JP7672832B2 - Mixed gas for preserving Satsumaage, method for preserving Satsumaage, and package containing Satsumaage - Google Patents

Description

The present invention relates to a mixed gas for preserving satsumaage, which is useful as a sealed gas in gas-substituted packaging of satsumaage, a method for preserving satsumaage using the mixed gas, and a package containing satsumaage.

Modified Atmosphere Packaging (MAP) is a known technology for extending the shelf life of food. Modified Atmosphere Packaging is a method of packaging food by replacing the air in the packaging container with a refined gas (preservation gas) suitable for preserving the target food. Modified Atmosphere Packaging can significantly extend the shelf life of food compared to normal atmospheric packaging, and it can reduce food waste, which is a global problem, and also contribute to expanding sales channels to distant areas and improving production plans, so modified atmosphere packaging is being introduced by various food manufacturers. Here, in order to effectively delay the deterioration of food quality using modified atmosphere packaging, it is important to select a preservation gas that is suitable for the food, taking into account various conditions such as the type and physical properties of the food to be preserved and the initial bacterial count. For this reason, the effects of single gases and mixed gases such as nitrogen, carbon dioxide, and oxygen that are recognized as food additives on the preservation of food quality, the composition range in which the effects are expressed, and combinations with food are being studied in detail.

For example, Non-Patent Document 1 describes that carbon dioxide has a bacteriostatic effect that inhibits the proliferation of bacteria, and oxygen has the effect of preserving the color of meat and the freshness of cut vegetables.
Non-Patent Document 2 describes that a mixture of carbon dioxide and nitrogen gas inhibits the growth of microorganisms in various foods such as kamaboko, seafood, and side dishes, and exhibits the effect of preventing the oxidation of the foods.
Furthermore, Patent Document 1 shows that in a replacement package for mapo tofu in which a mixed gas of nitrogen, carbon dioxide, and oxygen is sealed inside a packaging container, when the oxygen concentration is 7% by volume, the bacterial growth inhibitory effect is significantly reduced unless the carbon dioxide concentration is 20% by volume or more.

"Food and Development" 2018, Vol.53, No.8, p.12-15 "Monthly Food Chemical" August 2019 issue, p.3-6

JP 2015-116159 A

As described above, Non-Patent Document 2 describes that a mixed gas of carbon dioxide and nitrogen exhibits the effect of suppressing the growth of microorganisms in kamaboko. However, when the present inventors stored satsumaage, which is a fish paste product like kamaboko, in a packaging container and sealed in a mixed gas of carbon dioxide and nitrogen, they found that the growth of various bacteria was observed after two weeks, and it was found that a fully satisfactory best-before period could not be secured.
Therefore, the inventors narrowed down the preservation target to Satsumaage and conducted an experiment to find a mixed gas that effectively suppresses microbial growth during storage by adding other gases to a mixed gas of carbon dioxide and nitrogen and changing the composition ratio in various ways to evaluate the microbial growth suppression effect. As a result, it was found that a mixed gas containing oxygen in addition to carbon dioxide and nitrogen exhibits a high effect on microbial growth suppression. Furthermore, it was also found that when the carbon dioxide concentration of this mixed gas is lowered, the microbial growth is suppressed more than when the carbon dioxide concentration is 20% by volume. As described above, Patent Document 1 shows that a carbon dioxide concentration of 20% by volume or more is required for a mixed gas of oxygen, carbon dioxide, and nitrogen to exhibit a bacterial growth suppression effect. Therefore, it was an unexpected discovery that bacterial growth is further suppressed by lowering the carbon dioxide concentration.

Under these circumstances, the inventors conducted further research with the aim of finding a preservative gas that could extend the shelf life of satsumaage.

