Food packaging, method for manufacturing food packaging

Abstract

The peroxide value after freezing is obtained when food suitable for quality assessment is frozen and stored. [Solution] A food packaging in which frozen food is packaged, wherein the oxygen concentration inside the packaging is 0-10%, and the oxygen permeability of the packaging is 1000 ml / m² at a thickness of 25 μm according to JIS K 7126. 2 The temperature is 24hr·MPa (75%RH at 20℃) or less, the peroxide value of the food after freezing is 30meg / kg or less, and the packaging includes at least a packaging container comprising a container body 1 for containing the food and a lid material 2 to be attached to the container body 1.

Description

[Technical Field]

[0001] The present invention relates to a food packaging obtained by freezing food packaged in a thermoplastic resin packaging container, and to a method for producing the above food packaging. [Background technology]

[0002] Traditionally, pre-cooked foods such as curry, pasta, and prepared dishes have been widely packaged in thermoplastic resin containers made of polypropylene or polystyrene, and then frozen in a form of plastic wrap that tightly seals the container or in a bag that does not. The advantage of these foods is that, after being removed from the wrap or bag, they can be thawed and reheated with a single touch using a microwave oven or other heating appliance.

[0003] For example, the gas-purged deep-drawn packaging (gas pack) disclosed in Patent Documents 1 and 2 essentially involves replacing the air inside a thermoplastic deep-drawn packaging containing food with an inert gas such as nitrogen or carbon dioxide, before sealing and freezing it. This allows for a longer shelf life of the food compared to packaging that has not been gas-purged, and to obtain gas barrier properties, it has a polyamide resin (PA) layer or an ethylene-vinyl acetate copolymer saponified (EVOH) layer as an intermediate layer.

[0004] Furthermore, the gas barrier packaging container disclosed in Patent Document 3 is mainly composed of vinylidene chloride resin and has an oxygen permeability of 3 cc / m³ at 23°C. 2 The humidity is less than 0.24hrs.atm. and the surface area is 100cm². 2 This product contains 30g of linoleic acid per serving, is vacuum-sealed, and stored at 30°C for 90 days. The peroxide value of the linoleic acid obtained from this product is 3 meq / kg or less (see abstract). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-020535 [Patent Document 2] Japanese Patent Publication No. 2018-087025 [Patent Document 3] Japanese Patent Application Publication No. 06-312425 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, Patent Documents 1-3 do not disclose the peroxide value of frozen foods. The peroxide value is an indicator of the extent to which packaged foods have deteriorated due to oxidation, and is particularly useful for quality control of high-fat foods. In other words, frozen foods with a high fat content may deteriorate in quality due to the oxidation of fat.

[0007] Furthermore, the inventions described in Patent Documents 1 and 2 are expected to have the effect of extending the shelf life of various frozen foods such as ham and sausage, prepared foods, soups and broths, shumai, udon noodles, rolled omelets, and tofu (paragraph "0010"). In contrast, the invention described in Patent Document 3 addresses the problem of saturation of display space for frozen foods (see paragraph "0002") by preventing deterioration of food under long-term distribution and storage conditions using packaging materials for foods distributed at room temperature (see paragraph "0007").

[0008] In other words, the inventions described in Patent Documents 1 and 2 do not have the motivation to limit them to foods suitable for quality determination by peroxide value, as is the case with the invention described in Patent Document 3. Rather, limiting them to the above foods would contradict the purpose of the inventions described in Patent Documents 1 and 2. Therefore, it is difficult to easily conceive of a new invention based on the inventions described in Patent Documents 1-3 that addresses the long-term preservation of foods suitable for quality determination by peroxide value after freezing.

[0009] Therefore, the object of the present invention is to provide a food packaging that can obtain a desired peroxide value when food suitable for quality determination by peroxide value after freezing is frozen and a method for producing the food packaging. [Means for solving the problem]

[0010] In other words, the present invention relates to a food packaging in which frozen food is packaged, wherein the oxygen concentration inside the packaging is 0-10%, and the oxygen permeability of the packaging is 1000 ml / m² at a thickness of 25 μm according to JIS K 7126. 2 The temperature is 24hr·MPa (75%RH at 20℃) or less, the peroxide value of the food after freezing is 30meg / kg or less, and the packaging is characterized by comprising at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body.

[0011] Furthermore, the present invention relates to a method for manufacturing a food packaging in which frozen food is packaged, wherein the oxygen permeability of the packaging is 1000 ml / m² at a thickness of 25 μm according to JIS K 7126. 2 The method includes the steps of: placing the food inside the packaging, reducing the oxygen concentration inside the packaging to 0-10%, freezing the packaging, and storing the food so that its peroxide value is 30 meg / kg or less, wherein the packaging comprises at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body.

