JP7681441B2 - Method for producing aged meat - Google Patents

Description

The present invention relates to a method for producing aged meat, and to the aged meat produced by said method.

Immediately after slaughter, meat from livestock animals is soft and has high water retention (juiciness), but it lacks flavor and aroma. After some time has passed since slaughter, rigor mortis sets in and the meat hardens, making it difficult for the tissue to retain water, resulting in low water retention. However, by storing the meat at a lower temperature, it becomes soft again, regains water retention, and improves its flavor and aroma. This process of improving the texture and flavor of meat by storing it after rigor mortis is called aging. The mechanism of aging is the action of protein-degrading enzymes (proteases) on the myofibrils in the meat, and it is thought that the resulting structural change restores water retention. The reason for the improved flavor is that proteases break down meat proteins, increasing peptides and amino acids that have umami flavors. Peptides and amino acids are also the source of aromas that are released when meat is heated, so increasing their content is one of the factors that improve the aroma of cooked meat.

Meat aging methods can be broadly divided into two types: "wet aging" and "dry aging." Dry aging is an aging method in which the carcass, either whole or divided, is exposed to air. This method is expected to greatly improve palatability, as the surface dries out, concentrating umami components and the like. However, when aging is performed using this method, it is necessary to remove (trim) the dry parts of the surface and the parts where microorganisms such as mold have grown. For this reason, it is a more expensive aging method than the wet aging method described below. On the other hand, wet aging is a method in which meat is divided into chunks to a certain extent, then vacuum-packaged or gas-exchanged packaged and stored at low temperatures. Since contact with air is blocked during aging, drying and microbial contamination can be suppressed, making it a hygienic aging method. However, it is less effective in improving palatability than the dry aging method described above.

As a technique for improving flavor and taste and hygienically aging the meat, for example, Patent Document 1 discloses a method in which quick-frozen meat is thawed, the drips are wiped off, and then aromatic alcohol is added, the meat is packed in a packaging material, and then refrigerated at 4°C for 3 to 4 weeks. Patent Document 2 discloses a method for producing aged meat that prevents drips from leaking, enhances flavor, and prevents bacterial growth and spoilage by a process of drying the meat using a dehydrating action caused by osmotic pressure and a process of storing the meat in an oxygen-deprived environment after or during drying. Patent Document 3 discloses a method for aging meat that combines wet aging and dry aging.

JP 4-210579 A Patent Publication 2018-153115 Patent Publication 2018-124064

The methods described in Patent Documents 1 and 2 above do not involve dry aging, and therefore do not achieve the significant improvement in flavor and taste that can be achieved by dry aging. Patent Document 3 also discloses a maturation technique that combines wet aging and dry aging, but the purpose of this is to produce physiologically active peptides such as blood pressure lowering peptides, and does not specifically address the issues with dry aging, such as drying during the maturation process and control of microbial growth.

The present invention aims to provide a method for producing aged meat that can suppress the growth of microorganisms and produce aged meat with good flavor and taste derived from dry aging while maintaining a high yield.

The present invention provides the following:
(1) A method for producing aged meat, comprising the following steps (i) to (iii).
(i) subjecting meat to a dry-aging treatment;
(ii) contacting the surface of the meat after step (i) with a bacteriostatic agent; and (iii) subjecting the meat after step (ii) to a wet-aging treatment.
(2) The method according to (1), wherein the bacteriostatic agent contains at least one component selected from the group consisting of a peracetic acid preparation, an alcohol preparation, and a sodium lactate solution.
(3) The method according to (1) or (2), wherein the bacteriostatic agent contains a peracetic acid preparation as an ingredient, and the peracetic acid concentration of the bacteriostatic agent is 400 to 1800 ppm.
(4) Any of the methods (1) to (3), wherein the aging time is 400 to 1600 hours.
(5) The method according to (4), wherein the aging time includes a dry aging treatment time of 24 to 240 hours.
(6) Aged meat produced by any of the methods listed in (1) to (5).
(7) The aged meat according to (6), in which the total amount of free amino acids per 100 g is 100 mg or more. (8) The aged meat according to (6) or (7), in which the total amount of free amino acids per 100 g is 4 to 150 times the amount of inosinic acid.
(9) The aged meat according to any one of (6) to (8), having a general viable bacterial count of 1 x 10 ⁷ cfu or less per gram.
(10) Aged meat according to any one of (6) to (9), which, when cut to a thickness of 1 cm, heated and cooked on a hot plate at 180°C until the internal temperature reaches 70°C, and then cut into a piece measuring 1 cm long and 2 cm wide, has a breaking strength of 1000 gf or less.

