[Detailed Description of the Invention]
[Field of the Invention]
The present invention as defined in the claims relates to the use
of a curing agent and its use in a pickle for producing a processed meat such as
ham, bacon, roast pork or the like. More specifically, the present invention is
that when transglutaminase is used in a pickle, its viscosity is not increased,
the problem given in using the pickle is consequently solved, and qualities of a
processed meat such as ham, bacon, roast pork or the like are improved when the
pickle is injected.
Usually, ham, bacon or the like which is a processed meat is obliged
to be cured by law (according to Japanese Agricultural Standard(JAS)). As this method,
a dry curing method and the method of curing in a pickle have been conducted. Recently,
they have been mostly conducted by a pickle injection method. In the pickle used
at that time, sodium chloride and color-fixing agents are main components. In addition,
polyphosphates, different proteins or the like are incorporated to improve yield,
water-holding capacity, binding and the like, and seasonings, preservatives, coloring
agents and the like are also incorporated.
Further, transglutaminase (hereinafter abbreviated as "TGase") has
been lately incorporated at times in a pickle to improve texture, sliceability(yield
of slice) and the like. In this instance, a serious problem is as follows. That
is, a pickle is, in most cases, allowed to stand overnight at low temperatures after
preparation in order to completely dissolve different proteins or to conduct defoaming
through degassing, and is then used. However, there is a defect (problem) that when
TGase is added and dissolved in this pickle, both of TG and different proteins are
reacted while being allowed to stand, and the viscosity of the pickle is notably
increased, making it impossible to conduct injection. Accordingly, in order to satisfactorily
exhibit the function of TGase, it is necessary to control the viscosity of the pickle
(in other words, to control the TGase reaction). That is, it is required that even
when TGase is added and dissolved in a pickle, the reaction be controlled so as
not to increase the viscosity and the satisfactory effect by using TGase can be
exhibited on a processed meat in which the pickle is injected.
To make processed meat which is relatively highly injected, different
proteins at the level of 10% has to be incorporated into the pickle. The amount
to be added varies depending on qualities of a processed meat required. Generally
speaking, typically, soybean protein is between 1 and 8%, casein such as sodium
caseinate or the like is between 0.5 and 3%, albumen is between 2 and 5%, and whey
protein is between 2 and 5%.
When, for example, from 2 to 5 units of TGase are added to 100 g of
this pickle as such, a crosslinking reaction to polymerize protein molecules by
TGase proceeds over the course of time, and there occurs a defect that the viscosity
of the pickle is increased, making it impossible to conduct injection. For this
reason, the use of TGase in the pickle is much limited at present. To cope with
this, a method is known in which TGase is used in such a state that the amount of
soybean protein or casein such as sodium caseinate or the like is decreased in a
pickle (Japanese Patent Laid-Open No. 255,426/1995). However, this method involves
defects that since the amount of the protein is limited, the function of the protein
is not exhibited satisfactorily and when a long period of time lapses after preparation
of the pickle, the viscosity is increased, so that the period of time for which
to use the pickle is limited.
[Problems To Be Solved by the Invention]
In the above-mentioned background of the prior art, the present invention
aims to provide an excellent pickle in which even when incorporating TGase, the
above-mentioned defects are avoided.
[Means For Solving the Problems]
The present inventors have assiduously conducted investigations to
solve the above-mentioned problems, and have consequently found that the above-mentioned
problems can be treated with the use of a protein partial hydrolysate. The present
invention has been completed on the basis of such a finding.
That is, the present invention relates to a curing agent for meat
processing characterized by comprising transglutaminase and a protein partial hydrolysate,
a pickle in which this is dissolved in water, and a processed meat prepared by using
such a pickle.
[Mode of carrying out the Invention]
The present invention is described in detail below. As the protein
partial hydrolysate used in the present invention, a partial hydrolysate of a protein
which is generally used in a pickle can be used. Examples thereof include partial
hydrolysates of casein (including, in addition to free casein, salts such as sodium
caseinate and potassium caseinate), soybean protein, albumen, whey protein and plasma.