[0012] The oil content of the above foods should ideally be between 10% and 60%.

[0013] The freezing temperature for the above-mentioned foods should preferably be between -60 and 0°C.

[0014] The gas composition inside the above-mentioned packaging is preferably at least nitrogen and carbon dioxide, and may also contain oxygen and argon. [Effects of the Invention]

[0015] According to the present invention, when food suitable for quality determination by peroxide value after freezing is frozen and stored, it is expected that the desired peroxide value can be obtained. [Brief explanation of the drawing]

[0016] [Figure 1] It is a packaging container used for a food packaging body in an embodiment of the present invention. [Figure 2] It is a diagram showing the flow of a method for manufacturing a food packaging body in an embodiment of the present invention. [Figure 3] It is a graph showing the evaluation results of an example of the present invention. [Figure 4] It is a graph showing the evaluation results of an example of the present invention. [Figure 5] It is a graph showing the evaluation results of an example of the present invention. [Figure 6] It is a graph showing the evaluation results of an example of the present invention.

Mode for Carrying Out the Invention

[0017] Hereinafter, with reference to FIG. 1, a food packaging body (hereinafter also referred to as "this food packaging body") in an embodiment of the present invention will be described. In the description, terms indicating directions such as upward, downward, lateral, vertical, horizontal, inward, outward, central, and circumferential directions are basically based on the food packaging body installed in the normal orientation, and when other reference is made, it will be explained as appropriate. Plan view means looking at the above food packaging body from directly above.

[0018] <Overview of this Food Packaging Body> This food packaging body is, in short, one in which the oxygen concentration in the packaging body containing the food to be frozen is reduced to zero or less, and the peroxide value of the food after freezing is below a predetermined value. The food after freezing, that is, the frozen food, in other words, the state in which the food is frozen means a state in which various adverse effects such as oxidation by air and spoilage by microorganisms (bacteria) have little or no effect on the food or a state in which they are inactivated (a state in which the progress of the above adverse effects is slow), and it may reach the above state immediately after the start of freezing, or may reach the above state after a predetermined time has elapsed since the start of freezing, and is not limited to the specifications including the temperature and function of the freezer and the freezing time and period.

[0019] The foods covered by this food packaging (hereinafter simply referred to as "food") include any food that releases oil after freezing, after natural thawing, or after reheating in a microwave oven or the like due to its ingredients or cooking method. Examples include fresh meat and fish, processed foods such as ham, bacon, and sausage, and cooked meat dishes, fish dishes, curry, spaghetti, stew, fried rice, and various other grilled, stir-fried, deep-fried, and boiled foods.

[0020] The packaging used in this food packaging only needs to be capable of containing food in an environment with a desired oxygen concentration, and may be a packaging bag or a packaging container, but at least includes a packaging container, and as shown in Figure 1, the packaging container comprises at least a container body for containing the food and a lid material attached to the container body. The container body may or may not have gas barrier properties due to the synthetic resin film described later. The lid may be a top seal fused to the flange portion of the container body described later, or a gas barrier wrap that is not fused to the flange portion. In this embodiment, the description will be based on the premise that the packaging is the packaging container described above.

[0021] The method for creating the desired oxygen concentration environment described above may be gas-replaced packaging (MAP: Modified Atmosphere Packaging, hereinafter also referred to as "MAP"), in which the air inside the container body having gas barrier properties is removed and then the container is filled with nitrogen, carbon dioxide, or a mixture thereof and sealed with the top seal; gas-flush packaging, in which nitrogen, carbon dioxide, or a mixture thereof is injected into the container body regardless of whether or not it has gas barrier properties and then sealed with the wrap; or adding an oxygen absorber to the container body regardless of whether or not it has gas barrier properties.

[0022] The following describes packaging materials used in various methods for creating an environment with the desired oxygen concentration. When using MAP, for example, a combination of a container body with gas barrier properties and a top seal with gas barrier properties can be used. Furthermore, when using gas flush packaging, in which nitrogen, carbon dioxide, or a mixture thereof is injected into the container body and then the container body is sealed with wrap, the container body can be used regardless of whether it has gas barrier properties or not, and the wrap film can be one that has gas barrier properties. In addition, in a method of adding an oxygen absorber into the container body, if a wrap film with gas barrier properties is used, there are no particular restrictions on whether the container body has gas barrier properties or not, and if a top seal is used, the top seal and the container body must have gas barrier properties. In the present invention, in such combinations of packaging materials, the oxygen permeability according to JIS K 7126 is 1000 ml / m² at a thickness of 25 μm. 2 It is sufficient to achieve a pressure of 24hr·MPa (75%RH at 20℃) or less. In this embodiment, the above method is described on the premise that it is MAP.