The present invention provides a method for producing aged meat that can suppress the growth of microorganisms and produce aged meat with good flavor and taste derived from dry aging while maintaining a high yield.

The results of microbial tests on aged meat aged using various bacteriostatic agents 2, 17, and 31 days after the start of aging are shown in Fig. 1. Fig. 1 (A) shows the transition of general viable cell counts in aged meat aged using various bacteriostatic agents. Fig. 1 (B) shows the transition of coliform bacteria counts in aged meat aged using various bacteriostatic agents. The figure shows the total free amino acid content of meat aged using various bacteriostatic agents after 17 and 31 days from the start of aging. The error bars in the figure show the standard deviation for n=3. The results of microbial tests on aged meat aged using a bacteriostatic agent containing peracetic acid at various concentrations, 3 days, 18 days, and 33 days after the start of aging, are shown in Fig. 3. Fig. 3 (A) shows the transition of general viable bacteria counts in aged meat aged using a bacteriostatic agent containing peracetic acid at various concentrations. Fig. 3 (B) shows the transition of coliform bacteria counts in aged meat aged using a bacteriostatic agent containing peracetic acid at various concentrations. The figure shows the total free amino acid content of meat aged using a bacteriostatic agent containing peracetic acid at various concentrations, 18 days and 33 days after the start of aging. The error bars in the figure show the standard deviation for n=3. 5 is a graph showing the results of a microbial test for each aged hybrid meat. Fig. 5 (A) shows the transition of the general viable cell count. Fig. 5 (B) shows the transition of the coliform bacteria count. 6 is a graph showing the results of a microbial test for each aged meat of the Holstein breed. Fig. 6 (A) shows the transition of the general viable cell count, and Fig. 6 (B) shows the transition of the coliform bacteria count. 7 is a chart showing the results of the sensory test of each aged meat. Fig. 7(A) shows the result of the sensory test of the aged meat of the crossbreed. Fig. 7(B) shows the result of the sensory test of the aged meat of the Holstein breed. 8 is a graph showing the total free amino acid content of each aged meat. Fig. 8(A) shows the total free amino acid content of the crossbreed. Fig. 8(B) shows the total free amino acid content of the Holstein breed. 9 is a graph showing the amount of inosinic acid in each aged meat. Fig. 9(A) shows the amount of inosinic acid in a crossbreed. Fig. 9(B) shows the amount of inosinic acid in a Holstein. 1 is a graph showing the breaking strength of each aged meat. The error bars in the figure show the standard deviation of n=52 (D6W24, 2 samples), n=59 (D10W20, 2 samples), and n=48 (W30, 2 samples).

1. Method for Producing Aged Meat The method for producing aged meat of the present invention is characterized by comprising the following steps (i) to (iii):
(i) subjecting meat to a dry-aging treatment;
(ii) adding a bacteriostatic agent to the meat after step (i); and (iii) subjecting the meat after step (ii) to a wet ageing treatment.

The method of the present invention combines a relatively short-term dry aging process that does not require trimming with a wet aging process to further promote maturation, making it possible to obtain aged meat that has the flavor derived from dry aging and is sufficiently matured while maintaining a high yield. By performing the dry aging process first, maturation can be promoted without losing the umami components of the meat. However, if wet aging is performed first, it is not possible to prevent the reduction of umami components due to drip outflow, and even if dry aging is performed afterwards, it may be difficult to obtain aged meat with the desired flavor and taste.

Furthermore, the method of the present invention performs a bacteriostatic treatment between dry aging and wet aging, which removes or reduces the number of microorganisms that adhere to the surface of the meat during dry aging, enabling hygienic aging. Since microorganisms are removed or reduced before the wet aging process, relatively long-term aging is possible, similar to conventional wet aging.

In this specification, "meat" refers to muscle tissue parts of vertebrates that can be consumed by humans. There are no particular limitations on the organism from which it is derived, so long as it is edible, but commonly consumed meats such as beef, pork, chicken and mutton are preferred, with beef being particularly preferred. There are no particular limitations on the part of the meat, so long as it is a part made of muscle tissue, and any part such as loin, belly or shoulder loin can be used. In addition, the meat may have bones attached.

