JP4543233B2 - Prediction method of meat color retention days of beef by measuring antioxidant capacity - Google Patents

Description

  The present invention relates to a method for predicting the color change time of beef, and more particularly to a technique for predicting the color change (browning) of beef at an early stage in order to determine the longevity of beef at the transaction stage.

There are reports that examined how important the color of meat in beef at the retail stage. According to it, about 60% of Japanese consumers say that meat color is the most important factor when purchasing beef.
There are several factors that determine the color of beef, but it can be considered that it is mostly determined by myoglobin. Myoglobin is a chromoprotein that has the role of storing oxygen in muscle. Inside the fresh cut of carcass and meat chunk is dark red reduced myoglobin, which is easily combined with oxygen in the air to become bright red oxymyoglobin in about 15 to 30 minutes.
Although this color is the most popular meat color found in stores, oxymyoglobin is converted to brown metmyoglobin by autooxidation. It is said that when 30-40% or more of myoglobin is oxidized to metmyoglobin, the discoloration of the meat is visibly recognized and the consumer's willingness to purchase is lost.

The rate of oxidation from oxymyoglobin to metmyoglobin varies greatly depending on (1) muscle site, (2) age of slaughter, (3) feeding conditions, (4) content of antioxidants (such as vitamin E), etc. .
However, it is difficult to judge the meat color stability when the beef is fresh. For example, the added value of beef that is fattened by feeding vitamin E is evaluated at the carcass rating and beef trade stages. Hateful.
Therefore, it is necessary to develop a technology for predicting beef discoloration (browning) at an early stage in order to determine the longevity of beef at the transaction stage, but there has been no report on such technology development so far.

  An object of the present invention is to develop a technique for predicting beef discoloration early in a fresh stage.

  As a result of repeated studies to achieve the above object, the present inventors have found that there is a negative correlation between the amount of antioxidants in beef and the rate of oxidation of myoglobin that determines the color of meat. It was found that the discoloration of beef can be predicted by the above, and the present invention has been reached.

The present invention according to claim 1 uses the antioxidant capacity measurement kit to determine the content (x) of the antioxidant in the minced muscle collected from the sample beef, and substitutes this into the regression equation below. Thus, the method for predicting the meat color retention days of beef by measuring antioxidant ability is characterized by predicting the color change time (y) of the sample beef under normal display conditions at the store .
y = 11.393 x + 0.6363

  According to the present invention, since the beef discoloration (browning) can be predicted at an early stage in a fresh stage, it is possible to accurately determine the longevity of beef in a trading stage.

  There is no restriction | limiting in the beef to which this invention is applied, For example, what is derived from a black-haired Japanese breed, a hybrid breed, a Holstein breed, a brown-browned breed, etc. is supplied to a market. Moreover, it is not limited about the part of beef, the slaughter age, and the breeding conditions of the cow.

The present invention is a method for predicting discoloration of beef by focusing on the action of an antioxidant that suppresses the oxidation of myoglobin present in the muscles of cattle. Therefore, muscle is collected from the sample beef. Muscles collected from beef obtained by dismantling slaughtered cattle are minced, vacuum packaged, and stored frozen until they are used for experiments (usually several days to a few weeks).
Examples of muscle types include semi-tendon-like muscle, semi-membranous muscle, gluteus medius, longest chest muscle, longest waist muscle, and psoas major muscle. Necessary muscle sites are collected from the sample beef to be examined.
The fresh cut end of the carcass has a dark red color due to reduced myoglobin, but changes to bright red oxymyoglobin in about 15 to 30 minutes by reacting with oxygen in the air. This is a reaction called blooming. However, this color, which is most preferred by consumers, is not retained as it is, and is further oxidized over time to change to brown metmyoglobin.

When beef is kept at 4 ° C under irradiation of fluorescent lamps, which is a normal display condition at stores, when 30-40% of myoglobin is oxidized to metmyoglobin, discoloration of the meat becomes conspicuous, and consumer purchases It is said that the willingness is lost.
Therefore, as a result of examining the conditions under which 30-40% of myoglobin is oxidized to metmyoglobin as quickly as possible, the present inventors have collected a muscle site from beef and the amount of antioxidants in the muscle is reduced. It has been found that beef discoloration can be predicted because it affects the speed of myoglobin oxidation. As a result, it is possible to quickly determine the antioxidant capacity of the muscles and accurately determine the longevity of beef at the trading stage from this value.

