Note: Descriptions are shown in the official language in which they were submitted.
WO 99/39588 PCTNS98/02511
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"ENVIRONMENTALLY FRIENDLY CHEWING
GUM BASES INCLUDING POLYHYDROXYALKANOATES"
The present invention relates generally to chewing gum compositions and
methods for making same. More specifically, the present invention relates to
chewing gum compositions that are more environmentally acceptable than typical
compositions.
For hundreds of years, people have enjoyed chewing gum like substances.
In the late 1800's, the predecessor to today's chewing gum compositions were
developed. Today chewing gum is enjoyed daily by millions of people worldwide.
Chewed gum is usually disposed of in the wrapper that initially houses the
chewing gum. Likewise, chewed gum can be disposed of in other substrates by
wrapping the substrate around the chewed gum.
Although chewed gum can be easily disposed of without creating any
problems, chewed gum when improperly disposed can create environmental issues.
In this regard, the improper disposal of chewed gum, e.g., expectorating the
chewed
2 0 gum on a sidewalk, floor, or like area can create a nuisance. Typically,
these gum
cuds are mainly composed of a water insoluble masticatory part which is
represented
by the gum base. Due to their formulations, these gum cuds have an adhesive
like
characteristic. Therefore, the chewed gum cuds can stick to surfaces on to
which
they are placed. This can create environmental sanitation issues if the chewed
gum
2 5 cuds are improperly discarded.
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The present invention provides a chewing gum base, and resultant chewing
gum, that is environmentally friendly. As used herein the term
"environmentally
friendly" refers to a chewing gum composition that: will degrade; and can be
easily
removed from indoor or outdoor surfaces.
Pursuant to the present invention environmentally friendly gum bases are
provided that include polyhydroxyalkanoates.
To this end, the present invention provides a chewing gum base comprising
approximately 1 to about 99% by weight polyhydroxyalkanoates having side chain
lengths of C4 to Cue.
The polyhydroxyalkanoates can be either homopolymers or copolymers of
monomers with different side chains.
In an embodiment, the gum base does not include non-biodegradable rubbers
and resins.
In an embodiment, the polyhydroxyalkanoates have side chain lengths of C6
to CZZ.
In an embodiment, the polyhydroxyalkanoates comprise approximately 10%
to about 99% by weight of the gum base.
In an embodiment, the polyhydroxyalkanoate is derived from natural
2 0 occurring plants.
In an embodiment, the polyhydroxyalkanoate is derived from a fermentation
process.
In an embodiment, the polyhydroxyalkanoate is derived from a transgenic
plants.
2 5 In an embodiment, the polyhydroxyalkanoates include low molecular weight
biodegradable resins.
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In an embodiment, the low molecular weight biodegradable resins are chosen
from the group consisting of polyterpenes and wood rosin esters.
In another embodiment of the present invention, a chewing gum base free of
non-biodegradable rubbers and resins is provided comprising approximately 3%
to
about 99% by weight polyhydroxyalkanoates having side chain lengths of C4 to
C3o
and a filler.
In an embodiment, the filler is chosen from the group comprising of zein, oat
fiber, gluten, casein, cellulose, as well as calcium carbonate, talc,
magnesium
silicate, and other inorganic fillers.
In an embodiment, the polyhydroxyalkanoates have side chain lengths of C6
to Czo.
In an embodiment, the polyhydroxyalkanoates comprise approximately 10%
to about 80% by weight of the gum base.
In an embodiment, the polyhydroxyaikanoate is derived from natural
occurring plants.
In an embodiment, the polyhydroxyalkanoate is derived from a fermentation
process.
In still another embodiment, a chewing gum is provided comprising a water
soluble portion and a water insoluble base that includes at least one
2 0 polyhydroxyalkanoate having a chain length of C4 to C3o.
It is an advantage of the present invention to provide an environmentally
friendly chewing gum base.
Still further, it is an advantage of the present invention to provide a
chewing
gum composition made from an environmentally friendly chewing gum base.
2 5 Another advantage of the present invention is to provide a degradable
chewing gum containing an environmentally friendly chewing gum base.
