Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COMPOSITION FOR COATING FOODSTUFFS, METHOD FOR
MANUFACTURING A COATING AND METHOD FOR COATING FOODSTUFFS
FIELD OF THE INVENTION
The field of the invention is that of agri-food systems and, in particular,
the
processing of meat and fish in the form of sausages.
More specifically, the invention relates to a composition for coating a
foodstuff, or a
food preparation, which makes it possible, in particular, to form an edible
vegetable casing,
and to a corresponding method for coating a foodstuff.
The invention can be applied in particular in the production of sausages based
on
pork, lamb, mutton, beef, veal, poultry and/or fish. It can also be
implemented to produce
sausages prepared from vegetables, fruits and/or cheese.
It can also be implemented to coat the base of a vegetable or a cut edge of a
vegetable
and to preserve its freshness.
Casings, or skins, which are primarily based on vegetable matter and are also
called
commonly vegetable food casings when they are tubular in shape, are currently
widely used
in the agri-food industry.
Food casings of vegetable origin are thus very widely used in order to coat
the filling
or dough of a sausage owing, in particular, to their advantageous cost
compared to casings of
animal origin, and owing to the possibility they afford for production on an
industrial scale of
sausages of standardised size.
Peelable vegetable casings for dry sausage or raw sausage, such as salami, are
known.
For example US-5928737 proposes to provide a peelable casing from a slightly
hydrated paste made with starch and alginate.
It is also common for peelable casings of a known type to contain cellulose
fibres.
However, these thick peelable casings, which cannot be digested easily, are
not
intended for consumption with the filling of the sausage.
Thin (i.e. generally less than 100 micrometres thick) edible casings of
primarily
vegetable origin are also known, which are used, for example, as a casing for
cooked
sausages produced on an industrial scale.
These edible casings are usually obtained from an aqueous composition based on
alginate provided, in particular, in the form of a paste which is applied
directly to the
foodstuff to be coated, for example by dipping the foodstuff in the
composition, by spraying
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the composition over the surface of the foodstuff, or by co-extruding the
composition around
the foodstuff to be coated.
In accordance with another known technique, an edible casing can be formed by
extrusion in order to fill it with a food dough.
It has been suggested to incorporate collagen into the composition of edible
casings in
order to provide them with an acceptable resistance to stretching and/or in
order to increase
the viscosity of the composition based on alginate with the aim of being able
to form these
casings by extrusion or by co-extrusion.
A drawback of collagen is that it is primarily extracted from animal bones,
fish bones
or animal skin. It is not therefore suitable for the production of casings for
vegetarian, halal or
kosher food products.
A further drawback of collagen is that its use is likely to pose health risks
to the
consumer by enabling the transmission of diseases, such as the Creutzfeldt-
Jakob syndrome.
In addition, it is noted that a casing produced on the basis of collagen has
proven to be
fragile. It is therefore necessary to proceed with chemical post-treatment in
order to reinforce
it, for example by using aldehydes in the form of liquid smoke, which
significantly modifies
the taste of the food product consumed with its casing.
For these reasons, it has been sought to produce edible casings exclusively
from
vegetable matter.
It has thus been conceived to incorporate galactomannans, such as guar gum,
and/or
cellulose derivatives into the casing composition to act as a thickening
agent, and/or to
reinforce and stabilise the casing over time. For example, compositions based
on alginate and
galactomannans, or based on alginate and cellulose derivatives are known from
EP-A-
1311165.
A drawback of galactomannans is that they provide the casing with a smooth
texture
and a shiny appearance, which are unnatural, thus giving the impression of a
plastic material.
Based on a visual examination, a consumer in search of a quality product is
therefore likely to
be deterred from buying or eating a food product of which the casing contains
galactomannans, irrespective of the quality of this product.
It is also known that the addition of cellulose derivatives with a view to
thickening a
coating composition does not alone make it possible to provide the casing with
sufficient
flexibility enabling the avoidance of tearing of the casing during its
production or during
cooking.
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US-2009/0317522 thus proposes using a mixture of cellulose and starch to adapt
the
rheology, and in particular to thicken a paste based on alginate which is to
be applied by co-
extrusion around the filling of a sausage.
SUMMARY
One aspect of the invention is therefore, in particular, to overcome the above-
mentioned drawbacks of the prior art.
