Application of packaging technology in the hottest

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Application of packaging technology in the cold fresh meat project

cold fresh meat, also known as sour meat, refers to the raw fresh meat that strictly implements the veterinary quarantine system and quickly cools the carcass of slaughtered animals, so that the carcass temperature (later the center of the leg meat is the measuring point) is reduced to 0 ~ 4 ℃ within 24 hours, and is always maintained at 0 ~ 4 ℃ in the subsequent processing, circulation and sales process

developed countries began to promote cold fresh meat as early as the 1920s and 1930s. At present, cold fresh meat accounts for about 90% of their consumption of raw meat. In 1990, China's meat production surpassed that of the United States, ranking first in the world (FAO annual production report, 1990), while more than 90% of the meat consumed by Chinese consumers is unprocessed, most of which are hot and frozen meat, and the proportion of cold fresh meat is very low

1 advantages of cold fresh meat

the whole process of cold fresh meat production, from raw material processing to sales, is strictly monitored by the comprehensive quality management system, which ensures the high quality and standardization of products, and also realizes the scale and modernization of production. It overcomes the shortcomings and defects in the quality of hot fresh meat and frozen meat, and mainly has the following four advantages

(1) high safety factor: the whole process of cold fresh meat from raw material quarantine, slaughtering, segmentation to boning, packaging, transportation, storage and sales is always under strict monitoring. The product has been kept at a low temperature of 0 ~ 4 ℃, which not only greatly reduces the initial bacterial count, but also slows down the oxidation rate of lipids in cold fresh meat and reduces the formation of small molecular odors such as aldehydes and ketones, Prevent its adverse effects on human health, and its sanitary quality is significantly improved

(2) high nutritional value: cold fresh meat follows the basic rules of meat biochemistry, and at a suitable temperature, the carcass orderly completes the process of carcass stiffness, thawing, softening and maturation. Muscle protein is degraded normally, muscle acid excretion is softened, and tenderness is significantly improved, which is very conducive to human digestion and absorption. And because it has not been frozen, it does not need to be thawed before eating, and there will be no nutrient loss, which overcomes the nutritional defect of frozen meat

(3) high sensory comfort: cold fresh meat has bright color within the specified shelf life, and myoglobin will not browning. This is no different from hot fresh meat, which is adjusted according to the appearance and foundation map, and the meat is softer. Due to its gradual maturation at low temperature, the accumulation of some chemical components and a variety of small molecular compounds formed by degradation has significantly improved the flavor of cold fresh meat

(4) long shelf life: generally, the shelf life of hot fresh meat is only 1 ~ 2D, while the shelf life of cold fresh meat is generally more than a week under the temperature of 0 ~ 10 ℃. At the same time, cold fresh meat forms a layer of dry oil film on the surface under the cooling environment, which can reduce the evaporation of water and prevent the invasion of microorganisms and the reproduction on the meat surface

at present, with the improvement of people's living standards, the demand for cold fresh meat is also increasing, so many enterprises are preparing to produce cold fresh meat. Although the cold chain in China has tended to be perfect and standardized at present, the cold storage temperature of 0 ~ 4 ℃ for cold fresh meat can not completely inhibit the growth and reproduction of some psychrophilic microorganisms. Therefore, the shelf life of cold fresh meat is short, and the surface browning and juice loss are serious. Because the fresh-keeping period of cold fresh meat is very short, and the color is difficult to maintain, many enterprises are deterred. The key to large-scale production and distribution of cold fresh meat is to solve the problem of preservation

2 the main packaging form of chilled meat

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 large number of scientific and foreign products, and there are many missing studies. Many new meat preservation technologies, such as preservative preservation, radiation preservation, low water activity preservation, and other research results have been published frequently. According to relevant information, the variety and quality of meat products in China are far behind the world's advanced level. One of the main reasons is that the backward meat packaging technology restricts the development

choosing appropriate packaging materials and packaging technology can play a very significant role in improving the fresh-keeping period of chilled meat and ensuring the hygiene and quality of meat

211 modified atmosphere packaging technology

also known as gas replacement packaging, by replacing the gas environment in the packaging with appropriate gas composition, it can inhibit the growth and reproduction of microorganisms and prolong the fresh-keeping period. The specific method is to mix CO2, N2 and O2 in different proportions. CO2 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 concentration of 20% ~ 30%; N2 mainly prevents oxidative rancidity and inhibits the growth of mold; O2 is mainly oxygenated myoglobin, which keeps meat bright red and inhibits the reproduction of anaerobic bacteria