Of these, it is a soybean protein hydrolysate that increases the viscosity
in particular with the addition of TGase. Further, the soybean protein partial hydrolysate
imparts an excellent texture to final processed meat in comparison with the other
protein partial hydrolysates. Accordingly, the use of the soybean protein partial
hydrolysate, among others, especially the soybean protein partial hydrolysate having
the hydrolysis rate of from 3 to 20% is quite useful in comparison with the use
of the other protein partial hydrolysates.
With respect to the pickle comprising TGase, it is a requisite that
the viscosity is less increased, but the viscosity may be increased unless any trouble
is caused in practice. Meanwhile, it makes no sense if the function of TGase and
the function of the protein are impaired. It is inevitable that the function of
TGase and the desired function provided by the use of the protein are satisfactorily
exhibited on processed meat such as ham, bacon, roast pork or the like which is
prepared by injecting a pickle having the controlled viscosity.
The soybean protein partial hydrolysate is described in detail below.
The soybean protein is generally classified into a soy flour type, a separated protein,
and a concentrated protein type. As the protein used in the pickle, the concentrated
protein type and the separated protein type are mainly used.
In regard to these types, more native ones are used. However, since
these native proteins have a higher reactivity with TGase, the viscosity of the
pickle tends to increase. Accordingly, studies have been made on a protein in which
the pickle hardly increases the viscosity with the addition of TGase while maintaining
the function of these native proteins in the pickle. Consequently, the use of the
partially hydrolyzed soybean protein has been found.
The protein partial hydrolysate here referred to is a product obtained
by partially hydrolyzing protein, such as the soybean protein, with a protein hydrolase
(protease). As a protease, a protease type (endo type) which cuts a protein molecule
successively from an end and a type (exo type) which cuts only a specific site in
a molecule are known. In view of controlling the increase in the viscosity, a protein
may be treated with any of these protease. Further, a product which is partially
hydrolyzed with a mineral acid such as hydrochloric acid, sulfuric acid or the like
is also available.
What is important here is the hydrolysis rate. When a protein which
is not hydrolyzed at all is incorporated into a pickle, the increase in the viscosity
of the pickle is naturally invited. On the contrary, when the hydrolysis rate is
extremely high, the increase in the viscosity does not occur, but the effect provided
by the use of the protein is not exhibited on the product. Therefore, from this
standpoint, the hydrolysis rate to meet the object of the present invention is between
2 and 30%, preferably between 3 and 20%. The hydrolysis rate here referred to is
measured as follows. That is, a trichloroacetic acid (TCA) solution is added to
a protein solution having an adjusted solid content such that the final concentration
of the TCA solution reaches 0.2 M. The mixture is stirred, then maintained at 40°C
for 20 minutes, and centrifuged. The total nitrogen amount of the supernatant portion
is measured. This nitrogen amount is multiplied by 6.25 to calculate the protein
amount of the supernatant portion, and this protein amount is divided by the initial
protein amount of the overall solution. The resulting value is defined as a hydrolysis
The amount of the soybean protein in the protein partial hydrolysate
used in the present invention is not particularly limited. Generally, it can follow
an amount of a soybean protein used in the pickle. That is, generally with respect
to an amount of a soybean protein used in a pickle, a ratio occupied in the pickle
is between 1 and 8% as described earlier. This amount can be replaced as such with
that of the protein partial hydrolysate.
TGase used to prepare the pickle includes a calcium-dependent one
and a calcium-independent one, and both can be used in the present invention. As
the former, TGase derived from microorganisms (refer to, for example, Japanese Patent
Laid-Open No. 27,471/1989) can be mentioned. As the latter, TGase derived from the
guinea pig liver (refer to Japanese Patent Publication No. 50,382/1989), TGase derived
from fish [refer to, for example, Seki Nobuo et al., "NIPPON SUISAN GAKKAISHI, vol.