In this specification, "aged meat" refers to meat that has been stored at low temperatures for at least 12 hours. "Low temperature" here refers to 0 to 10°C. 0 to 5°C is particularly suitable.

In this specification, "yield" refers to the ratio of the weight of the aged meat produced to the weight of the raw meat before aging.

<Step (i) Dry aging treatment>
Each step of the method of the present invention will now be described.
Step (i) of the method of the present invention is a step of dry-aging meat. In this specification, "dry-aging" refers to storing meat at low temperature in contact with air. As long as the meat is aged in contact with air, other conditions are not limited, but it is preferable to use a dedicated aging chamber to suppress the spread of microorganisms to the surroundings. In addition, it is preferable to expose the meat to wind in order to further promote aging. If the surface of the meat is exposed to air, the meat may be covered with a nonwoven fabric or the like.

The size of the meat to be subjected to the dry-aging process may be a whole piece of meat such as a carcass, or meat cut into a thickness of several to several tens of centimeters. The time for the dry-aging process is not particularly limited, but is preferably 24 to 240 hours, and more preferably 48 to 120 hours. If the dry-aging process is carried out for more than 240 hours, it may become necessary to trim the dried parts and parts where microorganisms have grown, so from the viewpoint of production costs, it is preferable to move to the next process before that.

The humidity of the environment surrounding the meat during dry-aging is not particularly limited, but is preferably 40 to 100%, more preferably 60 to 97%, and even more preferably 80 to 95%.
In this specification, the term "humidity" refers to relative humidity, and specifically refers to the humidity calculated by the following formula:
Humidity (%) = actual water vapor amount / saturated water vapor amount

Dry aging causes moisture to evaporate from the surface of the meat, so even without trimming, the yield will be less than 100%. It is preferable to keep the yield at 85% or higher, and especially 88-94%.

<Step (ii) Bacteriostatic agent treatment>
Step (ii) of the method of the present invention is a step of contacting the surface of the meat after step (i) with a bacteriostatic agent. In this specification, the term "bacteriostatic agent" refers to an aqueous solution containing a component that can suppress the growth of microorganisms involved in meat spoilage and can be used as a food additive for food surface sterilization. As a bacteriostatic agent, a component that does not affect the flavor or taste of meat, or a component that has little effect on the flavor or taste, is particularly preferable. Such a component can be selected from, for example, a peracetic acid preparation, an alcohol-based preparation, a sodium lactate solution, and the like. In this specification, the term "peracetic acid preparation" refers to a food additive preparation containing peracetic acid, acetic acid, and hydrogen peroxide as main components. In this specification, the term "alcohol preparation" refers to a food additive preparation containing ethanol as the main component. In this specification, the term "sodium lactate solution" refers to an aqueous solution containing sodium lactate, which is distributed as a food additive preparation, at a concentration of about 50 to 60% by weight. Among these, a peracetic acid preparation can be preferably used as a bacteriostatic agent in the present invention, since it has little effect on the flavor of meat.

By contacting meat with a bacteriostatic agent, the bacteriostatic agent can be applied to the meat. The means for contacting meat with the bacteriostatic agent is not particularly limited as long as the bacteriostatic agent contacts the meat surface evenly, but for example, immersion, application, spraying, etc. can be used. Of these, immersion is preferred as it can more reliably apply the bacteriostatic agent components to the meat. When immersing, for example, the meat can be placed in the bacteriostatic agent so that the entire meat is immersed, and immersion can be carried out for about 30 seconds to 2 minutes. The temperature of the bacteriostatic agent at this time is preferably 0 to 25°C, particularly 0 to 10°C.

When using a peracetic acid preparation as a bacteriostatic component, the peracetic acid concentration of the bacteriostatic agent is preferably 400 to 1800 ppm, and particularly 1000 to 1500 ppm. By keeping the peracetic acid concentration within the above range, the number of bacteria on the surface of the meat can be reliably reduced, and the effect of peracetic acid on the flavor, etc. of the meat can be suppressed.

