BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The present invention relates to a pickle solution and it's use in
processed meat products such as ham, bacon and roast pork and a processed meat product
obtainable with the pickle solution. More specifically, according to the present
invention, the viscosity of protein-containing pickle is not increased when a transglutaminase
is added, and thus the problem in its use due to the increase of the viscosity of
the pickle is solved Therefore, the quality of processed meat products such as ham,
bacon and roast pork which are produced by being cured in the pickle or injecting
the pickle is improved.
DESCRIPTION OF THE RELATED ART
A curing step for permeating and dispersing a salting agent in solution
into raw meat materials is usually required for manufacturing processed meat products
such as ham and bacon. The methods include a dry-curing method, a curing-in-pickle
method, a pickle-injection method. Recently, the curing step is mostly effected
by the curing-in-pickle method and the pickle-injection method.
The pickle to be used in the step, which is a solution of a salting
agent, mainly comprises sodium chloride and color-fixing agents; for the purpose
of improving the yield, water holding capacity, binding capacity and color-fixing
ability and the like, polyphosphate salts and ascorbic acids are additionally blended
therein, together with seasonings, preservatives and color-fixing agents.
And for the purpose of improving products in terms of water retentivity,
emulsification ability, food taste and texture such as firmness and elasticity or
bindability, pickle types blended with various protein materials including egg white,
whey protein, caseins such as sodium caseinate or soy bean protein, are now mainly
In addition, for the purpose of further improving food taste and texture
and increasing slice yield (sliceability), recently a transglutaminase (abbreviated
as TGase hereinafter) is sometimes blended thereto as described for example in EP
0 028 113 A2. TGase not only reacts with proteins of raw material meat but also
reacts with the protein materials in the pickle permeated or injected into the.meat,
thereby remarkably improving the physical properties of the resulting final product.
Because the effect of TGase is exerted more in pickle containing more protein materials,
the use of TGase has been desired strongly for pickle having a higher content of
protein materials. However, in case that TGase is used in pickle at a higher content
of protein materials, there is a problem that the viscosity of the resulting pickle
Generally, a pickle is left to stand in a low-temperature stock chamber
for one night or about 2 to 4 days after preparation, so as to completely dissolve
powdery materials including protein materials or to remove bubbles and foam from
the pickle. Then the pickle is used. TGase is also supplied generally in the form
of powder and therefore should be dissolved along with the protein materials. However,
the protein materials in the pickle, particularly soy bean protein and sodium caseinate
and the like, are crosslinked and polymerized by TGase during the subsequent resting
period, so that the viscosity of the resulting pickle is notably increased disadvantageously,
making it impossible to conduct injection. Accordingly, in case that TGase is added
to pickle, some treatment has been required so as to avoid the increase of the viscosity
of the pickle during resting.
Japanese Patent Application Laid-open Nos. 255426/1995 and 56303/1999
report techniques for suppressing the increase of pickle viscosity caused by TGase.
The techniques comprise controlling the quantities of caseins' and soy bean protein
highly reactive with TGase among protein materials blended in pickle, or comprise
using partial hydrolysates prepared from them. These techniques suppress the viscosity
increase with no influence on TGase activity, by reducing the amount of raw materials
functioning as substrates of TGase (i.e., protein materials) or by substituting
such raw materials with materials causing less change of the physical properties.
However, when the quantity of the protein in pickle is controlled, functions demanded
for the protein, such as imparting physical properties and water-holding capacity
to the processed meat products, get so insufficient that disadvantages such as poor
elasticity and noticeable water release from the resulting product may occur. In
case that protein partial hydrolysates are used, the increase of the viscosity can
be suppressed within one day, but can never sufficiently be suppressed under storage
for a longer term. It is needless to say that, because caseins and soy bean protein
are used only in the form of their partial hydrolysates, the creation of diverse
food taste and texture or quality based on devising various blends of protein materials
is restricted. Hence, the use of TGase in pickle is still limited in such a manner
that TGase is used in pickle with less amount of protein materials blended or in
pickle to be consumed up within one day or to be disposed when unused.