[0023] <Overview of Container Body 1> As shown in Figure 1, the container body 1 is obtained by molding a molding sheet comprising a synthetic resin sheet that serves as a base material and a synthetic resin film laminated on the synthetic resin sheet, and has a bottom portion 11 on which food is placed, side portions 12 that rise continuously upward from the peripheral edge of the bottom portion 11, and flange portions 13 that extend continuously outward from the upper end of the side portions 12. The plan view shape of the container body 1 may be rectangular, square, pentagonal or more, circular, or a shape which is a deformed part of these.

[0024] <Capacity of container body 1> The container body 1 does not have a limited area for the bottom 11 or height for the sides 12, and the capacity determined by these can be any, for example, 100 to 1800 cc or 200 to 1000 cc. The bottom 11 and sides 12 may have one or more predetermined steps or reinforcing ribs in the vertical or horizontal direction, or they may be flush without them. The opening of the container body 1 is formed at the upper end of the side 12.

[0025] <Depth of container body 1> The depth of the container body 1 may be 10 mm to 45 mm, preferably 12 mm to 40 mm, more preferably 15 mm to 35 mm, and even more preferably 15 mm to 30 mm. If it is shallower than 10 mm, the size of the food is limited, and if it is deeper than 45 mm, the amount of gas to be replaced is too large, so both are unsuitable for MAP. The depth of the container body 1 refers to the vertical height from the surface of the bottom 11, which is the lowest part, to the upper end of the flange portion 13, which is the highest part.

[0026] <Thickness of container body 1> The thickness of the container body 1 may be 0.1 to 1 mm, preferably 0.2 to 0.8 mm, and more preferably 0.3 to 0.6 mm. If it is thinner than 0.1 mm, the desired strength cannot be obtained, and if it is thicker than 1 mm, cold air will not easily transfer to the food when freezing, and heat will not easily transfer to the food when reheating.

[0027] <Flange section 13> The flange portion 13 is not numbered, but it has an innermost flange end corresponding to the upper end of the side portion 12, a middle flange portion that extends continuously outward from the innermost flange end, and an outermost flange end that is both the middle flange portion and the outermost end of the container body 1. The middle flange portion may be approximately horizontal and flat, curved upward, or concave downward. The distance from the innermost flange end side to the outermost flange end side of the middle flange portion is 4 mm or more, but may be 3 mm or more and less than 4 mm. If the thickness of the middle flange portion is thinner than the thickness of the bottom portion 11 or the side portion 12, it is easier to increase the overall mechanical strength of the packaging container while maintaining the peel strength between the synthetic resin sheet and the synthetic resin film in the middle flange portion.

[0028] <Overview of Top Seal 2> The top seal 2 is composed of, from the non-food contact side, which is the outermost part when heat-bonded to the middle part of the flange, an adhesive resin layer such as polyamide (PA) and an olefin-based adhesive resin, a gas barrier layer such as ethylene-vinyl alcohol copolymer (EVOH), the above-mentioned adhesive resin layer, and a sealant layer (thermoplastic resin) having easy-opening properties, laminated in this order.

[0029] <Oxygen permeability of the package> After sealing the container body 1 with the top seal 2, the oxygen permeability of the package is such that the oxygen permeability according to JIS K 7126 is 1000 ml / m at a thickness of 25 μm 2 ·24 hr·MPa (at 20 °C and 75% RH) or less, preferably 750 ml / m 2 ·24 hr·MPa (at 20 °C and 75% RH) or less, more preferably 500 ml / m 2 ·24 hr·MPa (at 20 °C and 75% RH) or less, and when it is 1000 ml / m 2 ·24 hr·MPa (at 20 °C and 75% RH) or less, it is easier to maintain the gas concentration of the package described later, and when it is 500 ml / m 2 ·24 hr·MPa (higher than 20 °C and 75% RH), it is difficult to maintain the gas concentration of the package described later.