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Moreover, an advantage of the present invention is to provide a chewing gum
composition that when chewed, if improperly discarded will degrade naturally.
An additional advantage of the present invention is to provide a gum base
that includes environmentally friendly polyesters derived from either
fermentation
of carbohydrates or extraction of natural plants.
Still, an advantage of the present invention is to provide a source of
polyesters for the gum base that are firom renewable resources.
Additional features and advantages of the present invention are described in,
and will be apparent from the detailed description of the presently preferred
1 o embodiments and from the drawings.
ERIEF DESCRIPTION OF THE DRAWINGS
Figure 1 illustrates schematically the synthesis and degradation of
polyhydroxyalkanoates. As shown, they are from renewable resources and
therefore
are much more environmentally friendly than petroleum-based synthetic
polymers.
DETAILED DESCRIPTION
OF THE PRESENTLY PREFER_RFD EMEODI1VIENT~
The present invention provides improved chewing gum base. Specifically,
2 0 ~ the present invention provides chewing gum bases that are
environmentally friendly.
In this regard, the chewing gum base includes polyhydroxyalkanoates.
Additionally, improved chewing gums as well as ingredients used for chewing
gum
bases are described.
The chewing gum base of the present invention includes
2 5 polyhydroxyalkanoates. It has been surprisingly found drat gum bases
formed with
polyhydroxyalkanoates can be constructed so that they are biodegradable.
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Additionally, the chewing gums made from such gum bases possess similar
characteristics to conventional chewing gums.
Polyhydroxyalkanoates are a class of polymers that have rapid
biodegradability. Polyhydroxyalkanoates exist in some natural plants and also
can
be synthesized by a fermentation process. Thus, polyhydroxyalkanoates are
renewable polyesters that can be used to construct chewing gum. Figure 1
illustrates
schematically the cycle of polyhydroxyalkanoates.
Polyhydroxyalkanoates have the following general structure:
~"' jn
where R--H-C", and m~-3
Depending on the length of the side chain "R", the polymers can either be
plastics (short side chains) or elastomers (long side chains). Short side
chain
polyhydroxyalkanoates tend to be highly crystalline and lack elasticity. They
do not
therefore offer certain of the desirable chewing characteristics required by
chewing
Polyhydroxyallcanoates with long side chains, such as those having at least
2 0 four carbon lengths, e.g. C4 - C3o, have very little crystallinity and
possess high
elasticity. This is due to an increase in free volume. These long side chain
polyhydroxyalkanoates can thereby be used to replace rubbers and resins that
are
used in conventional gum bases. This results in a gum base that is not only
readily
biodegradable, but, additionally the ingredients are from renewable resources.
2 5 Moreover, the resultant gums possess similar chewing characteristics to
conventional
chewing gums.
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The present invention can be used to construct a variety of chewing gums.
In general, a chewing gum composition typically comprises a water-soluble bulk
portion, a water-insoluble chewable gum base portion and flavoring agents. The
water-soluble portion dissipates with a portion of the flavoring agent over a
period
of time during chewing. The gum base portion is retained in the mouth
throughout
the chew. The term chewing gum refers to both a chewing and a bubble gum type
gum in its general sense.
The insoluble portion of the gum, usually referred to as the gum cud,
typically may contain any combination of elastomers, vinyl polymers, elastomer
l0 plasticizers, fillers, softeners, waxes and other optional ingredients such
as colorants
and antioxidants.
The variety of gum base ingredients typically used provide the ability to
modify the chewing characteristics of gums made finm the gum base.
Elastomers provide the rubbery, cohesive nature to the gum which varies
depending on this ingredient's chemical structure, levei in the gum base, and
how it
may be compounded with other ingredients.
Elastomers suitable for use in the gum base and gum of the present invention
include polyhydroxyalkanoates having linear or branched saturated or
unsaturated
side chains of C4-Cue. Preferably, the polyhydroxyalkanoates have normal or
iso-side
2.0 chains of C4-Cue, and most preferably C$-C,B. The polyhydroxyalkanoates
elastomers
can have only one-size side chains, or any combination of different side
chains
throughout the polymer main chains.