As a result of intensive research to solve the above problems, the inventors have found that the proliferation of various bacteria can be significantly suppressed by sealing a mixed gas consisting of oxygen, carbon dioxide, and nitrogen with satsumaage at low concentrations of 5 to 10% by volume of oxygen and 0.01 to 5% by volume of carbon dioxide. The present invention has been proposed based on this knowledge, and specifically has the following configuration.

[1] A mixed gas for preserving fish cakes, comprising 5 to 10% by volume of oxygen, 0.01 to 5% by volume of carbon dioxide, and nitrogen.
[2] The mixed gas for preserving fish cakes according to [1], wherein the carbon dioxide concentration is 0.01% by volume or more and less than 0.04% by volume.
[3] The mixed gas for preserving fish cakes according to [1] or [2], which is used to inhibit the growth of aerobic and anaerobic bacteria.
[4] A method for preserving satsumaage, comprising preserving the satsumaage in a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01 to 5% by volume of carbon dioxide, and nitrogen.
[5] The method for preserving satsumaage according to [4], wherein the mixed gas has a carbon dioxide concentration of 0.01% by volume or more and less than 0.04% by volume.
[6] The method for preserving fish cakes according to [4] or [5], wherein the fish cakes are preserved in a sealed space filled with the mixed gas.
[7] The method for preserving fish cakes according to [6], wherein the sealed space is the internal space of a container.
[8] The method for preserving satsumaage according to [6] or [7], wherein the shelf life of the satsumaage is set using the residual oxygen concentration in the sealed space as an indicator.
[9] The method for preserving satsumaage according to [8], wherein the residual oxygen concentration in the sealed space at the time of expiration of the expiration date is 1% by volume or more.
[10] The method for preserving satsumaage according to [9], wherein the residual oxygen concentration in the sealed space at the time of expiration of the expiration date is 1 to 5% by volume.
[11] A container having a storage space for storing fish cakes,
The package containing the fish cakes is provided with the fish cakes contained in the storage space, and the container is filled with a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01 to 5% by volume of carbon dioxide, and nitrogen, and then sealed.
[12] The package containing satsumaage according to [11], wherein the mixed gas has a carbon dioxide concentration of 0.01% by volume or more and less than 0.04% by volume.
[13] The package containing satsumaage according to [11] or [12], wherein the satsumaage is satsumaage with vegetables.
[14] The package containing the fish cakes according to any one of [11] to [13], wherein the fish cakes contain a bacteriostatic agent.
[15] The package containing the fish cakes according to any one of [11] to [14], wherein the proportion of the space occupied by the fish cakes in the storage space is 20 to 70%.

By storing satsumaage in the mixed gas for preserving satsumaage of the present invention, deterioration of the quality of the satsumaage can be effectively delayed. A package containing satsumaage, in which the mixed gas for preserving satsumaage of the present invention is filled in a packaging container, can have a long shelf life because the quality of the satsumaage is maintained for a long period of time.

The present invention will be described in detail below. The following explanation of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower and upper limits.

[Mixed gas for preserving fish cakes]
The mixed gas for preserving Satsumaage of the present invention is a mixed gas containing 5 to 10 volume % oxygen (O ₂ ), 0.01 to 5 volume % carbon dioxide (CO ₂ ), and the remainder being nitrogen (N ₂ ). "The remainder being nitrogen (N ₂ )" means that the nitrogen concentration is the concentration obtained by subtracting the oxygen concentration and the carbon dioxide concentration from 100 volume %. However, the mixed gas for preserving Satsumaage of the present invention may contain impurity gas that is inevitably mixed in. Here, "inevitably mixed impurity gas" refers to gas with a concentration of 1 volume % or less. In the following description, the "mixed gas for preserving Satsumaage" may be simply referred to as "preservation mixed gas".
The method for preparing the mixed gas for storage of the present invention is not particularly limited, but for example, the mixed gas can be prepared by mixing the purified gas obtained by filtering the air to make it sterile with nitrogen gas, and adjusting the oxygen concentration and carbon dioxide concentration to a predetermined concentration, or by mixing the individual gases obtained by separating oxygen, carbon dioxide, and nitrogen from the purified gas so that the oxygen concentration and carbon dioxide concentration are a predetermined concentration. Here, the filtration of the air can be performed using a sterilizing filter. The composition ratio of the mixed gas can be measured using a commercially available gas analyzer (for example, the product name "Check Mate3" manufactured by PBI Dansensor).