[0030] <Gas concentration in the package> As the gas concentration for the food after sealing the container body 1 with the top seal 2, oxygen may be 0 to 10%, preferably 0 to 5%, more preferably 0 to 2.5%, nitrogen may be 55 to 100%, preferably 70 to 100%, more preferably 90 to 100%, still more preferably 98 to 100%, carbon dioxide may be 0 to 30%, preferably 0 to 5%, and also may be 1 to 30%, preferably 1 to 5%. According to these configurations, by reducing the ratio of oxygen, oxidation of the food is avoided, and together with the bacteriostatic action on the food according to the ratio of carbon dioxide, by increasing the ratio of nitrogen, the effect of storing the food in a desired peroxide value state even after freezing can be obtained.

[0031] <Heat transfer rate of the container body 1> The thermal transmittance of container body 1 is 30 W / m². 2 • Any value above K is acceptable, preferably 40 W / m 2 • K or higher, more preferably 50 W / m 2 The temperature is above 1K. The lower the heat transfer coefficient of the container body 1, the less heat is conducted through it, and the higher the coefficient, the easier it is to conduct heat. In other words, the rate at which the temperature difference between the outside and inside of the container body 1 decreases can be defined as slower when the heat transfer coefficient is low and faster when it is high. The heat transfer coefficient of the container body 1 is 30 W / m². 2 Any material is acceptable as long as it is above K, and it does not matter whether it is foamed or not, but generally non-foamed materials are preferable because they have a higher thermal conductivity than foamed materials, which improves the heat exchange efficiency (freezing efficiency) during freezing.

[0032] <Peroxide Value of Foods> The peroxide value of food in its packaging after freezing is 30 meg / kg or less, preferably 10 meg / kg or less, and more preferably 3 meg / kg or less. For example, if the value is 30 meg / kg or less, the lower the value, the easier it is to maintain the initial aroma immediately after cooking, the less likely it is to emit an undesirable oily smell, and the easier it is to maintain the initial taste of the seasonings. If the value is greater than 30 meg / kg, the above effects are less likely to be expected, and the food is more likely to deteriorate quickly.

[0033] <Oil content in food> The oil (lipid) content of frozen foods is 10-60%, preferably 20-60%. If it is less than 10% or more than 60%, it is difficult to suppress the deterioration of food quality, while if it is more than 20%, the above suppression effect is more easily obtained.

[0034] <Food freezing temperatures> The freezing temperature for food can be -60 to 0°C, or even -30 to 0°C. Temperatures below -18°C are more likely to preserve food quality, while temperatures above -18°C make it more difficult. Food can be frozen in a small freezer or a large commercial freezer.

[0035] It is preferable to freeze these foods rapidly. Rapid freezing allows the water in the food to turn into tiny ice crystals, preserving the flavor and texture of the food without damaging the cell membranes, thus making it easier to maintain the quality of the food. Here, rapid freezing refers to freezing the water contained in the food so that it passes through the maximum ice crystal formation temperature range (-5 to -1°C) within 30 minutes.

[0036] <Specifications of the material, molding method, dimensions, etc. of the synthetic resin sheet for the container body 1> The synthetic resin sheet may be made of polystyrene-based resin, such as polystyrene paper (PSP) or filler-filled polypropylene (PPF), or polyester-based resin such as polyethylene terephthalate, or olefin-based resin such as polyethylene or polypropylene. It may consist of a single layer or multiple layers, and may be colored, colorless and transparent, or opaque. It may also be made of a heat-resistant material. The synthetic resin sheet is formed by thermoforming, such as vacuum forming, hot plate pressure forming, vacuum pressure forming, or double-sided vacuum forming. The surface and / or back surface of the synthetic resin sheet may be covered with a synthetic resin film. The synthetic resin film may consist of a single layer or multiple layers having heat resistance, oil resistance, lamination suitability with printed layers, gas barrier properties, etc. If the surface of the synthetic resin sheet is covered, it may include a printed layer. Here, considering the refrigeration efficiency as described above, it is preferable to use a non-foamed filler-filled polypropylene (PPF) resin sheet, which conducts heat easily, rather than a foamed synthetic resin sheet, which has high thermal insulation properties.

[0037] Furthermore, as mentioned above, when using a wrap film with gas barrier properties as the packaging material, the container itself may be made of paper, for example. Such a configuration is expected to reduce the environmental burden.