Hereinafter, the method of the present invention will be described.
Muscles derived from beef collected from slaughtered and dismantled cattle can be immediately used as a sample for experiments, but preferably the beef is vacuum-packed and stored at 3-5 ° C, preferably 4 ° C. A columnar sample having a thickness of 1 cm and a diameter of 3 cm is prepared from the beef taken out of the vacuum package after about one week. This is placed on a plastic dish and placed in a 4 ° C. refrigerator for 30 minutes (for blooming).
The sample is then wrapped in oxygen-permeable wraps and each muscle site is kept at 4 ° C. under fluorescent light irradiation, which is a normal display condition, and the ratio of metmyoglobin on the beef surface (muscle Measure the color change ratio) daily.

The oxidation ratio (Met (%)) of myoglobin to metmyoglobin can be determined as follows according to the method of Stewart et al. (J. Food Sci., 30, p464-469, 1964).
That is, the spectral reflectance (CL (λ), unit:%) at 520, 530, 570 and 580 mμ of the sample is measured, and CL (525) and CL (572) are approximately calculated as follows. . Next, CL (525) and CL (572) are divided by 100 and converted to reflectance R (λ), and KS (λ) is obtained by the following calculation formula based on this value.
CL (525) = CL (520) − {CL (520) − CL (530)} × 1/2
CL (572) = CL (570) − {CL (570) − CL (580)} × 1/5
R (525) = CL (525) / 100
R (572) = CL (572) / 100

KS (λ) is called kubelka-Munk function and represents optical density. Since the reflectance of an object is not proportional to density, it must be converted to a certain function and corrected to a value proportional to density. In that case, the kubelka-Munk function is generally used.
Here, if α = KS (572) / KS (525), the relationship between α and Met (%) is a linear expression, so the value of Met (%) can be calculated from the graph of FIG. .

KS (λ) = [{1-R (λ)} ² ] / {2 × R (λ)}
α = KS (572) / KS (525)
Met (%) =-10000 × α / 84 + 1000/6

In this way, it is possible to measure the number of days (meat color retention days or discoloration days) when the metmyoglobin ratio of the sample beef reaches 30% under normal display conditions.
On the other hand, for the muscles of all parts collected from the sample beef, after thawing the minced frozen as described above, using the antioxidant capacity measurement kit, the content of antioxidant substances in the muscle as follows (X) is obtained.
A commercially available product can be used as the antioxidant capacity measurement kit, for example, an assay kit (trade name: Total Antioxidant Status, manufactured by RANDOX).
This kit measures the antioxidant capacity of beef by the ABTS (registered trademark of RANDOX, hereinafter the same) method, which is a method for evaluating the antioxidant capacity of food. The measurement principle of the antioxidant power by this ABTS method is as follows. That is, hydrogen peroxide having a strong oxidizing action oxidizes metmyoglobin and converts it to ferryl myoglobin combined with oxygen. ABTS (2,2′-Azino-di- [3-ethylbenzthiazoline sulphonate]) is oxidized by the action of the ferryl myoglobin, and becomes colored oxidized ABTS (shows blue-green, maximum absorption band is 600 nm). Therefore, when a certain amount of hydrogen peroxide, metmyoglobin, and ABTS are reacted, a certain amount of oxidized ABTS is generated, and the amount of the generated oxidized ABTS can be quantified by measuring the absorbance. When a sample is added to the hydrogen peroxide, metmyoglobin, and ABTS solution and reacted, if there is an antioxidant in the sample, hydrogen peroxide is digested, so the amount of ferryl myoglobin produced is reduced. However, the production amount of oxidized ABTS is also reduced. Therefore, the antioxidant substance in the sample can be measured by measuring the amount of oxidized ABTS produced in the reaction product by absorbance. The above is the measurement principle of the ABTS method.

