Method of packaging food product

• US 5,447,736 A
• Filed: 03/23/1994
• Issued: 09/05/1995
• Est. Priority Date: 05/20/1993
• Status: Expired due to Term

• Current Assignee: Cryovac Incorporated (Sealed Air)
• Original Assignee: World Class Packaging Systems Incorporated
• Inventors: Gorlich, Michael P.
• Primary Examiner(s): WEINSTEIN, STEVEN L
• Application Number:
  US08/216,918
• Time in Patent Office: 531 Days
• Field of Search: 426/396, 426/394, 426/415, 426/124, 426/118, 426/129, 426/418, 426/127, 426/316, 53/449, 53/478, 53/329.5, 53/433, 53/434
• US Class Current: 426/396
• CPC Class Codes: B65B 25/067 combined with its conservation
• CPC Class Codes: B65B 31/028 closed by a lid sealed to the upper rim of the container, e.g. tray-like container
• CPC Class Codes: B65B 7/168 by applying and securing double closures
• CPC Class Codes: B65D 2251/0031 Membrane
• CPC Class Codes: B65D 2251/0093 Membrane
• CPC Class Codes: B65D 2565/388 Materials used for their gas-permeability
• CPC Class Codes: B65D 51/185 the outer closure being a foil membrane
• CPC Class Codes: B65D 77/2024 the cover being welded or adhered to the container
• CPC Class Codes: B65D 77/30 Opening or contents-removing devices added or incorporated during filling or closing of containers B65D77/20 takes precedence
• CPC Class Codes: B65D 81/2076 in an at least partially rigid container
• CPC Class Codes: B65D 81/245 Internal membrane, floating cover or the like isolating the contents from the ambient atmosphere loosely-attached linings B65D25/16; dispensing pistons B65D83/0005; flexible bags for expelling the contents B65D83/0055
• CPC Class Codes: B65D 81/3294 Thermoformed trays or the like with a plurality of recesses for different materials located in different recesses

Abstract

A method of packaging a food product employing a tray having side walls defining a cavity in an outwardly directed flange extending around the perimeter of the tray, the flange being adapted to receive a pair of membranes to enclose the tray. The lower membrane is the more permeable of the two. It may be attached to a first surface of the flange. The second membrane is attached to a second outer surface of the flange without direct connection except through the tray to the more permeable membrane. The two connection surfaces may be separated by a depression to facilitate the cutting away of the material forming the more permeable membrane in a continuous manufacturing process. With the less permeable membrane in place, a desired gaseous environment may be maintained within the package. When it is desired to change the gaseous environment, the upper less permeable membrane may be peeled away allowing gaseous communication through the lower more permeable membrane.

Claims

1. A method for packaging a food product comprising the steps of:

providing a tray with a pair of spaced first and second sealing surfaces that are spaced apart by a depression recessed from at least one of said sealing surfaces;

placing a food product in said tray;

unwinding a pliant first membrane from a web and placing said first membrane on said first sealing surface and over said depression;

sealing said first membrane to said tray on said first sealing surface;

severing said first membrane from said web over said depression between said sealing surfaces while said first membrane is in place on said tray, said depression designed to facilitate the severing of said first membrane from said web in place on said tray during manufacture of the package; and

sealing a pliant second membrane to said tray on said second sealing surface so that said second membrane is over said first membrane and said second membrane is removable from the tray independently of the first membrane and so that said food product is enclosed in said tray covered by said membranes to form a package.

2. The method of claim 1, wherein an atmosphere is introduced inside said package which contains a relatively low concentration of oxygen.

3. The method of claim 2, wherein said atmosphere includes substantial concentrations of carbon dioxide or nitrogen to reduce exposure of the food product to oxygen.

4. The method of claim 1, wherein after said food product is placed in said tray and prior to the time when said second membrane is sealed to said tray, evacuating said tray of air and filling said tray with a gas which is lower in oxygen content than air.

5. The method of claim 1, further including the step of removing said second membrane to allow exposure of the food product to normal atmospheric conditions when said package is ready for retail display.

6. The method of claim 1 wherein said first membrane is sealed to said tray while said tray is in one packaging station of a packaging machine, said method including the steps of transferring said tray to a second station and performing said sealing of said second membrane at said second station.