[0038] In other words, there are no particular restrictions on whether the synthetic resin sheet is made of foamed resin or non-foamed resin, but considering the refrigeration efficiency, non-foamed resin is preferable. There are no particular restrictions on the thickness of the synthetic resin sheet, but for low-foamed resin with a foaming ratio of 1.5 to 3 times, it should be 0.5 to 3 mm, preferably 1 to 2 mm; for high-foamed resin with a foaming ratio of 5 to 15 times, it should be 1.5 to 5 mm, preferably 2 to 4 mm, more preferably 2.5 to 3.5 mm; and for non-foamed resin, it should be 0.2 to 1.0 mm, preferably 0.23 to 0.65 mm, and even more preferably 0.23 to 0.45 mm. The foaming ratio is calculated by measuring the specific volume (unit: cc / g) of the material before foaming (foaming composition) and the material after foaming (foamed sheet), and dividing the specific volume after foaming by the specific volume before foaming.

[0039] For synthetic resin sheets, heat-resistant polystyrene paper (heat-resistant PSP) with added heat resistance is preferably used. By using heat-resistant PSP, consumers can heat it in a microwave oven at home. Here, heat-resistant PSP is defined as a resin composition mainly composed of heat-resistant polystyrene resin, with a glass transition temperature of 110°C or higher as measured in accordance with JIS K7121. In order to obtain a resin composition with a glass transition temperature of 110°C or higher, the heat-resistant polystyrene resin used is preferably a resin containing polystyrene resin and polyphenylene ether resin, or at least one resin selected from styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-maleimide copolymer, and poly-p-methylstyrene. Heat-resistant PSP is obtained by extruding and foaming a resin composition mainly composed of these resins into a sheet.

[0040] Furthermore, non-foamed polypropylene (PPF) with fillers is particularly preferred as the synthetic resin sheet. Such PPF resin sheets may be obtained by containing 50-80% by weight of block polypropylene, 8-32% by weight of polyethylene, and 11-21% by weight of inorganic filler. With such a configuration, it is expected that the impact resistance in a frozen environment can be enhanced by the block polypropylene, the drawdown when molding the PPF resin sheet into a desired shape can be reduced by the polyethylene, and the heat resistance can be further enhanced by the inorganic filler.

[0041] There are no specific restrictions on the basis weight of PSP or heat-resistant PSP, but it should be between 120 and 210 g / m². 2 Preferably, it is 130-190 g / m². 2 It is more preferable that it be 140-160 g / m 2 It is even more preferable that this is the case. Furthermore, there are no particular restrictions on the sheet thickness (primary thickness) of PSP or heat-resistant PSP before molding, but it is preferably 1.0 to 2.5 mm, and more preferably 1.5 to 2.0 mm.

[0042] The synthetic resin sheet may be a polystyrene (PS) sheet, a high-impact polystyrene (HIPS) sheet, or a general-purpose polystyrene (GPPS) sheet, and may contain 70% or more by mass of polystyrene, preferably 75% or more by mass, and more preferably 85% or more by mass, and may also contain less than 30% by mass of other resins such as polyphenylene ether (PPE) or methacrylic acid.

[0043] <Specifications of the synthetic resin film for container body 1, including material, forming method, dimensions, etc.> The synthetic resin film may be laminated in the following order from the side furthest from the substrate: for example, a polypropylene resin layer, a printed layer, a dry lamination adhesive layer, a gas barrier layer, a dry lamination adhesive layer, and a polystyrene resin layer. Alternatively, the printed layer may be omitted, or it may be laminated with an adhesive layer other than the dry lamination adhesive layer, or a polypropylene resin layer, a gas barrier layer, and a polypropylene resin layer may be laminated in this order. In the container body 1 shown in Figure 1, the substrate is on the outside and the synthetic resin film is on the inside (food contact side).

[0044] <Polypropylene resin layer> The polypropylene resin layer is composed of, for example, polypropylene (PP), unoriented polypropylene (CPP), biaxially oriented polypropylene (OPP), polyethylene (PE), or two or more of these materials blended in a predetermined ratio, with unoriented polypropylene being preferred from the viewpoint of heat resistance.

[0045] The thickness of the polypropylene resin layer using unoriented polypropylene is 25 μm to 50 μm, preferably 30 μm to 45 μm. If it is thinner than 25 μm, it is difficult to obtain the desired heat resistance, and if it is thicker than 50 μm, it is difficult to obtain the desired peel strength even when the synthetic resin film and the substrate are heat-laminated. As a result, when opening the top seal 2 attached to the flange portion 13 of the container body 1 shown in Figure 1, there is a risk that the top seal 2 will not peel off from the synthetic resin film and delamination may occur.

[0046] <Print layer> The printed layer is a layer formed by applying printing ink to the substrate side of a polypropylene resin layer. The printing ink contains one or more types of resins, for example, urethane resins, acrylic resins, olefin resins, and other known resins, and preferably contains urethane resins from the viewpoint of coating the polypropylene resin layer and ensuring heat resistance.

