U.S. patent application number 13/862684 was filed with the patent office on 2013-09-05 for delivery of preservatives by food packaging.
This patent application is currently assigned to NEVADA NATURALS, INC.. The applicant listed for this patent is NEVADA NATURALS, INC.. Invention is credited to Anthony J. Sawyer, Richard F. Stockel.
Application Number | 20130231389 13/862684 |
Document ID | / |
Family ID | 49043180 |
Filed Date | 2013-09-05 |
United States Patent
Application |
20130231389 |
Kind Code |
A1 |
Sawyer; Anthony J. ; et
al. |
September 5, 2013 |
Delivery Of Preservatives By Food Packaging
Abstract
A composition comprising a polymeric material and a preservative
combination of 1) a preservative component selected from the salts
of N.sup..alpha.--(C.sub.1-C.sub.18) acyl di-basic amino acid
(C.sub.1-C.sub.18) alkyl ester; 2) a second component selected from
a food-safe solvent, food-safe nonionic surfactant or mixtures
thereof; and optionally; 3) a third component consisting of an acyl
mono-glyceride, wherein the preservative is diffusible from the
polymeric material.
Inventors: |
Sawyer; Anthony J.;
(Albuquerque, NM) ; Stockel; Richard F.;
(Bridgewater, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NEVADA NATURALS, INC. |
Albuquerque |
NM |
US |
|
|
Assignee: |
NEVADA NATURALS, INC.
Albuquerque
NM
|
Family ID: |
49043180 |
Appl. No.: |
13/862684 |
Filed: |
April 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12658200 |
Feb 4, 2010 |
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13862684 |
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12589155 |
Oct 19, 2009 |
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12658200 |
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13065972 |
Apr 4, 2011 |
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12589155 |
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61686869 |
Apr 13, 2012 |
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Current U.S.
Class: |
514/551 |
Current CPC
Class: |
B65D 81/28 20130101;
A01N 25/10 20130101; A01N 47/44 20130101; A01N 2300/00 20130101;
A01N 37/12 20130101; A01N 25/10 20130101; A01N 25/34 20130101; A01N
25/34 20130101; B65D 85/00 20130101; A01N 47/44 20130101 |
Class at
Publication: |
514/551 |
International
Class: |
B65D 85/00 20060101
B65D085/00 |
Claims
1. A composition comprising a polymeric material and a preservative
combination comprising 1) a preservative component selected from
salts of N.sup..alpha.--(C.sub.8-18) acyl di-basic amino acid
(C.sub.1-C.sub.8) alkyl ester, and 2) a second component selected
from a food-safe solvent with Hildebrand Solubility Parameter of at
least 11, a food-safe surfactant with an HLB between 4.0 and 25,
and mixtures thereof, wherein said preservative is diffusible from
said polymeric material.
2. The composition of claim 1, wherein said preservative
combination further includes a third component consisting of an
acyl mono-glyceride.
3. The composition of claim 2, wherein said acyl mono-glyceride has
an acyl chain length of between 8 and 16.
4. The composition of claim 3, wherein said acyl mono-glyceride is
glycerol monolaurate.
5. The composition of claim 1, wherein said
N.sup..alpha.--(C.sub.8-18) acyl di-basic amino acid
(C.sub.1-C.sub.8) alkyl ester is selected from
N.sup..alpha.--(C.sub.8-C.sub.18) acyl lysine (C.sub.1-C.sub.8)
alkyl ester, N.sup..alpha.--(C.sub.8-C.sub.18) acyl arginine
(C.sub.1-C.sub.8) alkyl ester, N.sup..alpha.--(C.sub.1-C.sub.18)
acyl ornithine (C.sub.8-C.sub.18) alkyl ester,
N.sup..alpha.--(C.sub.1-C.sub.8), acyl histidine (C.sub.1-C.sub.8)
alkyl ester and N.sup..alpha.--(C.sub.8-C.sub.18) acyl tryptophan
(C.sub.1-C.sub.8) alkyl ester.
6. The composition of claim 5, wherein said
N.sup..alpha.--(C.sub.8-C.sub.18) acyl di-basic amino acid
(C.sub.1-C.sub.8) alkyl ester is selected from salts of
N.sup..alpha.-lauroyl arginine ethyl ester and N.sup..alpha.-cocoyl
arginine ethyl ester.
7. The composition of claim 1, wherein said salts of said
preservative component include an inorganic anion selected from
chloride, bromide and iodide.
8. The composition of claim 1, wherein said salts of said
preservative component include an organic anion selected from the
group consisting of acetate, glycolate, lactate, propionate,
gluconate, octonoate, decanoate, and ascorbate and its
derivatives.
9. The composition of claim 1, wherein said solvent of said second
component is selected from the group consisting of glycerol,
1,2-propanediol, 1,3-propanediol and mixtures thereof.
10. The composition of claim 1, wherein said surfactant is selected
from the group consisting of sorbitan mono-caprate, sorbitan
mono-caprylate, sorbitan mono-laurate, sorbitan mono-myristate,
sorbitan mono-palmitate, sorbitan monostearate, sorbitan
mono-oleate, ethoxylated sorbitan mono-caprate, ethoxylated
sorbitan mono-caprylate, ethoxylated sorbitan monolaurate,
ethoxylated sorbitan mono-myristate, ethoxylated sorbitan
mono-palmitate, ethoxylated sorbitan monostearate, ethoxylated
sorbitan mono-oleate and mixtures thereof.
11. The composition of claim 1, wherein said preservative component
is present in an amount of about 0.1% to about 80 wt. % of said
preservative combination.
