Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Method of Freezing Salted Meat Products
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of
freezing cured protein products, such as salted or
smoked meat products by exposing them to a brine, more
particularly, to a freezing method that prevents or
reduces purge produced from the frozen salted meat
products and weight loss of such products.
2. Description of the Related Art
Conventional methods of freezing cured protein
products such as cured meat involve using air, blast
freezing, tunnel freezing, or brine (antifreeze
solution) which is cooled by a cooling medium, or
immersing the cured meat products in liquid nitrogen or
liquid carbon'dioxide. These freezing methods result in
a great amount of purge or drip from the salted or cured
meat products after thawing as the consequence of
destruction of the tissues and cells. The destruction of
tissues and cells causes loss of the meat weights and
deterioration in taste and texture. This consequence
becomes worse when the de-frozen salted and smoked meat
products have to be frozen again from time to time.
U.S. Pat. No. 4,601,909 to Nagoshi discloses a
Methods of Freezing Fishery Products. The method
includes the steps of preparing a brine containing
rapeseed oil, propylene glycol, calcium chloride and
water, cooling the brine and immersing the seafood in
the cooled brine until it is frozen. Such a brine
prevents or reduces the breakdown of muscle tissue in
the seafood due to ice crystal formation. The resultant
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deterioration in quality from freezing is thus
prevented.
A similar process for Quick Freezing of meat
is disclosed and claimed in U.S. Pat. No. 4,654,217
issued to the same inventor. The process disclosed in
this later patent similar to that disclosed in the
earlier patent except that it is applicable t~ beef,
poultry, pork and the like.
U.S. Pat. No. 4,657,768 to Nagoshi discloses a
Freezing Method for Perishable Foods which includes
placing a perishable food in a heat conducting container
and causing the other surface of the heat conducting
container to contact the cooled brine or a liquefied
gas. Accordingly, the perishable food is frozen quickly
without immersion.
U.S. Pat. No. 4,689,963 to Sakai relates to a
Method of Freezing Foods. The Sakai method is similar to
the method of the Nagoshi method except that a layer of
brine is placed in the heat conducting container along
with the perishable food.
U.S. Pat. Nos. 4,840,035, 4,840,034 and
5,001,047 to Liberman relate to methods of freezing
sensitive body fluids, tissue samples and organs,
respectively. The freezing methods described in these
patents are similar to the Nagoshi method except that
the freezing objects in Liberman patents are sensitive
body parts for the clinical use.
There is no teaching or suggestion in any of
these patents that the processes disclosed can prevent
or reduce the amount of purge or drip produced by salted
and smoked frozen meat products after thawing thereby
maintaining the flavor and texture of such salted meat
products.
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Accordingly, it is desirable to provide a process
for preventing or reducing purge produced from frozen
salted and smoked meat products after thawing.
SUMMARY OF THE INVENTION
An object of the present invention is to
provide a method of preventing or reducing purge
produced during the course of freezing cured protein
products. The method comprises the steps of preparing a
brine including a cruciferous oil; cooling the brine to
a temperature between about -22 °F and -43.6 °F; exposing
the surface of a cured. protein product, such as salted
or smoked meat, to the brine by placing the meat product
in a perforated container for a period that such protein
product is completely frozen.
Other objects and features of the present
invention will become apparent from the following
detailed description considered in conjunction with the
accompanying drawings. It is to be understood, however,
that the drawings are designed solely for purposes of
illustration and not as a definition of the limits of
the invention, for which reference should be made to the
appended claims. It should be further understood that
the drawings are not necessarily drawn to scale and
that, unless otherwise indicated, they are merely
intended to conceptually illustrate the structures and
procedures described herein.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
As used herein, the term "cured protein
product" means a product containing a substantial amount
of protein and is processed by way of, for example,
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salting or smoking or both, such as a salted or smoked
fish.
According to the present invention, the brine
solution used for freezing the salted and cured meat
products includes a cruciferous oil. In a preferred
embodiment, oil from a plant of the genus Brassica is
used. These oils include, but are not limited to, oil of
Brassica campestris, otherwise known as rapeseed oil,
and oil of Brassica hirta, also known as mustard oil.
Repessed oil has a solidification point of 14 °F (-
10°C), a specific gravity at 59 °F (15°C) of 0.915, a
refractive index at 122 °F (50 °C) of 1.4706, an iodine
value of 98.6 and a saponification value of 174.7. The
oil includes about 1o palmitic acid, the only saturated
component of the oil, about 32% oleic acid, about 15o
linoleic acid, about 10 linolenic acid and about 50%
erucic acid. Palmitic acid, otherwise known as
hexadecanoic acid is a saturated fatty acid having 16
carbon atoms and a molecular weight of 256.4.
Oleic acid, also known as (Z)-9-octadecenoic acid,
has 18 carbon atoms and a molecular weight of 282.5. The
position of unsaturation is between the ninth and tenth
carbon atoms in the chain. The molecule has a cis
configuration.