Natural elastomers used in conventional gum bases may include natural
rubber such as smoked or liquid latex and guayule, natural gums such as
jelutong,
2 5 lechi caspi perillo, massaranduba balata, massaranduba chocolate, nispero,
rosidinha,
chicle, gutta percha, gaffe kataiu, niger gaffe, tuna, chilte, chiquibul,
gutta hang
kang. Synthetic elastomers used in conventional gum bases may include high
WO 99/39588 PCT/US98/02511
molecular weight elastomers such as butadiene-styrene copolymers and
isobutylene-
isoprene copolymers, low to high molecular weight elastomers such as
polybutadiene and polyisobutylene, vinyl polymeric elastomers such as
polyvinyl
acetate, polyethylene, vinyl copolymeric elastomers such as vinyl
acetate/vinyl
laurate, vinyl acetate/vinyl stearate, ethylene/vinyl acetate, polyvinyl
alcohol or
mixtures thereof.
The elastomers for use in a gum base or gum of the present invention are the
polyhydroxyalkanoates alone or in combination with other typical gum base
ingredients. However, the gum base and gum of the present invention are free
of
non-degradable elastomers such as butadiene-styrene copolymers, isobutylene-
isoprene copolymers, polybutadiene, polyisobutylene, and vinyl polymeric
elastomers (polyvinyl acetate, polyethylene, vinyl acetate/vinyl laurate,
vinyl
acetate/vinyl stearate, ethylene/vinyl acetate) or mixtures thereof.
More preferably, the polymers used are polyhydroxyalkanoates alone, as
better illustrated in the pending Examples below.
Other optional ingredients such as antioxidants may also be used in the gum
base. Antioxidants pmlong shelf life and storage of gum base, finished gum or
their respective components including fats and flavor oils. Antioxidants
suitable for
use in gum base or gum of the present invention include butylated
hydroxyanisole
2 0 (BHA), butylated hydroxytoluene (BHT), beta-carotenes, tocopherols,
acidulants
such as Vitamin C, ascorbic acid, propyi gallate, other synthetic and natural
types of
mixtures thereof.
Preferably, the antioxidants used in the gum base are butylated
hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tocopherols, or mixtures
2 5 thereof.
Waxes aid in the curing of the gum made from the gum base as well as
improve shelf life and texture. Wax crystal also improves the release of
flavor. The
WO 99/3958$ PCT/US98/02511
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smaller crystal size allows slower release of flavor since there is more
hindrance of
the flavor's escape from this wax versus a wax having larger crystal sizes.
Elastomer plasticizers vary the firmness of the gum base. Their specificity
on elastomer inter-molecular chain breaking (plasticizing) along with their
varying
softening points cause varying degrees of finished gum firmness and
compatibility
when used in base. This may be important when one wishes to provide more
elastomeric chain exposure to the alkanic chains of the waxes.
Elastomer plasticizers optionally suitable for use in the present invention
include natural rosin esters such as glycerol ester of partially hydrogenated
rosin,
glycerol ester of polymerized rosin, glycerol ester of partially dimerized
rosin,
glycerol ester of rosin, glycerol ester of tall oil rosin, pentaerythritol
esters of
partially hydrogenated rosin, partially hydrogenated methyl esters of rosin,
pentaerythritol ester of rosin, synthetic elastomer plasticizers such as
terpene resins
derived from alpha- pinene, beta-pinene and/or d-limonene and mixtures
thereof.
Occasionally, both terpene and rosin ester resins may be used in the present
invention. The terpene rosin ester ratios may range from about 1:15 to about
15:1.
Softeners modify the texture of the base and introduce sharp melting
transitions during chewing. Softeners suitable for use in the gum base and gum
of
the present invention include triglycerides of non-hydrogenated, partially
2 0 hydrogenated and fully hydrogenated cottonseed, soybean, palm, palm
kernel,
coconut, safflower, tallow, cocoa butter, medium chain triglycerides and the
like.
The preferred softeners include unsaturated, partially saturated or fully
saturated oils that contain, as one or more of their constituent groups, fatty
acids of
carbon chain length of from 6 to 18.