12. The composition of claim 1, wherein said second component is
present in an amount of about 0.1% to about 80 wt. % of said
preservative combination.
13. The composition of claim 2, wherein said third component is
present in an amount of about 0.1 to about 50 wt. % of said
preservative combination.
14. The composition of claim 1, wherein said plastic polymer is
selected from: linear or branched very low density, low density,
medium density and high density polyethylene, polypropylene,
polystyrene, ethylene vinyl acetate, polyethylene terephthalate
(PET, PETE), polycarbonate, polyolefins, polycarbonate,
metallocene-type polyethylene, polylactic acid, bioplastics based
on starch, cellulose and polyester, polyvinylidene chloride,
ionomers, polyamides, polyvinyl alcohols, cellulose and modified
cellulose including chitosan, polypropylene copolymers,
poly(ethylene-vinyl acetate) copolymers, polystyrene copolymers,
polyvinyl chloride copolymers, polyvinylidene chloride copolymers,
polyethylene terephthalate copolymers, polyvinyl acetate
copolymers, polycarbonate copolymers, polyamides copolymers,
polyvinyl alcohol copolymers, cellulose and modified cellulose
copolymers including chitosan, and mixtures thereof.
15. The composition of claim 1, wherein said polymeric material is
in the form of a packaging film.
16. A food packaging product comprising a polymeric material and a
preservative combination comprising 1) a preservative component
selected from salts of a N.sup..alpha.--(C.sub.8-C.sub.18) acyl
di-basic amino acid (C.sub.1-C.sub.8) alkyl ester; 2) a second
component selected from a food-safe solvent with Hildebrand
Solubility Parameter of at least 11, a food-safe nonionic
surfactant with an HLB between 4.0 and 25 and mixtures thereof; and
optionally 3) a third preservative component consisting of an acyl
mono-glyceride.
17. The food packaging product of claim 16, wherein said plastic
polymer is selected from: linear or branched very low density, low
density, medium density and high density polyethylene,
polypropylene, polystyrene, ethylene vinyl acetate, polyethylene
terephthalate (PET, PETE), polycarbonate, polyolefins,
polycarbonate, metallocene-type polyethylene, polylactic acid,
bioplastics based on starch, cellulose and polyester,
polyvinylidene chloride, ionomers, polyamides, polyvinyl alcohols,
cellulose and modified cellulose including chitosan, polypropylene
copolymers, poly(ethylene-vinyl acetate) copolymers, polystyrene
copolymers, polyvinyl chloride copolymers, polyvinylidene chloride
copolymers, polyethylene terephthalate copolymers, polyvinyl
acetate copolymers, polycarbonate copolymers, polyamides
copolymers, polyvinyl alcohol copolymers, cellulose and modified
cellulose copolymers including chitosan, and mixtures thereof.
18. The food packaging product of claim 16, wherein said package is
mono-layered or multi-layered.
19. The food packaging product of claim 16, wherein said plastic
polymer is present in an amount of about 90 to 99 wt. % of said
packaging product, said preservative component is present in an
amount of about 0. 01 to about 8 wt. % of said packaging product,
said second component is present in an amount of about 0.01% to
about 10 wt. % of said packaging product, and said third component
is present in an amount of 0. 01% to about 5.0 wt. % of said
packaging product.
20. The food packaging product of claim 16, wherein said first
component is selected from salts of N.sup..alpha.-lauroyl arginine
ethyl ester and N.sup..alpha.-cocoyl arginine ethyl ester; said
second component is a solvent selected from the group consisting of
glycerol, 1,2-propanediol, 1,3-propanediol; a surfactant selected
from sorbitan mono-caprate, sorbitan mono-caprylate, sorbitan
mono-laurate, sorbitan mono-myristate, sorbitan mono-palmitate,
sorbitan monostearate and sorbitan mono-oleate, ethoxylated
sorbitan mono-caprate, ethoxylated sorbitan mono-caprylate,
ethoxylated sorbitan mono-myristate, ethoxylated mono-palmitate,
ethoxylated sorbitan monostearate, ethoxylated sorbitan mono-oleate
and mixtures thereof, or a mixture of said solvent and said
surfactant; and said third component is glycerol monolaurate.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional
Application No. 61/686,869 filed Apr. 12, 2012. This application is
also a Continuation-In-Part Application to U.S. Ser. No. 12/658,200
filed Feb. 4, 2010, which is a Continuation of Application U.S.
Ser. No. 12/589,155 filed Oct. 19, 2009, now abandoned. This
application is also a Continuation-In-Part Application to U.S. Ser.
No. 13/065,972.
FIELD OF THE INVENTION
[0002] The present invention is directed towards plastic packaging
comprising diffusible preservatives.
BACKGROUND OF THE INVENTION
[0003] Food quality and safety (longevity) are major concerns in
the food industry. Contamination of foods with bacteria normally
occurs at the surface due to post processing handling. For
decontamination, antimicrobial sprays or dips are often applied. A
drawback of external sprays and dips is that the active
preservatives can be neutralized on contact or diffuse rapidly from
the surface into the food mass. On the other hand a gradual
diffusion of the preservative from packaging materials allow the
preservatives continuously to come into contact with the food for
an extended period of time to kill bacteria, before being absorbed
by the food or deactivated by materials released by the foods. The
diffusion method extends the time during which the food is in
contact with preservatives, and maintains an effective level of the
preservative around the food. The shelf life of the food is thereby
maximized.
[0004] Incorporating preservatives into thermoplastics is an
emerging technology that could have a significant impact on shelf
life extension and food safety.
