The great role of high barrier packaging materials in the packaging of meat products

Packaging materials are an important factor affecting the quality and shelf life of meat products, and can affect product distribution channels and sales radius. At present, high-barrier packaging materials are widely used in meat product packaging, but the characteristics of high-barrier materials commonly used in meat product packaging and their impact on meat product quality and food safety have not yet been systematically summarized, compared and analyzed.

The packaging of most raw and cooked meat products in my country will be contaminated by light, moisture, oxygen and microorganisms during storage and transportation, resulting in shortened shelf life and even food safety issues. Therefore, how to better maintain the good quality of meat products, prevent the spoilage of meat products, and create a more convenient consumption pattern is a major problem facing meat production enterprises.

Appropriate packaging materials are conducive to maintaining product quality and facilitating product transportation and sales, and are a feasible solution to the above problems. The single-layer plastic film [such as polyethylene (PE) film] used in early packaging has high oxygen permeability, low water vapor barrier, and is not resistant to abrasion and puncture, which affects the quality of meat products. The emergence of composite packaging materials has solved the above problems. With the development of technology, high-barrier packaging materials have become widely used packaging materials in the meat industry, making important contributions to ensuring the quality of meat products and promoting the development of meat products.
 

What is a high-barrier packaging material?

High-barrier plastic packaging material is a kind of packaging material with good oxygen barrier, water barrier and high permeability, which can play a good role in quality preservation, freshness preservation and shelf life extension. Chemical structure and aggregate structure are the main factors that determine the breathability of packaging materials. It can be seen from the principle of similar compatibility that non-polar polymer materials easily permeate non-polar gases, such as polypropylene (PP), PE, ethylene-vinyl acetate copolymer (EVA), polystyrene (PS), and have very high performance. The air permeability belongs to the breathable packaging material. Low air permeability of polar polymers, such as polyamide (PA, also known as copolymerized nylon), polyacrylonitrile (PAN), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyethylene terephthalate Alcohol ester (PET), polyvinylidene chloride (PVDC), ethylene-vinyl alcohol copolymer (EVOH), etc. are all barrier packaging materials.

High-barrier packaging has greater advantages in the food industry than traditional single-layer breathable packaging materials. At present, according to statistics, the global annual demand for high-barrier packaging films is 4 million tons, non-transparent (aluminized) barrier films are about 2.5 million tons, and transparent materials are 1.5 million tons.

High-barrier plastic materials commonly used in the meat industry include PVDC, EVOH, PA6, PVA, aluminum foil, etc. Such packaging materials are often used as barrier layers in composite packaging materials.

For example: polyvinylidene chloride is often used for packaging ham and sausage in meat product packaging, EVOH is often used in the outer packaging of ham sausage, PET/EVOH/PE and PP/PA/EVOH/PA/AD/PE, with high barrier properties , can maximize the shelf life of cooked meat products. The new oxide coating material is a high-barrier film with excellent comprehensive properties, known as "transparent aluminum foil", which is widely used in high-end food packaging, and is expected to grow at a rate of more than 15% per year. The fastest growing packaging material in the century.

In recent years, people's requirements for high-barrier materials with high barrier properties, fresh-keeping properties, heat resistance, degradability, and antibacterial properties have continued to rise. In the future, high-barrier materials will develop in an environment-friendly direction. Inexpensive, high-performance high-barrier material.

Nowadays, high-barrier plastic materials have been widely used. The advantage is that it can provide a stable internal environment for meat products, thereby prolonging the storage period, avoiding the growth and reproduction of microorganisms, avoiding or reducing the generation rate of pathogenic bacteria, and reducing fat. The oxidation and quality deterioration of meat products can avoid the generation of odor and the change of meat color during the storage period of meat products.
 

 

The role of high barrier packaging materials in meat products

Using high-barrier packaging materials combined with vacuum or modified atmosphere to package fresh meat and cooked meat products, combined with sterilization technology can extend the shelf life of products and ensure the quality of meat products. The main indicators for judging the impact of high-barrier packaging materials on meat products include microbial spoilage and oxidative deterioration of meat products.

