JP2717852B2 - Method for measuring freshness of frozen surimi - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for measuring the freshness of frozen surimi. More specifically, the present invention relates to a method for measuring the freshness of frozen surimi using an ATPase activity measuring method.

[Conventional technology]

Conventional methods for measuring freshness of fish meat are roughly classified into a chemical determination method and a physical determination method.

Chemical judgment method: ATPase activity Salt soluble protein mass Nucleic acid component (K value) Histamine (Hm) Volatile base nitrogen (VBN) Volatile acid pH value Physical judgment method: Eye lens opacity (transparency of eyes) Fish hardness ( Belly and fleshy body) Colors of body surface and gills In these various methods, except for the ATPase activity measurement method, all target fresh fish and fillets and cannot be applied to frozen surimi. On the other hand, the ATPase activity method can be applied to any of these.

However, the conventional ATPase activity measurement method is an evaluation method that starts with the extraction of ATPase and ends with a colorimetric method using an absorptiometer. It is not used.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for measuring the freshness of frozen surimi by an ATPase activity measuring method which can be performed easily and in a short time and does not impose a burden on the apparatus.

[Means for Solving the Problems] and [Action] The method for measuring the freshness of frozen surimi of the present invention which achieves the above object is carried out in a buffer solution containing ATP and at least one of inorganic calcium salts and magnesium salts or EDTA. , Adding a frozen surimi homogenized in a buffer containing potassium chloride or sodium chloride, measuring the pH change of the entire system and comparing it with a reference value. The use of potassium or sodium chloride is also used.

The principle of the freshness measuring method according to the present invention is as follows.
That is, the reaction of ATPase (adenosine triphosphatase) is expressed as follows when the system is at around pH 8.

ATP: adenosine triphosphate ADP: adenosine diphosphate Thus, the enzymatic activity of ATPase can be determined by measuring the change in any one of these reaction products. The method of the present invention is a method for measuring the proton (H ⁺ ).

In the measurement, a reaction solution comprising ATP and at least one of inorganic calcium salts and magnesium salts or a buffer solution containing EDTA (ethylenediaminetetraacetate) and, if necessary, potassium chloride or sodium chloride is used.

ATP is generally used in an amount of about 0.1 to 10 mM corresponding to the ATPase content of actomyosin in frozen surimi.

As inorganic calcium or magnesium salts,
For example, calcium chloride, calcium carbonate, calcium nitrate, calcium sulfate, magnesium chloride, magnesium nitrate, magnesium sulfate and the like are used, and EDTA is an inorganic salt thereof, such as a sodium salt, a potassium salt, a manganese salt, a copper salt, an iron salt, Also used as zinc salt.

These act as activators to accelerate the reaction and not only cause a change in pH over time, but also to change the response characteristics such as the degree of pH change and the way of response by selecting the type. Can also. Such an activation effect can be seen at a minimum addition of about ^10-12 mM, while 50 m
Even if M is used, the effect has reached a saturated state, so no further effect can be expected.

In addition, generally about 10 ^{-12 to 5} M potassium chloride or sodium chloride can be added to the reaction solution, and when these are added, the amount of ATPase extracted and the reaction stability are increased.

These components are added to a buffer having a pH of about 5 to 10, preferably about 8, such as a tris-maleic acid type or a tris-hydrochloric acid type, to form a reaction solution. In the frozen surimi, there are substances, such as polymerized phosphate, which cause a change in pH of the system, but the effect of the buffer used here does not appear.

The frozen surimi serving as the measurement sample includes, for example, offshore surimi and onshore surimi of fish meat represented by Alaska pollack, and these frozen surimis are generally homogenized in a buffer solution containing about 10 ^{-12 to 5} M potassium chloride or sodium chloride. It is added to the above-mentioned reaction solution in a state where it is made to react. Here, as the buffer, the same pH as that used in the reaction solution,
The same composition is used. The reason why the homogenized homogenized buffer is added to the buffer is to extract and stabilize the ATPase in the frozen surimi so that it can be dispersed well in the reaction mixture.

The measurement was performed at about 0.000 per 40 ml of the total amount of the reaction solution and the homogenization solution.
Using frozen surimi in an amount of 01 to 10 g as a measurement sample,
It was homogenized in a buffer solution of KCl or NaCl, added to the reaction solution with or without stirring, and the pH change of the entire system was measured generally at a temperature of about 10 to 40 ° C., Reference value, for example, after a predetermined time
It is performed by a method of evaluating the freshness by comparing with a pH value.

As the measuring device, for example, the one shown in FIG. 1 is used, and the measurement is performed by using a pH electrode 2 connected to a pH meter 1.
The reaction solution 5 is placed in a thermostat 4 in which the stirring rod 3 is immersed, a homogenized solution of the frozen surimi is added thereto, and the pH is measured over time.

As described above, in the method of the present invention, the freshness of the frozen surimi is measured by measuring the pH change of the whole system and comparing it with the reference value. Since the pH of the liquid itself changes, the ATPase activity in the frozen surimi is affected by the pH, and this leaves a problem as an accurate method for evaluating the ATPase activity.

