Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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EDIBLE CASING FILM FORMULATION
Background of the Invention
For a number of years, edible films have been used
to replace membranes and casings made of animal viscera,
in the production of smoked meat products such as ham and
sausages. Currently available edible films include
collagen films, modified cellulose films and carrageenan-
based films.
Collagen films are composed of edible collagen,
plasticized with glyerol or other polyols. They are
manufactured by extrusion onto a belt followed by drying
to remove the moisture. The collagen slurry is applied
to the belt cold, and requires high-temperature drying to
remove all the excess moisture and bring the film to a
final moisture content of approximately 100. Apart from
the difficulty in processing films of this kind, these
materials can bring about allergic reactions in certain
consumers. Too, being derived from the coum layer of
beef or pork, collagen may be an unacceptable casing or
film material for religious and dietary reasons.
Modified cellulose films are for the most part
composed of modified hydroxypropyl methylcellulose. To
date, almost all films of this kind which have been
produced are cold water-soluble films which begin to
disintegrate on contact with water. For this reason,
they have not been used in meat processing.
Carrageenan is a polyanionic polysaccharide derived
from red algae. The material is an excellent film-former
and has been used in the formulation of edible food
packaging films (U. S. Patent No. 4,851,394) and heat-
sealable edible films (U.S. Patent No. 5,089,307 -
Ninomiya et al.). Films composed primarily of
carrageenan additionally exhibit excellent strength, are
not soluble in cold water and bind well to meat
substrates . SUBSTITUTE SH~~T' (SULK 26)
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However, because carrageenan forms a
thermoreversible gel, films composed of a predominant
carrageenan proportion tend to disintegrate in hot water,
i.e. above 70°C. The hot carrageenan aqueous solution
then re-gels upon contact with cooler water, less than
50°C.
It was one of our objectives to develop carrageenan-
based films which can effectively and economically
replace edible collagen films currently utilized in ham
and sausage production, while providing high yields and
high-quality product.
Collagen film is typically wrapped around hams
during production, for ease in netting removal after the
ham has been cooked. Collagen films appear to the
consumer to be part of the ham after cooking and, indeed,
are usually not taken note of by the average consumer.
Many styles of meats are processed using collagen films,
including various ham, chicken and turkey products.
General Descriution and Objects of the Invention
It is an object of the present invention to provide
polysaccharide films which would function well by
satisfying all of the following key attributes:
- composed of food ingredients which meet Food
Chemical Codex Specifications and are approved for
usage, i.e. GRAS rated in the United States
(generally regarded as safe).
- a film that would maintain its composition during
the cooking cycle, until the ham forms its own
natural protein skin.
- after cooking, film adheres to the finished product,
in that it does not fully disintegrate after a
prolonged exposure to hot water or steam.
- film is tender to eat following processing of the
meat product.
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film binds to the meat surface during and subsequent
to processing.
- film is permeable to flavouring smoke.
- film imparts an appealing shine and colour to the
cooked product.
We have found that excellent properties for edible
films can be achieved by including, along with the
carrageenan, suitable non-thermoreversible gel-forming
polymers, preferably Konjac and Gellan gums. Konjac is
extracted from the konjac tuber. This polysaccharide
hydrates immediately and can form either thermoreversible
or non-thermoreversible gels, depending on the conditions
under which the gel is formed. Gellan gum is a
polysaccharide gum produced from bacterial fermentation.
It is a strong gel former and produces gels that are non-
thermoreversible in the presence of Ca+z and other
multivalent anions. Both Konjac and Gellan gums are
edible and GRAS rated. We observed that Konjac tends to
form gels having a higher degree of elasticity than
Gellan, which forms gels having a more brittle texture.
According to present invention, edible films and
casing materials comprise a polymer base of
carrageenan/Konjac/Gellan, and also a suitable starch,
alginate or other polysaccharide, depending on the
specific attributes required.
Starch functions to reduce water absorption of the
film and it is preferred that a high-amylose starch be
used, as high-amylose starch is inherently a better film-
former than other starches.
