Starch coated polyester film for release of canned meat products

Abstract

An embodiment relates to a multi-layer, biaxially oriented polyester (BOPET) film comprising a food contact substance, wherein the BOPET has a percent release in a retort test after can lamination such that substantially all food contacting the BOPET during the retort test is released. Another embodiment relates to a method comprising applying a food contact material comprising a food contact substance to a multi-layer, biaxially oriented polyester (BOPET) film, wherein the food contact material is prepared at around room temperature without heating.

Claims

1. A film comprising a multi-layer film, comprising a base film comprising biaxially oriented polyester (BOPET) film and a release coating; the BOPET film having at least an A/B structure wherein layer A consists of an amorphous PET polyester with a melting point of 200-235 C. and layer B consists of a crystallized PET polyester with a melting point of 240-260 C., the release coating comprising a food contact substance comprising a starch in the coating, a release agent and a crosslinking agent that crosslinks the starch; the release coating is separate from the BOPET film and on the layer B, wherein the release coating has a percent release in a retort test after can lamination such that substantially all food contacting the release coating during the retort test is released.

2. The film of claim 1, wherein the release coating has a percentage release of at least 90 percent in a retort test after can lamination.

3. The film of claim 1, wherein the release agent comprises a wax.

4. The film of claim 1, wherein the crosslinking agent comprises glyoxal.

5. The film of claim 4, wherein the food contact substance comprises the starch and the glyoxal.

6. The film of claim 4, wherein the food contact substance comprises the starch and the glyoxal and a wax.

7. The film of claim 1, wherein the film contains no acrylic or bisphenol A.

8. The film of claim 1, wherein a gelatin solidified on a surface of the release coating is completely released from the release coating and wherein the release coating does not peel off from the base film by a tape test.

9. The film of claim 1, wherein the crosslinking agent comprises glyoxal, wherein the release coating further comprises NaOH.

10. The film of claim 1, wherein the release coating consists of the food contact substance consisting of the starch, the release agent, the crosslinking agent, and optionally NaOH and/or water.

11. The film of claim 1, wherein the release coating consists of the food contact substance consisting of the starch, the release agent, the crosslinking agent, NaOH and/or water.

12. The film of claim 1, wherein the A/B structure consists of the layer A and the layer B.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) The food release film may comprise one or more layers, preferably at least 3 layers. A multilayered food release film may include one or more of each of: a can-side or inside layer (i.e., heat seal layer), a food or outside layer, a coated layer which effects release of food There could also be multiple core layers between the heat sealant layer and the coating layer that effect barrier properties such as oxygen and moisture. This coating is in direct contact with the food in the can.

(2) The starch is dissolved in a water/alkaline solution. The starch can also be heated in a water solution to dissolve the starch, but this creates an unwanted increase in viscosity. Besides keeping the viscosity low, alkaline treatment also creates carboxyl groups which are beneficial to crosslinking. Crosslinking increases the cohesiveness of the starch coating and prevents the coating from being removed from the polyester film prematurely during the can lamination stage. It is hypothesized that once the film is laminated to the can, the coating behaves as a sacrificial layer that bonds to the meat protein during the retort process and is removed with the meat protein preventing the meat protein from attaching to the polyester film.

(3) Food Ingredients and Packaging Terms

(4) The Food and Drug Administration (FDA) Data Standards Council is standardizing vocabulary across the FDA. Therefore, the wording in some terms below may change slightly in the future.

(5) Biotechnologyrefers to techniques used by scientists to modify deoxyribonucleic acid (DNA) or the genetic material of a microorganism, plant, or animal in order to achieve a desired trait. In the case of foods, genetically engineered plant foods are produced from crops whose genetic makeup has been altered through a process called recombinant DNA, or gene splicing, to give the plant desired traits. Genetically engineered foods are also known as biotech, bioengineered, and genetically modified, although genetically modified can also refer to foods from plants altered through methods such as conventional breeding. While in a broad sense biotechnology refers to technological applications of biology, common use in the U.S. has narrowed the definition to foods produced using recombinant DNA. For additional information, see the Biotechnology Program on the CFSAN Internet.