[0005] According to The Wiley Encyclopedia of Packaging Technology,
the packaging materials may act as a carrier for antimicrobial
agents to perform their active role to control microorganisms. Some
of the antimicrobial agents may be coated or directly incorporated
into the packaging materials and subsequently migrate to the food
system. The antimicrobial action is achieved by release of the
antimicrobial agents from the packaging material. The released
antimicrobial agents can control the growth of microorganisms by
many different mechanisms, for example, such as by altering cell
membrane properties or by inhibiting essential metabolic pathways
of the microorganisms.
[0006] Most spoilage incidents occur primarily at the food surface
by the contamination of microorganisms. A concentration of
antimicrobial agent above its minimum inhibitory concentration
("MIC") is required to inhibit microbial growth and above its
minimum bactericidal concentration ("MBC") to kill the microbes.
Without the antimicrobial packaging concept, an excess amount of
preservatives such as benzoates and sorbates should be included in
foods to control the spoilage microorganisms. Thus, releasing
antimicrobial additives to the food surface conveniently increases
the additives concentration in the food surface above the MBC or
MIC while maintaining a preservative concentration inside the food
at sufficiently low level. Considering that the use of
preservatives for shelf-life extension has been strictly controlled
by food safety authorities, antimicrobial packaging is advantageous
in reducing potential risks of consuming excess amount of food
preservatives.
[0007] An additional advantage of antimicrobial packaging is its
sustainable antimicrobial activity. The antimicrobial agents
initially included in food ingredients might be inactivated by
interacting with other food components. For example, bacteriocins
and enzymatic antimicrobial agents applied to foods or onto the
food surfaces may interact with proteolytic enzymes in food and may
cause the loss of antimicrobial activities. Alternatively,
antimicriobial agents can be adsorbed onto food surfaces and
thereby lose their activity in the moisture surrounding the foods.
On the contrary, incorporation of the above substances in packaging
films prevents loss of antimicrobial activity while they remain in
the packaging film allowing continuing antimicrobial activity due
to their continuous controlled release from the packaging film.
Hence antimicrobial activity is maintained over longer periods.
[0008] Another advantage of antimicrobial packaging is the
maintenance of sterility of the packaging material in the event
that it is inadvertently contaminated with pathogenic bacteria
prior to use.
[0009] In most cases the incorporated antimicrobials dissolve in
the moisture surrounding the food. They then migrate to the food
surface in dissolved form. The migrating solutes are nonvolatile
materials such as organic acids and their salts, enzymes,
bacteriocins, fungicides and some natural extracts. The
antimicrobials act on bacteria that may be dispersed in the
moisture around the packaged foods and on the bacteria, which are
on the surface of the food. The surface of the food includes the
crevices and cracks within the bulk of the food where bacteria can
migrate and grow.
[0010] Diffusion is the mechanism by which nonvolatile solute is
transferred through the film matrix and it also controls the
release rate from the film. The migration kinetics of nonvolatile
solute follows Fick's second law of diffusion, where the diffusion
coefficient depends on the type of film materials, microstructural
voids in film matrix, and environmental temperature. The migration
of the antimicrobial agents from the film to the food surface can
be by direct contact with the food surface, through a very thin
layer of moisture surrounding the food or through copious liquids,
which are generally aqueous, in which the food is immersed. Contact
between the film matrix, the food surface, the surface moisture or
bulk liquid surrounding the food throughout the shelf-life of the
food is needed for antimicrobial migration and, consequently, for
effective preservative action. For this, the food should be a
continuous matrix without any factors that interfere with the
diffusional migration. This food matrix can be a liquid solution, a
semisolid paste, or a smooth solid matrix without significant
pores, holes, heterogeneous particles or a porous solid with pores,
holes or crevices. The antimicrobial agents on the food surface
will move through the food in solution by diffusion. Diffusion can
be through bulk liquids in which the food is immersed or through
the thin layer of surface moisture on the outside or within the
food. For example, raw meat, not suspended in an aqueous solution,
has an outer exposed surface surrounding the meat. This surface
will have a layer of surface moisture, which might be very thin,
e.g. 5 water molecules thick, or it might be quite thick e.g. 10
microns thick. Within the meat there are numerous pathways, for
example between the meat fibers, which are covered with surface
moisture. Diffusion will thus be both on the outer surface of the
meat or on the surfaces of the fibers within the meat. The
solubility and diffusion coefficients of the agent in the food are
very important factors that govern the rate of agent removal in the
food surface. The antimicrobial concentration on the food surfaces
needs to be maintained above the MIC and preferably above the MBC
for effectiveness in controlling the microbial growth.
[0011] By having functional preservative ingredients either in the
bulk or on the surface of the packaging film, the microbial
population can be controlled. Many classes of preservatives have
been evaluated in film structures both synthetic and natural. Also,
various kinds of packaging materials such as polyolefins and edible
polymers have been tested. Currently, polyethylene is the most cost
effective packaging film. In particular LDPE (low density
polyethylene) and LLDPE (linear low density polyethylene) are
preferred packaging materials. While natural or modified natural
polymers like chitosan or water swellable polymers are also
mentioned in the literature to be useful, they are not practical
from a cost-effective point of view.
[0012] When preservatives are incorporated into or on the surface
of packaging, they can diffuse through the packaging film and
migrate into the liquid surrounding the food and onto the food
surface. If the packaging is the sole source of preservative, a
good contact between the preservative film and food surface is
essential. A number of both synthetic and natural antimicrobials
have been investigated as a choice of preservatives with limited
success, because none have been shown to be effective against a
broad range of pathogens likely encountered in packaged foods.