2 5 Monoglycerides, diglycerides, acetylated monoglycerides, distilled mono-
and diglycerides and lecithin may, from their manufacturing processing,
contain
triglyceride levels less than 2 percent by weight. Though these ingredients
are
WO 99/39588 PCT/US98/02511
_ g _
softeners, they would not be considered as being of the same family as the
above
mentioned softeners oils and would be in a family of their own, namely
emulsifiers.
Optional fillers used in gum base modify the texture of the gum base and aid
in processing. Fillers suitable for use in the gum base and gum of the present
invention include carbonate or precipitated carbonated types such as magnesium
and
calcium carbonate, ground limestone and silicate types such as magnesium and
aluminum silicate, clay, alumina, talc, as well as titanium oxide, mono-, di-
and
tricalcium phosphate, cellulose polymers such as ethyl, methyl and wood or
mixtures
thereof.
The fillers can also be organic powders such as polystyrene, polyethylene,
oat fiber, wood fiber, apple fiber, zero, gluten, gliadin, casein, etc. For
the present
invention, natural organic fillers such as zero, oat fiber, gluten, casein,
and cellulose
are preferred since they will aid in faster biodegradation.
Particle size has an effect on cohesiveness, density and processing
. characteristics of the gum base and its compounding. The smaller the panicle
size,
the more dense and cohesive the final gum base. Also, by selecting fillers
based on
their particle size distribution, initial mass compounding may be varied, thus
allowing alteration of the compounding characteristics of the initial mass
during gum
base processing and ultimately the final chew characteristics of gums made
from
2 0 these gum bases.
Talc filler may be used in the gum base and gum of the present invention that
may come in contact with or employ acid flavors or provide an acidic
environment
needed to prevent degradation of an artificial sweetener by reacting with
calcium
carbonate type fillers. Mean particle size for calcium carbonate and talc
fillers
2 5 typically range from about 0.1 micron to about 1 S microns.
More preferably, the optional fillers used have a mean particle size range
from about 0.4 to about 14 microns and are calcium carbonate and talc.
WO 99/39588 PCTNS98/02511
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The starting mass preferably may comprise one or more of filler,
polyhydroxyalkanoates, and elastomer plasticizes. Preferably, the starting
mass is
comprised of some or all of the polyhydroxyalkanoates elastomer, some or all
of the
filler, and some or all of the elastomer plasticizes. The levels of gum base
ingredients present in the starting mass may range from about 0 percent to
about 40
percent elastomer plasticises, 0-1 S percent vinyl polymer, 0 to 40 percent
fillers, and
finm about 10 percent to about 40 percent elastomer, all by weight of the gum
base
ingredient.
Flavorants and colorants impart characteristics or remove or mask undesired
characteristics. Colorants may typically include FD&C type lakes, plant
extracts,
fivit and vegetable extracts and titanium dioxide. Flavorants may typically
include
cocoa powder, heat-modified amino acids and other vegetable extracts.
Preferably, the optional colorants and flavorants are FD&C lakes and cocoa
powder respectively and are present at levels fibm about 0 percent to about 15
percent by weight.
Gum bases are typically prepared by adding an amount of the elastomer,
elastomer plasticizes and filler, and on occasion a vinyl polymer, to a heated
(50-
240°F) sigma blade mixer with a front to rear speed ratio of from about
1.2:1 to
about 2:1, the higher ratio typically being used for chewing gum base which
requires
2 0 more rigorous compounding of its elastomers.
The initial amounts of ingredients comprising the initial mass may be
determined by the working capacity of the mixing kettle in order to attain a
proper
consistency and by the degree of compounding desired to break down the
elastomer
and increase chain branching. The higher the level of filler at the start or
selection
2 5 of a filler having a certain particle size distribution, the higher the
degree of
compounding and thus more of the elastorneric chain cross linking are broken,
causing more branching of the elastomer thus lower viscosity bases and thus
softer
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final gum base and gum made from such a base. The longer the time of
compounding, the use of lower molecular weight or softening point gum base
ingredients, the lower the viscosity and firmness of the final gum base.
Compounding typically begins to be effective once the ingredients have
massed together. Anywhere from 15 minutes to 90 minutes may be the length of
compounding time.
Preferably, the time of compounding is from 20 minutes to about 60 minutes.