56, 125-132(1990)"; and "1990th The Japanese Society of Fisheries Science, Annual
Meeting in Spring Abstracts, p. 219], and TGase present in the blood or the like,
which is called factor XIII (WO 93/15234) can be mentioned. Further, TGase produced
through recombination (Japanese Patent Laid-Open Nos. 300,889/1989, 225,775/1994
and European Patent Laid-Open No. EP-0693556A) can all be used. The origin and the
process for producing the same are not limited.
The amount of TGase used is the same as the amount which is ordinarily
used to make ham or bacon(refer to the above-mentioned Japanese Patent Laid-Open
No. 255,426/1995 and the like). Naturally, the amount of TGase added to the pickle
varies depending on the amount to be injected to meat. Usually, with respect to
ham, the amount of from 5 to 15 units per 100 g of the ham product is considered
appropriate. Accordingly, when a pickle is injected into pork at a extension level
of 50%, from 10 to 30 units of TGase per 100g of the pickle have to be added according
to the calculation. However, in general, it is sufficient to incorporate from 2
to 30 units of TGase per 100 g of the pickle. When the amount of TGase(the addition
level of TGase) is smaller than this, the effects of improvement of properties (improvement
of texture, improvement of binding, and the like) of ham by TGase are not obtained.
When the amount of TGase(the addition level of TGase) is larger than this, texture
is extremely hard inconveniently. Anyway, when the amount deviates from the above-mentioned
range, the desired objects are not provided.
The activity unit of transglutaminase referred to in the present invention
is measured and defined by a method in which the reaction is conducted using benzyloxycarbonyl-L-glutaminylglycine
and hydroxylamine as substrates, an iron complex is formed using the resulting hydroxamic
acid in the presence of trichloroacetic acid, an absorbance of 525 nm is then measured,
and the amount is found from a calibration curve (refer to the above-mentioned Japanese
Patent Laid-Open No. 27,471/1989).
The curing agent and the pickle of the present invention can be produced
according to a usual method of producing a curing agent and a pickle except that
a predetermined amount of TGase is added (dissolved) and various protein partial
hydrolysates including the soybean protein partial hydrolysate are used in the production,
and no special means or incorporation is required at all. Needless to say, the method
for producing processed meat can follow an ordinary method. Further, the curing
agent and the pickle of the present invention can of course be subjected to distribution
The present invention is illustrated more specifically by referring
to the following Examples.
In the evaluation of soybean protein in a gel, 7.5% solutions were
prepared using three products(unhydrolyzed proteins) selected on the basis of the
degree of NSI (water-soluble nitrogen index) shown in Table 1 below and one product
partially hydrolyzed with a protease. To each of these solutions was added a TGase
preparation "Activa TG-S" (made by Ajinomoto Co., Inc., specific activity 100 units/g)
such that it reached 7.5 units per 100 g of a pickle. The pickle was then incubated
at 25°C for 24 hours. The viscosity of the product was measured according to the
lapse of time shown in Table 2 below using a B-type viscometer "Vismetron" Rotor
No. 2 supplied by Shibaura Seisakusho.
The results are also shown in Table 2. The hydrolysis rate of "Ajipron"-HO,
i.e. a soybean protein partial hydrolysate obtained by partially hydrolyzing a soybean
protein with a protease was approximately 7.5%.
(NSI5 - water-soluble nitrogen index at 5°C)
- : unmeasurable
Time that lapses (hrs)
As is easily understandable from Table 2, the three products which
are not treated with an enzyme show an abrupt increase in the viscosity irrespective
of the degree of NSI, whereas "Ajipron"-HO (made by Ajinomoto Co., Inc.), an enzyme-treated
protein, shows only a slight increase in the viscosity even after 24 hours. By the
way, the three products not treated with an enzyme are also those made by Ajinomoto
Co., Inc., and they are all isolated soybean proteins.