Examples of known preservatives are nisin, grapefruit seed extract,
and triclosan. Triclosan is undesirable as a food additive since
its safety is unknown. Also, triclosan could be deactivated by
fatty acids found in meats, perhaps due to micelle formation or
absorption into the fat.
[0013] Further, preservative films are not commonly employed,
because logistics involved in the manufacture of preservative films
also affect the release of the preservatives and the performance of
the films. When a preservative is added to bulk plastic, it must
not deteriorate during film fabrication, distribution, and storage.
The preservative is preferably heat stable during extrusion at
temperatures that may exceed 200.degree. C., and stable to the
shear forces and pressure involved in the process conditions. Also,
the preservatives used must not adversely affect or discolor the
package polymeric materials.
[0014] When delivering preservatives from package films, an
important factor is the ability of the preservative to diffuse
through the packaging material to the film surface. In many cases
it is desirable for the preservative to dissolve in the liquid
surrounding the food substances. Compounds such as hydrochloride
salts of N.sup..alpha.-lauroyl arginine ethyl ester ("LAE") and
N.sup..alpha.-cocoyl arginine ethyl ester ("CAE") are safe and
effective as preservatives for foods and food products. These salts
are easily metabolized in the human body, and they rapidly
hydrolyze into their constituent amino acid, fatty acid and alcohol
components, all of which are benign and are further broken down
eventually into carbon dioxide, water and ammonium salts.
[0015] U.S. 2010/0056628 to Stockel, et al. teaches a
controlled-release composition comprising
N.sup..alpha.--(C.sub.1-C.sub.22) acyl di-basic amino acid
(C.sub.1-C.sub.22) alkyl ester cationic molecules, and polymeric or
monomeric anion.
[0016] U.S. Ser. No. 13/065,972 to Stockel, et al. teaches a method
of preserving food using LAE and an anionic counterion in a food
product packaging. None of these references addresses the issue
that LAE is only slowly soluble in water, or recognizes that LAE
might have difficulties in diffusing through plastic films or
diffuse therefrom.
REFERENCES
[0017] Buonocore, G. G., Sinigaglia, M., Corbo, M. R., Bevilacqua,
A., La Notte, E., Del Nobile, M. A. J. Food Prot., 67, (2004), pp
1190-1194 [0018] Cagri et al., J. Food Science 66, (2001), pp
865-870 [0019] Cagri et al., J., Food Science 67, Number 4, (2004),
pp 833-848(16) [0020] Chen et al., J. Food Preservation 20, (1996),
pp 379-3890 [0021] Perez et al., Advances in Agricultural and Food
Biotechnology (2006), p. 193-216
SUMMARY OF THE INVENTION
[0022] A composition comprising a polymeric material and a
preservative combination comprising 1) a preservative component
selected from the salts of N.sup..alpha.--(C.sub.1-C.sub.18) acyl
di-basic amino acid (C.sub.1-C.sub.18) alkyl ester; 2) a second
component selected from a food-safe solvent, food-safe nonionic
surfactant and mixtures thereof; and optionally 3) a third
component consisting of an acyl mono-glyceride, wherein the
preservative is diffusible from the polymeric material. The present
invention is further directed towards an article comprising the
polymeric material and the preservative combination, wherein the
article is in the form of food packaging.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] For a fuller understanding of the nature and advantages of
the present invention, reference should be made to the following
detailed description read in conjunction with the accompanying
drawings.
[0024] FIG. 1 illustrates ATR spectrums of two polymeric films,
each respectively contains 4% poly alpha olefin ("PAO"), with or
without 1% LAE. A full spectrum of 100% LAE ("Neat LAE") is also
shown. An arrow indicates spectrum peaks specific for LAE.
[0025] FIG. 2 illustrates ATR spectrums of two polymeric films,
each respectively contains 4% mineral oil, with or without 1% LAE.
An arrow indicates spectrum peaks specific for LAE.
[0026] FIG. 3 illustrates ATR spectrums of two polymeric films,
each respectively contains 2% glycerol, with or without 1% LAE. An
arrow indicates spectrum peaks specific for LAE.
[0027] FIG. 4 illustrates an ATR spectrum of a polymeric film that
contains 2% 1,3-propanediol and 1% LAE, and an ATR spectrum of a
polymeric film that contains 2% glycerol and 1% LAE. An arrow
indicates spectrum peaks specific for LAE.
[0028] FIG. 5 illustrates ATR spectrums of four polymeric films,
each contains a different amount of 1,3-propanediol, with or
without 1% LAE. An arrow indicates spectrum peaks specific for
LAE.
[0029] FIG. 6 illustrates ATR spectrums of four polymeric films,
each respectively contains 1% LAE with an enhancement additive. An
arrow indicates spectrum peaks specific for LAE.
DETAILED DESCRIPTION OF THE INVENTION
[0030] The present invention is directed to a composition
comprising a polymeric material and a preservative combination
comprising 1) a preservative component selected from the salts of
N.sup..alpha.--(C.sub.1-C.sub.18) acyl di-basic amino acid
(C.sub.1-C.sub.18) alkyl ester; 2) a second component selected from
a food-safe solvent, food-safe nonionic surfactant and mixtures
thereof; and optionally 3) a third component consisting of an acyl
mono-glyceride, wherein the preservative is diffusible from the
plastic film. The invention is also directed towards an article
produced from the polymeric material and the preservative
combination, wherein the article is in the form of packaging
products.