<Step (iii) Wet aging treatment>
In this specification, "wet aging" refers to storing meat at low temperature in a state where it is vacuum-packaged or gas-substituted packaged to prevent contact with air. In this specification, "vacuum packaging" and "gas-substituted packaging" refer to packaging in which meat is placed in a sealed packaging bag, the air inside is removed (vacuum packaging) or replaced with nitrogen gas (gas-substituted packaging), and then the bag is sealed. Vacuum packaging is particularly preferred. Any film-like material can be used for the sealed packaging, as long as it has gas barrier properties and is flexible enough to deform to fit the shape of the meat when the air is removed.

The wet aging process time is preferably 160 to 1576 hours, particularly 360 to 720 hours. Combined with the dry aging process time, the maturation time is preferably 400 to 1600 hours, particularly 408 to 792 hours. However, the conditions during maturation, such as temperature, humidity, and time, can be changed as appropriate depending on the condition of the meat being aged, and are not limited to the conditions shown here.

<Other processes>
The method of the present invention may include a washing step for removing foreign matter from the surface of the meat material before dry-aging. Washing can be carried out, for example, with physiological saline, an alcohol preparation, etc. In this case, it is desirable to avoid washing for a long period of time in order to prevent the loss of umami components in the meat.

In the method of the present invention, if the meat after dry-aging processing unintentionally becomes overdried or develops mold on the surface, a trimming step may be added as appropriate.

The method of the present invention may include a step of removing the aged meat after wet aging from the vacuum packaging or the like, cutting it, and packaging it as a product.

2. Aged meat The aged meat of the present invention is characterized by being produced by the above-mentioned method of the present invention. The aged meat of the present invention is aged meat that has been aged and has a good flavor by being produced by the method of the present invention. The total amount of free amino acids is one index of the degree of aging, and the total amount of free amino acids per 100 g of the aged meat of the present invention is preferably 100 mg or more, 150 mg or more, 200 mg or more, or 250 mg or more. Also, preferably, the total amount of free amino acids per 100 g is 4 to 150 times the amount of inosinic acid.

The general viable bacteria count per 1 g of the aged meat of the present invention is preferably 1×10 ⁷ cfu or less. The number of coliform bacteria per 1 g of the aged meat of the present invention is preferably 1×10 ⁵ cfu or less, particularly 1×10 ⁴ cfu or less. In this specification, the term "general viable bacteria count" refers to the number of bacteria measured by the following method. A predetermined weight of aged meat is immersed in 9 times the weight of PBS and treated with a stomacher for 1 minute to obtain a sample stock solution. This sample stock solution is serially diluted and mixed with a standard agar medium, cultured at 35° C. for 48 hours, the number of colonies grown on the plate is counted, and the number of colonies per 1 g of aged meat is calculated to obtain the general viable bacteria count (cfu/g). In this specification, the term "coliform bacteria count" refers to the number of bacteria measured by the following method. A predetermined weight of aged meat is immersed in 9 times the weight of PBS and treated with a stomacher for 1 minute to obtain a sample stock solution. This sample stock solution was serially diluted and mixed into Chromocult coliform agar medium (ES-UPA: approved by the United States Environmental Protection Agency) and cultured for 24 hours at 35° C. The number of colonies grown on the plate was counted, and the number of colonies per gram of aged meat was calculated to give the coliform bacteria count (cfu/g).

The aged meat of the present invention is cut into a thickness of 1 cm, cooked on a hot plate at 180°C until the internal temperature reaches 70°C, and then cut into a sample of 1 cm length x 2 cm width, and the breaking strength of the sample is preferably 1000 gf or less, particularly 900 gf or less, and more preferably 800 gf or less. In this specification, "breaking strength" refers to the load that causes breakage in a breaking strength measurement test, also called "breaking load". The breaking strength measurement test is not particularly limited, but can be carried out, for example, using a creep meter. Specifically, a cutter blade is used for the plunger of the creep meter, and the plunger is penetrated perpendicularly to the muscle fiber direction of the sample at a measurement speed of 1.0 mm/sec and a strain rate of 150%. At that time, the breaking load value can be calculated from the obtained stress-strain curve.

The present invention will be described in more detail below with examples, but the present invention is not limited to these.

