Principle and working mode of vacuum packaging machine
Vacuum packaging is the method of putting food into packaging bags, pumps out the air inside the packaging bags, and completes the sealing process after reaching the predetermined vacuum degree. And sometimes the machine fills the packaging bags with nitrogen or other mixed gases, before completing the sealing process.
The vacuum packaging machine consists of a vacuum system, an inflation system, an electrical control system, and a pneumatic control system. There are 3 different working modes generally:
- Vacuum mode: Put the packaged items under the heating rod and put the air nozzle into the bag → step on the foot switch → the heating rod slides down to the sponge strip under the action of the cylinder to press the bag mouth → the bag stops → vacuumize (Like a strapping machine, the vacuuming time can be set in advance according to the requirements) → the air nozzle retreats → the heating rod continues to slide down to press the bag opening to heat, seal, and cool → finished product → the heating rod returns to the highest position (the vacuum packaging machine is completed a duty cycle).
- Inflation mode: Put the package under the heating rod and put the air nozzle into the bag → step on the foot switch → the heating rod slides down to the sponge strip under the action of the cylinder to press the bag mouth → the bag mouth stops → vacuumize → Inflation → The air nozzle retreats under the action of the cylinder, and the heating rod continues to slide down to heat, seal, and cool → finished product → the heating rod is reset (the vacuum packaging machine completes a working cycle).
- Sealing mode: (can be used as a general sealing machine) put the package under the heating rod → step on the foot switch → the heating rod slides down to the sponge strip under the action of the cylinder to press the bag mouth, heating, sealing, cooling → Finished product → reset the heating rod (complete a working cycle).
The main function of vacuum packaging is to remove oxygen to help prevent food from deteriorating. Microbes and yeast need oxygen to survive, and vacuum packaging uses this principle to remove the oxygen in the packaging bag and food cells, so that the microorganisms lose their “survival environment”. Experiments have proved that: when the oxygen concentration in the packaging bag is ≤1%, the growth and reproduction speed of microorganisms will drop sharply, and when the oxygen concentration is ≤0.5%, most microorganisms will be inhibited and stop breeding. (Note: Vacuum packaging cannot inhibit the growth of anaerobic bacteria and food deterioration and discoloration caused by enzyme reactions, so it needs to be combined with other auxiliary methods, such as refrigeration, quick freezing, dehydration, high temperature sterilization, radiation sterilization, microwave sterilization, salt pickled etc.)
In addition to inhibiting the growth and reproduction of microorganisms, the vacuum deoxygenation of the vacuum packaging machine has another important function to prevent food oxidation. Because oily foods contain a large amount of unsaturated fatty acids, they are oxidized by oxygen, making the food taste and deteriorate. In addition, Oxidation also causes the loss of vitamins A and C, and the unstable substances in food pigments are affected by oxygen to darken the color. Therefore, oxygen removal can effectively prevent food from deteriorating and maintain its color, aroma, taste and nutritional value.
In addition to the function of oxygen preservation, the main function of vacuum air-filled packaging of vacuum packaging machine is to resist pressure, block gas, and keep fresh, which can more effectively keep the original color, aroma and taste of food for a long time , shape and nutritional value. In addition, many foods are not suitable for vacuum packaging but must be packed with vacuum inflation. Such as crispy and fragile food, food that is easy to agglomerate, food that is easy to deform and lose oil, food with sharp edges or high hardness that will puncture the packaging bag, etc. After the food is vacuum-packed, the inflation pressure inside the packaging bag is stronger than the atmospheric pressure outside the packaging bag, which can effectively prevent the food from being crushed and deformed under pressure without affecting the appearance and printing decoration of the packaging bag.
Vacuum packaging machine vacuum inflatable packaging is filled with nitrogen, carbon dioxide, oxygen single gas or a mixture of two or three gases after vacuum. The nitrogen gas is an inert gas, which acts as a filling to maintain a positive pressure inside the bag to prevent the air outside the bag from entering the bag and protect the food. Nitrogen dioxide could be melt easily into the fats or water, and the light carbonic acid brought up by this melting restrains some mircobials like mold and putrefactive bacteria. Its oxygen can inhibit the growth and reproduction of anaerobic bacteria, keep fruits and vegetables fresh and colorful, and high concentration of oxygen can keep fresh meat bright red.Tags: Shrink wrap machine, Vacuum packaging machine