The Preservative Component
[0031] The preservative component of this invention comprises a
salt of N.sup..alpha.--(C.sub.1-C.sub.18) acyl di-basic amino acid
(C.sub.1-C.sub.18) alkyl ester. The dibasic amino acid portion of
the salt is selected from the group consisting of arginine, lysine,
histidine, ornithine and tryptophan. The formation of a mono-acyl
amide combined with esterification of the carboxylic acid from the
dibasic amino acid results in a compound with one active cationic
center. The preferred dibasic amino acids are arginine, ornithine
and lysine with arginine being the most preferred.
[0032] While the chain length of the acyl group can be between 1
and 18 carbons in length, it is preferred that the acyl chain
length be between 8 and 18. While the chain length of the alkyl
group can be between 1 and 18 carbons in length, it is preferred
that chain length be between 1 and 8 carbons. In any event, the
total number of carbons in the acyl and alkyl chains on the salt of
N.sup..alpha.--(C.sub.1-C.sub.18) acyl di-basic amino acid alkyl
(C.sub.1-C.sub.18) ester should be between about 8 and 20. Examples
of preferred preservative components are salts of
N.sup..alpha.-lauroyl arginine ethyl ester and salts of
N.sup..alpha.-cocoyl arginine ethyl ester. The anionic portion of
the salt is not critical to the preservative performance of the
salt as long as the aqueous solubility of the preservative salt is
above the MIC and preferably above the MBC of the spoilage
bacteria. Preferably the aqueous solubility of the first component
should be at least 100 ppm and preferably more than 500 ppm of the
total composition at room temperature. Examples of the anionic
portion of the first component preservative salt include, but are
not limited to, an inorganic ion such as chloride, bromide and
iodide, or an organic carboxylate ion, such as acetate, glycolate,
lactate, propionate, gluconate, octanoate, decanoate, or ascorbate
and its water soluble derivates thereof.
[0033] A useful amount of the preservative component is in a range
of about 0.1% to 80 wt. % of the preservative combination. When the
preservative component is being incorporated into an article such
as food packaging or products for human use, an amount of 0.1 to 8
wt. % of the article is useful.
Second Component
[0034] The second component of this invention comprises either a
solvent or surfactant delivery enhancing agent or a mixture
thereof. A critical property of the solvent, if used as the sole
delivery-enhancing agent, is its Hildebrand Solubility Parameter
("HSB"). To be effective it needs to be significantly greater than
the Hildebrand Solubility Parameter of the plastic used for the
packaging. The Hildebrand Solubility Parameter is a numerical
value, which that indicates the cohesive forces between the
individual molecules of substances. The molecules in a substance
with a low Hildebrand Solubility Parameter have limited cohesive
forces holding them together generally being limited to weak Van
Der Waal forces while the molecules in a compound with a high
Hildebrand Solubility Parameter have much stronger cohesive forces
which might include, for example, intermolecular hydrogen bonding.
In relative terms, two substances with a similar Hildebrand
Solubility Parameter will dissolve in one another, whereas two
substances with very different Hildebrand Solubility Parameters
will tend not to mix. Therefore, Hildebrand Solubility Parameters
are most useful in determining the relative solvency behavior or
solubility of a solute in a specific solvent. Hildebrand Solubility
Parameters are derived from the heat of vaporization. The
Hildebrand Solubility Parameter, .delta., is equal to the square
root of the cohesive energy and can be calculated from the
following equation:
.delta.= c=[(.DELTA.H-RT)]/V.sub.m].sup.1/2
where c=cohesive energy density, .DELTA.H=heat of vaporization,
R=gas constant, T=temperature, V.sub.m=molar volume.
[0035] Polymeric materials such as polyethylene, polypropylene and
polystyrene have relatively low Hildebrand Solubility numbers,
because these plastics consist of hydrogen and carbon atoms only.
Plastics like nylon have higher Hildebrand Solubility Parameters
due to the additional presence of oxygen atoms in the molecule,
which allow for hydrogen bonding.
[0036] It is well known in the literature that if the
hydrophobicity of any salt is increased, the diffusion
("diffusibility") of the salt through any polymer is decreased.
This is particularly true for a very hydrophobic polymer such as
PE, polypropylene, or copolymers thereof. This is because of the
solubility of the hydrophobic salt in a hydrophobic polymer and
that more potential energy is required for the hydrophobic salt to
diffuse through the polymer layer.
[0037] For polyethylene, polypropylene and polystyrene plastic
films and packages, we have found that a preferable range for the
Hildebrand Solubility Parameter of the surfactant or solvent
delivery-enhancing agent is equal to or above 11 more preferably
above 15. When the Hildebrand Solubility Parameter of the
surfactant or solvent delivery-enhancing agent is lower than about
11, the primary preservative component tends to be highly
"compatible" with the plastic film and hence does not migrate
readily to the plastic film surface. Furthermore the solvent does
not promote diffusion of the primary preservative component into or
through the aqueous moisture surrounding the food. When the
Hildebrand Solubility Parameter of the solvent or surfactant is
above 11 it causes the preservative component to diffuse through
polyethylene, polypropylene and polystyrene films, which have
Hildebrand Solubility Parameters below 9.0, during manufacture, so
that much of the preservative component is at or close to the
surface of the plastic film. With polycarbonate and nylon films,
the minimum Hildebrand Solubility Parameter needs preferably to be
higher, for example, from about 13 or higher to help diffusion
through the plastic film and for much of the preservative component
to migrate to the surface of the plastic film during manufacture.