Therefore, the system as described above detects the pH change caused by the reaction of ATPase at around pH 8 with a glass electrode,
A new method is proposed in which alkali is automatically added so as to return the amount to, and the amount is recorded.

That is, by measuring the pH change of the entire system as the amount of alkali required to neutralize the entire system and comparing it with a reference value, the effect of pH can be reduced without giving the pH change to ATPase in frozen surimi. This enables more accurate measurement of freshness of frozen surimi. Specifically, KCl or NaCl
Of the alkali (e.g., about 1 to 100 mM KOH, NaOH) consumed to neutralize the released protons and maintain the pH at the start of the reaction The freshness of the fresh surimi is evaluated by self-recording the titer and comparing it with a reference value, for example a titer of the fresh surimi that has been measured for a certain period of time. Note that a pH stat is used as the measuring device.

〔The invention's effect〕

According to the method of the present invention, the freshness of frozen surimi is simply measured for pH change or the amount of neutralized alkali corresponding thereto using a simple measuring device, and the reproducibility (accuracy) can be improved in a short time with the conventional method. Can be evaluated with good correlation.

In addition, the evaluation target is not only frozen fish meat surimi but also lean meat,
It is also expanded to white fish fillets, livestock meat, and chicken.

〔Example〕

 Next, the present invention will be described with reference to examples.

Example 1 Measurement was performed using the measuring device shown in FIG.

pH meter: HM60S manufactured by Toa Denpa Co., Ltd. pH electrode: GST5311C manufactured by Toa Denpa: Stirred temperature chamber: TTA80 manufactured by Radiometer The SA class and the C class of frozen surimi are considered to have clearly different freshness from the viewpoint of the processing process. . Therefore,
The responses of these two individuals were compared for walleye pollack frozen surimi. The experimental conditions are as follows.

Reaction solution: 38 ml of 10 mM Tris-maleic acid buffer (pH 8.0) containing 4 mM ATP and 5 mM CaCl ₂ Temperature: 25 ° C Surimi: 0.2 g (105 ° C, dry weight for 3 hours 55 mg) 0.1 MK
Homogenized in 2 ml of the above buffer solution (pH 8.0) with Cl added. Heat inactivation condition: 60 ° C, 30 minutes. The measurement is performed by adding surimi to the reaction solution with stirring.
This is done by measuring the change over time, and the results are shown in the graph of FIG. The measurement width indicates the width of three measurements, and it can be seen that the SA-class surimi and the C-class surimi can be distinguished with good reproducibility. In addition, heat-inactivated samples showed no response, indicating that the measurement method reflects the ATPase reaction. In addition, the influence of the polymeric phosphate which is one component of the frozen surimi formulation is excluded by the buffer capacity of the solution.

Example 2 In addition to Ca-ATPase, Mg-ATPase,
It is thought that enzymes such as kinases also exist. Therefore, at the time of measurement in Example 1, 1 mM MgCl ₂ instead of 5 mM CaCl ₂
(FIG. 3) or 1 mM MgCl ₂ with 5 mM CaCl ₂ (FIG. 4) to see the effect on response.

In the case of adding Mg alone, a V-shaped response not observed in the case of adding Ca alone (FIG. 2) was observed. In the case of adding Mg-Ca simultaneously, the V-shaped response was slightly relaxed, and the pH was lowered again after a lapse of time. A phenomenon was observed. From these results, it is considered that the reaction of the complex enzyme system in the surimi activated by Mg or Ca is measured at the same time, and this measurement method has the possibility of measurement called enzyme spectrum. Is shown.

In the case of the Mg-containing system, various kinds of enzymes are expected to be activated. Therefore, if it is desired to simplify the evaluation, the Ca system is considered to be more preferable.

Example 3 In Example 1, the concentration of the KCl-containing buffer used for homogenizing the surimi was changed from 0.1 M to 0.5 M, and 0.5 M KCl was added to the reaction solution. This is because a low concentration of the KCl-containing buffer is considered to affect the amount of ATPase extracted, reaction stability, and the like. As shown in the graph of FIG. 5, the result shows a larger response than the result of FIG. From this, it is considered that the extraction amount of ATPase increased and the reaction stability increased due to the high salt concentration.

Example 4 It is known that the storage temperature is also directly related to the freshness of the frozen surimi. Therefore, the same measurement as in Example 1 was performed on SA-grade surimi stored at −30 ° C. or 4 ° C. for about one month. The results are shown in the graph of FIG.
In the case of storage at -30 ° C., almost no decrease in activity was observed even after one month, whereas in the case of storage at 4 ° C., a significant decrease in activity was observed.

Example 5 Since EDTA is also considered to activate ATPase,
The same measurement as in Example 1 was performed for a sample to which 5 mM sodium salt of EDTA was added as an activator (marked with ○) and a control without adding any activator (marked with ●). The results, as shown in the graph of FIG. 7, show that the addition of EDTA sodium salt responded more greatly than the control, indicating that the addition of EDTA is effective as a means for expanding the response.

