Soups, ravioli, or noodles: Up to now, caterers and kitchens have had to allow hot food to cool down to be vacuum-packed effectively. This costs time and reduces flexibility - and in the case of active cooling, this also takes energy. The alternative from MULTIVAC, the packaging specialist, is the new SFP Light steam flushing system.

Fun fact: It is impossible to cook an egg on Mount Everest. Because the lower the air pressure, the lower the boiling point of water. Water vaporizes at 70 °C on the highest mountain in the world, which is 8,848 meters above sea level. But 83 °C is required for an egg to become rigid. No problem for mountaineers. They do without or switch to a steam cooker. But the physical principle presents a challenge to caterers and central kitchens - particularly if they want to use a packaging machine to vacuum pack hot food directly after cooking so that the shelf life can be extended. Why? Here the so-called vapor pressure curve comes into play. The greater the negative pressure, the lower the boiling point - exactly as on the mountain. If the machine creates a negative pressure of 200 m bar, for example, the water content in the product vaporizes at 60 degrees centigrade. From this point onwards, further reducing the pressure is no longer possible.

That is the problem: When vacuum packing hot food, some residual air remains, which can adversely affect the shelf life

When vacuum packing hot products, some residual air with 21 percent oxygen content always remains in the header space. A residual air content can reduce the shelf life of the food. “Many caterers and kitchens let the hot food cool down before vacuum packing. Or they use active cooling. But by doing this, they lose either time or energy,” says Dominik , product manager, Thermoforming Packaging Machines, MULTIVAC. “To ease the burden on caterers and kitchens, we have launched a new steam flushing system for small to medium batch sizes onto the market, and this is called SFP Light.” SFP is an abbreviation for Steam Flush Packaging.

The solution: The SFP Light steam flushing system packs hot products without a vacuum source

SFP Light is available with immediate effect for MULTIVAC thermoforming packaging machines. “Our thermoforming packaging machines have been used successfully for decades throughout the world. They are groundbreaking in terms of the use of resources, process reliability, efficiency, flexibility, reproducibility, and ease of operation. SFP Light also provides another important benefit. The steam flushing system enables hot food to be vacuum packed directly after cooking,” adds Dominik.

The thermoforming packaging machine first forms the pack cavities for the product from a plastic film - for packing five kilograms of goulash for example at a temperature of 60 °C. The portions then travel into a hermetically enclosed sealing station. Hot steam at a temperature of 180 °C now flows through the station. Finally, the upper web is sealed to the formed film, and the steam remains in the pack. The secret: Gases have a significantly greater volume than liquids. When the steam turns to water again during cooling, the pack automatically contracts. “Thanks to SFP Light, it is possible to pack hot products without any significant residual air pockets. And all this without any vacuum source, which always has a limited effect due to the vapor pressure curve,” explains Dominik Eberhard. “There is also no danger of the products boiling or packs bursting since there is no negative pressure in the product space.” Another beneficial side effect of the steam flushing system. The hot gas at 180 °C kills bacteria on the surface of the food so that the shelf life is extended.

And why SFP Light? “MULTIVAC has offered an SFP system for many years now for thermoforming packaging machines with high throughputs on an industrial scale. The new version is designed for smaller batch sizes in kitchens and catering companies. It is less complex as well as being space-saving and more cost-effective.”