Journal of Food Science, Vol. 61, No. 6, 196, pp. 1234-1238 relates
to the application of transglutaminase to hacked fish products ("surimi").
Journal of Food Science, Vol. 60, No. 4, 1297, pp. 715-717, 726 discloses
the treatment of hacked fish with transglutaminase and ammonium salt. The concentration
of ammonium salt is given as 0.1 mol or higher in relation to the hacked fish.
Agric. Biol. Chem. (49), 2283-2286, 1985; EP-A-0 898 895; Fisheries
Science 61(6), 968-972 (1995) and JP-A-07 008 225 (Patent Abstracts of Japan) relate
to transglutaminases and their use in the modification of food. The combination
of ammonium salts with transglutaminase is not mentioned in these documents.
The document Nippon Suisan Gakkaishi, 59(6), 1017-1021 (1993) discloses
the treatment of hacked fish which contains transglutaminase with ammonium salts.
US 5,948,662 discloses a composition comprising transglutaminase and
an ammonium salt and its application to the industrial production of various foods.
SUMMARY OF THE INVENTION
On such background of the conventional techniques as described above,
it is an object of the present invention to provide a pickle solution comprising
a salting agent without any of the disadvantages described above even after the
salting agent is blended with TGase and with no need of any modification or treatment
of raw protein materials of the pickle, and to provide a pickle using the same.
The present inventors have made investigations so as to solve the
problems as stated above, and have found a method for exerting the conventional
effect of TGase, comprising adding a substance suppressing the reaction by TGase,
namely an ammonium salt in an amount above 0.001 mol/liter to below 0.1 mol/liter,
to a pickle containing TGase, thereby regulating the activity of TGase to suppress
the increase of the viscosity of the pickle, and still recovering the activity of
TGase in the final product. Thus, the present invention has been achieved. In accordance
with the present invention, in other words, TGase can be added to pickles having
compositions that conventionally would never allow the addition of TGase thereto
because of the increase of the viscosity, with no modification of the compositions.
The invention is essentially different from the conventional techniques, in respect
of controlling the TGase activity.
More specifically, the present invention relates to a pickle solution,
comprising a protein for use in pickle, a transglutaminase, an ammonium salt in
an amount above 0.001 mol/liter to below 0.1 mol/liter, and water; the use of said
pickle solution for meat processing; and a processed meat product, obtainable by
treating a meat product with said pickle solution.
DETAILED DESCRIPTION OF THE INVENTION
The invention is now described specifically hereinbelow.
TGases are classified into calcium-independent and calcium-dependent
types. Either can be used in the present invention. Examples of the former include
those derived from microorganisms such as Actinomycetes and Bacillus subtilis (see,
for example, JP-A-64-27471). Example of the latter include those derived from guinea
pig liver (see, for example, JP-B-1-50382), those derived from microorganisms such
as Oomycetes, those derived from animals such as bovine blood, swine blood , those
derived from fishes such as salmon, red sea bream (see, for example, Seki Nobuo
et al., Nippon Suisan Gakkaishi, vol.56, pp.125-132 (1990), and Proceedings of Nippon
Fisheries Science Association, Congress in Spring, 1990, page 219), so-called Factor
XIII present in blood (WO 93/15234), and, those derived from oyster. Also, those
produced by methods of genetic engineering (see, for example, JP-A-1-300889, JP-A-6-225775,
JP-A-7-23737 and EP-0693556A) can be mentioned. In accordance with the present invention,
any of these TGases can be used, with no specific limitation of the origin and the
preparation method. However, in view of the function and the economics in the food
applications, the calcium-independent TGases are preferable. For example, the TGases
derived from microorganisms (JP-A-64-27471 mentioned above) meet all conditions,
and are considered to be the most suitable at present.
