Soft can also called high-temperature cooking bag, which is made of polyester, aluminum foil, polyolefin and other materials composite multi-layer composite film made of soft packaging containers. With the improvement of the technical level and the continuous emergence of new materials, the two-layer and three-layer high-temperature cooking bags are currently used more widely. For the three-layer composite bag, its inner layer is generally called the sealing layer, and polypropylene plastic and polyethylene plastic are often used. Both plastics have the features of low price and good sealing performance; the middle layer is blocked Layer, the role is to block the intrusion of oxygen, harmful microorganisms, can be used aluminum foil, polyester plastic, nylon and other materials; the outer layer is a strengthening layer, but also play a role in decoration and protection, you can use polyester plastic,
Nylon and so on. In fact, the high-temperature cooking bags currently used are the result of a combination of the aforementioned several film materials. In terms of specific foods, the following aspects should also be considered when selecting materials for high-temperature cooking bags.
First, select packaging materials should consider several factors (a) shelf life. To make the shelf life of soft cans longer, the barrier properties of the bags are required to be good. Currently used as oxygen barriers, harmful microorganisms invade the material mainly aluminum foil, polyester plastics and poly-based plastics, the best barrier properties of these three kinds of plastic, followed by polyester plastic. If the product's shelf life is within one month, what kind of materials can be used, if the product's shelf life is less than three months, you can only use aluminum foil and polyester plastic, if the shelf life of more than nine months, it is best to use aluminum foil As a barrier layer.
In theory, increasing the thickness of the plastic film can improve the barrier properties, but this increase is not proportional to the product, and cannot guarantee that the product has sufficient shelf life. If the thickness of the composite film is the same, the barrier properties of the two layers are not as good as those of the three layers. Good barrier properties, which is one of the reasons we often use multi-layer composite film. For example, two combinations of polyester plastics/adhesives/polyethylenes and polyester plastics/adhesives/polyester plastics/adhesives/polyethylenes, if the thickness of the two composite films is the same, the latter The barrier property is better than the former, and the latter should be preferred when used.
(b) sterilization requirements. The plastic materials used in high-temperature cooking bags are different from ordinary metal materials when heated because they do not have the melting point of the fixed assets, but gradually soften as the temperature rises.
During the process of softening, some plastic additives will melt out, affecting the quality of food. Therefore, high temperature resistance is an important indicator of plastic materials. Plastics have the disadvantages of reduced strength and reduced sealing strength during softening, and should be given sufficient attention when used.
The high-temperature resistance of the high-temperature cooking bag composite film material is not the same, and it is in descending order: low-pressure high-density polyethylene, modified polypropylene, polyester, polyamide, and aluminum foil. Different sterilizing temperatures should use different composite materials. For high temperature sterilization below 100Â°C, use two layers of structure, such as: polyester/polyethylene; nylon/polyethylene. For high temperature sterilization below 120Â°C,
Three-layer structure can be used, such as: polyester / aluminum foil / modified polypropylene; nylon / aluminum foil / modified polypropylene and so on.
For higher sterilization temperatures, a four-layer structure can be used, for example, polyester/aluminum foil/polyester/modified polypropylene; polyester/aluminum foil/nylon/modified polypropylene.
(c) The price situation. The price of high-temperature cooking bags is formed by superimposing the prices of the composite films at each layer. For composite bags that can satisfy the sterilization requirements and meet the storage requirements, of course, the combination of lower prices should be selected. For example, polyester/adhesive/aluminum foil/adhesive/modified polypropylene combination and polyester/adhesive/
Compared with the combination of aluminum foil/adhesive/high-density polyethylene, since the price of polyethylene is slightly lower than that of polypropylene,
So from the price point of view, the latter is often preferred.
The combination of layers of different materials will have different properties. Under the conditions that meet sterilization and storage requirements, the combination of fewer layers should be preferred.
In addition, since the same kind of plastic is used with different additives or the processing technology is different, it will have different high-temperature withstand capabilities. If you do not pay attention when using it, it is easy to cause quality accidents. For example, polyethylene plastic, according to the different processing technology, it has four basic types, and only low-pressure high-density polyethylene has high temperature resistance, and the rest can not be used in high-temperature cooking bags.
Second, the choice of beverage packaging materials Different beverage varieties, should use different high temperature cooking bag. Mainly based on the above-mentioned shelf life, sterilization temperature, price and other factors.
(A) The choice of acidic beverages for packaging bags. Acid beverages generally refer to beverages with a pH of 4.5 or less. In general, acidic beverages can be pasteurized to basically kill pathogenic bacteria in the beverage.
During the preservation of the beverage, since the beverage is acidic, pathogenic bacteria invading the beverage cannot be propagated, thereby extending the shelf life of the beverage. Therefore, the use of two-layer plastic composite bags for acidic beverages can meet the sterilization and preservation requirements. The material combinations of these bags are commonly used: polyester/polyethylene; nylon/polyethylene; polyester/polypropylene; nylon/polypropylene and the like. Since the price of polyethylene is slightly lower than that of polypropylene, the first two are preferred for use. Beverages suitable for these packages include formulated yoghurt,
Jujube juice, grape juice, sour milk, fruit tea, bayberry juice and so on. For longer shelf life drinks,
A combination of polyester/aluminum foil/polyethylene can be used. Although the price is higher, the barrier properties will be better.
(b) Selection of neutral beverages for packaging materials. The neutral beverage has an HP value of 4.5 or higher, which requires high sterilization temperature and good storage conditions. At present, the sterilization temperature of neutral beverages is mostly set at 120Â°C or higher, which basically can kill pathogenic bacteria in beverages. If you do not invade oxygen and microorganisms during storage, you can achieve long-term preservation. Packages for neutral beverages are: polyester/aluminum foil/polypropylene; polyester/aluminum foil/nylon/polypropylene; nylon/aluminum foil/polypropylene; polyester/aluminum foil/polyester/polypropylene and so on.
For neutral drinks with a shelf life of less than three months, there are also aluminum foils that do not use as barriers.
The price of high-temperature cooking bags can be reduced. Neutral beverages include: soy milk and soy milk beverages, peanut milk and its peanut milk beverages, fresh milk and beverages, sesame milk and the like.
Third, the choice of meat and food packaging materials There are many types of meat food, processing technology is different, resulting in a variety of high-temperature cooking bags, such as fire sausage packaging, chicken packaging and so on.
For meat products, aluminum foil is often used in combination with polypropylene or polyethylene to make high-temperature cooking bags. However, because aluminum foil is not suitable for printing, many companies often pack a beautifully printed bag outside the packaging bag to meet the needs of decoration. Although this type of packaging has a good display, it is not easy to prevent counterfeiting and it is costly. The best method is to use a polyester/aluminum foil/polypropylene composite bag, which not only has good printing performance but also saves money.
The choice of high-temperature cooking bag material is a technically high thing. There are many composite film materials that can be used in high-temperature cooking bags. There are many options for different foods. Each material has its strengths and weaknesses. Two or more films can be combined to achieve both sterilization and preservation