Examples of suitable solvents or surfactants include but are not
limited to, glycerol or glycerin, 1,2-propanediol, and
1,3-propanediol. It must be noted that hydrocarbon-based compounds,
such as poly alpha olefin and mineral oil, are not desirable
because they have very low Hildebrand Solubility Parameter. Indeed
these liquids may encase the preservative in the polymeric material
and assure minimal diffusion of the preservative through the
plastic film.
[0038] Another advantage of using a solvent with a high Hildebrand
Solubility Parameter is that it helps the preservative dissolve in
the aqueous layer surrounding the food and helps it migrate to
where it is needed for its preservative benefits. In this regard a
Hildebrand Solubility Parameter of between 20 and 35 is ideal.
[0039] A critical property of the surfactant, if used as part of or
all of delivery enhancing agent is its Hydrophilic-Lipophilic
Balance ("HLB"), which should be between about 4.0 and 25. A
preferred range for HLB is between about 10.0 and 20.0. The HLB of
a surfactant is its balance between hydrophilic and hydrophobic
properties, which defines how water-soluble or water miscible it is
and how oil soluble or oil miscible it is. Surfactants with
relatively low HLBs tend to mix easily with oils and are effective
in producing water in oil emulsions whereas surfactants with
relatively high HLBs tend to mix easily with water and are
effective at producing oil in water emulsions. The presence of
surfactants with the right HLB tend to help to rapidly disperse the
preservative component into the aqueous medium surrounding the food
being preserved. Furthermore surfactants or the right HLB help the
moisture surrounding the food to more effectively wet all surfaces
and hence to enhance coverage of the preservative component.
[0040] Examples of suitable surfactants include, but are not
limited to, to sorbitan mono-carboxylates such as sorbitan
mono-caprate, sorbitan mono-caprylate, sorbitan mono-laurate,
sorbitan mono-myristate, sorbitan mono-palmitate, sorbitan
monostearate and sorbitan mono-oleate, some of which are
manufactured under the trade name "Span". Also suitable are the
ethoxylated sorbitan mono carboxylates such as ethoxylated sorbitan
mono-laurate (polysorbate 20), ethoxylated sorbitan mono-caprate,
ethoxylated sorbitan mono-caprylate, ethoxylated sorbitan
mono-myristate (polysorbate 40), ethoxylated sorbitan
mono-palmitate (polysorbate 60), ethoxylated sorbitan monostearate
(polysorbate 80) and ethoxylated sorbitan mono-oleate, some of
which are manufactured under the trade name of "Tween".
[0041] When incorporating the solvent or surfactant into the bulk
polymeric material such as plastic film, another critical property
of the solvent or surfactant is their ability to withstand
degradation due to heat. Specifically, the solvent and surfactant
have to be stable at the melt temperature of the polymer substrate,
e.g. LDPE, LLDPE, or VLDPE melt between about 140.degree. C. to
about 200.degree. C. Also, the melt process can be conducted under
an inert atmosphere, e.g. N.sub.2, etc. Therefore, to be practical,
the second component solvent or surfactant must be stable to
temperatures above about 200.degree. C. Thus many solvents or
surfactants with an appropriate .delta. value of greater than about
11.0 cannot be used due to their heat sensitivity. For example,
ethanol, with .delta.=12.92, cannot be used because it is volatile
and boils at 78.degree. C.
[0042] Another factor is the safety of the solvent or surfactant.
To be useful in foods, the solvent or surfactant needs to be
completely food safe, i.e. it needs to be considered GRAS.
Therefore, although solvents such as ethylene glycol
(.delta.=16.3), have useful solubility parameters, many are known
to be toxic to humans and not useful for the present invention.
[0043] A useful amount of the second component is in the range of
0.1 to 80 wt. % of the preservative combination. When the component
is being incorporated into an article such as food packaging or
products for human use, an amount of 0.01 to 8 wt. % is useful.
Third Component
[0044] The optional third component, acyl monoglyceride, is an
agent, which we have found to be synergistic with the first
preservative component. To be effective the acyl monoglyceride
should have 8 to 16 carbons in the acyl group. The preferred acyl
monoglyceride is glycerol monolaurate. Glycerol monolaurate is a
GRAS food additive, which is found naturally in breast milk.
Glycerol monolaurate has been shown to synergistically enhance the
effectiveness of lauroyl arginine ethyl ester hydrochloride as a
food preservative. A useful amount of acyl monoglyceride is in a
range of about 0.1 to about 50 wt. % of the preservative
combination. An amount of 0.1 to 5 wt. % of acyl monoglyceride is
also useful.
Polymeric Material
[0045] Examples of suitable polymeric material include, but are not
limited to linear or branched very low density, low density, linear
low density, medium density and high density polyethylene,
polypropylene, polystyrene, ethylene vinyl acetate, polyethylene
terephthalate (PET, PETE), modified polyethylene and ethylene
copolymers, and polycarbonate. Other suitable polymeric materials
include polyolefins and copolymers thereof, polyesters, polyvinyl
chloride, polyacrylate, polyamide, etc., that are suitable for
packaging food products. More suitable polymeric materials include
metallocene-type polyethylene, polylactic acid, bioplastics based
on starch, cellulose and polyester, polyethylene, polypropylene,
poly(ethylene-vinyl acetate), polystyrene, polyvinylidene chloride,
ethylene copolymers and ethylene carboxylic acid copolymers,
ethylene alkyl ester copolymers, ethylene cyclic olefin copolymers,
polyethylene terephthalates, polyvinyl acetate, polycarbonate,
polyamides, polyvinyl alcohols, cellulose and modified cellulose
including chitosan, polyethylene copolymers, polypropylene
copolymers, poly(ethylene-vinyl acetate) copolymers, polystyrene
copolymers, polyvinyl chloride copolymers, polyvinylidene chloride
copolymers, ionomers, polyethylene terephthalate copolymers,
polyvinyl acetate copolymers, polycarbonate copolymers, polyamide
copolymers, polyvinyl alcohol copolymers, and cellulose and
modified cellulose copolymers including chitosan. In particular,
modified polyethylene and ethylene copolymers such as
ethylene/hexene plastomer sold under the trade name EXACT.RTM. by
ExxonMobil are useful.
