The development of the hottest flexible packaging

2022-08-05
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The development of flexible packaging in food industry (II)

5 Pearlescent film

pearlescent film has milky pearl color. It is a BOPP film produced by adding pearlescent pigment into plastic particles and heat setting by biaxial stretching. Because the film has a special pearl like luster after surface printing, it has been widely used in food packaging, such as ice cream, popsicles, candy, snacks and so on

a typical pearlescent film is BOPP pearlescent film produced by a/b/a3 layer coextrusion biaxial stretching method, in which B is polypropylene mixed with pearlescent masterbatch, and a is a PP copolymer varying with the surface properties of pearlescent film, which has good heat sealing property. Biaxial stretching is carried out below the melting point of material B and above the melting point of material a

as there are many pearlescent inorganic pigment particles in material B, the result of biaxial stretching is that polypropylene molecules are oriented along the direction of external force, while the distance between pearlescent pigment particles is widened to form pores, making layer B a mechanically foamed plastic. Therefore, the pearlescent film of a/b/a structure is a biaxially stretched BOPP foam plastic film, with a specific gravity of 0.7 ~ 0.75, which is smaller than that of general BOPP film, while the specific gravity of general BOPP film is about 0.9

a material layer can protect B material layer in BOPP pearlescent film and endow the pearlescent film with certain heat sealing property. Therefore, the pearlescent film with a/b/a structure has good heat sealing property. However, the pearlescent film produced only with material B can only rely on the porosity of the film and the slight heat sealing of a small number of non oriented PP molecules. The pearlescent film after heat sealing is easy to tear off

6. Thin food packaging paper

as a paper for special purposes, thin food packaging paper must meet the following requirements: ① the production water must comply with GB5749 sanitary standard for drinking water; ② Do not use fluorescent brighteners and chemical AIDS harmful to human body; ③ Pipes must be stainless steel or plastic steel; ④ The raw materials used in the paper production process must be pure bleached coniferous wood pulp, self-made natural color or bleached long fiber Bast Pulp and hemp pulp, and waste paper, straw pulp and other moldy pulp shall not be used; ⑤ Workshop hygiene and personal hygiene of employees must comply with gb15979 hygienic standard for disposable sanitary articles

the raw materials and their proportions used in the production of paper are also different due to different packaging contents. For example, the proportion of bast fiber should be larger for food bag paper with higher requirements for tensile resistance; As for the packaging paper used as the inner bag of drugs, it only requires good antibacterial, moisture-proof and sealing properties, and does not require high paper strength. 100% bleached coniferous wood pulp can be used. At the same time, the amount of additives should be larger, while the amount of surface sizing should be smaller

thin food packaging paper is not only required to bear large tension and tension under extremely thin conditions, but also has special properties such as oil resistance, water resistance, moisture resistance, heat resistance and easy adhesion

III. in addition to the functions of vacuum packaging and vacuum inflatable packaging, it also has the functions of compression resistance, gas resistance and preservation, which can more effectively maintain the original color, aroma, taste, shape and nutritional value of food for a long time

(1) compression resistance - after vacuum inflation packaging, the food has strong medium resistance. Since the inflation pressure in the packaging bag is greater than the atmospheric pressure outside the packaging bag, it can effectively prevent the food from being crushed and deformed under pressure, and will not affect the appearance of the packaging bag and the printing and decoration effect. Many crunchy and fragile foods (tea, puffed foods, fruit and vegetable chips, etc.), easily caked foods (meat floss, milk powder, etc.), easily deformed and oily foods (cakes, moon cakes, etc.), foods with sharp edges and corners or high hardness that will puncture the packaging bag, etc. must be packaged with vacuum inflatable packaging.

(2) gas barrier - the packaging bags used for vacuum packaging and vacuum inflatable packaging generally use composite films with good air tightness, However, there is still a certain air permeability, so the air outside the bag will penetrate into the packaging bag, affecting the shelf life of the food. After vacuum inflatable packaging, the pressure inside the packaging bag is greater than the pressure outside the packaging bag, and it is difficult for the air outside the bag to enter the bag, effectively extending the shelf life of food

(3) fresh keeping - the filling gas is generally a single gas such as nitrogen, carbon dioxide and oxygen or a mixture of 2-3 gases

nitrogen is an inert gas with extremely stable chemical properties. In addition to filling, it can also maintain positive pressure in the bag and prevent air outside the bag from entering the bag. It has the effect of quality assurance and fragrance preservation. Vacuum nitrogen filled packaging is widely used. It is mainly used for packaging tea, nuts, meat floss, puffed food, fruits and vegetables, reducing the diameter of monofilament and orienting molecules to arrange crisps, milk powder, dehydrated vegetables, etc

carbon dioxide can dissolve in all kinds of fat or water to produce carbonic acid with weak acidity, which can inhibit the activity of microorganisms such as molds and putrefactive bacteria. However, excessive use of carbon dioxide may make food slightly sour

oxygen can inhibit the growth and reproduction of anaerobic bacteria and keep fruits and vegetables fresh. High concentration of oxygen can also keep fresh meat bright red

some baked goods, such as moon cakes and cakes, have medium water content and high oil content. If they are packed in ordinary packaging, the shelf life is very short, especially when the temperature is high. The shelf life of vacuum inflatable packaging (filled with nitrogen and carbon dioxide, in which nitrogen accounts for 30% ~ 60% and carbon dioxide accounts for 70% ~ 40%) can be 2 ~ 5 times longer than that of ordinary packaging

fresh pork and beef were originally frozen at -18 ℃ for preservation, which affected nutrition and taste and was not popular with consumers. Vacuum aerated packaging (filled with oxygen and carbon dioxide, with the mixture ratio of oxygen accounting for 60% ~ 40% and carbon dioxide accounting for 40% ~ 60%) shall be adopted. It shall be refrigerated at - 1 ~ + 3 ℃ for 10 ~ 14 days. Vacuum inflatable packaging not only solves the problem of fresh meat storage and transportation, according to experts, the nutritional value of refrigerated meat is higher than that of fresh meat just slaughtered

the vacuum and vacuum aerated packaging technology of food plays an important role in food packaging technology. Some functions and functions cannot be easily replaced by other packaging technologies. China's vacuum packaging technology was developed in the early 1980s, while the vacuum inflatable packaging technology began to be used in a small amount in the early 1990s. With the promotion of small packaging and the development of supermarkets, its scope of application will be more and more extensive, and it will gradually replace hard packaging in some fields, with a very good prospect.

IV. new development trend of food soft packaging technology

with the continuous development of modern science and technology, the market's requirements for food soft packaging are increasing, and the food soft packaging technology presents the following development trends

ccp management technology, including preventing impurities from mixing into the meter; Conveyor belt capable of heating and sterilization; Detection of impurities or metals; Determination of environmental dust and planktonic bacteria index; Environmental sterilization and dust removal on the surface of various packaging materials

2. Container forming and filling system under sterile conditions

3. Transparent soft film automatic packaging system for vegetables and fruits to replace the tray (simplified packaging)

4. A packing bag with openings of various shapes capable of filling and discharging gas into the soft bag is attached

5. All kinds of milk plastic packaging, namely the internationally popular 200 ~ 500 ml packaging with long service life

6. Technology for preventing peeling between layers of food or condiment composite packaging bags

7. Low cost packaging combined with circulation conditions

8. A system in which bag making and filling are carried out simultaneously

9. Flexible packaging materials that can discharge the gas generated by food, and various functional packaging

136 upstream and downstream technology industry factories

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