(6) CEDI/ADI DatabaseFor a large number of food contact substances, CFSAN maintains a database of Cumulative Estimated Daily Intakes (CEDIs) and Acceptable Daily Intakes (ADIs). The CEDIs and ADIs are based on currently available information and may be revised when information is submitted or made available. The CEDI/ADI database is updated approximately twice annually. The CEDIs and ADIs are based on currently available information and may be subject to revision on the basis of new information as it is submitted or made available to OFAS.

(7) Color AdditiveA color additive is a dye, pigment or other substance, which is capable of imparting color when added or applied to a food, drug, cosmetic, or to the human body. The legal definition can be found in Section 201(t) of the Federal Food, Drug, and Cosmetic Act (FD&C Act) and provides exclusions as well. Color additives for use in food, drugs, and cosmetics require premarket approval. Color additives for use in or on a medical device are subject to premarket approval, if the color additive comes in direct contact with the body for a significant period of time. For additional information, consult the Color Additive Program on the CFSAN Internet.

(8) ColorantA colorant is a dye, pigment, or other substance that is used to impart color to or to alter the color of a food-contact material, but that does not migrate to food in amounts that will contribute to that food any color apparent to the naked eye. The term colorant includes substances such as optical brighteners and fluorescent whiteners, which may not themselves be colored, but whose use is intended to affect the color of a food-contact material. (21 CFR 178.3297(a)).

(9) EAFUSThe Everything Added to Food in the United States (EAFUS) database is an informational database maintained by CFSAN under an ongoing program known as the Priority-based Assessment of Food Additives (PAFA). PAFA contains administrative, chemical and toxicological information on over 2000 substances directly added to food, including substances regulated by the FDA as a direct food additive, secondary direct food additive, color additive, GRAS and prior-sanctioned substance. In addition, the database contains only administrative and chemical information on approximately 1000 such substances. Information about the more than 3000 total substances comprise EAFUS. For a complete listing of EAFUS substances, see the EAFUS list.

(10) Food AdditiveA food additive is defined in Section 201(s) of the FD&C Act as any substance the intended use of which results or may reasonably be expected to result, directly or indirectly, in its becoming a component or otherwise affecting the characteristic of any food (including any substance intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food; and including any source of radiation intended for any such use); if such substance is not GRAS or sanctioned prior to 1958.sup.1 or otherwise excluded from the definition of food additives.

(11) Food Contact Substance (FCS)Section 409 of the FD&C Act defines an FCS as any substance that is intended for use as a component of materials used in manufacturing, packing, packaging, transporting, or holding food if such use of the substance is not intended to have any technical effect in such food. Additional information can be found on the Food Contact Substances Notification Program page.

(12) There is a hierarchy from Food Contact Substance (FCS) through Food Contact Material (FCM) to Food Contact Article (FCA). The Food Contact Substance (the subject of an FCN) is a single substance, such as a polymer or an antioxidant in a polymer. As a substance, it is reasonably pure (the Chemist's definition of substance). Even though a polymer may be composed of several monomers, it still has a well-defined composition. Food Contact Material (FCM) is made with the FCS and (usually) other substances. It is often (but not necessarily) a mixture, such as an antioxidant in a polymer. The composition may be variable. The Food Contact Article is the finished film, bottle, dough hook, tray, or whatever that is formed out of the FCM.

(13) GRASGRAS is an acronym for the phrase Generally Recognized As Safe. Under sections 201(s) and 409 of the FD&C Act, any substance that is intentionally added to food is a food additive, that is subject to premarket review and approval by FDA, unless the substance is generally recognized, among qualified experts, as having been adequately shown to be safe under the conditions of its intended use, or unless the use of the substance is otherwise excluded from the definition of a food additive. GRAS substances are distinguished from food additives by the type of information that supports the GRAS determination, that it is publicly available and generally accepted by the scientific community, but should be the same quantity and quality of information that would support the safety of a food additive. Additional information on GRAS can be found on the GRAS Notification Program page.