"Alginate" herein refers to the alginates which are
commonly used in the food industry, namely polypropylene
glycol alginate, sodium alginate or calcium alginate.
Alginate in compositions according to the present
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invention tend to produce strong films exhibiting good
adhesion.
Specific methods and formulations are described in
more detail below, but generally we have found the
following compositions to provide useful edible films:
Component Suggested Range
Low (wt.%) High (wt.%)
Carrageenan 2 35
Gellan* 0 35
Konj ac* 0 35
Locust bean gum (LBG) 0 10
Protein 0 15
Starch** 0 2 0
Alginate** 0 35
Sodium Citrate 1 5
Sorbitan Monostearate 0.25 3
Glycerol 1.0 35
Other Plasticizert 0 25
Water 8 35
2 0 ~~ total of Gellan & Konjac
gums should be no less than
about
5 wt% and up to about 35 wt%
total of starch + alginate should be no less than about
5 wt% and up to about 35 wt%
polyhydric alcohols, other than glycerol
The synergistic effects of the main polymers, Gellan
Konjac and carrageenan, function to produce a film of
high tensile strength, hot and cold water resistance and
gum substrate adherence.
The use of a protein source is desirable to provide
the film with both improved adhesion and shine
functionality. The presence of some (at least about 50)
of alginatge or starch component is necessary to give
sufficient film casing adhesion.
Other polysaccharides, as discussed below, may be
added to impart specific desired properties to the film.
Glyerol was added for its elasticizing effects.
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Optionally, calcium chloride or potassium carbonate may
be utilized to improve the film strength and hot water
resistance.
From other formulations tested it is possible to
significantly alter the relative amounts of each gel-
forming polymer in the film to produce films exhibiting
some varying degree of hot water solubility.
Detailed Description of the Invention
Polymer solutions were prepared for film casting as
follows: glyerol or other plasticizers were added to the
requisite amount of hot water. While maintaining the
solution at an elevated temperature (80-90° C), then the
dry ingredients were added and the solution vigorously
mixed to homogeneity. The polymer solution was then
continuously mixed under slow agitation for 1-2 hours to
remove trapped air bubbles.
Once the polymer solution appeared to be smooth and
free of lumps, it was cast into film, using either a
casting box or with a standard draw down bar. Care must
be taken to ensure that the hot solution is cast in a
uniform thin layer. In all of the experimental examples
given below, film was formed by drawing the solution down
onto a hot (90°C) stainless steel belt with a Gardener
dye. The films were either air dried overnight at room
temperature, or dried over a hot water bath and then
removed for testing.
Films produced this way would initially be tested
for thickness using a micrometer (Gauge) and tensile/tear
strength.
The methods for measuring tear strength and
elongation are those specified in ASTMD638. Normally 5
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specimens are tested from each of 5 samples with the
following conditions
~ 201bf load cell
~ Crosshead speed: 2 in./minute
~ Die "C" cut specimens
Films that met these requirements would then be
tested for hot water solubility by placing strips of the
film in boiling water and then allowing the water to cool
with the film sample in it. After cooling, the water
would then be drained off and non-solubilized material
would be placed with the drain dish in the drying overn.
If the film was reconstituted after drying then the film
was deemed to have maintained its structure during
exposure to the hot water. If the film was not resistant
to the water then it would become soluble and could be
poured off. (Hence no film left after drying)
After a particular sample had been characterized as
above, it would be subjected to the same process
conditions under which commercial meats are produced. In
particular the film would be wrapped around a particular
meat substrate (turkey, ham, chicken) and then the
wrapped meat sample dried in a convection oven until a
protein skin could be seen forming on the sample. After
this the sample was transferred into a steam cooker for
the completion of cooking. The internal temperature of
the meat sample would have to reach 70-80°C. After the
completion of cooking, the sample was allowed to cool and
the final product examined and results recorded. Samples
were then packed away under vacuum for shelf-life
testing.
Films according to the invention which we tested on
meat film wrap were also produced using the following
polysaccharides, supplementary to starch and/or alginate,
with Gellan and/or Konjac: agar, modified starches, guar
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gum, cellulose gum, modified cellulose gum, gum arabic,
pullian and xanthate.