[0047] In other words, by having the printed layer consist of printing ink (colorant) containing a urethane-based resin, it is possible to prevent melting and bleeding even when heat from food-derived oils is transferred through the polypropylene-based resin layer.

[0048] The urethane resin content of the printing ink is preferably 1% to 80% by mass, more preferably 10% to 70% by mass. If it is less than 1% by mass, it will not adhere well to the polypropylene resin layer, and if it is more than 80% by mass, the viscosity will be high and it will be difficult to apply to the polypropylene resin layer.

[0049] The printing ink may contain metal powder, and the printed layer may be glossy. The metal powder may be, for example, aluminum powder, gold powder, silver powder, copper powder, bronze powder, zinc powder, or other known powders, and may be a single type or a combination of two or more types. The average particle size of the above powders is 2 μm to 50 μm, preferably 5 μm to 40 μm, and more preferably 10 μm to 30 μm. If it is smaller than 2 μm, it will be affected by the color of the substrate, and if it is larger than 50 μm, the brightness may be unsuitable. The printing ink may be colored by mixing in colorants such as yellow or red, and may also contain known materials other than various resins, metal powders, and colorants, such as solvents and fillers.

[0050] <Dry laminate adhesive layer> The dry lamination adhesive layer is the adhesive layer used in the dry lamination method, and can be, for example, a polyester-based adhesive, an olefin-based adhesive, a polyurethane-based adhesive, or an ether-based adhesive. From the viewpoint of heat resistance, a polyester-based adhesive (so-called retort grade) is preferred. The dry lamination method generally involves applying a specified adhesive to the surface of a specified film, drying it, and then heat-pressing it to bond it with another film.

[0051] Polyester adhesives, compared to polyether adhesives, for example, have a relatively smaller molecular weight, allowing them to penetrate between the various resins and powders that make up the printing ink applied to the polypropylene resin layer as a printing layer, thus facilitating the curing of the printing ink. Furthermore, polyester adhesives contain a relatively higher amount of isocyanate as a curing agent compared to polyether adhesives, for example, thus facilitating the curing of the aforementioned printing ink. Therefore, polyester adhesives can prevent the printing layer from softening due to heating, and even if oils from food permeate the polypropylene resin layer, they can be less likely to permeate the printing layer, thus preventing delamination.

[0052] <Gas barrier layer> A gas barrier layer is a layer that suppresses the permeation of gases such as oxygen, water vapor, and carbon dioxide. Specifically, according to JIS K 7126, the oxygen permeability is 1000 ml / m² at a thickness of 25 μm. 2 The resin must have a pressure of 24hr·MPa (75%RH at 20℃) or less, such as ethylene-vinyl alcohol copolymer (EVOH) polyamide (PA).

[0053] The thickness of the gas barrier layer is 30 μm or less, preferably 15 μm or less. If it is thicker than 30 μm, heat will not be easily transferred to the polystyrene resin layer during heat bonding, resulting in insufficient adhesive strength between the gas barrier layer and the polystyrene resin layer, which may induce delamination.

[0054] The manufacturing method for this food packaging (hereinafter also referred to as "this manufacturing method") will be described below with reference to Figures 1 and 2.

[0055] As shown in Figure 2, this manufacturing method involves placing the food to be frozen into the container body 1 in a food storage step (step S-1), purging gas inside the container body 1 in a gas exchange step so that the oxygen concentration after sealing with the top seal 2 is 0-10% (step S-2), sealing the opening of the container body 1 with the top seal 2 in a top seal sealing step (step S-3), transporting the food packaged in the packaging container into a freezer and freezing it in a freezing step (step S-4), and storing the food in a storage step so that the peroxide value of the food is 30 meg / kg or less (step S-5).

[0056] The entire process from food storage (Step S-1) to storage (Step S-5) may be carried out at a single location, such as within the food manufacturing plant or retail store. However, for example, the food storage process (Step S-1) to the top-sealing process (Step S-3) may be carried out within the food manufacturing plant or retail store, while the freezing process (Step S-4) to storage (Step S-5) may be carried out at a separate location. The storage process (Step S-5) is intended to be semi-permanently sustainable, but depending on the material, contents, best-before date, or expiration date of the food, it may be for a period ranging from a few hours after the start of freezing to 36 months (3 years) after the completion of the freezing process.

