The hottest food under vacuum and vacuum inflatabl

Vacuum and vacuum inflatable flexible packaging of food (Part 2)

5. Flexible packaging materials

vacuum packaging or vacuum inflatable packaging are usually three side sealed packaging bags made of double-layer composite film or three-layer aluminum thin composite film. The thickness of the composite film is generally between 60um and 96um, of which the inner layer is a heat sealing layer, which needs to have good heat sealing performance. The thickness is between 50um and 80um of the tensile machine, and the outer layer is a sealing layer, It needs to have good air tightness and printability, certain strength, and the thickness is between 10um and 16um

polyethylene (PE) is commonly used as the inner base material of composite film, high temperature resistant polypropylene (CPP) is used as the high-temperature cooking bag, and stretched polypropylene (OPP), polyester (PET), nylon (PA) is commonly used as the outer base material. Opp is cheap, but its air tightness and strength are slightly poor. Pet has good air tightness and high tensile strength, but it is sensitive to notch and has low tear strength. PA has good air tightness, puncture resistance and high strength, but the price is expensive and the water vapor transmission rate is high

after compounding, the properties of various substrates will be improved or improved. The compounding process includes dry compounding and coextrusion compounding. The packaging bags that need color printing adopt dry compounding. The printing layer is between the inner and outer substrates, which can play a protective role. Some transparent packaging bags can adopt coextrusion compounding

some foods such as tea, milk powder and other high-fat foods need to be packaged with light blocking packaging to prevent the food from changing its color, aroma and taste due to the influence of light. The method is to compound a very thin aluminum foil (AL) between the inner and outer substrates, and its air tightness is also strengthened. Another coating process uses vacuum evaporation to form a thin aluminum coating on the surface of the substrate to increase the light resistance. Another method is to apply a thin layer (1 ~ 2um) of polyvinylidene chloride (PVDC) on both sides of the substrate or between two substrates. PVCD has excellent air tightness

6. Packaging machine

vacuum or vacuum inflatable packaging machine is commonly used in cavity type and external extraction type. Cavity packaging machine is divided into vacuum packaging machine and vacuum filling machine, which can produce ultra-high strength but still very light material gas packaging machine. The external pumping packaging machine has several functions, such as vacuum packaging and vacuum inflatable packaging, so it is also called multi-functional modified atmosphere packaging machine

6.1 vacuum packaging machine: the vacuum packaging machine is a cavity structure, which consists of upper and lower chambers to form a vacuum chamber that can be sealed. The mouth of the food packaging bag is placed between the upper and lower sealing devices, and the vacuum chamber is vacuumized first; The packaging bag is vacuum at the same time, and then sealed under vacuum to ensure high vacuum in the packaging bag. Commonly used models include single room, double room, conveyor belt type, etc. food packaging bags are placed horizontally. When packaging liquid containing objects or liquids (such as pickles, fresh water bamboo shoots, soft canned fruits, etc.), the liquid is easy to overflow and is not suitable. I designed and obtained the national patent of the liquid vacuum packaging machine in 1995. Its heat sealing device is installed obliquely in the vacuum chamber, and the article packaging bag is almost placed vertically, so the liquid will not overflow. 6.2 vacuum inflatable packaging machine: a set of inflatable device is added to the cavity vacuum packaging machine to form a vacuum inflatable packaging machine. The mouth of the food packaging bag is sleeved on the inflatable nozzle and placed between the upper and lower thermal packaging places. First, vacuum the vacuum chamber; Vacuum the bag at the same time, and then fill the vacuum chamber with gas; The bag is inflated at the same time, and then sealed to form a vacuum inflatable package. However, when the bag mouth is open during inflation, the pressure in the bag is basically the same as that in the vacuum chamber, and it is negative pressure, so the inflation effect is poor and the gas utilization rate is low. The vacuum inflatable packaging machine designed by me in 1996 and patented by the state adds a sealing device at the mouth of the article packaging bag. When inflating, the packaging bag is sealed first, and then inflated, which improves the utilization rate of inflating gas, and the amount of inflation is adjustable. 6.3 multi function modified atmosphere packaging machine: the modified atmosphere packaging machine has the functions of ordinary sealing packaging, vacuum packaging and vacuum inflatable packaging. It is an external pumping type (also known as liquid crystal rubber tensile testing machine software function introduction of Jinan new era Gold Testing Instrument Co., Ltd.: direct pumping type, tube pumping type, etc.) packaging machine. There is no vacuum studio. The packaging bag is covered on the inflation nozzle and placed between the upper and lower sealing devices and the upper and lower heat sealing devices, The packaging bag is sealed by the sealing device first, and then the vacuum or vacuum inflation in the packaging bag is directly made, and then the inflation nozzle retreats, and finally the heat sealing device works to seal. The inflation volume of this model is arbitrarily adjustable, and it is not limited by the packaging volume within the sealing length range. The packaging effect is direct and considerable. The disadvantage is that the vacuum degree is relatively low compared with the cavity vacuum packaging machine, and powder and liquid containing food are not applicable

7. Conclusion

the vacuum and vacuum inflatable flexible packaging technology of food occupies a certain position in food packaging technology, and some functions and functions cannot be easily replaced by other packaging technologies. China's vacuum packaging technology has overcome their basic shortcomings and developed in the early 1980s, while vacuum inflatable packaging technology has just begun 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 some will gradually replace hard packaging, and the prospect will be very promising