The kit includes the following:
・ Buffer: PBS (Phosphate Buffer Saline)
・ Chromogen: metmyoglobin 6.1μmol / l, ABTS 610μmol / l
Substrate: H ₂ O ₂ 250 μmol / l
Standard solution: 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (concentration varies depending on kit lot number)

An example of the measurement method using this kit is as follows.
First, the minced sample as described above is vacuum-packed and frozen, preferably stored at a low temperature of −80 ° C., and thawed during analysis. Take a sample in a tube of about 2 g, add pure water, mix with voltex, centrifuge, collect the supernatant, and use this as the sample. After adding 20 ml each of blank (pure water), standard solution and the above sample at a ratio of 1 ml of Chromogen, the absorbance at 600 nm is measured (A1).
Next, add 200 μl of substrate and warm. Heating is performed, for example, in a water bath of 35 to 40 ° C., preferably 37 ° C. After a predetermined time (usually 3 minutes), the absorbance at 600 nm is measured again (A2). The difference between the measured values of A1 and A2 thus obtained is determined, and the amount of oxidized ABTS produced and the antioxidant mass in the sample are calculated.
The calculation formula for determining the antioxidant content is as follows.
A2-A1 = ΔA
Factor = concentration of standard solution / [ΔA (blank) −ΔA (standard solution)]
Antioxidant content (mmol / l) = Factor × [ΔA (blank) −ΔA (sample)]

Finally, the antioxidant content and discoloration days for each muscle site obtained in this way are plotted in a scatter plot using excel, and a linear approximation formula (regression formula) using the least squares method is created from the relationship between the two. To do.
y = 11.393 x + 0.6363

  By substituting the antioxidant content (x) measured by the above method into this equation, the color change time (y) of the sample beef can be predicted. According to this method, the meat color retention days under the normal display conditions, that is, the discoloration days can be predicted on the day when the carcasses are disassembled into partial meats, and theoretically also predicted at the carcass stage. it can.

  Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited thereto.

Example 1 (Measurement of the ratio of metmyoglobin)
〔Materials and methods〕
Japanese tender fattening cattle that were fattened at the Kinki Chugoku Shikoku Agricultural Research Center and slaughtered at 28 months of age. The longest muscle of the chest (rib loin), the longest muscle of the lower back (sirloin), and the greater psoas muscle (fin) were collected.
The collected muscle was vacuum-packed and stored at 4 ° C. until testing, and a portion was minced and stored at −80 ° C.
The general schedule from slaughter to analytical testing is as follows.

Monday: slaughter → carcass (refrigerated at 0 ° C)
Tuesday: Rating (same method as market)
Wednesday: Dismantling → Partial meat (vacuum packed, stored at 4 ° C, minced at -80 ° C)
Thursday to Sunday: Sample storage period Monday: Measurement start date of metmyoglobin ratio (may be deviated by 1 day for convenience)

The sample of the vacuum pack stored at 4 ° C was taken out of the vacuum pack one week after slaughter to prepare a cylindrical sample having a thickness of 1 cm and a diameter of 3 cm, placed on a plastic dish, and placed in a refrigerator at 4 ° C for 30 minutes. (Due to blooming. Spectral reflectance data will be inaccurate if reduced myoglobin remains, so it must be all oxy-type at the start of the measurement.)
This was wrapped in an oxygen permeable wrap and exhibited under a fluorescent lamp at 4 ° C. (normal display), and the metmyoglobin ratio (muscle discoloration ratio) on the beef surface on days 0 to 9 was measured daily.

  The ratio of metmyoglobin was determined nondestructively by the method of Stewart (reflectance absorption spectrometry). That is, using a spectroscopic color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd .: SE2000), spectral reflectances (CL (λ), units:%) of 580, 570, 530 and 520 mμ are measured nondestructively. CL (572) and CL (525) are calculated from this data. Based on the reflectance R (λ) obtained by dividing CL (525) and CL (572) by 100, KS (λ) and α are obtained by the above formula. Further, the value of Met (%) is obtained from FIG. 1 based on the value of α. FIG. 2 shows the changes over time in the ratio of metmyoglobin under normal display conditions obtained in this way for each muscle site. From this figure, the number of days (meat color retention days) at which the metmyoglobin ratio reached 30% under normal display conditions was approximately obtained.

Example 2 (Measurement of Antioxidant Content)
In Example 1, except that each muscle part collected from the partial meat after being disassembled on Wednesday was minced and vacuum-packed and stored at −80 ° C., it was thawed at the start of the test in the same manner as in Example 1. About the obtained sample, the antioxidant content was measured using an assay kit (trade name: Total Antioxidant Status, manufactured by RANDOX). The measurement principle and contents of the kit are as described above, and the method is shown below.