Example 1: Comparison of various bacteriostatic agents
2500-3500 g of frozen beef (sirloin) as raw meat was thawed, washed with 2% saline, and cut to a thickness of 5 cm. The meat was left to stand in a refrigerator and dry-aged. The dry-aging treatment was carried out for 48 hours, during which the temperature in the refrigerator was 0.2-4.0°C and the humidity was 63.2-89.1%. The yield of beef after dry-aging treatment was 91%. The beef after dry-aging treatment was immersed in a peracetic acid preparation (Parsan MP2-J (Envirotech Japan Co., Ltd.), diluted with water to a peracetic acid concentration of 400 ppm), an alcohol preparation (Kilbact 59 (Ueno Foods Co., Ltd.), ethanol 59%, undiluted), and a sodium lactate solution (Corbion Japan Co., Ltd., 60% undiluted) for 30 seconds each. As a control, meat that was not immersed in these bacteriostatic agents was also prepared. After wiping off the moisture on the surface of the meat after immersion, it was vacuum-packed. The vacuum-packaged beef was left to stand in a refrigerator and wet-aged for 15 and 29 days. The temperature inside the refrigerator was 0.6 to 4.3°C. The general viable bacteria count and coliform bacteria count in the beef under each condition (microbiological test) were confirmed, and the free amino acids that affect the flavor and taste were measured. The above aging test was performed in triplicate (n=3), and the average value of each measurement was displayed as the measurement result.

The general viable bacteria count test was carried out in the following manner. 225 mL of PBS was added to 25 g of beef, and the mixture was treated with a stomacher for 1 minute to obtain a sample stock solution. This sample stock solution and appropriate serially diluted solutions were mixed into a standard agar medium and cultured at 35°C for 48 hours. The number of colonies grown on the plate was counted to obtain the general viable bacteria count.

The coliform bacteria count test was carried out as follows. 225 mL of PBS was added to 25 g of beef, and the mixture was processed in a stomacher for 1 minute to obtain a sample stock solution. This sample stock solution and appropriate serial dilutions were mixed into Chromocult Coliform Agar medium (ES-UPA: approved by the United States Environmental Protection Agency) and cultured at 35°C for 24 hours. The number of colonies grown on the plate was counted to obtain the coliform bacteria count.

Figure 1 shows the results of microbial testing of aged meat under each condition, 2, 17, and 31 days after the start of aging. (A) shows the general viable bacteria count, and (B) shows the change in coliform bacteria count. It was confirmed that, compared to meat that did not use a bacteriostatic agent, both the general viable bacteria count and the coliform bacteria count were significantly reduced in aged meat that used any bacteriostatic agent.

Free amino acids were measured using the following method. A perchloric acid solution twice the volume of the sample was added and homogenized. Centrifugation was performed, and the supernatant was filtered to remove insoluble matter. The filtrate was neutralized with potassium hydroxide and used as the sample stock solution. The sample stock solution was diluted 4-fold and analyzed using HPLC (Shimadzu Nexera, manufactured by Shimadzu Corporation). The column used was an InfinityLab Poro-Shell HPH-C18 (3.0 mm ID x 100 mm) manufactured by Agilent. Seventeen types of amino acids (glutamic acid, aspartic acid, glycine, alanine, proline, threonine, histidine, arginine, valine, methionine, leucine, isoleucine, phenylalanine, cysteine, lysine, tyrosine, and serine) were measured as total free amino acids.

Figure 2 shows the total free amino acid content of the aged meat under each condition, 17 and 31 days after the start of aging. The total free amino acid content of meat without aging is also shown. There was no significant difference in the total free amino acid content between the aged meat using any bacteriostatic agent and the aged meat without bacteriostatic agent, indicating that the bacteriostatic agent is unlikely to have a negative effect on aging.

A sensory evaluation was conducted to confirm the change in palatability due to aging. Beef was cut into 1 cm steaks, vacuum-packed, and cooked in a water bath at 80°C for 10 minutes. Four experienced panelists evaluated the impact on flavor, including off-flavors and off-odors, of aged meat with a 31-day aging period (2 days of dry aging + 29 days of wet aging), which was not treated with a bacteriostatic agent, and aged meat treated with a bacteriostatic agent containing a peracetic acid preparation, an alcohol preparation, or a sodium lactate solution. The results confirmed that the aged meat treated with a peracetic acid preparation had the least impact on flavor of the bacteriostatic agent.