The food to which the preservation mixed gas of the present invention is applied is "Satsumaage". "Satsumaage" is a food product made by molding ingredients including fish paste and deep frying them in oil. The ingredients of Satsumaage may be only fish paste, or may contain other ingredients, seasonings, and binders such as egg white and starch. Other ingredients include vegetables such as onion, cabbage, carrot, burdock, lotus root, potato, and edamame, and seafood such as octopus, squid, and whelk. In addition to the above ingredients, food additives such as bacteriostatic agents and pH adjusters may be added to Satsumaage. For an explanation and specific examples of bacteriostatic agents, please refer to the description in the "Preservation method of Satsumaage" section. The volume and weight of Satsumaage are not particularly limited, but are usually 45 to 50 g/piece and 41 to 57 cm ³ /piece.

As mentioned above, satsumaage may contain many kinds of ingredients, and is fried in oil, so it is considered that its physical properties and bacterial growth conditions are different from those of kamaboko. Therefore, even if the mixed gas of carbon dioxide and nitrogen used for preserving kamaboko is directly used for satsumaage, it is not possible to sufficiently delay quality deterioration such as bacterial growth. In contrast, when satsumaage is preserved in the preservation mixed gas of the present invention, the action of oxygen, carbon dioxide, and nitrogen contained at a predetermined concentration works together, and it is considered that the growth of various microorganisms that deteriorate the quality of satsumaage is effectively suppressed. This allows the quality of satsumaage to be maintained for a long period of time, and the shelf life can be significantly extended. As a result, it can also greatly contribute to reducing food waste, which is a global problem. In addition, the mixed gas for preserving satsumaage of the present invention exhibits an effect of effectively suppressing the growth of various microorganisms, and is therefore useful as a mixed gas for suppressing microbial growth for satsumaage. Here, the bacteria for which the preservation mixed gas of the present invention exhibits a growth suppressing effect are both aerobic bacteria and anaerobic bacteria. Examples of aerobic bacteria include Staphylococcus bacteria such as Staphylococcus aureus, and Bacillus bacteria such as Bacillus cereus. The preservation mixed gas of the present invention also exerts a growth inhibitory effect on obligate anaerobic spore-forming bacteria such as Clostridium bacteria and coliform bacteria.

In the preservation mixed gas of the present invention, the oxygen concentration is preferably 5 to 10% by volume, more preferably 6 to 10% by volume, and even more preferably 6 to 8% by volume.
In the preservation mixed gas of the present invention, the carbon dioxide concentration is preferably lower than the oxygen concentration, more preferably 0.01 to 5% by volume, even more preferably 0.01 to 1% by volume, and particularly preferably 0.01% by volume or more and less than 0.04% by volume.
By setting the oxygen concentration and carbon dioxide concentration within the above ranges, a higher microbial growth inhibitory effect can be obtained.

[How to store Satsumaage]
The method for preserving satsumaage of the present invention is a method for preserving satsumaage, which comprises preserving the satsumaage in a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01 to 5% by volume of carbon dioxide, and nitrogen.
For an explanation of Satsumaage and mixed gases, please refer to the description in the above section titled "Mixed gases for preserving Satsumaage."
The satsumaage preserved by the preservation method of the present invention may be satsumaage immediately after deep frying, or may be satsumaage that has been deep fried and then cooled to a core temperature of -3 to 10°C, but is preferably deep fried within 30 minutes. In the following explanation, "immediately after cooking" may mean "within 30 minutes of deep frying."