[Reagent preparation]
Buffer (PBS): Use as it is. Can be stored until expiration date (refrigerated).
Chromogen: 1 vial is diluted with 10 ml of buffer and used. Can be stored refrigerated for 2 days and at room temperature for 8 hours.
-Substrate: Use 1 ml of substrate diluted with 1.5 ml of buffer solution. Can be stored refrigerated for 24 hours.
Standard solution: Use 1 vial diluted with 1 ml of pure water. Can be stored refrigerated for 2 days. Can be stored frozen for 1 month.

[Measurement procedure]
(1) Thaw a minced sample by a normal method.
(2) Weigh about 2 g of sample into a 15 ml tube. (Record the weight.)
(3) Add 4ml of pure water and mix with voltex for about 1 minute.
(4) Add 4 ml of pure water and mix with voltex for about 1 minute.
(5) Centrifuge at 3000rpm, 15min, 4 ℃.
(6) Collect 4-5 ml of supernatant with a Pasteur pipette without removing fat and store at 4 ° C.
(7) Add 1 ml of Chromogen to 20 μl each of blank (pure water), standard solution and sample of (6).
(8) The absorbance is measured at 600 nm with a spectrophotometer (HITACHI, U-1500) (A1).
(9) Add 200 μl of substrate, immediately place in a 37 ° C. water bath, and react for 3 minutes extremely accurately. After 3 minutes, the absorbance is measured in the same manner as in (8) above (A2). Care should be taken because the measurement results fluctuate in seconds.
(10) Based on the measured values of A1 and A2 and the concentration of the standard solution, determine the antioxidant concentration as follows.
It is assumed that A2−A1 = ΔA.
Factor = concentration of standard solution / [ΔA (blank) −ΔA (standard solution)].
Antioxidant content (mmol / l) = Factor × [ΔA (blank) −ΔA (sample)]
The results are shown in Table 1.

  Next, FIG. 3 shows a scatter diagram in which the relationship between the meat color retention days determined in Example 1 (the number of days until the metmyoglobin ratio reaches 30%) and the antioxidant concentration determined above is plotted for each sample. (N = 18). A linear regression analysis was performed on this scatter diagram. The approximate expression obtained is shown below. N represents the number of samples.

y = 11.393 x + 0.6363
R = 0.746 (p <0.01)
(Y is the number of days until the metmyoglobin ratio reaches 30% under normal display conditions, that is, the meat color retention days; x is the antioxidant content; R is the correlation coefficient; p <0.01 is significant at the 1% level. It means that there is.)

  As is clear from FIG. 3, there is a clear correlation between the antioxidant concentration and the meat color retention days. By this formula, the meat color retention days under normal display conditions can be accurately predicted from the antioxidant mass contained in fresh beef.

  According to the present invention, since it is possible to accurately determine the meat color stability at the carcass rating and beef trading stage, it is possible to conduct an appropriate transaction taking into account the meat color change that is very important at the retail stage. it can. Therefore, the present invention can contribute to the livestock industry and the distribution industry.

The relationship between the ratio of metmyoglobin in meat (%) and the KS value (KS (572) / KS (525)) of the sample obtained by reflection absorption spectrometry is shown. The time-dependent change of the metmyoglobin ratio (%) in each muscle region under normal display conditions (4 ° C., under fluorescent light) is shown. In the drawing, LL is the longest lumbar muscle, LT is the longest thoracic muscle, ST is the semi-tendonoid muscle, SM is the semi-membranous muscle, PM is the psoas major muscle, and GM is the gluteal muscle. The relationship between the number of days of meat color retention under normal display conditions (the number of days until the metmyoglobin ratio reaches 30%) and the antioxidant content in beef is shown.

Claims (1)

Using the antioxidant capacity measurement kit, the antioxidant content (x) in the muscle mince collected from the sample beef is calculated and substituted into the following regression equation to obtain the normal display conditions at the store. A method for predicting the meat color retention days of beef by measuring antioxidant capacity, wherein the color change time (y) of sample beef is predicted.
y = 11.393 x + 0.6363

Images