A pickle was prepared according to a recipe shown in Table 3 below.
To this was added a TGase preparation "Activa" TG-S (made by Ajinomoto Co., Inc.,
specific activity 100 units/g) at a ratio of 0.0% (0 unit per 100 g of the pickle),
0.15% (15 units on the same basis), 0.20% (20 units on the same basis) or 0.40%
(40 units on the same basis). The mixture was allowed to stand at room temperature
of 5°C, and the viscosity thereof was measured over the course of time shown in
Table 4 below. The results are also shown in Table 4. The viscosity remains unchanged
naturally in the absence of TGase. However, even when TGase is added at a ratio
of 0.2% which is presumably an appropriate amount, the viscosity is slightly increased.
The viscosity exceeds 100 cp for the first time after 48 hours. Thus, this ratio
is considered satisfactorily practical. With the addition of TGase at a ratio of
0.4%, the viscosity is abruptly increased, and the practical use at this ratio is
found to be difficult. Further, this proves that the optimum viscosity can be selected
by selecting the amount of TGase added. These results are quite suggestive.
*1: umami seasoning composed mainly of monosodium
glutamate (made by Ajinomoto Co., Inc.)
*2 Sodium ascorbate
- : unmeasurable
TG concentration (%)
Time that lapses (hrs)
With respect to "Ajipron"-HO, the product of the present invention,
the comparative experiment was conducted on the basis of the recipe (c) in Table
3 of Example 2, using "Ajipron"-HS2 selected in Example 1 as a control. Consequently,
the results shown in Table 5 below were obtained.
Viscosity after 24 hours (cp)
Evaluation of expert panelists on qualities of ham
Soft, Smooth, and slightly unpleasant texture
Firm and quite pleasant texture with good bite
"Ajipron"-HS2 (Common product)
Soft and unpleasant texture with weak bite
Slightly hard and slightly tough texture
However, the viscosity of the pickle is high, injection is difficult
and workability is quite bad.
As is seen from Table 5, when TGase is added to "Ajipron"-HS2, a common
product (unhydrolyzed protein), the viscosity exceeds 100 cp. Meanwhile, when "Ajipron"-HO,
a partial hydrolysate, is used, the viscosity is little increased even with the
addition of TGase.
Further, the pickle after 24 hours was actually injected into pig
loin, and ham was prepared in a usual manner. Qualities thereof were then evaluated.
As a result, qualities of ham prepared by using both the soybean partial hydrolysate
and TGase were very good. Further, a pickle obtained from a combination of the protein
partial hydrolysate and TGase less increased the viscosity, and the workability
was extremely good.
[Effects of the Invention]
When TGase is ordinarily used in prepared meat product such as ham
or the like through a pickle, different proteins contained previously in the pickle,
especially a vegetable protein such as a soybean protein or the like is reacted
with TGase to notably increase the viscosity of the pickle. For this reason, the
use of TGase has been greatly limited.
However, according to the present invention, a protein partial hydrolysate,
preferably, a soybean protein partial hydrolysate, more specifically, a soybean
protein partial hydrolysate having a specific hydrolysis rate is combined with TGase,
whereby the limitation of the use of TGase is extremely reduced without increasing
the viscosity of the pickle. Further, the function of TGase and the function of
the soybean protein are satisfactorily exhibited on prepared meat product such as
ham, bacon or the like upon using this pickle, making it possible to satisfy the
inherent functions thereof. In other words, according to the present invention,
the viscosity of the pickle containing TGase can be controlled by selectively using
the protein partial hydrolysate of the soybean protein or the like. Thus, the possibility
of using TGase in prepared meat product is greatly enlarged. Still further, TGase
is used in prepared meat product, making it possible to produce a product having
an improved texture, an improved slice yield during the production and an excellent
binding capacity at a low cost.
Thus, it contributes very much toward the production of prepared meat