An example of a mode of storing satsumaage in a mixed gas is a mode of storing satsumaage in a sealed space filled with the mixed gas. In the following description, the space in the sealed space occupied by the satsumaage is referred to as the "satsumaage-occupied area", and the space other than the satsumaage-occupied area is referred to as the "free area". The number of satsumaage contained in the sealed space may be one or more. The volume of the sealed space may be a volume that leaves a free area when the satsumaage are contained, and may be appropriately selected depending on the size and number of the satsumaage. The volume of the sealed space that contains the satsumaage is usually about 200 to 350 ^cm3 .

The proportion of the area occupied by the satsumaage in the sealed space (satsumaage occupancy rate) is preferably 10-80%, more preferably 15-75%, and even more preferably 20-70%. When two or more satsumaage are contained in a sealed space, the satsumaage occupancy rate is the total area including the areas occupied by each satsumaage, and the satsumaage occupancy rate is the ratio of the total volume including the areas occupied by each satsumaage to the total volume of the sealed space. By setting the satsumaage occupancy rate within the above range, the mixed gas can fully exert its effect without impairing the taste and flavor of the satsumaage, effectively delaying deterioration in the quality of the satsumaage.

It is preferable that the space (free space) of the sealed space other than the space occupied by the fishcakes is filled with the mixed gas. Note that in addition to the components of the mixed gas (oxygen, carbon dioxide, nitrogen), trace gases may be present in the sealed space. Examples of trace gases that may be present in the sealed space include inert gases such as helium (He), neon (Ne), and argon (Ar). However, it is preferable that the proportion of the trace gas is 1% by volume or less of the mixed gas.

A specific example of an enclosed space is the internal space (storage space) of a sealed packaging container. For an explanation and specific examples of packaging containers, please refer to the description in the "Package containing satsumaage" section below.

As a method for storing satsumaage and a mixed gas in a sealed space, a gas replacement packaging technique can be used, in which the gas (e.g., air) originally present in the storage space is replaced with a mixed gas while the food is placed in the storage space, and then the storage space is sealed. In gas replacement packaging, for example, (A) a gas flush replacement method in which a mixed gas is flushed into the storage space of a packaging container containing satsumaage to replace the gas in the storage space, (B) a chamber replacement method in which a packaging container containing satsumaage is brought into a chamber and vacuum-degassed, and then a mixed gas is introduced into the chamber to fill the storage space, or (C) a nozzle replacement method in which a nozzle is inserted into a packaging container containing satsumaage, and then a mixed gas is introduced from the nozzle, and the gas in the storage space is replaced with the mixed gas by a gas replacement method, and then the packaging container is sealed. A known bonding method such as heat sealing can be used to seal the packaging container. In addition, if the packaging container has an open surface, the container can be sealed by covering the open surface with a lid film and bonding it to the packaging container. An example of a gas replacement packaging machine that can automatically perform this type of gas replacement packaging is the Traysealer (Traysealer T700 or T800) manufactured by Multivac.

When storing satsumaage in a mixed gas, the temperature of the storage environment is preferably −10 to 10° C., more preferably −5 to 10° C., and even more preferably in the chilled temperature range (0 to 10° C.). This makes it easier to maintain the quality of the satsumaage. The temperature of the storage environment is preferably constant during storage, but may vary within a range of ±2° C.
The storage period for satsumaage in a mixed gas varies depending on the ingredients of the satsumaage, the cooking conditions, and the temperature of the storage environment. For example, if the temperature of the storage environment is in the chilled temperature range and gas replacement packaging is carried out immediately after cooking and storage begins, the storage period (best before date) can be set to 14 to 22 days.

