Food or edible material: processes – compositions – and products – Packaged or wrapped product – Three or more layered packaging materials
Reexamination Certificate
2000-12-07
2003-07-01
Bhat, Nina (Department: 3721)
Food or edible material: processes, compositions, and products
Packaged or wrapped product
Three or more layered packaging materials
C426S129000, C426S412000, C426S415000, C053S479000, C053S480000
Reexamination Certificate
active
06586026
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The present invention relates to packaged food articles, specifically articles where a food product is cooked after being packaged.
2. Background of the Invention
Many food products are processed in thermoplastic film packages by subjecting the packaged product to elevated temperatures produced by, for example, immersion in hot water or exposure to steam. Such thermal processing often is referred to as cook-in, and films used in such processes are known as cook-in films.
A food product that is packaged and processed in this manner can be refrigerated, shipped, and stored until the food product is to be consumed or, for example, sliced and repackaged into smaller portions for retail display. Many sliced luncheon meats are processed in this fashion. Alternatively, the processed food can be removed immediately from the cook-in package for consumption or further processing (e.g., sliced and repackaged).
A cook-in film must be capable of withstanding exposure to rather severe temperature conditions for extended periods of time while not compromising its ability to contain the food product. Cook-in processes typically involve a long cook cycle. Submersion in hot (i.e., about 55° to 65° C.) water for up to about 4 hours is common; submersion in 70° to 100° C. water or exposure to steam for up to 12 hours is not uncommon, although most cook-in procedures normally do not involve temperatures in excess of about 90° C. During such extended periods of time at elevated temperatures, any seams in a package formed from a cook-in film preferably resist failure (i.e., pulling apart).
The cook-in film preferably possesses sufficient adherence to the food product to inhibit or prevent “cook-out” (sometimes referred to as “purge”), which is water and/or juices that collect between the surface of the contained food product and the food-contact surface of the packaging material during the cook-in process. Preventing cook-out can increase product yield, provide a better tasting product, improve shelf life and provide a more aesthetically appealing packaged product. Films that adhere well to the packaged food product help reduce cook-out.
Many cook-in films are corona treated to increase the surface energy of their food-contact layers. However, corona treatment can be inconsistent, can result in a film with inconsistent adhesion, can result in a film having a surface energy that decays over time, and can interfere with the sealability of a film.
Following the cook-in process, the film or package preferably conforms, if not completely then at least substantially, to the shape of the contained food product. Often, this is achieved by allowing the film to heat shrink under cook-in conditions so as to form a tightly fitting package. In other words, the cook-in film desirably possesses sufficient shrink energy such that the amount of thermal energy used to cook the food product also is adequate to shrink the packaging film snugly around the contained product. Alternatively, the cook-in film package can be caused to shrink around the contained food product prior to initiating the cook-in procedure by, for example, placing the package in a heated environment prior to cooking.
Some presently available cook-in films adhere well with the meat product and do a good job of reducing cook-out. Additionally, most such films are able to withstand extended time periods at the elevated temperatures described supra; accordingly such films are adequate for many cook-in applications. However, some cook-in applications impose even more stringent performance requirements. For example, some food products that are processed via cook-in procedures are oxygen sensitive. Cook-in films for these products need to include one or more oxygen barrier layers. Other cook-in applications require that the film or the package made therefrom be printable and be able to retain any image printed thereon.
An increasingly important requirement of cook-in films is that they provide an aesthetically pleasing packaged food product. For example, as mentioned previously, the cook-in film generally shrinks until it at least substantially conforms to the shape of the enclosed food product; however, unless the shape of that food product is itself aesthetically pleasing, the resulting packaged food article does not have an aesthetically pleasing shape.
Because pre-forming the food article prior to packaging is impractical (and often impossible), providing a cook-in film that can provide a resulting packaged food article with an aesthetically pleasing shape is highly desirable.
SUMMARY OF THE INVENTION
Briefly, the present invention provides a packaged food article which includes a meat product and a thermoplastic, heat shrinkable film. The film includes a meat-contact layer that contains a polymer which includes mer units derived from a C
2
-C
4
&agr;-olefin. The film is sealed so as to form a bag which encloses the meat product. At least one sealed edge of the bag defines an arc which includes at least four segments. Each of the segments has a radius of curvature which differs from the radius of curvature of any adjoining segment.
When the packaged food article is subjected to a temperature of from about 50° C. up to about the Vicat softening point of the meat-contact layer polymer that includes mer units derived from a C
2
-C
4
&agr;-olefin, preferably up to about 100° C., the packaged food article advantageously takes the general shape of, for example, a poultry breast. Because the arc of the bag edge includes at least four segments with varying radii of curvature, the general shape of the packaged food article is not essentially spherical. Rather, the packaged food article has a more irregular, yet generally rounded appearance such as is observed in actual poultry breasts.
To assist in understanding the more detailed description of the invention that follows, certain definitions are provided immediately below. These definitions apply hereinthroughout unless a contrary intention is explicitly indicated:
“polymer” means the polymerization product of one or more monomers and is inclusive of homopolymers as well as copolymers, terpolymers, tetrapolymers, etc., and blends and modifications of any of the foregoing;
“mer unit” means that portion of a polymer derived from a single reactant molecule; for example, a mer unit from ethylene has the general formula —CH
2
CH
2
—;
“homopolymer” means a polymer consisting essentially of a single type of repeating mer unit;
“copolymer” means a polymer that includes mer units derived from two reactants (normally monomers) and is inclusive of random, block, segmented, graft, etc., copolymers;
“interpolymer” means a polymer that includes mer units derived from at least two reactants (normally monomers) and is inclusive of copolymers, terpolymers, tetrapolymers, and the like;
“polyolefin” means a polymer in which some mer units are derived from an olefinic monomer which can be linear, branched, cyclic, aliphatic, aromatic, substituted, or unsubstituted (e.g., olefin homopolymers, interpolymers of two or more olefins, copolymers of an olefin and a non-olefinic comonomer such as a vinyl monomer, and the like);
“(meth)acrylic acid” means acrylic acid and/or methacrylic acid;
“(meth)acrylate” means acrylate and/or methacrylate;
“anhydride functionality” means an group containing an anhydride moiety, such as that derived from maleic acid, fumaric acid, etc., whether blended with one or more polymers, grafted onto a polymer, or polymerized with one or more monomers;
“oxygen permeance” (in the packaging industry, “permeance” often is referred to as “transmission rate”) means the volume of oxygen (O
2
) that passes through a given cross section of film (or layer of a film) at a particular temperature and relative humidity when measured according to a standard test such as, for example, ASTM D 1434 or D 3985;
“longitudinal direction” means that direction along the length of a film, i.e., in the direction of the film as it is formed during extrusion and/or coating;
“transverse
Ramesh Ram K.
Troutt Terry L.
Bhat Nina
Cryovac Inc.
Ruble Daniel B.
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