More specifically, an objective of the invention is to provide a composition
and
corresponding method for coating a foodstuff which satisfies the quality
criteria currently
required by the majority of consumers.
In particular an objective of the invention is to provide a composition which
gives the
coating a texture and appearance which are similar to that of a conventional
casing of animal
origin.
An aspect of the invention also intends to provide a composition which limits
the
exudation of liquid by the foodstuff (i.e. syneresis) and makes it possible to
keep the
appearance and feel of the casing's surface as dry as possible.
A further objective of the invention is to provide a composition which does
not
change the taste of the coated foodstuff, moreover without posing any danger
to the
consumer.
An aspect of the invention also also intends to provide a composition which
makes it
possible to obtain a coating which exhibits a suitable mechanical resistance
and a suitable
elasticity.
A further aspect of the invention further further intends to provide a
composition
which makes it possible to obtain a coating which is stable over time, at
least over a number
of days.
DETAILED DESCRIPTION
When searching for a water-based composition for coating a foodstuff, said
composition comprising water as a major component, and making it possible to
achieve these
objectives, the applicant surprisingly and unexpectedly found that by
combining mainly
alginate, starch and cellulose gum with water in specific and previously
unreported
proportions, it was possible to obtain a substantially white casing, with a
matte and opaque
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appearance, a texture, elasticity and mechanical resistance that are similar
to those of an
animal casing.
To this end an aspect of the invention relates to a composition comprising
between
about 2 and about 5 % wet weight of alginate, between about 1 and about 2.5 %
wet weight
of starch, and between about 0.6 and about 1.3 % wet weight of carboxymethyl
cellulose.
The alginate may be sodium alginate, or any suitable type of alginate or
mixture of
alginates of a known type.
As a result of an aspect of the invention a composition is obtained, in the
form of a
coating paste, which advantageously combines an appearance which is close to
that of a
natural animal casing with rheological properties which make it able to be
applied around the
foodstuff in an optimal manner by co-extrusion, by spray coating or by
dipping. In particular
most compositions have an apparent viscosity between 40 and 70 Pa=s and they
can
advantageously be used to produce sausage casings by co-extrusion using
existing co-
extrusion equipment without having to make substantial changes to this
equipment. By
carrying out simple routine tests, the person skilled in the art will be able
to adapt the
respective dosage of alginate, starch and carboxymethyl cellulose of the
composition
according to the invention suitable for the co-extrusion equipment available
to him in order to
ensure a constant flow and pressure at the co-extrusion nozzle.
In addition it is noted that the casing obtained after gelification of the
coating has a
level of bonding suitable for the foodstuff and remains stable over a number
of days or
weeks, even though it is formed largely of water. Furthermore, it is noted
that the casing
obtained does not split if it is subjected to a treatment in an acid bath and
to cooking, for
example when the food preparation and its casing are cooked in the oven,
boiled or fried.
The applicant has further noted a very sensitive and unusual limitation of
syneresis at
the surface of the casing, which it had not been observed previously for
compositions based
on alginates and galactomannans for example.
In accordance with a possible hypothesis and not bein bound to any theory,
this
combination of coating qualities could be explained, at least in part, by a
particularly
effective synergy between the alginate and starch in the proportions disclosed
herein, this
synergy being associated with a weak action of the carboxymethyl cellulose,
also known as
cellulose gum, over the chemical bonds formed between the alginate and the
starch.
It should be noted that, within the scope of the invention, the expression
`water as a
major component' is understood to mean compositions comprising at least 85 %
water,
preferably at least 90 % water and more preferably at least 92 % water.
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In at least one advantageous embodiment of the invention, such a composition
comprises between about 4 and about 5 % wet weight of alginate, between about
1.2 and
about 1.8 % wet weight of starch, and between about 0.9 and about 1.2 % by
weight of
carboxymethyl cellulose.
5 The mass ratio of starch to alginate in said composition is preferably
between 0.2 and
0.45.
The applicant has in fact discovered, unexpectedly, that a particularly
effective
synergy between the starch and alginate is produced within this mass ratio
range, in particular
in terms of the texture and elasticity of the composition obtained.
The mass ratio of carboxymethyl cellulose to starch in said composition is
advantageously between 0.4 and 0.8.
A composition is thus obtained which exhibits both elasticity and viscosity
which are
suitable, in particular, for an application by co-extrusion.