When satsumaage is stored in a mixed gas, the composition ratio of the mixed gas may change over time. Specifically, the oxygen concentration decreases over time, while the carbon dioxide concentration tends to increase gradually, albeit slightly. Furthermore, when the residual oxygen concentration becomes less than 1% by volume, the microbial growth inhibitory effect may not work sufficiently. Therefore, in the method for storing satsumaage of the present invention, it is preferable to set the storage period (best-before period) and the expiration date using the residual oxygen concentration in the sealed space (the ratio of oxygen to the total amount of gas remaining in the sealed space) as an indicator. Specifically, it is preferable to set the expiration date (expiration date of the storage period) so that the residual oxygen concentration at the end of the storage period is 1% by volume or more, and it is more preferable to set the expiration date (expiration date of the storage period) so that the residual oxygen concentration at the end of the storage period is 1 to 5% by volume. The residual oxygen concentration in the sealed space can be measured using a commercially available gas analyzer (for example, the product name "Check Mate3" manufactured by PBI Dansensor).

In order to further extend the shelf life, food additives such as bacteriostatic agents and pH adjusters may be added to the satsumaage preserved by the preservation method of the present invention. Examples of bacteriostatic agents include organic acid salts and amino acids such as glycine. Examples of organic acid salts that serve as bacteriostatic agents include sodium salts, potassium salts, and calcium salts of organic acids such as acetic acid, citric acid, lactic acid, tartaric acid, fumaric acid, gluconic acid, and malic acid. These bacteriostatic agents may be used alone or in combination of two or more.
The amount of organic acid salt added to the satsumaage is preferably 0.1 to 2% by mass, more preferably 0.1 to 1% by mass, and even more preferably 0.5 to 1% by mass, based on the total mass of the satsumaage. By adding the bacteriostatic agent in the above-mentioned amount, the bacteriostatic effect can be fully exerted without impairing the original taste and flavor of the satsumaage. For example, when satsumaage to which 0.5 to 1% by mass of an organic acid salt is added as a bacteriostatic agent is cooked and immediately packaged in a mixed gas replacement and stored and managed in a chilled temperature range (0 to 10°C), a best-before date of 14 to 22 days from the date of manufacture can be set. This best-before date corresponds to about 1.5 to 2.3 times the best-before date of satsumaage packaged in normal air.
When a bacteriostatic agent is added to satsumaage, the timing of addition is not particularly limited, and the bacteriostatic agent may be added to the ingredients before frying in oil, or may be added to the product after frying in oil.

[Package containing fish cakes]
The package containing satsumaage of the present invention has a container having a storage space for storing satsumaage, and is configured by storing satsumaage in the storage space and filling the space with a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01 to 5% by volume of carbon dioxide, and nitrogen, and then sealing the container.
For an explanation of satsumaage and the mixed gas, please refer to the description in the above section ``Mixed gas for preserving satsumaage'', and for an explanation of additives that may be added to satsumaage, please refer to the description in the above section ``Method of preserving satsumaage''.

The container constituting the package containing satsumaage of the present invention can be a packaging container that is normally used for gas replacement packaging of food, i.e., a packaging container made of resin or metal having gas barrier properties. Examples of materials for the packaging container include polyamide resins such as polyvinyl alcohol (PVA) and nylon (NY), ethylene/vinyl alcohol copolymer (EVOH), polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), and polyvinyl chloride (PVC), as well as metal films such as aluminum laminate (AL) and aluminum vapor deposition film (VM), silica vapor deposition film, and multilayer laminate films such as PET/NY/polypropylene (PP) or polyethylene (PE), PET/NY/AL/PP or PE, PP/EVOH/PE, and PP/PVA/PE.

