacteria and fungi, especially at the initial stage of bacterial reproduction. The bacteriostatic effect is the best at low temperature and 20% - 30% concentration; N: It mainly prevents oxidative rancidity and inhibits the growth of mold; 0: it mainly oxidizes myoglobin, keeps meat bright red, and inhibits the reproduction of anaerobic bacteria

2. Vacuum packaging technology makes the packaging close to the meat in the form of vacuum, inhibits the seepage of water in the meat crystal, blocks oxygen, inhibits bacterial reproduction, and improves the safety of meat. Vacuum body fitted packaging and heat shrinkable packaging are widely used in the packaging of segmented meat. Thermoforming stretch packaging is also used abroad

both modified atmosphere packaging and vacuum packaging have a common feature, that is, materials are required to have high barrier, so as to prevent the invasion of external air and bacteria, internal moisture loss, etc., so as to improve the hygiene and safety of meat products. The materials selected for these packages are the key to whether the packaging effect is obvious or not. Their common feature is the selection of polyvinylidene chloride (PVDC) high barrier packaging materials

high barrier packaging materials

at present, the three recognized high barrier materials in the world are PVDC, EVOH and pan. The three materials are copolymers, and EVOH is better than PVDC and PVDC is better than pan in terms of oxygen barrier; EVOH is better than PVDC and PVDC is better than pan for the barrier of water vapor. However, under high humidity conditions, EVOH is easy to absorb moisture and its barrier property will be significantly reduced due to the - OH group in its molecular structure. At the same time, the barrier property of pan material decreases significantly with the increase of environmental humidity. PVDC is a kind of packaging material with the best comprehensive barrier performance in the world

pvdc is an excellent food packaging material, especially resistant to high temperature cooking and good barrier to oxygen, steam and various odors, which is unmatched by other plastics. At the beginning, it was mainly processed into film, which was used in the packaging of weapons and ammunition during World War II. In the late 1950s and early 1960s, it gradually shifted to food packaging, and then gradually applied in the fields of hand medicine packaging. With the acceleration of modern packaging technology and the pace of modern people's life, the popularity of microwave ovens and refrigerators, the consumption of fresh-keeping film has increased sharply, making the application of PVDC more popular. EVOH, a new high barrier material appeared in the 1980s, once threatened the development of PVDC because of its recyclable performance and its unique environmental protection effect. However, its barrier property against humidity decreased significantly. It must be protected from humidity to achieve a high oxygen barrier effect, which greatly limits its scope of application

pvdc is the only large-scale industrialized plastic in the world that can withstand high temperature cooking and has high barrier properties. The film made with it has been widely used in China, and the biggest use is as sausage casing. These applications fully show the performance and unparalleled advantages of PVDC materials. However, PVDC is also a plastic that is difficult to synthesize and process. Only a few large companies in the world have these syntheses. On the morning of November 17, the foundation laying ceremony and processing technology were held in Changkou new area of the national Fuyang Economic and Technological Development Zone. Therefore, the output is small, the price is expensive, and the scope of promotion and application is narrow. The annual output of the world is only more than 100000 tons. However, due to its unique performance, it occupies an important position in the plastic packaging material industry, especially in the food packaging industry. Using it as an intermediate layer to manufacture multilayer composite materials is the frontier of technological progress and technological innovation in the plastic packaging industry at present

China has started the research on the practical application of PVDC resin since the early 1980s. First, the birth of ham sausage introduced PVDC film into China. Then, represented by Luoyang Chundu, it broke the blockade of the United States and Japan on this technology, introduced the processing technology and equipment of PVDC film, and vigorously promoted the project construction, which is to implement the reform and development plan proposed by Yuncheng municipal Party committee The specific actions of creating a first-rate in all work have created China's PVDC film processing industry. In the late 1990s, a group of packaging materials researchers represented by Luoyang Chundu tried to apply PVDC plastics to other packaging fields and achieved success

pvdc used for cooling meat packaging

the PVDC plastic used for cooling meat packaging is not a simple PVDC film, but a multi-layer coextrusion film with PVDC as the barrier layer, which is made of vinylidene chloride, methyl acrylate, methacrylic acid, acrylonitrile copolymer as the barrier layer, and other wear-resistant materials, heat sealing materials, etc. through coextrusion process. This kind of film has extremely high oxygen barrier, and the oxygen transmittance is 50 ml/m2 · ATM · 24h · 23 ℃ · 65% RH; Extremely high water vapor barrier, water vapor transmission rate 5g/m2 · ATM · 24h · 23 ℃ · 90% RH. At present, the more common structures in the world are PE/tie/PVDC/tie/PE and PE/tie/PA/tie/PVDC/tie/PE five or seven layer structures. Multi layer coextrusion high barrier film used in modified atmosphere packaging technology is mainly made by tape casting and film blowing, which does not have shrinkage, and the thickness is generally 90 μ m~150 μ m. With high transparency and puncture resistance, it can inhibit microbial reproduction by changing the gas environment inside the package. Vacuum shrinkable packaging is mainly made of multi-layer coextrusion double bubble blowing film. PVDC is used as barrier layer. After coextrusion with other special materials by double bubble method and off-line treatment, the product shrinkage is about 35% - 45%. Using the heat shrinkability of the shrink film to make it close to the surface of meat products, it can prevent moisture seepage, and the thickness is generally 50 μ m~90 μ m。 The PVDC coextrusion films with these structures have been produced and researched by enterprises such as Luoyang Chundu, Hebei Qinhuangdao and Xingtai in China since the late 1990s, but they have not been localized so far. A small number of Chinese enterprises are using high barrier packaging materials, which are completely dependent on imports

by using PVDC coextrusion film to pack chilled meat, the fresh-keeping period of meat can be extended, including information such as manufacturer, batch number and raw material batch number, which expands the sales field of meat processing enterprises and can cover long-distance markets at home and abroad. For export-oriented enterprises, the storage period of meat products in long-distance transportation is greatly improved and the quality of meat products is guaranteed. According to the survey, at present, less than 1% of chilled meat processing enterprises use high barrier plastic packaging materials, and they are only used in the export packaging of beef and mutton

conclusion

with the gradual maturity of the domestic chilled meat market, hot fresh meat and frozen meat will gradually withdraw from the mainstream of raw meat consumption, and chilled meat will "enter the homes of ordinary people" at an unprecedented rate of development. For domestic raw meat processing enterprises, the pressure when starting the experiment and pressurizing until the carton collapses is the carton compressive strength industry, which also puts forward new requirements in terms of packaging. We are glad to see that some domestic raw meat export-oriented enterprises and packaging manufacturers have keenly captured this information and have begun to use and produce this new high barrier packaging material. Such as grassland Xingfa, Changchun Haoyue, Baoquanling, Hua'an cattle industry, etc. Qinhuangdao jiaruite Plastic Technology Co., Ltd., Zhengzhou Baolan Packaging Technology Co., Ltd. and other enterprises committed to the development and research of new packaging products in China are stepping up the development of this packaging material

with the development of science and technology and the continuous demand of the market, the demand for high barrier packaging materials in the packaging of raw and fresh meat will be greater and greater, and more and more packaging science and technology workers will invest in the ranks of development and research. China's chilled meat packaging will have a more brilliant tomorrow. Of course, any kind of fresh-keeping technology has certain shortcomings. The adoption of scientific new packaging technology and packaging materials can not completely solve all the problems of chilled meat in production, circulation and storage. Only by comprehensively utilizing various fresh-keeping measures and improving the hygienic conditions of processing, can chilled meat production enterprises really have fresh-keeping effects

author/Jia Junzhu

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