At present, China's grain packaging bags are mainly woven bags and composite plastic bags. There are many problems that need to be solved in the links of grain circulation, including transportation, handling, storage, and retailing.
A plastic woven bag is a narrow tape made of a plastic film with a certain width, or a high-strength plastic flat tape obtained by a hot stretching method and then woven into a bag. The plastic woven bag is much stronger than the plastic film bag, and it is not easily deformed and has good impact resistance. At the same time, since the surface has woven patterns, the anti-slip property is improved and stacking is facilitated. However, there are shortcomings such as poor insect protection, poor moisture resistance, and large environmental pollution. Composite plastic bags are composed of high-barrier packaging materials and other multi-layer plastics, with certain promotion and practical value, but due to environmental issues, and the toxicity of plastic products hinder its development.
For a long time, the losses caused by poor packaging during the storage, transportation, and sales of grain in China have been astonishing. In the past, due to poor packaging, the rate of disintegration of grain was as high as 48.6%. After the packaging was improved, the average decontamination rate dropped to about 5%, but it was far from the national 2.5% loss requirement. At present, the post-production loss of grain in China accounts for 12%-14.8% of the total grain output. It is estimated that if the loss is reduced by 1%, the food transported by rail can be reduced by 500,000 tons per year.
A multi-layer paper grain packaging bag has been started for domestic and export flour and starch products. This kind of paper package has a 1.5-fold increase in strength compared to ordinary paper bags. The packaging bag is reasonable and firm in structure. For example, the bottom pockets are trapezoidal and each layer is bonded independently to make it stronger. A bag of four-layer stretch paper bags full of 25 kg of flour falls freely at a height of 1.2 meters 10 times without breaking the bag. The paper itself has hygroscopicity, can absorb the excess moisture of the food, and can effectively prevent the food from moisture due to the damp environment. At the same time, the tightness of the paper bag is better than that of the cloth bag. Under the same conditions, the shelf life can be extended by two to three months.
The prominent advantages of the paper bag are non-toxic, odorless, non-polluting, and in line with national food hygiene standards. Because the printability of the paper is good, graphic characters can be printed according to the user's request. The valve paper bag made of this paper is very convenient and rapid in the filling process of the flour, the filling speed can be increased by 3 times, and there is no dust flying, and the working environment can be improved. In addition, since the paper bag is rectangular after filling, it is easy to stack and easy to slide. The same amount of storage can increase the storage capacity by 10%. The handling process does not contaminate the clothes of the operators. Therefore, the promotion of the use of paper grain packaging is inevitable in the future replacement of food packaging. It is also the development trend of grain packaging in the future.
The main cause of grain deterioration is caused by the invasion of moisture and oxygen and the physiological metabolism of microorganisms. The temperature, moisture, and gas in the storage environment are the basic conditions for the food itself and the life activities of the microorganisms. The moisture causes the microorganisms to reproduce and the oxygen oxidizes and degenerates the food. Multi-layer paper bags solve the problem of food mildew (barrier to moisture intrusion), while oxygen prevention and discharge depend on aids. The paper bags are filled with air protection, while nitrogen and carbon dioxide are used. They are colorless, odorless, non-toxic gases, and their chemical properties are relatively stable. According to tests, the content of carbon dioxide in the air reaches 50%, which is strong for mildew microorganisms. The inhibition of extermination. All kinds of foods have the ability to absorb carbon dioxide. Carbon dioxide inhibits the decomposition and oxidation of food. When the food absorbs carbon dioxide, it is in a "sleeping" state, so as to extend the effective storage period. However, grain absorption of carbon dioxide is a reversible phenomenon. If the paper bag breaks, the carbon dioxide content inside the paper bag will decrease, which will cause desorption of carbon dioxide gas by the food.
Multi-layer paper bags belong to the scope of small packages, domestic research has just begun, such as packaging weight specifications, bag shape, size, different kinds of food requirements of the atmosphere, shelf sales and different shelf life, storage, transportation methods, surface decoration ,print. At the same time, the establishment of standards for monitoring multi-layer paper bags and the degree of automation of their packaging machines have been further studied. But no matter what, as people are increasingly pressing on the demand for green food, the packaging of grain paper bags will become more and more urgent, and the packaging of grain paper bags will become more and more widely used.
China's grain packaging has different reversal direction according to different requirements for transport packaging and sales packaging. The direction of development of grain transportation and packaging is changed from "small package" to "big package". That is, containerized transportation, a large number of raw grain packaging should be changed to bulk, using containers and container bags. Grain bulk transport is the mainstream of the world's grain transport development. More than 80% of developed countries have achieved bulk transport. This will not only reduce losses and reduce costs, but also meet the development trend of large-scale social production and large circulation. At present, most of our country's grain is currently packaged and transported. It does not require manual packing, loading or unloading, which means that it can speed up transportation and save a lot of packaging. At present, the annual circulation of grain in China is up to 150 million tons. If the promotion of the use of bulk grain is comprehensive, it can save at least 2 billion yuan annually.
Grain sales and packaging are developed from large packages to small packages. This is the shift of China's grain circulation from product distribution to market consumption economy. People's life consumption changes from subsistence to convenience, hygiene, nutrition and rapid change. The Inevitable Trend of New Consumption Concept and Consumption Structure Requirement for Improvement of Packaging Methods for Food Products . People need high-quality rice noodles, which requires easy purchase and easy carrying. However, traditional grain sales and packaging are almost independent of the transportation and packaging. There is no special package for retail relieving, and it is inconvenient to adopt the whole bag to purchase the live bulk phenomenon at the time of sale. It is not hygienic. Therefore, in terms of sales mitigation, it is necessary to improve the food packaging and increase the hygienic, sturdy, convenient, and aesthetically pleasing packaging. In some large and medium-sized cities, there have been small grain packages below 2.5 KG. Particularly worth mentioning is the paper packaging of Heilongjiang rice. It uses 0.5-1 kg paper bags as small packages and 10 small packages into corrugated cardboard boxes as outer packages. . The packaging is very hygienic, reliable and convenient, and the packaging waste can be recycled and recycled, which is conducive to environmental protection. However, at present, there are only a few food packaging products, and the main one is still a stacked sales method in the farmers' market.
Small food packaging must meet the following properties: 1) The safety protection performance of food quality, this design shielded, protective, stability, and hygienic safety; 2) The working performance of machine-made paper bags, which involves processing, Workability, printing, hot air; 3) Convenient performance for the use of packaging, which requires light weight packaging, easy to carry, easy to store, easy to open, easy to open, marked, easy to buy; 4) economic performance, this requirement Packaging has the simplicity, rationality and energy saving of production; 5) Environmental protection performance, small package of food consumes a large amount of packaging materials, produces a large amount of packaging waste, and its recyclability or degradability determines whether the material is available The standard gauge. Therefore, the development of small packaging involves production, technology, raw materials, economy, environmental protection and other issues. The development of suitable packaging materials, the development of high-efficiency dedicated grain packaging equipment, and the design of fully functional packaging structures are important links in the improvement of grain sales and packaging.