In recent years, with the rapid development of supermarkets and chain stores and the formation of cold chains, frozen food has become more and more popular. According to the statistics of relevant departments, the annual output of frozen food in China has reached about 6.5 million tons, and is increasing at the rate of 25% per year. The per capita annual consumption has reached nearly 10 kg. With the growing popularity of frozen food packaging, higher requirements have been put forward for the performance of packaging materials.

The current situation and problems of frozen food packaging The basic requirements of frozen food packaging are from production, transportation to sales, to maintain the quality characteristics of its products, to prevent bacterial contamination and to be convenient to eat. To this end, packaging materials must have the following conditions: a certain mechanical strength (high and low temperature resistance); It has barrier property (high barrier property to gas and liquid); Resistance to contents (acid and oil resistance); Hygienic; Operational resistance.

At present, there are two types of frozen food packaging: soft type and hard type. The soft type is based on plastic film. Thick and hard packaging, such as slightly thicker paper packaging boxes, composite aluminum foil stamping containers, etc., the former accounts for a large proportion. Now, the common frozen food packaging in the market mostly adopts the following structures: OPP/LLDPE, which can achieve the product performance of moisture-proof, cold resistance, and strong low-temperature heat sealing tension, and the cost is relatively economical; NY/LLDPE The packaging performance of this structure can withstand freezing, impact and puncture, and the cost is relatively high. The product packaging performance is good. PET/LLDPE and PET/NY/LLDPE and PET/VMPET/LLDPE are also used in frozen products, but the use rate is relatively low; In addition, there is a simple PE bag, such as vegetable packaging; The above product structures are concentrated in the packaging of low-temperature frozen products in the domestic market.

In actual production, frozen food packaging is prone to the following problems:

1. The impact resistance of the bag is poor, and it is easy to be damaged by external forces during transportation, loading and unloading, and shelf placement. It is very easy to break and open the bag, which not only affects the appearance of the packaged product, but also cannot play a role in the packaging itself.

2. The smoothness of the packaging bag itself is not good, which is characterized by poor opening and low production efficiency during the production process. At the same time, the use rate of the packaging bag will be reduced, causing waste to the cost.

3. The insufficient heat sealing strength and high heat sealing temperature of the packaging bag cause damage to the heat sealing layer, which reduces the protection performance of the packaging bag, greatly shortens the shelf life of the contents, and makes the contents fail to reach the corresponding shelf life.

4. The peeling strength between the layers of the packaging bags is small, the tensile force is not enough, and the mechanical properties of the packaging bags are poor, resulting in the layering of the packaging bags and the failure of the packaging bags to achieve the due load-bearing effect, which can not effectively protect the contents.

5. The cold resistance of frozen food does not meet the requirements. In the case of low temperature, the original performance of the material cannot be maintained. The packaging material is brittle, which reduces the mechanical strength of the packaging material, causing the packaging bag to break and crack, and can not meet the protection of the contents.

6. The function of the easy tear opening of the packaging bag cannot be effectively played. Too high tear strength makes the packaging bag difficult to open, and too low tear strength reduces the mechanical performance of the packaging bag. Therefore, it is necessary to meet the humanized design of the easy tear opening of the packaging bag, and also to complete the protection function of the product.

7. The puncture performance of the packaging bag. Frozen food is generally hard after freezing, especially fish and meat products, which contain bones and hard objects. During transportation and stacking, product extrusion can easily puncture the packaging bag, causing damage to the sealing of the packaging bag. Therefore, frozen food requires high puncture performance of the packaging bag.

To ensure food safety, packaging of frozen food has been paid more attention as an important means to ensure the safety and health of frozen food. In actual production, frozen food packaging should pay attention to the following aspects:

1. The characteristics of frozen food and the required protection conditions.

To study the sensitive factors that affect the main components of frozen food, especially the nutrient components such as fat, protein and vitamins, including light, oxygen, temperature, microorganisms, physics and mechanical mechanics. Only by mastering the biological, chemical, physical characteristics and sensitive factors of the packaged frozen food, and determining the required protection conditions, can we determine what packaging materials and packaging technology to use for packaging operations, so as to achieve its protection function and appropriately extend its storage period.

2. Packaging performance, scope of application and conditions of packaging materials. There are many kinds of packaging materials with different performances. Therefore, only when we understand the packaging performance of various packaging materials and containers can we choose packaging materials that can not only protect the flavor and quality of frozen food, but also reflect its commodity value, and make comprehensive packaging reasonable according to the protection requirements for packaged frozen food.

3. Market positioning and circulation regional conditions of commodities. The market positioning, transportation mode, climate and geographical conditions of the circulation area are the factors that must be considered when designing frozen food packaging. The packaging and decoration requirements for goods sold domestically and exported to different countries are different, and the protective requirements for packaging are also different for different modes of transportation. For frozen food packaging, the climate change in the commodity circulation area is crucial, because the temperature has a great impact on the chemical changes of the internal components of frozen food and the barrier of microorganisms and their packaging materials.

4. The impact of the overall packaging structure and packaging materials on frozen food. Easy tear tape is used to understand the migration of additives and other components in packaging materials to frozen food, as well as the influence of penetration and adsorption of some components in frozen food into packaging containers on the quality of frozen food during circulation.

5. Carry out reasonable packaging structure design and decoration design. According to the protective requirements of frozen food, it is expected that the packaging cost, packaging volume and other conditions should be reasonably designed, including the design of container shape, compressive strength, structural form, size, sealing method, etc. The packaging structure should be reasonable, material saving, transportation space saving and in line with the trend of the times, and excessive packaging and deceptive packaging should be avoided.

6. Carry out packaging inspection. Qualified commodities must have qualified packaging. In addition to testing the product itself, commodity testing must also test the packaging. Only qualified commodities can enter the circulation field. There are many packaging inspection items, but not every package needs to be comprehensively inspected. The specific tests to be carried out on the specific packaging should be determined according to the characteristics and sensitive factors of the frozen food, the types of packaging materials and the requirements of national standards and regulations. The following tests can be carried out for frozen food packaging bags: ① Testing the strength and strength of packaging bags; ② Heat sealing strength test of packaging bag; ③ Opening performance test of packaging bag; ④ Impact performance test of packaging bag; ⑤ Sealing test of packaging bag; ⑥ Tearing performance test of packaging bag; ⑦ Heat resistance; ⑧ Oil resistance test.

7. Packaging standards and regulations. The packaging operation shall strictly comply with the national standards and regulations, and the export products shall also comply with the relevant standards and regulations of the importing country. Only in this way can the supply of raw materials, packaging operations, commodity circulation, international trade and other processes be carried out smoothly. With the development of market economy and international trade, the standardization of packaging is becoming more and more important. Only in this way can our goods go further