Said alginate is advantageously arranged in such a manner that an aqueous
solution
including about 1% by weight of said alginate has a viscosity between 0.3 and
0.5 Pa=s at 20
C.
By favouring alginates of low viscosity it is then possible to precisely
adjust the
viscosity of the composition by an appropriate dosage of the amounts of starch
and cellulose
gum.
In accordance with a particularly advantageous embodiment of the invention,
said
starch is a starch which is soluble when cold, preferably modified potato
starch which is
soluble when cold.
It is thus possible to obtain, by simple mixing, a substantially homogeneous
composition which is free from agglomerates or lumps of starch owing to the
solubility of the
cold water soluble starch in water at ambient temperature. It is not therefore
necessary to heat
the composition in order to dissolve the starches contained, which makes it
possible to make
savings in terms of energy and time.
It should also be noted that, in a manner known per se, the cellulose gum
which is
also included in the composition according to the invention is advantageously
a cold water
soluble additive.
Said water advantageously has a hardness less than 2 ppm (2 mg/L CaCO3),
preferably less than or equal to 1 ppm (1 mg/L CaCO3).
The level of calcium is therefore controlled and consequently so is the
gelification of
alginates. The composition can consequently be implemented on a co-extrusion
machine with
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no risk of solidifying or blocking the extruder through which it flows, for
example in the case
of a temporary stopping or breakdown of the machine. It is only when the
coated foodstuff is
immersed, after co-extrusion, in a gelification bath or fixing bath containing
calcium salts in
which the alginate gels that the coating becomes a solid casing.
In at least one embodiment of the invention a composition as described above
comprises an acidifying compound belonging to the group comprising at least
lactic acid,
citric acid, acetic acid or a mixture of at least two of said acids.
The stability of the casing over time is thus improved.
The pH of said composition is preferably between 3.8 and 4.2.
By thus controlling the pH of the composition, the charge density of
polysaccharides
present in the composition, such as starch and cellulose gum, is reduced.
The gelification of the alginate is consequently not affected by the presence
of
polysaccharides in the composition. In addition, the viscosity of the
composition obtained
makes it possible to co-extrude the composition around the foodstuff using
conventional co-
extrusion equipment.
In accordance with a specific aspect of the invention, the composition
comprises a
vegetable protein weight which is lower than the alginate weight in said
composition.
The addition of vegetable proteins in the composition makes it possible, in
particular,
to improve the coagulation of the coating upon contact with a calcic bath,
thus leading to
retraction of the casing together with that of the filling during cooking of
the coated
foodstuff. The presence of vegetable proteins in the composition also makes it
possible, in
some cases, to make the appearance of the coated foodstuff more attractive, in
particular in
terms of colour.
The vegetable proteins present in the composition can be selected, for
example, from
gluten proteins, pea proteins, soya proteins and mixtures thereof.
It should also be noted that by limiting the amount of vegetable proteins in
the
composition so as to keep it below the amount of alginate, the total amount of
gelifying
agents in the composition is restricted. The risk of wrinkling and tearing of
the coating is
therefore avoided. In other words the addition of vegetable proteins in
proportions lower than
that of the alginate improves the adherence of the coating without
significantly affecting its
rheological properties, and in particular its viscosity and the performance of
the gel.
Furthermore, it is not necessary to proceed with an additional treatment of
the casing
in order to ensure its performance for several days.
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In at least one embodiment of the invention, the composition optionally
comprises at
least one compound belonging to the group comprising at least:
- food colouring agents, preferably cochineal carmine and/or paprika
oleoresin;
- food preservatives, preferably potassium sorbate and/or sodium benzoate;
- food flavourings, in particular liquid smoke;
- visual and/or taste marking agents, preferably spice particles in the form
of a powder of
suitable granulometry, said particles enabling co-extrusion of said
composition around said
foodstuff.
The percentage by weight of this or these additional compound(s) is preferably
less
than 0.5 % wet weight of the composition, and even more preferably less than
0.2 % wet
weight of the composition.
It is thus possible to provide the end food product with a considerable
variety of
colours and tastes as well as a suitable storage period.
In addition, in compositions in which fine particles of milled spices, for
example
pepper particles, are incorporated the composition is advantageously filtered
in order to
prevent these particles from blocking the nozzle of a co-extruder.
