Views: 104 Author: Site Editor Publish Time: 2022-02-11 Origin: Site
Currently, freezer bags commonly used in our lives come in various forms, such as vacuum freezer bags, freezer bags for meat, freeze vegetable bags and insulated frozen food bags.
At present, the plastic flexible packaging used in the frozen food field is mainly divided into two categories:
One type is composite packaging, which uses adhesives to bond two plastic films together. The adhesives mostly contain harmful substances such as esters and benzene, which can easily penetrate into food and cause pollution.
The second category is the international advanced multi-layer co-extrusion high barrier packaging. It is produced with environmentally friendly packaging materials, with five, seven and nine layers. It does not use adhesives but uses more than 3 extruders to melt and extrude resin materials with different functions such as PA, PE, PP, PET, EVOH, etc., respectively. It has the characteristics of pollution-free, high barrier, high strength, flexible structure, etc., which makes the production process of food packaging and packaging materials achieve pollution-free. For example, the seven-layer co-extruded high-barrier package is composed of more than two layers of nylon, which greatly improves the tensile and tear strength of the package. It can withstand low temperature of -45℃ and high temperature of 120℃, and the vacuum degree can reach 100%. It is not easy to break and freeze. It is resistant to high and low temperature, storage and transportation, and easy to keep. It can effectively avoid food oxidative deterioration and moisture loss, inhibit microbial reproduction, and extend the shelf life of frozen food.
With the progress of society, the improvement of people's living standards and the acceleration of the pace of life, people are eager to reduce kitchen work. Frozen food is favored by people because of its convenience and variety. Vacuum seal freezer bags are an important part of frozen products. What are the precautions for frozen bags for food?
1. Cold resistance
The production, storage, circulation and sales of frozen food must be kept in a frozen state, so packaging materials should be cold-resistant. There are many irregular lumps on the surface of frozen food, which can easily cause cracks, punctures and pinholes in the packaging materials. The cold resistance of packaging materials not only refers to the characteristics of non-whitening and brittleness at low temperatures, but also refers to the impact strength, tear strength, puncture strength, pinhole resistance and sealing integrity at low temperatures.
Most plastic films have a certain degree of cold resistance, but they tend to harden and impact strength decline at low temperatures. The cold resistance strength is preferably stretched nylon (PA), PET and OPP, etc., which are often used as the outer layer material of frozen food packaging film or composite film. The puncture strength of the packaging material is related to the packaging method, partition and buffer layer placement method. For items stored in the refrigerator, the cold resistance of freezer reusable bags is one of the basic properties. In fact, there are some freezer bags suitable for refrigerators, such as seal freezer bags, zip popsicle bags and catering freezer bags.
2. Water resistance and moisture barrier
Frozen food uses low temperature to suppress food deterioration, and moisture exists in the frozen food as fine ice crystals. Frozen food needs to control environmental conditions during storage, transportation, and circulation, and select materials with good moisture barrier and water resistance. The water vapor transmission rate of most plastic films at low temperatures is much lower than at high temperatures.
3. Oxygen barrier
During the long-term storage, transportation and sales of frozen food, the surface of the food is in a dry state, which is prone to oxidative discoloration, freeze-burning, and qualitative changes such as peculiar smell or loss of flavor. Therefore, packaging materials with low oxygen transmission rate and good fragrance retention are required.
4. Thermal insulation
With the popularity of convenience foods and the use of microwave ovens, frozen foods are required to withstand hot water, steam and heating in microwave ovens.