Patent ID: 7629012

Claim:
A method of packaging a food product, the method comprising the steps of: (a) operating a web transport conveyor to transport a non-perforated lower web of flexible packaging material from upstream to downstream locations through a series of stations including (1) a loading station for placing the food product in a package defined by the lower web, (2) a closing station for closing the package with an upper web of flexible packaging material, and (3) a pasteurization station for pasteurizing the food product, wherein the pasteurization station is located downstream of the loading station and upstream of the closing station and comprises a pasteurization chamber defined by a lower chamber member located below the non-perforated lower web and an upper chamber member located above the non-perforated lower web; (b) moving at least one of the upper and lower chamber members towards the other of the upper and lower chamber members into closed positions, respectively, wherein the upper and lower chamber members directly seal with and sandwich the non-perforated lower web therebetween, and wherein the non-perforated lower web and the upper chamber member define the boundaries of a pocket in the pasteurization chamber holding the food product; (c) supplying pasteurizing medium to the pocket via an entry port in the upper chamber member when the upper and lower chambers are in the closed position, wherein the entry port is configured such that during operation the pasteurizing medium passes into the pocket without passing through the non-perforated lower web, without passing through an interface between the upper and lower webs, without passing between the upper and lower webs, and without the upper web in the pasteurization chamber; (d) continuously venting pasteurizing medium that is supplied to the pocket when the upper and lower chamber members are in the closed position via an exit vent in the upper chamber member and spaced from the entry port, the exit vent being open to the pocket so as to receive and continuously vent pasteurizing medium that is supplied to the pocket via the entry port when the upper and lower chamber members are in the closed position, wherein the exit vent is configured such that during operation the pasteurizing medium passes out of the pocket without passing through the non-perforated lower web, without passing through an interface between the upper and lower webs, without passing between the upper and lower webs, and without the upper web in the pasteurization cavity; (e) moving at least one of the upper and lower chamber members away from the other of the upper and lower chamber members into an open position; (f) advancing the web transport conveyor to convey the food product away from the pasteurizing station and to advance new food product for processing to the pasteurization station; and (g) repeating steps (b) through (f).