[0057] In the food storage process (step S-1), the food may be placed in the container body and frozen beforehand, or pre-frozen food may be placed in the container body. After that, the air inside the container body containing the food may be removed and filled with nitrogen, carbon dioxide, or a mixture thereof (step S-2), and then a top seal sealing process (step S-3) may be performed in which a top seal is heat-fused to the flange of the container body filled with the mixed gas.

[0058] In the storage process (step S-5), it is preferable to store the product at -18°C or below, and the storage period may be, for example, within 36 months (3 years), within 24 months (2 years), within 12 months (1 year), or within 6 months. After the desired storage period (step S-5), the food packaging may be shipped to the intended store or another storage location. The temperature during transport after shipment is preferably maintained at -18°C or below, and it may also be -18°C or below when sold to the end consumer. [Examples]

[0059] This study compares the peroxide value and sensory evaluation of foods that have undergone MAP testing (hereinafter also referred to as "MAP foods") and foods that have not undergone MAP testing (hereinafter also referred to as "non-MAP foods").

[0060] The prerequisites are as follows: Target food product: Cooked beef short ribs (Expiration date indicated on the label: 11 months) Food oil content: 20% Freezing temperature: -18℃ Oxygen concentration: 0% MAP gas composition: 100% nitrogen Oxygen permeability of packaging material (JIS K 7126): 1,000 ml / m² at a thickness of 25 μm 2 • 24hr·MPa (75%RH at 20℃) or less Packaging material: PPF Layer composition of the laminated film on the above substrate: (towards the substrate) Unoriented polypropylene (CPP), dry lamination adhesive (dry Adh), ethylene-vinyl alcohol copolymer (EVOH), dry lamination adhesive (dry Adh), unoriented polystyrene (CPS)

[0061] <Measurement of peroxide value> The acetate-isooctane method will be used. The subjects of measurement are cooked food immediately before freezing (0 months), and MAP foods and non-MAP foods that have been removed from the freezer and opened at 4, 8, 12, and 16 months after freezing.

[0062] [Table 1]

[0063] As shown in Table 1, the peroxide value of non-MAP foods was higher than that of MAP foods from 4 months after the start of freezing, confirming that food deterioration progresses faster even after freezing if MAP is not applied. Furthermore, it can be easily inferred that non-MAP foods deteriorate relatively faster than MAP foods from the start of freezing.

[0064] <Sensory evaluation after reheating> Four, eight, and twelve months after the start of freezing, MAP foods and non-MAP foods were taken out of the refrigerator and reheated in a 500W microwave for 1 minute and 30 seconds. Four to six evaluators then tasted the reheated foods, and each evaluator assessed the odor and taste of the respective foods, quantifying their respective evaluations.

[0065] [Table 2]

[0066] As shown in Table 2, the above quantification was based on an evaluation level of "0" (baseline) for impressions obtained from tasting cooked food immediately before freezing (0 months prior). Tasting MAP foods and non-MAP foods at 4, 8, and 12 months after freezing was performed, with an evaluation level of "1" for impressions that were slightly different from the baseline, "2" for impressions that were significantly different from the baseline, and "3" for impressions that were significantly different from the baseline. Furthermore, for each impression, a stronger impression than the baseline was evaluated as "+" and a weaker impression as "-". For example, for the impression of sweet aroma, an impression that was slightly less sweet than the baseline was evaluated as "-1", an impression that was slightly sweet was evaluated as "+1", an impression that was less sweet than the baseline was evaluated as "-2", an impression that was sweet was evaluated as "+2", an impression that was very less sweet than the baseline was evaluated as "-3", and an impression that was very sweet was evaluated as "+3". The average value of the above evaluators was used as the final evaluation value.

[0067] [Table 3]

[0068] In the evaluation of odor, the sweet aroma was evaluated as follows, as shown in Table 3 and Figure 3: MAP foods were evaluated as -0.3 after 4 months, -0.5 after 8 months, and -1.0 after 12 months, while non-MAP foods were evaluated as -0.3 after 4 months, -1.3 after 8 months, and -1.3 after 12 months. In other words, the sweet aroma at 4 months was the same for both, but the sweet aroma was not detected in the non-MAP foods at 8 months and 12 months, confirming that the deterioration of MAP foods was relatively slower.

[0069] In the evaluation of odor, the aroma of seasonings was evaluated as follows, as shown in Table 3 and Figure 4: MAP foods were evaluated as -0.3 after 4 months, -0.8 after 8 months, and -2.3 after 12 months, while non-MAP foods were evaluated as -0.8 after 4 months, -1.3 after 8 months, and -2.3 after 12 months. In other words, the aroma of seasonings was similar in both cases after 12 months, but the aroma of seasonings was less noticeable in non-MAP foods after 4 months and 8 months than in MAP foods, confirming that the deterioration of MAP foods was relatively slower.