Example 2: Examination of the concentration of bacteriostatic agent
5000-6000g of beef was cut into 5cm thick pieces. The pieces were left in a refrigerator and dry-aged. The dry-aging process was carried out for 72 hours, during which the temperature in the refrigerator was 0.6-3.6°C and the humidity was 75.5-96.9%. The yield of beef after dry-aging was 89%. The beef after dry-aging was immersed in peracetic acid preparations (Persun MP2-J diluted with water) with peracetic acid concentrations of 1000ppm and 1500ppm for 30 seconds. As a control, meat that was not immersed in these bacteriostatic agents was also prepared. After wiping off the moisture on the surface of the meat after immersion, it was vacuum-packed. The beef after vacuum packaging was left in a refrigerator and wet-aged for 15 and 30 days. The above aging test was carried out in triplicate (n=3), and the average value of each measurement was displayed as the measurement result.

The general viable bacteria count and coliform bacteria count in each beef were confirmed, and the total free amino acids were measured in the same manner as in Example 1. In addition, inosinic acid was also measured. The results of the microbial test on the aged meat under each condition, 3 days, 18 days, and 33 days after the start of aging, are shown in Figure 3. It was shown that the bacteriostatic agent containing 1500 ppm of peracetic acid is effective in suppressing the number of bacteria, especially in the coliform bacteria count. (A) shows the general viable bacteria count, and (B) shows the progress of the coliform bacteria count. In addition, the total free amino acid amount in the aged meat under each condition, 18 days and 33 days after the start of aging, is shown in Figure 4. The total free amino acid amount in the meat without aging is also shown. Increasing the concentration of peracetic acid did not have a significant effect on the total free amino acid amount, indicating that the bacteriostatic agent is unlikely to have a negative effect on aging.

Inosinic acid was measured by the following method. A perchloric acid solution was added in an amount twice that of the sample, and the sample was homogenized. The sample was centrifuged, and the supernatant was filtered to remove insoluble matter. The filtrate was neutralized with potassium hydroxide, and used as the sample stock solution, and was analyzed by HPLC (Shimadzu UFLC, manufactured by Shimadzu Corporation). The column used was Shim-pack CLC-ODS (6.0 mm ID x 150 mm, manufactured by Shimadzu Corporation).
The ratio of total free amino acids (mg/100 g) to inosinic acid (mg/100 g) for each aged meat is shown in Table 1.

A sensory evaluation was conducted to confirm the change in palatability due to aging. Beef was cut into 1 cm steaks, vacuum-packed, and cooked in a water bath at 80°C for 10 minutes. First, six experienced panelists evaluated the impact on flavor, including off-flavors and off-odors, of aged meat with a 33-day aging period (3 days of dry aging + 30 days of wet aging) without bacteriostatic treatment, and aged meat treated with bacteriostatic agents at a peracetic acid concentration of 1000 ppm and 1500 ppm. As a result, it was evaluated that the bacteriostatic agent had almost no effect on flavor and no off-flavors or off-odors due to aging in all test groups. It was also confirmed that no change in physical properties occurred due to the presence or absence of a bacteriostatic agent.

Next, five experienced panelists evaluated the texture of the aged meat. Each panelist tasted two samples each of meat immediately after thawing and aged meat (without bacteriostatic agent) that had been aged for 33 days and evaluated them (n=10). The evaluation items were "tenderness" and "umami flavor," and the evaluation criteria were set as follows, with meat that was not aged being rated "0."
-Softness +3: Very soft; +2: Soft; +1: Slightly soft; -1: Slightly hard; -2: Hard; -3 Very hard -Umami +3: Strong umami taste; +2: Excellent umami taste; +1: Slightly excellent umami taste; -1: Slightly inferior umami taste; -2: Poor umami taste; -3: Almost no umami taste can be felt.

The average scores for each panelist's evaluation were 1.25 for "softness" and 0.8 for "umami." This shows that aging clearly improved the texture.

Example 3: Study on dry aging period
(1) Preparation of sample (beef) Three sirloins each from crossbred (castrated) and Holstein (castrated) were used as samples. The weight per piece was about 12-14 kg for the crossbred and about 8-9 kg for the Holstein.

