The principle of design and selection of modern food packaging is: according to the protective requirements of the packaged food, scientifically select packaging materials with good protection function, carry out reasonable structural design and packaging and decoration design, use sophisticated and reliable packaging machinery and equipment, adopt advanced Packaging technology methods to achieve the purpose of protecting food and extending shelf life.
First, we must understand the requirements of food for protection
The chemical composition and physical and chemical properties of different foods are different, so different foods have different protective requirements for packaging. For example, cakes are more oily, soft, and have a certain optimum water content. Therefore, at least the following requirements should be met: oil-proof high oxygen barrier (to prevent oil leakage and grease oxidation), high moisture resistance ( Prevent the cake from losing moisture and dry and harden). For example, the packaging of tea should be high oxygen barrier (to prevent the active ingredients from being oxidized), high moisture resistance (tea leaves moisture and mildew), high light resistance (the chlorophyll in tea leaves will change due to sunlight), high resistance aroma Sex (the molecular aroma component of tea leaves is easy to disperse and loses the taste of tea. In addition, tea leaves are also very easy to absorb external odors, and a considerable part of the tea on the market is usually packaged in transparent plastic bags such as PE and PP, which greatly wastes the active ingredients of tea. The quality of the tea is not guaranteed. Therefore, the packaging should be scientifically designed according to the different nature of the food itself.
Second, choose the packaging material with appropriate protection function
Traditional packaging materials are mainly glass bottles, metal cans, cartons, and cartons. Modern food packaging materials mainly include plastics, papers, composite materials, glass bottles, metal cans, etc. Details are as follows:
Composite materials are the most widely used and widely used flexible packaging materials. There are currently more than 30 types of plastics used in food packaging, and there are hundreds of multi-layer composites containing plastics. Composite materials generally use 2-6 layers, but special needs can reach 10 or even more layers. The use of plastic, paper or tissue machine, aluminum foil and other substrates, scientific and rational composite or laminate compatibility, can almost meet the requirements of a variety of different food packaging. For example, Tetra Pak milk made from multiple layers of plastic/cardboard/aluminum plastic/plastic can last up to six months to a year. Some high-resistance flexible packaged meat cans have a shelf life of up to 3 years. In some developed countries, the shelf life of composite packaging cakes can reach more than one year. After one year, the nutrition, color, aroma, taste, shape and microbial content of the cake still meet. Claim. Design composite packaging should pay special attention to the selection of each layer of substrate, the combination must be scientific and reasonable, the comprehensive performance of each layer must meet the comprehensive requirements of food packaging.
There are also fifteen or six kinds of plastics used in food packaging in China, such as PE, PP, PS, PET, PA, PVDC, EVA, PVA, EVOH, PVC, and ionomer resin. Among them, PVA, EVOH, PVDC, PET, PA, etc., high-resistance moisture, PVDC, PP, PE, etc.; radiation-resistant such as PS aromatic nylon; low temperature resistance such as PE, EVA, POET, PA, etc.; good oil resistance and mechanical properties such as ionomer resin, PA, PET, etc., ie high temperature sterilization and low temperature resistance, such as PET, PA and so on. The plastics of various plastics have different molecular structures, different degrees of polymerization, different types and amounts of additives, and different properties, even if the properties of the same plastics are different. Therefore, the choice of suitable plastic or plastic and other materials must be selected according to the requirements. Improper selection may result in degraded food quality or even loss of food value. For example, a PVC plastic corrugated box is used in place in the northeast to replace apples in corrugated boxes, because the performance of PVC blocking carbon dioxide, oxygen and water is far greater than that of the carton and the moisture resistance, so that the apple can not maintain a certain breath, resulting in a large amount of decay.
3. Paper and cardboard
Modern packaging mainly uses various processed potato (cardboard), composite paper, laminated paper (cardboard), etc., such as polymer processing paper, wax processing paper, oil processing paper, cellophane, parchment paper, aluminized paper, paper / aluminum foil Laminated paper, etc. In transport packaging, corrugated paperboard is used the most, corrugated boxes, and almost all of the pallets replace wooden boxes. Honeycomb cartons are the latest high-strength cardboard containers. In addition, it should be noted that aluminized paper, aluminized plastic and paper/aluminum foil laminates, plastic/aluminum foil laminates have different internal structures, properties, costs, etc., and should be appropriately selected according to different protection requirements and cost requirements. .
4. Glass bottle
Traditional glass bottles are fragile and have a large weight/volume ratio. Modern packaging uses thin-walled light bottles (light bottles). This specially treated or physically treated container can reduce the weight by 1/3-1/2, but the strength is greatly improved, thus improving the glass container in food packaging. Competitiveness in the market.
5. Metal cans
The traditional metal packaging is mainly made of tinplate (aluminized steel sheet) made of three-piece cans. In addition to tinplate, modern food packaging also uses cans made of thin aluminum plates. In addition to the three-piece can, there are two cans, shaped cans, spray cans, and the like.
Third, the use of advanced packaging technology methods
In order to extend the shelf life of food, we adopt new packaging technologies that are constantly being developed, such as active packaging, anti-mild packaging, moisture-proof packaging, anti-fog packaging, anti-static packaging, selective venting packaging, non-slip packaging, cushion packaging, etc. New technologies, China’s applications are not universal, and some methods are still blank. The application of these advanced technologies can significantly improve the protection function of packaging.