The packaging container is not particularly limited in shape or size as long as it has a storage space sufficient to store the satsumaage and the mixed gas to be preserved. The volume of the storage space is usually about 200 to 350 ^cm3 . For the preferred range of the satsumaage occupancy rate in the storage space, the preferred range of the satsumaage occupancy rate in the sealed space described in the above section [Satsumaage preservation method] can be referred to.
Examples of the shape of the packaging container include tray-shaped, cup-shaped, bag-shaped, box-shaped, can-shaped, etc., and the tray-shaped is preferred because it is easy to store the satsumaage. Examples of the tray-shaped packaging container include a container in which a bottom, a rising wall that rises from the periphery of the bottom to form a side, and a flange part that protrudes from the upper part of the rising wall are integrally formed. The shape of the container in plan view is not particularly limited, and may be any of a substantially square shape, a substantially rectangular shape, a circle, an ellipse, an oval shape, etc. Here, it is preferred that a plurality of ribs are formed on the inner side surface (bottom surface) of the bottom of the container. As a result, when satsumaage is placed on the bottom surface, a gap is formed between the back surface of the satsumaage and the rib groove, and the mixed gas can be distributed to the back surface of the satsumaage. Such a tray-shaped packaging container can be sealed by covering the open surface with a lid film and bonding the flange part and the lid film by a known sealing method such as heat sealing. For the lid film, a film of a gas barrier resin exemplified as a material for the packaging container can be used.

The satsumaage may be stored directly in the storage space of the packaging container, or indirectly in the storage space of the packaging container by placing a sheet on the bottom of the packaging container and then placing the satsumaage on the sheet.

The features of the present invention are explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, processing contents, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.

In this example, the bacterial growth inhibitory effect of the mixed gas was evaluated using vegetable-filled satsumaage (volume: 49 ^cm3 , weight: 45 g/piece) as the preserved object. This vegetable-filled satsumaage was made by deep-frying a mixture of fish paste, vegetables (cabbage, onion, carrot, burdock), egg white, starch, sugar, salt, soy protein, and a bacteriostatic agent (organic acid salt). The amount of the bacteriostatic agent added was 0.85% by mass relative to the total mass of the satsumaage.
Microbiological tests were performed according to the following methods in accordance with the "Official Method" or the "Food Sanitation Inspection Guideline: Microbiology" or "Hygiene Test Methods: Commentary 2010".
The specimen was aseptically collected in a stomacher bag using a previously sterilized tool, and 9-fold dilution solution was added to homogenize the specimen. The specimen was diluted 10-fold with dilution solution as necessary to prepare diluted specimen. Then, the specimen was mixed with agar medium in a Petri dish or anaerobic pouch and solidified, the specimen was taken in a liquid medium, or 0.1 ml of the specimen was dropped onto the surface of a medium solidified in advance as a plate and smeared over the entire surface of the plate with a conlarger stick, and cultured at a specified temperature and time. After culture, the number of bacteria was measured by multiplying the number of colonies on the plate by the dilution factor, and the qualitative test was judged as negative or positive.
The test method is as follows.
General viable bacteria count: Standard agar medium pour culture method Coliform group: BGLB fermentation tube method Staphylococcus aureus: Egg yolk-added mannitol salt agar plate smear method Bacillus cereus: Egg yolk-added NGKG agar plate smear method Anaerobic bacteria: GAM agar medium pour culture method Clostridium spp. (anaerobic spore-forming bacteria): Clostridium medium anaerobic culture method

(1) Evaluation of bacterial growth inhibition activity Four freshly cooked vegetable-filled satsumaage were placed in a tray-shaped packaging container (made by Barrier PSP, volume of storage space: 208 ^cm3 ) in the atmosphere at room temperature (25°C), and the air in the storage space was replaced with a mixed gas using a tray sealer (made by Multivac: tray sealer T700 or T800) using the chamber replacement method, and the packaging container was sealed by covering it with a lid film (made by NY/EVOH/NY/PE, thickness: 22 μm) to obtain packages containing satsumaage (packages 1 to 3, comparative packages 1 to 3). The composition of the mixed gas sealed in the packaging container is shown in Table 1. The mixed gas used was prepared by mixing purified gas, which had been made sterile by filtering the air, with nitrogen gas, and adjusting the oxygen and carbon dioxide concentrations.
After storing each of the prepared packages at 10°C for 15 days, a microbial test was conducted to evaluate the bacterial growth inhibitory effect of each mixed gas. The results are shown in Table 1. In Table 1, "-" indicates that the bacteria in question were negative, and "+" indicates that the bacteria in question were positive.