(2) Aging (dry aging + wet aging)
The sample was divided into 7 parts, washed with 2% saline, and then placed in a refrigerator for dry aging. The dry aging was performed for 6 or 10 days. The humidity in the refrigerator during this period was 80.7±3.2%. The dry aging sample was immersed in a peracetic acid preparation (Persun MP2-J (Envirotech Japan Co., Ltd.), diluted with water to a peracetic acid concentration of 1500 ppm) for 30 seconds. After wiping off the moisture on the surface of the immersed sample, each was vacuum-packaged. The vacuum-packaged sample was placed in a refrigerator for wet aging. The aging period was 15 days or 30 days in total for dry aging and wet aging. During the above aging period, the temperature in the refrigerator was 2.1±0.2°C. Hereinafter, dry aging will be abbreviated as "D" and wet aging as "W". For example, if dry aging treatment is performed for 6 days and wet aging treatment is performed for 24 days, the aging treatments will be abbreviated as "D6W24".

(3) Aging (wet aging only)
For comparison, the same sample was aged only by the wet aging method according to the following procedure. Seven divided samples were immersed in a peracetic acid preparation (Parsan MP2-J (Envirotech Japan Co., Ltd.), diluted with water to a peracetic acid concentration of 1500 ppm) for 30 seconds. After immersion, the moisture on the surface of the sample was wiped off, and then vacuum-packaged. The vacuum-packaged sample was left to stand in a refrigerator and subjected to wet aging treatment for 15 or 30 days. During the above aging period, the temperature inside the refrigerator was 2.1±0.2°C.

(4) Yield and Appearance Table 2 shows the results of measuring the yield of various samples. As shown in Table 2, the yield of the samples dry-aged for 10 days was 90.4% for the crossbred and 85.8% for the Holstein. After that, the samples were immersed in a peracetic acid preparation and wet-aged. However, there was no particular increase in weight, and almost no dripping was observed after aging, suggesting that there was little adsorption of peracetic acid.

In terms of appearance, both the crossbred and Holstein samples showed surface hardening and browning, particularly in samples that had been dry-aged for 10 days. However, it was confirmed that subsequent wet aging improved the surface moisture retention and reduced the browning.

(5) Microbiological Testing The general viable cell count and coliform bacteria count (microbiological testing) of each sample were confirmed in the same manner as in Example 1. Figures 5 and 6 show the results of the microbiological tests of the crossbred and Holstein breeds, respectively. (A) shows the general viable cell count, and (B) shows the coliform bacteria count, respectively. In both breeds, an increase in the viable cell count was observed during the dry aging period. However, the viable cell count was significantly reduced by treatment with a bacteriostatic agent after the dry aging period. Furthermore, the viable cell count in the samples that were subsequently wet aged did not show a significant difference at the stage of a total aging period of 30 days compared to the samples that were only wet aged for 30 days.

(6) Sensory Evaluation Crossbred and Holstein samples aged at D6W24, D10W20, and W30 were cut into 1 cm thick pieces, cooked on a hot plate at 180°C until the internal temperature reached 70°C, and then cut into 2 cm wide pieces. Each cooked sample was eaten by 14 panelists and evaluated in terms of softness, umami, flavor intensity, aroma intensity, and the presence or absence of peracetic acid odor. The evaluation criteria for softness, umami, flavor intensity, and aroma intensity were as follows, with the W30 sample being rated "0".

<Softness> 3: Very soft; 2: Soft; 1: Slightly soft; 0: No difference; -1: Slightly hard; -2: Hard; -3: Very hard.
<Umami> 3: Very strong; 2: Strong; 1: Slightly strong; 0: No difference; -1: Slightly weak; -2: Weak; -3: Very weak.
<Intensity of flavor> 3: Very strong; 2: Strong; 1: Slightly strong; 0: No difference; -1: Slightly weak; -2: Weak; -3: Very weak.
<Intensity of fragrance> 3: Very strong; 2: Strong; 1: Slightly strong; 0: No difference; -1: Slightly weak; -2: Weak; -3: Very weak.

Figure 7 shows the results of evaluation of each evaluation item in crossbreeds and Holsteins. (A) Crossbreeds, (B) Holsteins. In crossbreeds, D6W24 showed significantly higher values for tenderness, flavor intensity, and aroma intensity compared to W30 (p<0.01, t-test). D10W20 also showed significantly higher values for all four items, tenderness, umami, flavor intensity, and aroma intensity (p<0.01, t-test). In Holsteins, D6W24 and D10W20 showed significantly higher values for all four items, tenderness, umami, flavor intensity, and aroma intensity compared to W30 (p<0.05, t-test).

In addition to the above samples, similar sensory evaluations were also conducted on samples of crossbred and Holstein beef aged on D6W9 and D10W5. Many panelists rated the flavor at this stage as being stronger than that of W30 (not shown).