(14) Guidance DocumentGuidance documents are documents prepared for FDA staff, applicants/sponsors, and the public that describe the agency's interpretation of or policy on a regulatory issue. Guidance documents include, but are not limited to, documents that relate to the design, production, labeling, promotion, manufacturing, and testing of regulated products; the processing, content, and evaluation or approval of submissions; and inspection and enforcement policies. Guidance documents do not legally bind the public or FDA or establish legally enforceable rights or responsibilities. They represent the agency's current thinking (21 CFR 10.115). A complete listing of CFSAN's guidance documents is available on the Internet.

(15) Indirect Food AdditiveIn general, these are food additives that come into contact with food as part of packaging, holding, or processing, but are not intended to be added directly to, become a component, or have a technical effect in or on the food. Indirect food additives mentioned in Title 21 of the U.S. Code of Federal Regulations (21 CFR) used in food-contact articles, include adhesives and components of coatings (Part 175), paper and paperboard components (Part 176), polymers (Part 177), and adjuvants and production aids (Part 178). Currently, additional indirect food additives are authorized through the food contact notification program. In addition, indirect food additives may be authorized through 21 CFR 170.39.

(16) PAFAThe Priority based Assessment of Food Additive (PAFA) database is a database that serves as CFSAN's institutional memory for the toxicological effects of food ingredients known to be used in the United States. Currently, PAFA contains oral toxicology information on over 2100 of approximately 3300 direct food ingredients used in food in the US. PAFA also contains minimal information on over 3200 indirect additives including the names, CAS number and regulatory information of the indirect additives in the Code of Federal Regulations. The EAFUS list and the Indirect Additive list on the CFSAN Internet consist of selected fields of information generated from PAFA.

(17) Prior Sanctioned SubstanceA substance whose use in or on food is the subject of a letter issued by FDA or USDA offering no objection to a specific use. The prior sanction exists only for a specific use of a substance in food delineating level(s), condition(s) and product(s) set forth by explicit approval by FDA or USDA prior to Sep. 6, 1958. Some prior sanctioned substances are codified in 21 CFR Part 181.

(18) SCOGS ReportSCOGS is the acronym for the Select Committee On GRAS Substances. Beginning in 1972, under a contract with FDA, the Life Sciences Research Office of the Federation of American Societies for Experimental Biology convened the Select Committee, which independently undertook a comprehensive review of the safety and health aspects of GRAS food substances on the FDA's then proposed GRAS list. The Select Committee published its evaluations in a series of reports known as the SCOGS Reports. A listing of opinions and conclusions from 115 SCOGS reports published between 1972 and 1980 is available on the CFSAN Internet.

(19) Secondary Direct Food AdditiveThis term is in the title of 21 CFR 173, which was created during recodification of the food additive regulations in 1977. A secondary direct food additive has a technical effect in food during processing but not in the finished food (e.g., processing aid). Some secondary direct food additives also meet the definition of a food contact substance. For more on food contact substances, consult the Food Contact Substance Notification Program.

(20) Threshold of Regulation (TOR) ExemptionA substance used in a food contact article may be exempted from the requirement of a food additive listing regulation if the use in question has been shown to meet the requirements in 21 CFR 170.39. For details, see 21 CFR 170.39. For a complete listing of the TOR exemptions, consult the Threshold of Regulation inventory on the CFSAN Internet.

(21) Film

(22) The present invention comprises a polyester film which can be laminated to a metal plate for canning which is typically made of tin-free steel, with a dimensional change of not more than 2.0% after a heat treatment of 210 C.