Linoleic acid has two positions of unsaturation and
is also known as cis.cis-9,12-octadecadienoic acid. The
acid has 18 carbon atoms and a molecular weight of
280.5.
Linolenic acid has three positions of unsaturation
and is also known as (Z.Z.Z)-9.12.1 5-octadecatrienoic
acid. Linolenic acid has 18 carbon atoms and a molecular
weight of 278.4.
Erucic acid, a major component of the oils of the
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genus Brassica, is also known as (Z)-13-docosenoic acid.
Erucic acid has 22 carbon atoms with one position of
unsaturation and a molecular weight of 338.6.
Mustard oil is similar. Mustard oil has a specific
5 gravity at 59 °F. of 0.9145. a refractive index at 1 22
°F. of 1.475, an iodine value of 102 and a
saponification value of 174. Mustard oil includesl.3o by
weight myristic acid, the only saturated acid, 27.20 by
weight oleic acid, 16.60 by weight linoleic acid, 1.80
by weight linolenic.acid, 1.1o by weight behenic acid,
1.0o by weight lignoceric acid and 51.0% by weight
erucic acid. Myristic acid, also known as tetradecanoic
acid. has 14 carbon atoms and a molecular weight of
228.4.
Behenic acid is also known as docosanoic acid. It
has 22 carbon atoms and a molecular weight of 340.6.
Lignoceric acid, also known as tetracosanoic acid, has
24 carbon atoms and a molecular weight of 368.6. The
other components of mustard oil are described above.
The oil is used in an amount less than about 1o by
weight, more preferably less than about 0.8o by weight
and most preferably between about 0.1 and 0.5o by weight
of the brine.
It is to be understood that oils other than
rapeseed oil and mustard oil can be used in accordance
with the invention. For example, synthetic oils having
the characteristics ' described would be useful. In
addition, the manner in which the oils function is
described in detail below and it will be readily
apparent that other oils will function acceptably in
accordance with the invention and can be readily
determined.
In addition to the cruciferous oil, the brine also
generally includes a glycol, an inorganic salt and
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water. Suitable glycols include, but are not limited to,
ethylene glycol, propylene glycol. benzylene glycol,
butylene glycol. diethylene glycol, diphenyl glycol.
ethylidene glycol, and the like. Any glycol can be used
alone or in combination with other glycols. Propylene
glycol is used in a preferred embodiment. The glycol
component is present in an amount between about 30 and
50o by weight of the brine, more preferably between
about 35 and 45o by weight and most preferably in an
amount of about 40o by weight.
Salts which are useful in accordance with the
invention include, but are not limited to, calcium
chloride, calcium bromide, calcium iodide, potassium
chloride, potassium bromide, potassium iodide and the
like. In a preferred embodiment. calcium chloride is
used. The salt is present in an amount between about 5
and 15o by weight of the brine, more preferably in an
amount between about 7 and 13o by weight and most
preferably in an amount of about 10% by weight.
Water is present in an amount between about 40 and
60o by weight, more preferably in an amount between
about 45 and 55o by weight and most preferably in an
amount of about 50o by weight.
In an especially preferred embodiment, the brine
includes between about 0.1 and 0.5o by weight
cruciferous oil, about 40o by weight propylene glycol.
about 10o by weight- calcium chloride and a balance of
water. The cruciferous oil is preferably rapeseed oil.
It is presently believed that when the brine
including the oil is cooled to a temperature between
about-22 and -43.6 °F " fine ice crystals form in the
brine and are uniformly distributed. These crystals
permit efficient cold transfer and an increase in the
expected chilling rate of a salted meat product immersed
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in the brine. Consequently, the time required to chill a
meat product is reduced. In a preferred embodiment,
means are provided for withdrawing heat from the brine
as a meat product is brought into a heat transfer
relationship therewith. This permits the temperature of
the brine to be maintained substantially constant when a
meat product is introduced. Accordingly, the meat
product can be chilled rapidly with minimum formation of
ice crystals, breakdown of cellular tissue and
deterioration of the protein or meat product.
In practice, protein products such as fish, pork
and beef may be cured by dry salting or being soaked in
a salted solution so that the salt content of each such
product is increased. This serves to preserve the meat
and enhance the flavor and texture of the meat.
Subsequent this salting step, the salted meat product
may be further cured by way of, for example, smoking, so
that the flavor and texture of the salted meat products
can be further enhanced.
As a result of the above described salting, the
cells of the salted meat products contain a high
concentration of salt. Under a slow freezing process,
the cell plasma of the salted meat product tends to
freeze out fresh water first leaving the salt within the
unfrozen cell plasma. The salt concentration in the
unfrozen cell plasma of the slated meat products thus
becomes even higher resulting in more water entering
into the cells through osmosis, which eventually causes
an expansion of the cell plasma volume. When the slow
freezing process is completed, a large amount of ice
crystals are formed, which break the cell membrane
causing purge and consequential weight loss and
faccidity.