The marking agents can be formed from any suitable known coloured food powder
which is noticeable or neutral in terms of taste.
The invention also relates to a method for manufacturing a water-based
composition
for coating foodstuffs comprising a step of filtering the composition through
a filter with a
mesh size lower than or equal to 120 micrometers.
In at least one embodiment of the invention, said filter mesh size is about
80, 100, 110
or 120 micrometres.
Impurities or clusters of alginate are filtered, thereby allowing the
injection of the
composition continuously, and with a constant flow into a co-extruder die of a
known type,
whose spacing is generally between 30 and 200 micrometers, and most often
between 80 and
120 micrometers, avoiding the cloging of the die and the stop of the
production.
This fine filtration step may advantageously be implemented for the
preparation of a
composition which can be used to form an edible casing comprising such
ingredients as
collagen, galactomannans, cellulose derivatives and/or monocrystalline
cellulose or any other
protein, polysaccharide, sugar, and/or suitable hydrocolloid.
An aspect of the invention also relates to a method for coating a foodstuff
with an
edible vegetable casing.
According to the invention such a coating method comprises the following
steps:
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- obtaining a water-based composition such as any one of the compositions
described above;
- immersing a substantial part of said foodstuff in the composition, spray
coating said
composition around a substantial part of said foodstuff, or co-extrusion of
said composition
around said foodstuff so as to coat said foodstuff;
- bringing the coated foodstuff into contact with a gelling agent, in order to
gel the coating.
In particular, the gelling agent may be present in the form of a calcic
solution into
which the coated foodstuff is dipped, or which is sprayed onto the coating.
In at least one embodiment of the invention, the coating method comprises
filtering
the composition through a filter with a mesh size smaller than or equal to 120
micrometers.
This filtration step can for example be implemented before putting the
composition
into the co-extrusion line, or at the inlet of the co-extrusion nozzle.
Further characteristics and advantages of the invention will become clearer
upon
reading the non-limiting practical examples given by way of simple
illustration.
Preparation of a composition - Example 1
40 g of lactic acid and 5000 g of softened water of hardness less than 1 ppm
are
introduced into a tank of a cutter with a maximum capacity of 15 litres. Once
the cutter is
started, 450 g of sodium alginate powder, 180 g of modified potato starch
powder which is
soluble when cold, 110 g of carboxymethyl cellulose powder, and 10 g of
potassium sorbate
granules are added progressively. As soon as the powders and the granules are
partially
hydrated, 4210 g of additional softened water is added to the composition and
the
composition is mixed and sheared at high speed for 6 minutes until 10
kilograms of a
homogeneous paste is obtained in which the powders and granules are completely
hydrated.
This paste has a pH equal to 4, an apparent viscosity of 62 Pa=s at a
temperature of 20
C (measured using a TA Instruments AR 2000 rheometer in a stainless steel plan-
cone
geometry with 1 of angle and 6 cm of diameter, 180 20 rpm) and a sugar
content of
approximately 6 degrees Brix.
The alginate used to prepare this composition has a pH of 6.8 and a viscosity
of 0.35
Pa=s at 20 C (measured using a Brookfield viscometer model RV spindle n l, 20
rpm) when
it is diluted to 1 % in softened water.
The paste is avantageously pumped through an 80 micron mesh filter, making it
possible to remove impurities, and is packaged in a plastic container. A sheet
of plastic
protection is placed over the surface of the paste and the container is stored
in a cold chamber
kept between 0 and 8 C, in which the paste can be preserved for 8 months.
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In a variant embodiment of Example 1, 20 g atomized black pepper powder with a
particle size below 50 microns are substituted for 20 g of softened water in
the composition.
Preparation of a composition - Example 2
This second composition comprises 9270 g of softened water, 430 g of sodium
alginate, 160 g of modified maize starch which is soluble when cold, 125 g of
cellulose gum,
g of sodium benzoate and 5 g of cochineal carmine for colouration.
No acidifying agent is added to the composition.
This composition has a viscosity of 70 Pa=s at 20 C and a pH of 4.2. It has
proven to
10 be less elastic than that of Example 1.
Preparation of a composition - example 3
This third composition combines each of the compounds of Example 2 in the same
proportions except for cellulose gum, of which the mass is reduced to 80 g,
and the total mass
of softened water (9275 g). Furthermore, 40 g of citric acid are incorporated
into this third
composition.