(23) The film is biaxially oriented and has at least two layer structure A/B, wherein A is a layer made from polyester having a melting point of 200-235 C. referred to as amorphous polyester (APET) which is laminated to the metal plate and B which has a melting point of 240-260 C. referred to as crystalized polyester (CPET)

(24) The above mentioned film also has a release coating which is applied inline to the CPET side of the film during the film making process.

(25) Polyester Film and Process

(26) Preferably the PET film suitable for use in the embodiments herein is biaxially oriented prior to laminating it to the metal substrate. The films are biaxially oriented by conventional methods. Typically, a raw material PET resin is supplied in solid form to a melt processing device, preferably a continuous screw extruder. The heating of the melt processor is controlled to maintain the PET resin above its melting point but below polymer degradation temperature. PET molten resin is extruded from an appropriately shaped die to form a thin, flat ribbon of polymer melt. The polymer ribbon is quenched in air and or on a chilled roll to form a solid, self-supporting film. The film is taken up by sets of rollers turning at different rotation speeds that stretch the film in the direction of continuous forward motion, referred to as the machine direction (MD). The stretching can be accompanied by heating of the film to establish crystal orientation in the MD. The mono-directionally oriented film is clamped at its opposite edges in and stretched in the transverse machine direction (TD) laterally perpendicular to the MD in a tenter oven. The tenter oven is heated to temperatures operative to establish crystal orientation in the TD thus forming a biaxially oriented PET film. Preferably biaxially oriented PET film for use in the embodiments herein is stretched about 100%-400% in the MD and 100%-600% in the TD. The biaxially oriented film can be heat set at temperatures can be preferably between about 300 F. and about 490 F., more preferably about 350 F. to about 460 F.

(27) The coating is applied after the MD stretch and is stretched in the TD direction along with the film and must be compatable with the thermal conditions necessary to heat set the film as mentioned above.

(28) Coating

(29) A food release coating that contains an effective amount one or more agents. The coating is typically applied to CPET side of the filmthe food side. The coating ingredients must be able to survive though the film making conditions, and also avoid transferring to the non-food side of the film with an agent that may reduce the adhesion of the APET, heat extrusion or adhesive layer that will be coated or extruded on the non-food side. The coating that we used in our product adhered well to the CPET polyester film.

(30) Starch

(31) Modified starches provide a solution for a wide variety of papermaking applications such as sizing, retention, strength, film-forming and coating. Starches are also used in adhesives used for corrugated boxes, multiwall bag. The textile industry relies on starches for sizing and finished fabrics. It is also used as natural binder systems for granular and fibrous applications for many different building products. Ceiling tiles, wallboard, paint and building adhesives are several examples. Starch can help optimize mining and drilling operations with natural binders and recovery aids.

(32) Acid-treated starch, also called thin boiling starch, is prepared by treating starch or starch granules with inorganic acids, e.g. hydrochloric acid breaking down the starch molecule and thus reducing the viscosity.

(33) Other treatments producing modified are: dextrin roasted starch with hydrochloric acid alkaline-modified starch with sodium hydroxide or potassium hydroxide bleached starch with hydrogen peroxide oxidized starch with sodium hypochlorite, breaking down viscosity enzyme-treated starch maltodextrin, cyclodextrin monostarch phosphate with phosphorous acid or the salts sodium phosphate, potassium phosphate, or sodium triphosphate to reduce retrogradation distarch phosphate by esterification with for example sodium trimetaphosphate, crosslinked starch modifying the rheology, the texture acetylated starch esterification with acetic anhydride hydroxypropylated starch, starch ether, with propylene oxide, increasing viscosity stability hydroxyethyl starch, with ethylene oxide starch sodium octenyl succinate starch used as emulsifier adding hydrophobicity starch aluminium octenyl Succinate cationic starch, adding positive electrical charge to starch carboxymethylated starch with monochloroacetic acid adding negative charge and combined modifications such as phosphated distarch phosphate acetylated distarch phosphate acetylated distarch adipate hydroxypropyl distarch phosphate acetylated oxidized starch
Crosslinking

(34) Oxidation of starch mainly causes the scission of the glucosidic linkages and oxidation of hydroxyl groups to carbonyl and carboxyl groups. The scission of the glucosidic linkage results in depolymerization of amylose and amylopectin, hence decreases swelling power and paste viscosity. Formation of the carbonyl and carboxyl groups discontinuously along the chains reduces gelatinization temperature, increases solubility, and decreases gelation.