Example 6 In Example 3, simultaneous measurement of H ⁺ ion (ΔpH) measured by this method and inorganic phosphorus (Pi) measured by a conventional colorimetric method were performed, and the correlation between the two methods was evaluated for SA class and C class. The graded surimi (which was placed in a refrigerator at 4 ° C. and the activity of ATPase in the surimi was reduced to reduce its activity) was examined.

The measurement was performed at 5 minutes after the start of the reaction, and the results are shown in the graph of FIG. From these results, a good correlation was found between the two methods, and the correlation coefficient was 0.93 (n = 10). The theoretical equation is represented by Y = 0.47X + 10 ^-4 .

Example 7 Reaction solution: 38 ml of 5 mM Tris-maleate buffer (pH 8.0) containing ₁ , ₂ , 3, or 4 mM ATP, 5 mM CaCl ₂ , 0.5 M KCl Temperature: 25 ° C. Surimi: SA grade walleye pollock frozen surimi 0.2 g (105 mg, dry weight for 3 hours, 55 mg) was added to the above buffer (pH 8.
0) What was homogenized in 2 ml The measurement was performed by adding surimi under stirring to the reaction solution and neutralizing it with the change in pH over time, and 10 mM KOH consumed to maintain the pH at 8.0. The titer was self-recorded with a pH stat (HSM-10A manufactured by Toa Denpa), and the results are shown in the graph of FIG. 9 for each ATP concentration.

From these results, it can be seen that the KOH titer increases as the ATP concentration increases, which suggests that ATP is acting as a substrate.

Example 8 In Example 7, a reaction solution having an ATP concentration of 1 mM was used, and the weight of the SA-grade surimi was set to 0.2 g or 0.4 g. The measurement results are shown in the graph of FIG. 10 for each surimi weight.

From this result, it can be seen that the KOH titer increases as the surimi concentration increases, and it can be concluded that the prepared sample shows the action of ATPase.

Example 9 In Example 7, an ATP concentration of 1 mM was used as a reaction solution, and 0.2 g of a SA-grade or C-grade as a walleye pollack frozen surimi was used, and the measurement results were plotted in the graph of FIG. 11 for each type of surimi. Indicated.

From this result, it can be seen that the SA class surimi and the C class surimi can be clearly distinguished.

Furthermore, comparison was also made based on gel strength, which is a conventional method for determining the quality of frozen surimi. That is, 3% salt is added to the frozen surimi, stirred, and then packed in a casing at 35 ° C.
Heating was performed for 60 minutes and at 85 ° C. for 20 minutes to make a slab shape, and a 13 mm thick sample was cut out, and the gel strength was measured using a rheometer (RMT-1300 manufactured by Iio). As a result, it is about 2000 g for SA grade and about 200 g for C grade,
Differences in gel strength were confirmed as differences in titer.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a measuring device used in the method of the present invention. FIG. 2, FIG. 3-4, FIG. 5, FIG. 6 and FIG.
The figure is a graph showing the measurement results in Examples 1 to 5, respectively. FIG. 8 is a graph showing the correlation between the method of the present invention and the colorimetric method. 9 to 11 show Embodiment 7 respectively.
10 is a graph showing the measurement results at ９9. (Explanation of reference numerals) 1... PH meter 2... PH electrode 3... Stirring rod 4... Constant temperature bath 5.

Continuation of the front page (72) Inventor Noboru Kato 6083-7-F-1-11-1, Oaza, Kawagoe-shi, Saitama (72) Inventor Shuzo Sakuma 2-19-8, Ohara, Urawa-shi, Saitama (72) Inventor Nakagawa Noriwa 2-chome, Iiyama Mitsumachi, Funabashi City, Chiba Prefecture

Claims (4)

(57) [Claims] (1) In a buffer containing ATP and at least one of inorganic calcium salts and magnesium salts or EDTA,
Add the homogenized frozen surimi in a buffer containing potassium chloride or sodium chloride, and adjust the pH of the whole system.
A method for measuring the freshness of frozen surimi, wherein the change is measured and compared with a reference value. 2. A frozen surimi which is homogenized in a buffer containing potassium chloride or sodium chloride in a buffer containing ATP, potassium chloride or sodium chloride and at least one of inorganic calcium salts and magnesium salts or EDTA. And measuring the pH change of the whole system and comparing it with a reference value. 3. A buffer containing ATP and at least one of inorganic calcium salts and magnesium salts or EDTA,
Add the homogenized frozen surimi in a buffer containing potassium chloride or sodium chloride, and adjust the pH of the whole system.
A method for measuring the freshness of frozen surimi, wherein the change is measured as the amount of alkali required to neutralize the entire system and compared with a reference value. 4. A frozen surimi homogenized in a buffer containing potassium chloride or sodium chloride in a buffer containing ATP, potassium chloride or sodium chloride and at least one of inorganic calcium salts and magnesium salts or EDTA. A method for measuring the freshness of frozen surimi, wherein pH change in the whole system is measured as the amount of alkali required to neutralize the whole system, and the measured value is compared with a reference value.