Effectively slow down the oxidation of meat

In recent years, the deterioration of product quality caused by the oxidation of meat and meat products has gradually attracted attention and has become the focus of scientific research.

The study found that the thiobarbituric acid (TBA) value of fresh duck breast meat vacuum-packed in PVC bags was higher than that of products vacuum-packed in aluminum foil composite bags, which may be due to the PVC treatment. The oxygen content in the group is higher, and the PVC packaging has lower oxygen barrier properties. Therefore, using high-barrier aluminum foil composite bags to vacuum-pack duck meat can effectively slow down fat oxidation.

The study also found that the degree of oxidation (POV value) of vacuum-packaged beef in sauce was significantly lower than that of the products packaged in plastic wrap after being stored at 0°C to 5°C for 5 days (P<0.05).

In the bacon products, due to the poor blocking properties of ordinary packaging materials, the POV value is at a higher level compared with the high barrier type, while the aluminum foil bag packaging selected as a control has a high blocking property and a small change in POV value.

Compare two high-barrier packaging materials with ordinary packaging materials: PET·SiO2 coating/nylon 15/modified CPP; Kurarister coating/OPET/CPP, (Kurarister coating is a barrier layer based on inorganic nano-materials and organic polymers) , PET/nylon packaging Dezhou braised chicken storage found that the high barrier packaging material can effectively prevent the entry of oxygen, and the contact with braised chicken, its smell and taste are better than ordinary packaging materials; and ordinary packaging Dezhou braised chicken produces oxidation , there is a slight hara flavor produced. In terms of inhibiting the peroxide value of Cantonese-style bacon, the PET/AL/NY/PE with the best oxygen barrier has better effect, and the PET/PE packaging material with the worst barrier has the worst effect.

Another study found that at 4°C, sodium caseinate/glycerol film can significantly delay the fat oxidation of cooked turkey slices compared with the unpackaged group, and the combination of the barrier property of the protein film and the secondary oxidation products has a significant effect on the storage process. Product oxidation has a certain inhibitory effect.

Some scholars have found that high-barrier packaging films containing PVDC can effectively reduce the degree of protein oxidation of meat products and achieve better storage effects.

In addition, some studies have found that PVDC materials with higher barrier properties can effectively inhibit the two kinds of "salami" caused by oxidation compared with PET/PA/CPP materials after 6 months of storage of braised chicken products.

Meat products are rich in protein, and most meat products are rich in fat. The oxidation of meat products is mainly the oxidation of lipids and proteins. A large number of studies have confirmed that the products of fat oxidation and protein oxidation products can promote each other's oxidation. This mutual promotion relationship is particularly prominent in the effect on fat oxidation and protein oxidation. The mutual promotion of fat oxidation and protein oxidation not only destroys the sales appearance of the product, but also reduces the edible quality and greatly shortens the shelf life of the product. Oxidation of meat will lead to changes in product flavor, juiciness, tenderness, color, and even produce cytotoxicity, causing harm to the human body; reactive oxygen species is the main cause of muscle protein oxidation, which can lead to the structure of essential amino acids in the human body. The shape is destroyed, the nutritional value of the meat is reduced, the deformation and aggregation of the protein reduces the absorption of the protein by the human body, and at the same time brings about the deterioration of the quality. Among them, the partial pressure of oxygen can greatly affect protein oxidation. The oxidation level of meat products is mainly affected by factors such as oxygen content, water activity, temperature, light, fat content and unsaturation of fatty acids. In general, the oxidation of meat products is positively correlated with the above factors. It has been reported that the photosensitive oxidation of fat in container display generally only occurs on the surface of meat, and the effect of light on fat is far less than that of partial pressure of oxygen. Therefore, under the same conditions, the use of high-barrier plastic materials is more than ordinary plastic materials. Compared with blocking the infiltration of oxygen, ensuring an appropriate partial pressure of oxygen can effectively ensure the quality, thereby slowing down the degree of oxidation of meat products.