(35) Crosslinker

(36) It is believed that after oxidation with NaOH to control the viscosity, the main functional group would still be the hydroxyl groups. Berrcet 2040 was chosen because it is a highly effective insolubilizing and crosslinking agent based on dialdehyde chemistry. Bercet 2040's reactivity is greatly accelerated during the drying cycle which results in higher wet rub and wet pick resistance. It also crosslinks all normally used synthetic and natural binders in pigmented or non-pigmented systems as well as reacting with the hydroxyl or amino group containing coating binders.

(37) In regards to food contact, Bercet 2040 is FDA compliant, subject to the provisions of: Title 21 CFR 176.180 without limitations, and Title 21 CFR 176.170, when used as an insolubilizing agent in starch and protein based coatings that contact foods.

(38) Gelatin Test

(39) In order to screen and test coating for release, a 5% gelatin solution was used as a substitute to a meat product. The gelatin was dissolved in boiling water and applied to the coated substrate while hot and left to dry overnight. As the gelatin cooled, it solidified on the surface with varying levels of release from the coating. A rating of 1 indicates complete release from the coating. 2 partial and 3 no release.

(40) Tape Test

(41) After drying, 3M 810 tape is applied to the coating surface with heavy finger pressure. The tape is then pulled off at a 45 degree angle as quickly as possible. The area under the tape was given a subjective rating from 1-3 based on how much of the coating has been pulled away from the surface. 1 being no coating removal, 2 being 20% and 3 being greater than 30% removal. This test is a measure how well the coating is adheres to the polyester film

(42) Retort Test

(43) A food mixture of egg/beef/flour at a ratio of 3/2/1 was prepared. The coated film was placed in a 8 oz glass canning jar with the coated layer facing the interior of the jar. If the laminated can is being tested a circular metal disk which has been laminated with coated polyester in a previous step is placed at the bottom of the jar. The meat mixture was placed in the jar against the coated side of the polyester. The jar is sealed, placed in a pressure cooker with water and heated to boiling on a hot. As used in relation to this invention, the term retort process means a procedure in which the inside or outside of a metal container with a wall composed of a composite of a metal substrate having a polymer film laminated onto the inside, the outside or both sides of the substrate is treated with live steam for a period of time. Live steam means that steam directly contacts the surface of the container. The steam is usually superheated, i.e., above the boiling point of water. A nominal retort process calls for exposure to steam at temperature of 260 F. for 90 minutes. The temperature and duration of exposure of the retort process can vary to provide an approximately equivalent sterilization and food pasteurization effectiveness. For example, the temperature might be higher for a shorter duration or lower for a longer duration.

(44) The jars were removed after 90 minutes and left to cool. The jars are tipped over and were rated with a percentage of how much food mixture easily fell off the film or laminated can.

(45) The term substantially all food contacting the BOPET during the retort test is released means that the percent release in the retort test before and after can lamination is greater than 80 percent, preferably at least 85 percent.

(46) Process of Dissolving Starch

(47) Starch granules are insoluble in cold water. When starch is heated in water, granules absorb water and swell. The absorption of water by amorphous regions within the granules destabilizes their crystalline structure. Upon continuous heating, granules tend to swell to greater extents, and the crystallites melt, resulting in increased molecular motion that eventually leads to complete separation of amylose and amylopectin. The typical way to dissolve starch in water is by heating to160-180 F for 10 min. This method leads to an unwanted increase in viscosity which would limit the amount of solids that can be used in a coating recipe. Using a Brookfield Viscosity (spindle #2 @ 100 rpm) the viscosity using this method is 100 cps.

