The technique is called the MicVac method, as it was developed by packaging firm MicVac, working with Sealpac. It involves filling a MicVac tray with fresh food ingredients.
A valve is applied to the top film, which is sealed to the tray on a Sealpac A7 traysealer. The tray is transported to a microwave tunnel, where the contents are cooked at higher speeds than traditional pasteurisation methods. During this heating process, the valve opens due to pressure caused by the food releasing steam.
As soon as the pasteurisation process stops and cooling in the spiral freezer be gins, the valve will close again. The remaining steam condenses, causing an under-pressure in the tray.
Together with ELS in Germany, Sealpac developed a special application device for the patented MicVac valve on the A7 traysealer. Servo-driven film transport ensures accurate punching of the hole and positioning of the valve.
The Sealpac A7’s high sealing pressure and accurate control of sealing temperature guarantees that the seal of the top film on the trays is strong enough to withstand the internal pressure during pasteurisation and heating up in the microwave – yet remains easy to peel away.
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