Block moisture and oxygen, inhibit the growth of microorganisms

The growth and reproduction of microorganisms requires the participation of oxygen and moisture. The increase of oxygen and moisture content will lead to aggravation of corruption. Improving the barrier properties of packaging materials to moisture and oxygen can inhibit the growth of aerobic microorganisms. Selecting suitable high-barrier plastic materials to effectively extend the shelf life will avoid spoilage. Research and development of new high-barrier materials or reduce the production cost of high-barrier materials and prolong the shelf life of meat products is one of the key directions of research.

Some scholars use high-barrier EVOH-based composite packaging materials and 4 kinds of materials such as PET/PA/CPP, PA/modified PE, PA/CPP, PE/PA/EVOH/PA/LLDPE to package Taiwan sausages, and found that EVOH materials reduce bacterial colonies. There is a significant advantage in the total number, and the product has a longer shelf life;

Scholars use PA/PE, OPP/CPP, PA/CPP, PET/AL/PE packaging materials for vacuum packaging of fresh mutton, and the selected PA/CPP (nylon/cast polypropylene film) and PET/AL/PE The packaging material has a low number of microorganisms. It can be seen that under the same storage temperature, the PA/CPP and PET/AL/PE packaging groups with better barrier properties are better than PA/PE in controlling the total number of colonies;

Another scholar used polyester bags, aluminum foil composite bags, and fresh-keeping bags to vacuum-pack chilled beef. The results showed that the total number of colonies in the products packaged in polyester bags and aluminum foil bags was significantly lower than that in fresh-keeping bags;

The high barrier material containing PVDC and the medium barrier material and low barrier material containing PET were used to package fresh beef, and it was found that the total number of colonies in the low barrier group was significantly greater than that in the medium barrier and high barrier groups, and the medium and high barrier materials could prolong the 14d shelf life; compared the high-barrier high-temperature retort bag made of nylon and polyethylene with ordinary polyethylene aseptic bag and film preservation of chilled chicken breast, and found that the total number of colonies of chicken breast packaged in high-temperature retort bag was significantly lower than other Packaging method (P<0.05).

It is worth exploring that some scholars have studied the effect of 4 packaging materials with different barrier levels to preserve fresh pork, and found that the packaging material with the best barrier performance does not have the best packaging effect, but BOPP/PA with the second lowest barrier performance. /CPP composite plastic bag, the oxygen permeability is 328.55×10-6cm3 (/m2·24h·0.1MPa), the effect is the best, the color is the best, the sensory score is the best, and the shelf life is 8d. However, the pork packaged in the high-barrier material BOPP/AL/PET/CPP composite plastic bag with an oxygen permeability of 18.539×10cm3 (/m2·24h·0.1MPa) deteriorated on the 4th day. The reason for this may be that the brittleness of the packaging bag is increased due to the aluminized material, the puncture resistance is decreased, and it is damaged during storage, and the meat product is exposed to the air.

High-barrier plastic materials can prolong the storage time for meat product packaging, but high-barrier plastic materials should be combined with the correct packaging method to complement each other. It does not mean that the higher the barrier property of the packaging material, the better the barrier effect; the higher the barrier property of the material, the less oxygen enters the packaging bag, but it will lead to a large growth of anaerobic microorganisms, which will also lead to meat products. of corruption. At the same time, in order to improve its own barrier performance, the packaging material will increase the thickness of the packaging film and add metal substances. The increase in thickness will lead to a change in appearance and an increase in volume, which is more "clunky" and affects transportation efficiency. Adding metal substances , it will cause the toughness of the packaging material to change, become easy to break and break, and the breakage rate of the product will increase. Although high-barrier plastic materials have been greatly developed, due to the high cost of production technology and raw materials, the price is quite different from that of ordinary packaging materials. Widely used, the current price is the key to restrict the application of high-barrier plastic materials.