(48) A preferred method of dissolving starch in water is to use an alkali to depolymerize the amylose and amylopectin, which decreases the swelling power of the starch. The viscosity using this method is 10 cps.

EXAMPLES AND COMPARATIVE EXAMPLES

(49) The invention is better understood with reference to the following Examples (Ex.) and Comparative (C. Ex.) to illustrate specific embodiments within the overall scope of the invention.

Comparative Example 1

(50) Acrylic emulsion, Neocryl A1095, was diluted to 8% solids with water and 4% wax emulsion was added and coated with a #3 mayer rod. After stretching 400% this gives an effective dry coat weight of 0.11 gsm. This film passes the retort and gelatin test but an acrylic polymeric binder would be not be favorable as a food additive.

Example 2

(51) 9% Starch, Purecoat B792 from GPC, is dispersed in water and then 2% solution of 10% Sodium hydroxide solution is mixed in. This does not have a wax additive. This passes the gelatin, retort and tape release tests and does not interfere or detract from food taste.

Example 3

(52) 9% Starch, Purecoat B790 from GPC, is dispersed in water and a 2% solution of 10% sodium hydroxide solution is added. A 1% solution of wax emulsion Syncera CW1245 fom Paramelt is also added. This passes the gelatin, tape and retort test and is the preferred example to pass both can lamination and the retort test

Comparative Example 4

(53) The polyester film without the release coat does not pass the retort and gelatin tests.

Comparative Example 5

(54) 100% canauba wax only. Release is good with the retort test before lamination but fails the retort test after lamination. This shows that the wax is sacrificial and is lost or reduced during the can lamination process.

Comparative Example 6

(55) Starch that is hydrated under normal thermal conditions with no NaOH and wax additives does not have high enough release properties after retort.

Comparative Example 7

(56) Starch oxidized with higher amount of NaOH showed poor release on the retort tests. It is hypothesized the higher pH degrades the proteins in the starch as opposed to creating crosslinking sites. Ideally NaOH addition should be 2-4% of the coating.

Comparative Example 8

(57) 8% Starch, Purecoat B792 by GPC was dissolved by the standard thermal method of heating in water for 10 minutes. A wax additive, Syncera CW 1245, Carnuba wax, was mixed into this solution. This did not pass the gelatin test and did not have the best adhesion before or after the retort test. The viscosity of this solution was 100 cps.

(58) Table 1 shows data on composition and test results of examples and comparative examples.

(59) TABLE-US-00001 TABLE 1 Test data on composition and test results Retort Retort Test after Test Gelatin Tape can before can Coating Composition % Test Test lamination lamination Example # Starch Acrylic NaOH Glyoxal wax water ranking ranking % release % release C. Ex. 1 0 8 0 0 4 88 1 2 90 100 Ex. 2 9 0 2 4 0 85 1 1 90 100 Ex. 3 9 0 2 4 1 84 1 1 100 100 C. Ex. 4 0 0 0 0 0 0 3 3 50 60 (base film) C. Ex. 5 0 0 0 0 6 94 1 3 70 90 C. Ex. 6 8 0 0 4 4 84 3 1 80 80 C. Ex. 7 9 0 5 4 0 82 3 1 50 60 C. Ex. 8 8 0 0 0 4 87 3 2 70 80

(60) Table 2 shows list of additives used in the embodiments herein.

(61) TABLE-US-00002 TABLE 2 Additives Additive Company Name Description type DSM Neoresins Neocryl A 1095 Acrylic emulsion Binder Grain Processing Purecoat B 792 Modified Food Binder Corp. (GPC) Starch Grain Processing Purecoat B 790 Modified Food Binder Corp Starch Paramelt BV Syncera CW 1245 Canauba Wax Release emulsion Aldrich NaOH Sodium Hydroxide pH control Bercen Inc Bercet 2040 Glyoxal crosslinker