As shown in Table 1, in the comparative package 1 using a mixed gas containing no oxygen and having a carbon dioxide concentration of 20% by volume, the growth of anaerobic bacteria and Clostridium bacteria (anaerobic spore-forming bacteria) was observed. In the comparative packages 2 and 3 in which the oxygen concentration of the mixed gas was 1% or 3% by volume and the carbon dioxide concentration was 0.03% by volume, the growth of Clostridium bacteria was suppressed, but the growth of anaerobic bacteria was observed. In contrast, in the packages 1 to 3 in which the oxygen concentration of the mixed gas was in the range of 5 to 10% by volume and the carbon dioxide concentration was in the range of 0.01 to 5% by volume, the growth of all aerobic bacteria, anaerobic bacteria, and obligate anaerobic spore-forming bacteria was suppressed. From this, it was confirmed that the growth of microorganisms was effectively suppressed and the shelf life of Satsumaage was significantly improved by using a mixed gas with an oxygen concentration of 5 to 10% by volume, a carbon dioxide concentration of 0.01 to 5% by volume, and the remainder nitrogen as the storage gas for Satsumaage.
Furthermore, when the composition of the gas remaining in the storage space of packages 1 to 3 was measured on the final day of the storage period, the residual oxygen concentration was 1 to 5% by volume, and the residual carbon dioxide concentration was 2 to 4%. Since a certain amount of oxygen remained on the final day of the storage period, it is believed that the microbial growth inhibitory effect was at work throughout the storage period. The increase in carbon dioxide concentration from the initial concentration is believed to be due to the respiration of the small amount of microorganisms remaining in the satsumaage and the packaging container.

The mixed gas for preserving satsumaage of the present invention can significantly extend the shelf life of satsumaage, which can greatly contribute to reducing waste of satsumaage, expanding sales channels to distant areas, and improving production planning. Therefore, the present invention has a high industrial applicability.

Claims (12)

A mixed gas for preserving fish cakes, comprising 5-10% by volume of oxygen, 0.01% by volume or more and less than 0.04% by volume of carbon dioxide, and nitrogen. The mixed gas for preserving fish cakes according to claim 1 , which is used to inhibit the growth of aerobic and anaerobic bacteria. The method for preserving satsumaage comprises preserving the satsumaage in a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01% by volume or more and less than 0.04% by volume of carbon dioxide, and nitrogen. The method for preserving fish cakes according to claim 3 , wherein the fish cakes are preserved in a sealed space filled with the mixed gas. The method for preserving fish cakes according to claim 4 , wherein the sealed space is the inner space of a container. The method for preserving satsumaage according to claim 4 or 5 , wherein the shelf life of the satsumaage is set using the residual oxygen concentration in the sealed space as an index. The method for preserving satsumaage according to claim 6 , wherein the residual oxygen concentration in the sealed space at the time of expiration of the expiration date is 1% by volume or more. The method for preserving satsumaage according to claim 7 , wherein the residual oxygen concentration in the sealed space at the end of the expiration date is 1 to 5% by volume. A container having a storage space for storing fish cakes,
The package containing the fish cakes is provided with the fish cakes contained in the storage space, and the container is filled with a mixed gas consisting of 5 to 10% by volume of oxygen, 0.01% by volume or more and less than 0.04% by volume of carbon dioxide, and nitrogen, and then sealed. The package containing fish cakes according to claim 9 , wherein the fish cakes are fish cakes containing vegetables. The package containing the fish cakes according to claim 9 , wherein the fish cakes contain a bacteriostatic agent. The package containing the fish cakes according to any one of claims 9 to 11 , wherein the proportion of the space occupied by the fish cakes in the storage space is 20 to 70%.