The presence or absence of a peracetic acid odor was evaluated according to the following criteria.
4: Almost no effect on flavor; 3: Some effect but tolerable; 2: Some effect and somewhat unacceptable; 1: Severe effect and inedible.

Table 3 shows the evaluation results for the presence or absence of peracetic acid odor in each sample. It was confirmed that the peracetic acid odor had almost no effect on the flavor of any of the samples.

(7) Measurement of free amino acids The free amino acid content was measured for samples dry-aged for 6 and 10 days, and for samples wet-aged only, after a total aging period of 15 and 30 days. The free amino acid content was measured under the same conditions as in Example 1. The free amino acid content of each sample is shown in Figure 8. (A) shows the free amino acid content of the crossbred, and (B) shows the free amino acid content of the Holstein. It was confirmed that the samples dry-aged for 6 and 10 days had higher free amino acid content than the samples wet-aged only.

(8) Measurement of inosinic acid The inosinic acid contents of samples dry-aged for 6 and 10 days and samples wet-aged only were measured after a total aging period of 15 and 30 days. The inosinic acid measurements were performed under the same conditions as in Example 1. The amount of inosinic acid in each sample is shown in FIG. 9. (A) shows the amount of inosinic acid in the crossbred, and (B) shows the amount of inosinic acid in the Holstein. It was confirmed that the reduction in inosinic acid due to aging in the samples dry-aged for 6 and 10 days was not significantly different from that in the samples wet-aged only.

(9) Breaking strength test The hybrid D6W24, D10W20 and W30 samples were cut to a thickness of 1 cm, cooked on a hot plate at 180°C until the internal temperature reached 70°C, and then cut into 1 cm length x 2 cm width. Each cooked sample was subjected to a creep meter (Yamaden Co., Ltd., RE2-33005B) to measure the breaking load (breaking strength) value. A cutter blade was used for the plunger of the creep meter to penetrate perpendicularly to the muscle fiber direction of the sample at a measurement speed of 1.0 mm/sec and a strain rate of 150%, and the breaking load value was calculated from the obtained stress-strain curve. The number of tests was 52, 59 and 48 times in total for D6W24, D10W20 and W30, using two samples each. The breaking load value of each sample is shown in Figure 10. As shown in FIG. 10, it was confirmed that the breaking load value was significantly lower in the dry-aged sample than in the wet-aged sample (p<0.01, t-test).

These test results confirm that in a method for producing aged meat that combines dry aging and wet aging, it is possible to obtain aged meat with sufficiently low general viable bacterial counts and coliform bacteria counts, a soft texture, and strong flavor, aroma, and umami, regardless of whether the dry aging period is 6 or 10 days.

The present invention relates to a food manufacturing method and food, and can be used in the food manufacturing and sales industry.

Claims (8)

The following steps (i) to (iii):
(i) subjecting meat to a dry-aging treatment;
(ii) contacting the surface of the meat after step (i) with a bacteriostatic agent; and (iii) subjecting the meat after step (ii) to a wet-aging treatment .
Equipped with
The bacteriostatic agent contains at least one component selected from the group consisting of a peracetic acid preparation, an alcohol preparation, and a sodium lactate solution.
A method for producing aged meat. The method according to claim 1 , wherein the bacteriostatic agent comprises a peracetic acid preparation as an ingredient, and the peracetic acid concentration of the bacteriostatic agent is 400 to 1800 ppm. The method according to claim 1 or 2 , wherein the maturation time is from 400 to 1600 hours. The method according to claim 3 , wherein the dry aging treatment time is 24 to 240 hours. The method according to any one of claims 1 to 4 , wherein the total amount of free amino acids per 100 g of the aged meat is 100 mg or more. The method according to any one of claims 1 to 5 , wherein the total amount of free amino acids per 100 g of the aged meat is 4 to 150 times the amount of inosinic acid. The method according to any one of claims 1 to 6 , wherein the general viable cell count per gram of the aged meat is 1 x 10 ⁷ cfu or less. The method according to any one of claims 1 to 7 , wherein when the aged meat is cut into a thickness of 1 cm, heated and cooked on a hot plate at 180°C until the internal temperature reaches 70°C, and then cut into a size of 1 cm length x 2 cm width, the breaking strength of the cut piece is 1000 gf or less.