The amount of added elastomer plasticizes depends on the level of elastomer
and
filler present. If too much elastomer plasticizes is added, the initial mass
becomes
over plasticized and not homogenous.
After the initial ingredients have mass homogeneously and compounded for
the time desired, the balance of the base ingredients are added in a
sequential manner
until a completely homogenous molten mass is attained. Typically, any
remainder
of elastomer, elastomer plasticizes, vinyl polymer and filler, are added
within 60
minutes after the initial compounding time. The filler and the elastomer
plasticizes
would typically be individually weighed and added in portions during this
time. The
optional waxes and the oils are typically added after the elastomer and
elastomer
plasticizers and during the next 60 minutes. Then the mass is allowed to
become
homogenous before discharge. '
2 o Typical base processing times may vary from about one to about three
hours,
preferably finm about 1 %Z to 2'/2 hours, depending on the formulation. The
final
mass temperature when dumped may be betw~n 70°C and 130°C and
preferably
between 100°C and 120°C. The completed molten mass is emptied
from the mixing
kettle into coated or lined pans, extruded or cast into any desirable shape
and allowed
2 5 to cool and solidify. Those skilled in the art will recognize that many
variations of
the above described procedure may be followed.
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Examples of the process to make the inventive gum base may differ fmm the
typical process and are detailed in the pending Examples below. These are
presented
to exemplify embodiments of the present invention and in no way are presented
to
limit the scope of the present invention.
Gum formulas may comprise from about 10 to about 95 weight percent a
gum base made in accordance with the present invention in a gum formula
typically
known to those in the art.
The water-soluble portion of the chewing gum may comprise softeners,
sweeteners, flavoring agents and combinations thereof. The sweeteners often
fill the
role of bulking agents in the gum. The bulking agents generally comprise from
about 5 percent to about 90 percent, preferably from about 20 percent to about
80
percent.
Softeners are added to the chewing gum in order to optimize the chewability
and mouth feel of the gum. Softeners typically constitute from about 0.5
percent to
about 25.0 percent by weight of the chewing gum. Softeners contemplated for
use
in the gum include glycerin, lecithin and combinations thereof. Further,
aqueous
sweetener solutions such as those containing sorbitol, hydrogenated starch
hydrolysates, corn syrup and combinations thereof may be used as softeners and
bulking agents in gum. Sugar-free formulations are also typical.
2 o Sugar sweeteners generally include saccharide-containing components
commonly known in the chewing gum art which comprise, but are not limited to,
sucrose, dextrose, maltose, dextrin, dried invert sugar, fructose, levulose,
galactose,
corn syrup solids and the like, alone or in any combination.
The sweetener for use in the present invention can also be used in
2 5 combination with sugarless sweeteners. Generally, sugarless sweeteners
include
components with sweetening characteristics but which are devoid of the
commonly
known sugars and comprise, but are not limited to, sugar alcohols such as
sorbitol,
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mannitol, xylitol, hydrogenated starch hydrolysates, maltitol and the like,
alone or
in any combination.
Depending on the particular sweetness release profile and shelf life stability
needed, bulk sweeteners of the present invention can also be used in
combination
with coated or uncoated high-intensity sweeteners or with high-intensity
sweeteners
coated with other materials and by other techniques.
High-intensity sweeteners, or artificial sweeteners and peptide sweeteners as
they may be referred to, typically may include, but are not limited to,
alitame,
thaumatin, aspartame, sucralose, acesulfame, saccharin and dihydrochalcones.
The
1 o range of these sweetener types in gum typically may range from about 0.02
to 0.10
weight percent for sweeteners such as alitame, thaumatin and dihydrochalcones,
and
from about 0.1 to about 0.3 weight percent for sweeteners like aspartame,
sucralose,
acesulfame and saccharin.
A flavoring agent may be present in the chewing gum in an amount within
the range from about 0.1 to about 10.0 weight percent and preferably from
about 0.5
to about 3.0 weight percent of the gum. The flavoring agents may comprise
essential
oils, synthetic flavors, or mixtures thereof including, but not limited to,
oils derived
from plants and fiuits such as citrus oils, fruit essences, peppermint oil,
spearmint
oil, clove oil, oil of wintergreen, anise and the like. Artificial flavoring
components
2 0 are also contemplated for use in gums of the present invention. Those
skilled in the
art will recognize that natural and artificial flavoring agents may be
comhined in any
sensory acceptable blend. All such flavors and flavor blends are contemplated
for
use in gums of the present invention.