212 vacuum packaging technology

through the form of vacuum pumping, the packaging is close to the meat, inhibiting the seepage of water in the meat, blocking oxygen, inhibiting bacterial reproduction, and improving the safety of meat. Vacuum body fitted packaging, heat shrinkable packaging and thermoforming stretch packaging are widely used in the packaging of segmented meat

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

3 application of PVDC high barrier film in cold fresh meat packaging

311 packaging material pvdc

pvdc is the English abbreviation of polyvinylidene chloride, which is a high molecular compound formed by polymerization of vinylidene chloride monomer (hereinafter abbreviated as VDC). 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. 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 for ham sausage casings. These applications fully show the performance and unparalleled advantages of PVDC materials. Because of 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 began the research work on the practical application of PVDC resin in 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 created China's PVDC film processing industry. In the late 1990s, a group of packaging materials researchers represented by Mr. Shude, a famous PVDC film processing expert in China and senior engineering teacher of Luoyang Chundu, tried to apply PVDC plastics to other packaging fields and achieved success

312 PVDC high barrier film for cold fresh meat packaging

PVDC plastic is used in cold fresh meat packaging. It is not a simple PVDC film, but a multi-layer coextrusion film with PVDC as the barrier layer. Vinylidene chloride and methyl acrylate, methacrylic acid, acrylonitrile copolymer are used as the barrier layer, and it is made by coextrusion process with other wear-resistant materials, heat sealing materials, etc. This film has extremely high oxygen barrier, oxygen transmittance of 50 ml/m2, ATM, 24h, 23 ℃, 65% RH, and extremely high water vapor barrier, water vapor transmittance of 5g/m2, ATM, 24h, 23 ℃, 90% RH. At present, pe/tie/pvdc/tie/pe and pe/tie/pa/tie/pvdc/tie/PE five layer and seven layer structures are commonly used internationally

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 ~ 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 film is mainly made by multi-layer coextrusion double bubble blowing. PVDC is used as the barrier layer. After coextrusion with other special materials by double bubble method and off-line treatment, the shrinkage rate of the product is 35% ~ 45%. Using the rapid shrinkage of the shrinkable film in case of heat, it is close to the surface of meat products to prevent moisture seepage, and the thickness is generally 50 ~ 90 μ m。

4 typical vacuum shrink packaging process of cold fresh meat

after boneless, segmentation, trimming and other processes, the meat pieces are transferred to the vacuum packaging machine. Workers visually check the size of the meat pieces, draw shrink bags of corresponding specifications, put the meat pieces on the packaging table, and then vacuum and seal the bags. At this time, although the packaging bag has been close to the meat, there are still many folds formed by plastic covering the surface of the product, which is easy to produce capillary phenomenon, suck out and store water, and affect the appearance and shelf life of the product

the vacuum bags must also be heat shrinkable. In hot water at 85 ℃, the shrinkage rate of heat shrinkable bags is generally 30% - 40%. There are usually two heat shrinking methods abroad, one is tunnel spray type, and the other is immersion type. The former is to install a rectangular channel in the middle of the conveyor belt conveying the meat bag, with an internal electronic sensor. When the meat bag passes, it will automatically spray 85 ℃ water curtain, and the meat bag will be contracted after passing. Regardless of the size of the meat bag, it can fully shrink, and the process is fully automatic. Each potential customer has received the test samples, and it only needs one worker to process about 30 pieces in a minute; Immersion type needs to transport the meat pieces to the top of the water tank with 85 ℃ hot water, use the rhythmic up and down movement of the gripper to immerse the meat bag in the hot water, and then lift it after instant shrinkage to continue to transport. This shrinkage process requires at least three workers to operate, processing 5 ~ 6 pieces per minute, and there may be insufficient shrinkage of the upper layer of the meat bag, so it is more suitable for factories with small output. As for water temperature control, electrical control can be used, which will be more accurate and stable; Steam control can also be used, which is more energy-saving, but it must be above 4 atmospheres to provide stable temperature control

the proper size of the packaging bag is also crucial for heat shrinkable packaging. Too large bags will produce wrinkles, affect the appearance after shrinkage, and cause waste when cutting edges. The contracted inner bag is wiped dry and weighed, and then put into the carton. There are two air holes on both sides of the box. After sealing and labeling, the products are sent to the cold storage, waiting to be sent to the sales area

5 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. The demand for high barrier packaging materials in the packaging of raw and fresh meat will be increasing. By using PVDC coextrusion film to pack cold fresh meat, the fresh-keeping period of meat can be extended, the storage period of meat in long-distance transportation can be greatly improved, the sales field of meat processing enterprises can be expanded, and the long-distance markets at home and abroad can be covered

Author: quiet

reprinted from: meat industry

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