This composition has a pH of 4 and a reduced apparent viscosity equal to 43
Pa=s at a
temperature of 20 C.
Example 4 of preparation of a composition
This fourth composition comprises 9205 g of softened water, 450 g of sodium
alginate, 150 g of modified maize starch which is soluble when cold, 90 g of
cellulose gum,
10 g of potassium sorbate, 35 g of lactic acid and 60 g of soya protein.
After gelification these four compositions have an opaque, matte and whitish
appearance, and a texture which are close to those of an animal casing.
In the variant embodiment of example 1, there is preferably a homogeneous
distribution of marking pepper particles on the surface of the casing,
allowing to detect at first
glance that it is a pepper sausage. Consequently, the rate of pepper in the
dough, and
therefore in the end product, may be substantially reduced.
Mechanical tests carried out on gelified casings obtained from these
compositions
have confirmed that the elasticity and resistance to stretching of the casings
is satisfactory.
They also make it possible to form casings for sausages, for example
Knackwurst sausages,
by an extrusion process.
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After gelification it is noted by visual examination and by touch that
syneresis is the
least pronounced in the composition of Example 1.
It is also observed that the compositions of examples 1 and 4 have proven to
be the
most stable over time.
5 The paste prepared in accordance with Example 1 has been used to form
casings for
sausages produced continuously by a co-extrusion method.
To this end the production line of sausages is equipped with a co-extruder and
a
stuffer directing the sausage dough in the direction of the co-extruder,
produced and sold by
MAREL. It is noted that the value of the viscosity of the paste of Example 1
is
10 advantageously set at 62 Pa=s by adjusting the dosages of starch and
cellulose gum in order to
ensure a constant flow of 30 kg/h and a constant pressure between about 4 and
about 5 bars at
the inlet to the nozzle of the co-extruder.
For this production the sausage dough is formed, in particular, of pork belly
and pork
fat, sodium nitrite, calcium acetate, sodium lactate or potassium lactate, and
spices such as
pepper.
At the outlet of the co-extrusion head, the continuous tube of sausage is
continuously
sprayed with a gelling solution.
The gelling solution is formed of tap waterand calcium chloride solubilised in
a
proportion of 25 % of the total weight of the solution.
Upon contact with the gelling solution, the alginate forms a calcium alginate
gel, thus
forming a resistant casing.
The sausage tube then enters the jaws of a crimper, which jaws, by a rotating
movement, cut the tube into 10 centimetre portions and pinch the ends of the
casing of each
portion, so as to enclose the dough inside the casing.
The casing of these sausages maintains a satisfactory shape, in particular it
does not
split or rip, and its ends do not burst or allow the filling to escape when
the sausages are
boiled, cooked, fried or pasteurized.
Furthermore, these sausages demonstrate performance under cooking, assessed by
measuring the weight of the sausage after cooking, which is from 5 to 10 %
greater than that
of an identical sausage comprising a natural animal casing.
It should be noted that, by lowering the proportion of cellulose gum in the
composition under about 0.8 % w/w whilst maintaining a mass ratio of cellulose
to starch
between about 0.4 and about 0.8, it is possible to obtain a coating paste
having, in addition to
a suitable elasticity, a viscosity which is sufficiently low to distribute
said paste over the
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surface of a foodstuff by spraying, or else by dipping whilst maintaining a
substantially
constant thickness.
For example (Example 5) a casing formed from a paste incorporating 9400 g
softened
water, 40 g of lactic acid, 350 g of sodium alginate, 120 g modified potato
starch soluble
when cold (i.e. a mass ratio of starch to alginate equal to 0.34), 80 g of
cellulose gum (i.e. a
mass ratio of carboxymethyl to starch equal to 0.67), and 10 g of potassium
sorbate was
tested.
The appearance of the casing of Example 5 is satisfactory, but the strength of
this
casing is low and it also deteriorates significantly after two days.
The casing of Example 5 has a viscosity below 40 Pa.s suitable for application
by dipping or
spraying.
However, it is unsuitable for application by coextrusion. Indeed, the low
viscosity
composition can flow into the channels of the stuffer's vacuum pump, and into
the co-
extrusion head, which is not maintained under pressure when production stops.
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