Optional ingredients such as colourants, emulsifiers and pharmaceutical
2 5 agents may be added to the chewing gum.
In general, chewing gum is manufactured by sequentially adding the various
chewing gum ingredients to a commercially available mixer known in the art.
After
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the initial ingredients have been thoroughly mixed, the gum mass is discharged
from
the mixer and shaped into the desired form such as by rolling into sheets and
cutting
into sticks, extruded into chunks or casting into pellets.
Generally, the ingredients are mixed by first melting the gum base and adding
it to the running mixer. The base may also be melted in the mixer itself.
Colourants
or emulsifiers may also be added at this time. A softener such as glycerin may
also
be added at this time, along with syrup and a portion of the bulking
agent/sweetener.
Further portions of the bulking agent/sweetener may then be added to the
mixer. A
flavoritng agent is typically added with the final portion of the bulking
1 o agent/sweetener. A high-intensity sweetener is preferably added after the
final
portion of bulking agent and flavor have been added.
The entire mixing procedure typically takes from five to fifteen minutes, but
longer mixing times may sometimes be required. Those skilled in the art will
recognize that many variations of the above described procedure may be
followed.
By way of example, and not limitation, examples of the present invention
will now be given:
Ezample 1
To a laboratory gum base mixer (Plastograph from Brabender Corp.,
Rochelle Parl~ N.>) set at 90°C, 35 grams of polyhydroxyalkanoate (PHA-
1) was
2 0 added, then 20 grams of calcium carbonate powder (mean particle=4.5-S.0
micron)
was slowly added while the mixer compounded the polymer. ' After 20 minute
mixing, 2.5 grams of fully hydrogenated cotton seed oil and 2 grams of
partially
hydrogenated soya oil were added. The gum base was homogeneous and smooth.
The PHA-1 elastomer that was added was a copolymer of 3-hydroxctanote
and 3-hydroxynhexanote (about 91:9 ratio). It possess a Tg of -35°C. A
Tm of
61 °C, and heat of fusion DH=15.0 J/g as revealed by differential
scanning
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calvrimetry (DSC). Gel permation chromatography (GPC) showed Mn=75,000 and
Mw=127,000 relative to polystyrene standards. X-ray crystallinity is less than
25%.
Example 2
Same as Example 1, but PHA-2 was used in place of PHA-1. PHA-2 is a
copolymer of units with side chains Cg and C,~. It was much softer than PHA-1.
GPC analysis showed Mn=65,000 g/mol and Mw=106,700 g/mol relative to
polystyrene standards. DSC showed Tg=-30°C, Tm=61 °C, and
DH=15.0 J/g.
Example 3
Same as Example 1, but oat fiber (200 mesh through) was used to replace
calcium carbonate.
Example 4
Same as Example 1, but talc was used to replace calcium carbonate.
Example 5
To a laboratory gum mixer set at 50°C was added 25 grams of gum
base
Example 1, 77 grams of 6x sugar, 25.5 grams of 45Be corn syrup and mix them
for
minutes. Then 0.6 g 96% glycerol and 0.8 grams of peppermint flavor was added.
Additional 5 minutes was continued before discharging.
Example 6
To the gum mixer set at 50°C was added 20.0 grams of PHA-2, 5
grams of
2 0 C,C03 powder, 59.4 grams of 6x sugar powder, and 20 grams of 45 Be corn
syrup.
After mixing for 20 minutes, 0.6 grams of peppermint oil were added.
Additional
5 minutes mixing was extended before discharging the gum.
It should be understood that various changes and modifications to the
presently preferred embodiments described herein will be apparent to those
skilled
2 5 in the art. Such changes and modifications can be made without departing ~
from the
spirit and scope of the present invention and without diminishing its
attendant
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advantages. It is therefore intended that such changes and modifications be
covered
by the attendant claims.
