System and method for packaging
In one embodiment of an apparatus and process for packaging foodstuffs or other materials in a rigid container sealed by a flexible cover, a desired quantity of material to be packaged containing or together with some water or other liquid is placed in the container, the flexible cover is secured on the container so as to leave at least one unsealed opening, the container is heated and/or placed in a partial vacuum to bring the liquid above its boiling point to cause or permit vapor generated by the boiling liquid to expel other gases from the container through the unsealed opening, and the container is sealed while gas or vapor is still flowing out of the container through the unsealed opening.
1. A process for packaging materials in a container comprising a body sealed by a flexible cover, comprising:
(a) placing a desired quantity of material comprising liquid in the container body;
(b) securing the flexible cover on the container body by sealing the flexible cover to a more rigid rim of the cover and sealing the rim to the container body so as to leave at least one unsealed opening formed by at least one portion where the flexible cover is not sealed to the rim;
(c) bringing the temperature of the liquid to a temperature higher than its boiling temperature;
(d) permitting vapor generated by the boiling liquid to expel other gases from the container through the at least one unsealed opening; and
(e) sealing the container by sealing the flexible cover to the whole rim while gas or vapor is still flowing out of the container through the at least one unsealed opening.
2. A process according to claim 1 , wherein the material is a moist foodstuff, and the liquid is water within the foodstuff.
3. A process according to claim 1 , comprising sealing the flexible cover to the more rigid rim of the cover with at least one portion where the flexible cover is not sealed to the rim before placing the cover on the container body.
4. A process according to claim 1 , wherein the flexible cover is formed of plastic or laminate film, and the more rigid rim is formed of metal.
5. A process according to claim 1 , wherein the container body comprises a rigid metallic, plastic or glass container.
6. A process according to claim 1 , wherein the total area of the at least one unsealed opening is less than 10% of the surface of the container.
7. A process according to claim 6 , wherein the total area of the at least one unsealed opening is less than 2% of the surface of the container.
8. A process according to claim 7 , wherein the total area of the at least one unsealed opening is less than 1% of the surface of the container.
9. A process according to claim 1 , wherein bringing the temperature of the liquid to a temperature higher than its boiling temperature comprises raising the temperature of the container.
10. A process according to claim 1 , wherein bringing the temperature of the liquid to a temperature higher than its boiling temperature comprises reducing the pressure of the container.
11. A process according to claim 1 , wherein sealing the container while gas or vapor is still flowing out of the container through the at least one unsealed opening comprises sealing the container under a partial vacuum.
12. A method of forming a sealed container under partial vacuum, comprising:
(a) placing material comprising a volatile liquid in a container body;
(b) securing a flexible cover fixed to a more rigid rim on the container body so as to leave at least one unsealed opening formed by at least one portion where the flexible cover is not sealed to the rim;
(c) bringing the volatile liquid to a subatmospheric pressure and a temperature at which the volatile liquid is above its boiling point at the subatmospheric pressure;
(d) permitting vapor generated by boiling of the liquid to expel other gases from the container through the at least one unsealed opening;
(e) sealing the container while vapor is still flowing out of the container through the at least one unsealed opening; and
(f) cooling the container to a temperature at which the vapor pressure of the volatile liquid is substantially less than the ambient pressure outside the container.