[0046] The polymeric material is in the form of a film or a
coating. The polymeric film can be made of any type of plastic,
which can be used to package or store foods or other products for
human use.
[0047] Furthermore, the invention is also directed towards an
article such as a preservative package for foods or other products
for human use comprising about 90 to 99.9 wt. % of a polymeric
material, by weight of the packaging material, and a preservative
combination comprising 1) about 0.01 to about 8%, by weight of the
packaging material, of a preservative component selected from salts
of N.sup..alpha.--(C.sub.1-C.sub.18) acyl di-basic amino acid
(C.sub.1-C.sub.18) alkyl ester, (2) a second component in an amount
of from about 0.01% to about 10.0%, by weight of the packaging
material, either of a food-safe (GRAS, or "Generally Recognized As
Safe") solvent with a Hildebrand Solubility Parameter of 11 and
above and a thermal stability above 200.degree. C., a nonionic
surfactant with an HLB between 4.0 and 25 and a thermal stability
above 200.degree. C., or mixtures thereof; and optionally (3) from
about 0.01 to about 5.0%, by weight of the packaging material, of a
third component consisting of an acyl mono-glyceride, which may be
synergistic with the first preservative component.
[0048] For articles such as preservative packages, the polymeric
material is preferably in the form of a film layer. The package
itself can be either mono-layered or multi-layered, such that the
preservative combination is present in the layer that is in a
direct contact with the contained food or product for human use,
while any extra layer within the package provides protection and
other properties
[0049] Additionally, this invention is also directed towards a
method of preserving food or products for human use by the
application or incorporation of from 0.01 to about 10% by weight of
the packaging material of a preservative combination onto or into
packaging material containing the food or products for human use,
the preservative combination comprising (1) about 0.1% to about
80%, by weight of the combination, of a preservative component
selected from salts of N.sup..alpha.--(C.sub.1-C.sub.18) acyl
di-basic amino acid alkyl (C.sub.1-C.sub.18) ester, and (2) from
about 0.1% to about 80%, by weight of the combination, of a second
component consisting either of a food-safe solvent with a
Hildebrand Solubility Parameter of at least 11 and a thermal
stability above 200.degree. C., from about 0.1% to 80%, by weight
of the combination of a nonionic surfactant with an HLB between 4.0
and 25 and a thermal stability above 200.degree. C., or mixtures
thereof and, optionally, (3) from about 0.01% to 5% by weight of
the combination of a third component consisting of an acyl
mono-glyceride, which may be synergistic with the preservative
component.
EXAMPLE 1
[0050] Preparation of Multi-Layered Film Comprising Enhancement
Additives with or without LAE
[0051] Firstly, pellets of polymers with enhancement additives were
produced. Secondly, those pellets were coated with or without
LAE-HCl, melted, mixed and re-formed into pellets. Thirdly, the
pellets from the second step were melted and extruded to form a
surface layer of a multilayer film.
Step 1. Preparation of Polymer/Additive Masterbatch Pellets
[0052] EXACT.RTM. 3040 ethylene/hexene plastomer (ExxonMobil
Chemical Company, Houston, Tex.) was loaded into a hopper and fed
into the main feed port of a 50 mm co-rotating twin screw
extruder.
[0053] The feed zone of the twin screw extruder was heated to
95.degree. C. and the remainder of the extruder and die was heated
to 150.degree. C. The plastomer was fed into the extruder screws,
and was extruded at 250 RPM. Upon establishing a stable extrudate,
an additive selected from polyalpha olefin fluid, mineral oil,
glycerolol or glycerine and 1,3-propanediol was delivered into the
molten plastomer with a gear pump via an injection port. Each
additive was added to a separate but equal amount of extrudate.
[0054] Upon exiting the mixing section, the polymer/additive blend
moved through the extruder's pressurization section and a four-hole
die to form continuous strands. The strands were immediately
chilled in a water bath. Upon exiting the water bath, an air knife
removed the remnant surface moisture on the strands. Lastly, the
strands where cut into pellets by a rotating knife.
Step 2. Preparation of Polymer/Synergist/LAE.HCl Blend Pellets
[0055] 0.1 Kg of the LAE-HCl powder was blended with the previously
made plastomer-additive pellets, and sufficient plain plastomer
pellets were balanced to produce a final batch of 10 kg. The amount
of plastomer-additive pellets varied according to the different
additives. This mixture was fed into a 50 mm twin screw extruder at
about 45 kg/hr. The twin screw extruder homogenized the mixture at
150 RPM in heated condition.
[0056] Once mixed, the blend moved through a pressurization section
and a four-hole die to form continuous strands. The strands were
immediately chilled in a water bath. Upon exiting the water bath,
an air knife removed the remnant surface moisture on the strands.
Lastly, a rotating knife cut the strands into pellets. A set of
pellets without LAE-HCl was also produced. In the samples without
LAE-HCl, 0.1 kg of plain pellets were used as replacement. By mass
balance, the pellets comprised each additive in final amounts that
ranged from 2 to 6 wt. % as listed in Table 1, with or without 1.0%
LAE-HCl with the remainder being plastomer.