In some of the formulations, the following proteins
were included: gelatin, Soya protein concentrate, soya
protein isolate, whey protein concentrate, albumin,
miscellaneous vegetable proteins, collagen and collagen
hydrolysates.
The following general observations arose from our
experiments:
(i) Either Gellan and/or Konjac is required for
synergistic reaction with the carrageenan and
other gums or polysaccharide to provide the
desired hot water resistance. The proportion of
Gellan and/or Konjac is that amount necessary to
modify carrageenan sufficiently to ensure that the
film will not disintegrate upon exposure to hot
water. Films could be made out of Konjac or
Gellan alone, but these would be far less
economical than the combination with other
polysaccharide and in any event would have
inferior physical properties, e.g. poor film
strength, susceptibility to hydration, etc.
(ii) The presence of starch or alginate is essential in
these compositions to impart proper adhesion at
the final film in its intended use as food film
and casing.
(iii) Added protein is highly advantageous, to ensure
proper adherence of the film to the meat after
completion of cooking and for the aforementioned
aesthetic purpose of mimicking the glossy
appearance imparted by collagen.
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The film compositions may also be modified by the
addition of compounds for specific purposes, such as
1. anti-microbial;
2. release agents;
3. colourants (i.e. caramels, oleoresins and other
synthetic or natural colourants - iron oxide);
4. flavors and spices.
With particular application to meat processing,
black films can be produced using caramel, so that
processors need no longer dip the meat products in a
liquid caramel to obtain that colour.
Examples of Edible Film Formulations
Example 1
Component Parts
Gellan 15
Locust bean gum 3
Kappa carrageenan 3
Konj ac 8
Sodium citrate 3
Calcium chloride 2
Maltodextrin 10
Glycerol 25
Water 30
This film exhibited very high tensile strength (140
kg/cm2) and good elongation (300). The film showed
outstanding resistance to tear and had excellent handling
properties. The film could be removed from a meat
product after cooking very easily. (low adhesion)
Example 2
Component Parts
Gellan 8
Kappa carrageenan 10
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Konj ac 3
Locust bean gum 2
HVP 7
High amylose starch 9
Sodium citrate 1
Sorbitan monostearate 1
Glycerol 25
Polyethylene glycol 5
Water 29
The film exhibited very high tensile strength (135-
140 kg/cm2) and elongation (35%), and in particular
showed excellent wet tensile strength. Again this film
showed outstanding mechanical handling properties and on
a meat product had very good adhesion.
Example 3
Component Parts
Gellan 4
Kappa carrageenan 7
Konj ac 2
Locust bean gum 1
HVP 7
High amylose starch 14
Glycerol 32
Caramel 4
Water 29
This film exhibited good tensile strength (110
kg/cm2) and elongation (350) and because of the addition
of caramel powder was black in colour. The film had good
adhesion properties as well as excellent mechanical
handling properties.
Example 4
Component Parts
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Gellan 10
Locust bean gum 5
Kappa carrageenan 8
Hydrolyzed collagen 10
Maltodextrin 7
Propylene glycol alginate 2
Silicon dioxide 6
Sodium citrate 2
Potassium chloride 2
Glycerol 30
This film exhibited moderate tensile strength (100
kg/cm2) and good elongation (250) and utilized collagen
to give the film reasonable adhesion to a meat product.
Example 5
Component Parts
Carrageenan 30
Konj ac 15
Alginate 20
Glycerol 25
Water 10
This film was completely clear and exhibited a very
high tensile strength (200 kg/cmz) with and elongation of
400. It showed very high adhesion and could not be
removed from the meat product after cooking.
Finally, an unexpected advantageous property which
we observed in films made according to the invention was
efficient heat sealability at 180°C, suggesting
usefulness of these films as a replacement for
hydroxypropyl methyl cellulose films in casings and food
pouches.
RIDOUT & MAYBEE
Toronto, Canada
Patent Agents