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To avoid or reduce purge produced in a slow
freezing process thereby preserving the flavor and
texture of salted or salted and smoked meat products
after such products are frozen, it is crucial to employ
a freezing method that rapidly and uniformly freezes the
salted and cured meat products such that the volume of
the cell plasma is not increased during the freezing
process. The present invention achieves this object by
rapidly freezing the salted or salted and smoked meat
products using the above described brine.
A salted or salted and smoked meat product may be
frozen by being planed in a suitable container, such as
a plastic bag, which is immersed in the brine until the
meat is completely frozen. Preferably, the product is
vacuum packed in the container then immersed in the
brine because vacuum packaged products require less time
to be completely frozen. A perforated board such as a
plastic mesh is preferred to carry such meat product
because the entire surface of the product can be exposed
to the brine in this manner. The amount of time required
for freezing such meat products various depending on the
type, size and the surface/weight ratio of the product,
but can be readily determined by a person of ordinary
skill in the art.
The salted or salted and smoked frozen meat product
so produced causes much less purge and much less weight
loss after thawing. In one example, the conventional
freezing method results in the amount of purge about 2-3
times as much as the freezing method employed in the
present invention, in other words, the present invention
reduces the amount of purge produced from frozen salted
or salted and smoked meat product by 2-3 folds. The
advantage of the present invention in reducing purge or
preventing weight loss of the salted or salted and
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smoked frozen meat products becomes more evident when
such products are refrozen after being thawed.
The following example represents a particular
embodiment of the present invention, which serves to
further illustrate the present invention. It shall not
be construed as limitations of various aspects of the
present invention.
EXAMPhE
Fish filets were divided into three groups, Group
I, Group II and Group III, each group consisting of six
pieces of filets with predetermined weights. Group I was
treated with conventional freezing process, Group II was
treated with TRUFRESH freezing process, and Group III
was kept unfrozen (fresh). Then the fish filets in
Groups I and II were thawed. After thawing, all of these
filets were salted and smoked by a known process. The
weight losses of each piece of filets in the three
groups was measured as shown in TABLE I. An average
percentage of the weight loss in each group after
thawing and smoking was shown in TABLE II.
TABhE I
Filet No. Weight.(Kg) Weight.(Kg) (Smoked)
Weight Loss (%)
Group I (frozen by conventional freezing process)
1 1.10 1.00 9.1
2 1.35 1.22 9.6
3 1.45 1.30 10.3
4 1.25 1.10 12.0
5 1.25 1.13 9.6
6 1.15 1.05 8.7
Average 1.26 1.13 9.9
Group II (frozen by TRUFRESH freezing process)
1 1.30 1.20 7.7
2 1.15 1.10 4.3
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3 1.25 1.16 7.2
4 1.45 1.36 6.2
5 1.40 1.35 3.6
6 1.45 1.40 3.4
5 Average 1.33 1.26 5.4
Group III (unfrozen)
1 1.45 1.35 6.9
2 1.40 1.27 9.3
10 3 1.35 1.24 8.1
4 1.40 1.28 8.6
5 1.25 1.15 8.0
6 1.25 1.15 8.0
Average 1.35 1.24 8.1
TABhE II
Group No. Weight Loss (%)
Group I 9.9
Group II 5.4
Group III 8.1
The above result shows that the fish filets subject
to the TRUFRESH frozen process lost weight about half as
much as those subject to the conventional frozen
process.
After the above described procedure, each group was
again divided into three sub-groups and each sub-group
was again subj ect to the above described three types of
treatments, i.e. conventional frozen, TRUFRESH frozen
and unfrozen. Loss of purge was measured in each sub
group, the results of which are shown in TABLE III.
TABhE III
Group I
Treatment Purge Doss (%)
Unfrozen 0.800
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Unfrozen 0.574
TRUFRESH 0.308
TRUFRESH 0.455
Conventional 0.708
Conventional 0.667
Group II
Unfrozen 0.500
Unfrozen 0.545
TRUFRESH 0.259
TRUFRESH 0.147
Conventional 0.444
Conventional 0.429
Group III
Unfrozen 0.444
Unfrozen 0.394
TRUFRESH 0.242
TRUFRESH 0.313
Conventional 0.696
Conventional 0.783
In each of the above group, purge loss is
significantly reduced in the sub-groups treated with
TRUFRESH freezing process, whether they were previously
treated with conventional or TRUFRESH freezing process,
or unfrozen.
Thus, while there have shown and described and
pointed out fundamental novel features of the invention
as applied to a preferred embodiment thereof, it will be
understood that various omissions and substitutions and
changes in the form ' and details of the devices
illustrated, and in their operation, may be made by
those skilled in the art without departing from the
spirit of the invention. For example, it is expressly
intended that all combinations of those elements and/or
method steps which perform substantially the same
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function in substantially the same way to achieve the
same results are within the scope of the invention.
Moreover, it should be recognised that structures and/or
elements and/or method steps shown and/or described in
connection with any disclosed form or embodiment of the
invention may be incorporated in any other disclosed or
described or suggested form or embodiment as a general
matter of design choice. It is the intention,
therefore, to be limited only as indicated by the scope
of the claims appended hereto.