Step 3. Preparation of Polymer/Synergist/LAE.HCl Blend Films
[0057] A three-extruder cast film line equipped with a die was
configured to produce cast film comprising three discrete
layers.
[0058] The first surface layer of the film comprised a blend of 75%
by weight of EXACT.RTM. 3040 ethylene/hexene plastomer and 25%
BYNEL.RTM. 41E710 maleic anhydride-grafted polyethylene (E. I. du
Pont de Nemours and Company, Wilmington, Del.). The center layer
comprised Nippon Gohsei SOARNOL ET3803, a hydrolyzed copolymer of
ethylene and vinyl acetate (Noltex, LLC, LaPorte, Tex.). A second
surface layer comprised pellets of the processed blend from step
2.
[0059] The extruder used to process the blend from step 2 had four
zones and each operated under different heated conditions. The
speed of the extruder was set to 80 RPM. The back pressure, motor
load and melt temperature depended on the specific composition
being processed. Upon exiting the die at about 200 mm wide, the
film was immediately chilled on a cold, rotating roll maintained at
a temperature of 15.degree. C. The chilled film was wound into a
roll.
[0060] The multi-layer film samples were subjected to ATR
measurement. ATR, or Attenuated Total Reflectance, is an FTIR-based
means of characterizing the infrared spectrum of the surface
penetrating 0.5-5.0 microns of a tested object. ATR measurement of
the film indicated the relative abundances of LAE on the surfaces
of the plastic films. An ATR measurement was also conducted on the
LAE compound alone ("NEAT LAE") to detect peaks that identify the
presence of LAE.
[0061] As shown in FIG. 1, the ATR spectrum of "NEAT LAE" shows
peaks between 1800 cm-1 and 1640 cm-1. During the subsequent
analyses, the signals between 1640 cm-1 and 1800 cm-1 baseline are
arbitrarily defined as a measurement of the relative abundance of
LAE on the surface of the film.
[0062] Also, in FIG. 1, it can be shown that the film that contains
4% PAO with or without LAE shows little or no presence of LAE on
the surface of the film.
EXAMPLE 2
[0063] Two film samples were produced according to the method
described in Example 1. One film sample contained 4% mineral oil
and 1% LAE, the other film contained 4% mineral oil and no LAE. An
ATR measurement was conducted on the samples. The ATR results as
shown in FIG. 2 indicate that same as in the previous example,
there were little or no peaks of LAE on the surface of the tested
films. Thus, there was little or no diffusion of LAE using mineral
oil as the enhancement additive.
EXAMPLE 3
[0064] Two film samples were produced according to the method as
described in Example 1. One film sample contained 2% glycerol and
1% LAE, and the other film sample contained 2% glycerol and no LAE.
An ATR measurement was conducted on the samples. The ATR results as
shown in FIG. 3 indicate that contrary to Examples 2 and 3, there
is one sharp peak around 1640 cm-1, indicating a significant
presence of LAE, and therefore indicating that LAE had diffused to
the surface of the film sample.
EXAMPLE 4
[0065] Two film samples were produced according to the method as
described in Example 1. The first film sample contained 2% glycerol
and 1% LAE, and the second film sample contained 2% 1,3-propandiol
and 1% LAE. An ATR measurement was conducted on the samples. The
ATR results as shown in FIG. 4 indicate that although there was
some diffusion of LAE to the surface in the second sample, a
greater presence of LAE had diffused to the surface in the first
sample.
EXAMPLE 5
[0066] Four film samples were produced according to the method as
described in Example 1. The first sample contained 2%
1,3-propandiol. The second sample contained 4% 1,3-propandiol and
the third sample contained 6% 1,3-propandiol. All of these samples
also contained 1% LAE. The fourth sample contained 2%
1,3-propandiol, without LAE. ATR measurements were conducted on the
samples. The ATR results, as shown in FIG. 5, indicate that
heightened amounts of the 1,3-propandiol increased the presence of
LAE on the surface of the film. Baseline and peak values were
determined from FIG. 5.
TABLE-US-00001 TABLE 1 1640 cm.sup.-1/ Additive Concentration 1800
cm.sup.-1 1640 cm.sup.-1 1800 cm.sup.-1 1,3-propanediol 2% 0.0256
0.029 1.14 glycerol 2% 0.0248 0.036 1.44
EXAMPLE 6
[0067] Four film samples were prepared according to the method as
described in Example 1. The first film sample contained 2% glycerol
and 1% LAE, the second film sample contained 4% 1,3-propandiol and
1% LAE, the third film sample contained 4% mineral oil and 1% LAE,
and the fourth sample contained 4% PAO and 1% LAE.
[0068] ATR measurements were conducted on all four samples. The ATR
results as shown in FIG. 6 indicate that that the first and second
samples have a higher surface presence of LAE than the third and
fourth samples. This result again demonstrates that solvents of
Hildebrand Solubility Parameter of at least 11 facilitate diffusion
of LAE to the surface of the film, while solvents with lower
Hildebrand Solubility Parameter, such as hydrocarbon compounds
retain the LAE within plastic and thereby hinder diffusion.
Baseline and peak values were determined from FIG. 6.
TABLE-US-00002 TABLE 2 1640 cm.sup.-1/ Additive Concentration 1800
cm.sup.-1 1640 cm.sup.-1 1800 cm.sup.-1 mineral oil 4% 0.0195 0.027
1.36 PAO fluid 4% 0.0195 0.027 1.36 1,3-propanediol 4% 0.0195 0.043
2.21 Glycerol 2% 0.0195 0.037 1.90
* * * * *