In accordance with the invention, the substance suppressing the reaction
a substance reversibly inhibiting the reaction of TGase, namely inorganic or organic
ammonium salts. Practically, inorganic ammonium salts are simply used, including
for example ammonium chloride, ammonium carbonate, ammonium hydrogen carbonate,
ammonium aluminium sulfate, ammonium persulfate, ammonium sulfate, diammonium hydrogen
phosphate, and ammonium dihydrogen phosphate. Organic ammonium salts include for
example ammonium citrate. These can be used singly or in combination of two or more
The substance suppressing the reaction is selected depending on the
kind of the protein and the amount of the enzyme added to the pickle to be prepared,
because each substance has its own ability to suppress the reaction in a certain
weight amount. Among them, ammonium chloride is the best as the substance suppressing
the reaction in accordance with the invention, because it is commonly used as a
seasoning and a baking powder in premix and is approved as an enzyme stabilizer,
and additionally because it is very inexpensive.
In the use of the substance suppressing the reaction in a pickle,
the amount thereof to be added is very significant. The substance is added at an
amount enough to inhibit TGase activity to such an extent that the increase of the
viscosity of the resulting pickle is sufficiently suppressed but not to substantially
reduce the effect of TGase in the final food product because the inhibiting activity
is lowered in the raw material meat after the injection due to the lower concentration
of the substance therein. The optimum amount of the substance suppressing the reaction
varies, depending on the amount of TGase added, the ability to suppress the reaction
per weight of the substance, the protein composition in the pickle used, the demanded
level of viscosity suppression, and the conditions for the ham production.
In accordance with the invention, an ammonium salt amount above 0.001
mol/liter, preferably 0.002 mol/liter, can generally exert the effect on viscosity
suppression in a pickle of a composition with possible viscosity increase due to
TGase addition. When the ammonium salt concentration is above 0.2 mol/liter, sufficient
effect corresponding to the amount of TGase added is never exerted in the final
food product. According to this invention, the ammonium salt concentration is below
The amount of TGase to be added to pickle varies, depending on the
pickle injection ratio, and the level of the effect and the function expected from
TGase. Generally, TGase is used at a concentration within a range of 20 U to 1,000
U/liter in pickle.
The activity of TGase in the present invention and the activity unit
thereof can be assayed and defined by the following hydroxamate method. More specifically,
the TGase reaction is conducted in a reaction system containing as substrates benzyloxycarbonyl-L-glutamylglycine
and hydroxylamine in Tris buffer, at pH 6.0, and a temperature of 37°C; and the
hydroxamic acid formed is transformed into an iron complex in the presence of trichloroacetic
acid. Then, the absorbance is measured at 525 nm and the hydroxamic acid formed
is calculated from a standard curve. Then, the enzyme producing 1 µmol hydroxamic
acid per minute is defined as one unit (1 U) of TGase activity (see Japanese Patent
Laid-open No. 27471/1989 and USP 5,156,956).
Because the preparation according to the present invention is an enzyme
preparation of TGase with an ammonium salt in mixture, the ratio of the ammonium
salt and TGase blended in the enzyme preparation is within a range simultaneously
satisfying the individual concentrations when added to pickle. More specifically,
a case of 20 U/liter of TGase blended with 0.2 mol/liter of an ammonium salt (outside
the scope of the invention) in pickle corresponds to a case of 10 moles of ammonium
salts per 1,000 U of TGase in the preparation; and a case of 1,000 U/liter of TGase
blended with 0.001 mol/liter of an ammonium salt in the pickle corresponds to a
case of 0.001 mole of ammonium salts per 1,000 U TGase in the preparation. Thus,
the enzyme preparation according to the present invention contains at least these
two ingredients, the ammonium salt being blended from 0.001 mole to 10 moles, preferably
0.002 mole to 5 moles, per 1,000 U of TGase. When shown in terms of per weight of
TGase, the ammonium salt is blended in amounts from 0.02 mole to 200 moles, preferably
0.04 mole to 100 moles per gram of the pure-enzyme protein.