[0070] [Table 4]

[0071] In the evaluation of taste, the taste of seasonings was rated as -0.5 after 4 months, -0.5 after 8 months, and -0.8 after 12 months for MAP foods, as shown in Table 4 and Figure 5. For non-MAP foods, the ratings were -0.8 after 4 months, -0.8 after 8 months, and -0.8 after 12 months. In other words, the taste of seasonings was the same for both after 12 months, but the taste of seasonings was less noticeable in non-MAP foods after 4 months and 8 months than in MAP foods, confirming that the deterioration of MAP foods was relatively slower.

[0072] In the evaluation of taste, the level of greasiness was rated as 0 for MAP foods after 4 months, 0 after 8 months, and 1.0 after 12 months, as shown in Table 4 and Figure 6. For non-MAP foods, the levels were 0 for 4 months, 0 after 8 months, and 1.8 after 12 months. In other words, the impression of greasiness was the same for both after 4 months and 8 months, but the greasiness was perceived more in the non-MAP foods after 12 months than in the MAP foods, confirming that the deterioration of MAP foods was relatively slower.

[0073] Overall, the sensory evaluation results showed that MAP foods deteriorated more slowly in terms of odor and taste than non-MAP foods, confirming a causal relationship between the peroxide value of food and the odor and taste after reheating.

[0074] In other words, the present invention relates to a food packaging in which frozen food is packaged, wherein the oxygen concentration inside the packaging is 0-10%, and the oxygen permeability of the packaging is 1000 ml / m² at a thickness of 25 μm according to JIS K 7126. 2 The temperature is 24hr·MPa (75%RH at 20℃) or less, the peroxide value of the food after freezing is 30meg / kg or less, and the packaging includes at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body, as shown in Figure 1.

[0075] Furthermore, the present invention relates to a method for manufacturing a frozen food packaging in which frozen food is packaged, wherein the oxygen permeability of the packaging is 1000 ml / m² at a thickness of 25 μm according to JIS K 7126. 2 The oxygen level is 24hr·MPa (75%RH at 20℃) or less, and as shown in Figure 2, the process includes the steps of: placing the food inside the packaging; reducing the oxygen concentration inside the packaging to 0-10%; transporting the packaging to a freezer; and freezing the food so that its peroxide value is 30 meg / kg or less. The packaging includes, as shown in Figure 1, at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body.

[0076] This configuration allows for the expectation of obtaining the desired peroxide value when freezing and storing foods suitable for quality assessment based on peroxide value after freezing.

[0077] Furthermore, this embodiment and this embodiment are not limited to the above-described content, and include all physical properties, material components, mixing ratios in relation to materials, position, shape, and dimensions of parts, design in relation to parts, manufacturing methods, and usage methods, as long as equivalent effects can be obtained. [Explanation of symbols]

[0078] 1. Container body 11 Bottom 12 Side 13 Flange section 2. Top seal

Claims

1. A food packaging in which frozen food is packaged in a packaging body, The oxygen concentration inside the packaging is 0 to 10%. The oxygen permeability of the aforementioned packaging is 1000 ml / m² at a thickness of 25 μm, according to JIS K 7126. ２ - The pressure is 24hr·MPa (75% RH at 20°C) or less. The peroxide value of the food after freezing is 30 meg / kg or less. The packaging includes at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body. Food packaging.

2. A method for manufacturing a food packaging in which frozen food is packaged in a packaging body, The oxygen permeability of the aforementioned packaging is 1000 ml / m² at a thickness of 25 μm, according to JIS K 7126. ２ - The pressure is 24hr·MPa (75% RH at 20°C) or less. A step of placing the food product inside the packaging, A step of adjusting the oxygen concentration inside the package to 0-10%, The process of freezing the packaged body, The process includes storing the food product so that its peroxide value is 30 meg / kg or less. The packaging includes at least a packaging container comprising a container body for containing the food and a lid material to be attached to the container body. A method for manufacturing food packaging.

3. The oil content of the aforementioned food is 10-60%. A method for manufacturing a food packaging according to claim 1 or a food packaging according to claim 2.

4. The freezing temperature of the aforementioned food is -60 to 0°C. A method for manufacturing a food packaging according to claim 1 or a food packaging according to claim 2.

5. The gas composition inside the packaging is at least nitrogen and carbon dioxide. A method for manufacturing a food packaging according to claim 1 or a food packaging according to claim 2.

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