Hermetic sealing device for packages containing food products

A hermetic sealing device for packages containing food products, comprising:

• a unit for gripping and/or feeding a piece of thin flexible material forming a piece of film used to cover and at least partly seal a food product in a package;
• a sealing element comprising a rheostat including an annular body and two terminals extending from the annular body and connectable to a voltage generator capable of generating and maintaining an electrical potential difference at the ends of the two terminals to cause a flow along the rheostat of an electric current capable of heating the annular body to a predetermined sealing temperature;
• each terminal including at a point of contact connection to the annular body of the rheostat, a first cross section having a surface area which is smallest as compared to all other cross sections of the terminal;
• the annular body configured to come into contact with the piece of film positioned in contact with a predetermined portion of the package for a predetermined length of time long enough to seal the piece of film along the package to hermetically seal the food product between the package and the piece of film;
• wherein, at the point of contact connection of each terminal with the annular body of the rheostat, an electrical node is defined where the electric current is divided into two secondary currents which flow along the annular body and meet at the other terminal;
• wherein, at each electrical node, a portion of the terminal residing around the first cross section defines a predetermined electrical resistance which is largest as compared to the all other cross sections of the terminal.