Any type of protein materials for general use in pickle, namely soy
bean protein, caseins, egg white, whey protein, gelatin, collagen and plasma protein,
can be used for preparing pickle using the present salting agent, according to conventional
methods with no concern of viscosity increase of the pickle.
The salting agent of the present invention is dissolved in cold water
in the same way as conventional salting agents, protein materials and sodium chloride
generally used, and it is used as a pickle solution. The pickle solution right after
the preparation contains foam, which deteriorates the quality of the final product.
Therefore, the foam is to be removed by evacuating the pickle or leaving the pickle
in cold storage at least overnight. The pickle solution is injected into the raw
meat materials using a pickle injector. Afterwards, the meat is tumbled and the
pickle is dispersed uniformly in the meat.
The application of the salting agent according to the present invention
is not limited to the manufacture of meat products. The salting agent can also be
used in the general applications other than meat products in which food raw materials
are treated with a solution comprising TGase and protein materials.
The invention is now described in detail in the following examples.
The technical scope of the invention is not limited to these examples.
"Activa TG" (1,000 U/g; manufactured by Ajinomoto, Co.) containing
as 'the major ingredient TGase derived from genus Streptoverticillium (Streptoverticillium
mobaraense IFO 13819) was used as the TGase in the examples.
Example 1 (Effects of a reaction-suppressing substance on the suppression
of viscosity increase of pickle and improvement of firmness in model ham)
A pickle solution of the composition shown in Table 1 was prepared
by the following process. Water cooled at 5°C was put into a vessel with a mixer
and the protein materials were dissolved and mixed, and then the other raw materials
were dissolved. Afterwards, "Activa TG" was added to.the pickle to the following
final concentrations: (1) 0 %; (2) 0.005 %; (3) 0.010 %; (4) 0.015 %; and (5) 0.020
% according to Table 2. Alternatively, ammonium chloride was added at the following
concentrations, while the amount off "Activa TG" added was fixed at 0.020 %: (6)
0.002 mol/liter; (7) 0.02 mol/liter: and (8) 0.2 mol/liter.
Blend amount (%)
Soy bean protein for ham
Polymerized phosphate (salt)
Pickle viscosity and model ham
The pickle samples were left to stand in a low-temperature chamber
at 5°C; and the viscosity was measured over time. Meanwhile, 100 parts of each pickle
sample one day later were added to 100 parts of minced meat prepared by finely chopping
and cutting pork loin through a 5-mm-sieve plate; then, the mixture was mixed together
with a Stefan cutter for 3 minutes and filled in a fibrous casing (Ø 90 mm),
followed by drying and aging at 60°C in a smoke chamber for 120 minutes, smoking
at 60°C for 60 minutes, and steam boiling at 75°C for 120 minutes, to prepare a
model ham. The change of the pickle viscosity over time (measured with a viscometer
of Type B; No. 2 rotor at 30 rpm) as well as the breaking strength of the resulting
model ham (measured with a plunger of Ø 5 mm at 6 cm/min) was measured, while
quality assessment was also performed. The results are collectively shown in Table
*: Effect of the TG on firmness
Pickle viscosity and physical properties and quality assessment of model ham
Pickle viscosity in cP at 5 °C
Breaking strength of model ham
Quality assessment of model ham*
Immediately after preparation
one day later
2 days later
3 days later
X : insufficient;
Δ : slightly insufficient; and
○ : sufficient.
The viscosity scarcely changed in the no TGase group (1); as the amount
of "Activa TG" added was increased, the pickle viscosity was more increased (Experimental
groups (2) to (5)); and the viscosity in a group with addition of 0.02 % "Activa
TG" was above 3,000 cP on day 3, so the pickle absolutely never could be used. On
contrast, the increase of the viscosity was significantly suppressed in the ammonium
chloride groups (Experimental groups (6) to (8)). Additionally, the viscosity was
less increased as the amount of ammonium chloride was increased.
Breaking strength of model ham
The break strength of model ham was larger as the amount of "Activa
TG" was increased, indicating the enhancement of the. firmness and elasticity as
food taste and texture. Alternatively, the break strength was slightly decreased
in the ammonium chloride groups as the amount of ammonium chloride was increased.
Compared with the influence on the pickle viscosity, the decrease was very slight.
The same tendency was observed in the anserine and carnosine groups. In other words,
it is indicated that TGase activity was inhibited in the pickle samples, but was
restored in the resulting ham models.
Example 2 (Preparation of salting agent for meat products)
One existing enzyme preparation and three enzyme preparations for
meat products in accordance with the present invention were prepared according to
the recipes A, B, C and D in Table 4. "Activa TG" was used as the TGase; and ammonium
chloride commercially available as a food additive was used.
*: Activa TG (1g) contains
1,000 U TGase activity/g.
To the pickle of the composition shown in Table 1, the preparation
shown in Table 4 was added at the following percentages: (1) No addition; (2) Preparation
A at 0.2 %; (3) Preparation B at 0.2 %; (4) Preparation C at 0.2 %; and (5) Preparation
D at 2.0 %. The TGase concentration was constant in all the experimental groups
(2) to (5). The change of the viscosity of the pickle was measured over time. The
results are shown in Table 5. In Table 5, compositions with experimental groups
3 and 4 are according to the invention.
Increase of pickle viscosity
Amount added to pickle
Concentration in pickle
Pickle viscosity in cP at 5 °C
TGase in U/liter
NH4Cl in mol/liter
Immediately after preparation
one day later
2 days later
3 days later
Roast ham was prepared concurrently by using these pickle samples
one day later. The roast ham was prepared from a raw material pork loin in a conventional
The pickle was injected into pork loin using a pickle injector. The
pickle injection ratio was 100 % by weight to the raw material meat, and then tumbling
was carried out overnight at 5°C. The tumbled meat was filled in a fibrous casing
with the folding width of 11 cm and was cooked, Cooking conditions were 60°C and
2 hours for drying, 60°C and 1 hour for smoking and 75°C and 2 hours for steam boiling.
The ham was sliced into pieces of 2-mm thickness. The food taste and texture was
evaluated by sensory evaluation. The results are shown in Table 6. In Table 6, examples
with experimental groups (3) and (4) are according to the invention.
* Effect of the TG on firmness
Sensory evaluation of roast ham
Soft with insufficient firmness
Good firmness at the same level as in (2)
Good firmness at the same level as in (2)
Slightly softer than (2) but with sufficient firmness
X : insufficient;
Δ : slightly poor; and
○ : sufficient.
The viscosity increase in the pickle of group (2) with the addition
of the Preparation A with no content of ammonium chloride was very rapid. On contrast,
the viscosity increase was remarkably suppressed in the pickle of groups (3), (4)
and (5) with the addition of the Preparations B, C and D, respectively, each containing
ammonium chloride. Furthermore, , the Preparation C containing more ammonium chloride
exerted higher effect on the suppression of the viscosity. Compared with the no
addition group (1), the effect of TGase on the physical properties of ham was almost
at the same level in the three experimental groups (2), (3) and (4). Compared with
the group (2), the group (5) was slightly short of firmness, but the preparation
of the group (5) sometimes serves as an effective blend for a case in which no increase
of pickle viscosity is allowed.
Advantages of the Invention
When a salting agent for food processing which contains TGase and
a substance suppressing its reaction, i.e. an ammonium salt in an amount above 0.001
mol/liter to below 0.1 mol/liter, is used in pickle, the increase of the viscosity
of the pickle can.be markedly suppressed, with almost no influence on the action
of TGase to the taste and texture of the resulting final food product.