A container and method for heating and thawing frozen foods.

Abstract

The present invention provides a heating and thawing container that allows for the convenient and uniform heating and thawing of frozen foods without compromising their quality. [Solution] A heating and thawing container for heating and thawing frozen food, comprising a container body, an inner tray placed on the container body and having a water-holding space capable of holding water, an upper tray placed on the inner tray and on which frozen food is placed, a lid, and a heating device housed between the container body and the inner tray, wherein when the lid is removed and water is contained in the water-holding space of the inner tray, the tearing string of the heating device is pulled from the outside, causing the water bag and heating agent bag to tear open, the water in the water bag and the heating agent to react chemically and generate heat, the water in the water-holding space of the inner tray is heated, and the frozen food placed on the upper tray is heated and thawed.

Description

Technical Field

[0001] The present invention relates to a container for heating and thawing frozen food and a heating and thawing method. In particular, the present invention relates to a heating and thawing container capable of uniformly heating and thawing frozen food without impairing its taste, and a heating and thawing method using the same container.

Background Art

[0002] In recent years, various foods have been sold along with changes in eating habits and lifestyles. Among these, frozen foods are widely prevalent as they are frozen in a cooked state, can be stored for a long period of time, and are ready to eat and drink only by heating. This trend also applies to frozen sushi, which is composed of a cooked rice portion called shari and an ingredient portion called neta. However, the degree of denaturation under heating is completely different between the cooked rice portion and the ingredient portion in frozen sushi, and it is known that the ingredient portion in particular is easily denatured by heating, which significantly degrades the taste.

[0003] To solve the above problem, a method has been proposed in which the surface and upper part of frozen sushi are covered with aluminum foil or the like when thawing in a microwave oven, so that the cooked rice portion is heated more than the ingredient portion (for example, see Patent Documents 1 and 2).

[0004] On the other hand, it is known that when cooked rice is thawed, a phenomenon called white waxing occurs, which significantly degrades the taste of the cooked rice. White waxing is a phenomenon in which when thawing freshly cooked rice, moisture is gradually lost due to dry cold air or the like, and when thawing is completed, the moisture content of the cooked rice decreases, turning white and dry and crumbly, resulting in reduced flavor and texture. To avoid this white waxing, a method has been proposed in which an additive containing carbohydrates such as trehalose is added to cook the rice, thereby changing the quality of the rice and producing cooked rice for frozen sushi with suppressed white waxing (for example, see Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] To prevent deterioration of the ingredients in frozen sushi, natural thawing without heating is considered. However, natural thawing takes about 2-3 hours, and especially in winter, the thawing time is even longer, making it impossible to eat quickly. In summer, although the thawing time is shorter than in winter, deterioration and spoilage may occur due to being left at high temperatures. Furthermore, natural thawing makes the whitening of the rice more pronounced, significantly reducing the taste.

[0007] Therefore, a method using dielectric heating with microwaves via a microwave oven can be considered. The microwave oven method described in Patent Documents 1 and 2 significantly reduces the time required for thawing compared to natural thawing. However, it requires cumbersome steps such as removing aluminum foil after thawing, and there is still room for improvement in terms of ease of use and convenience. In addition, when using a microwave oven, uneven heating occurs, resulting in a mixture of areas that are too hot to touch and areas that remain cold, and the problem of not being able to thaw to the same quality as before freezing still remains. Furthermore, the methods described in Patent Documents 1 and 2 do not employ any means to prevent the rice portion from becoming dry during thawing, and there is still room for improvement. On the other hand, the method described in Patent Document 3 may impair the taste of the frozen food due to the addition of sugar-containing additives.

[0008] The present invention has been made in view of the above problems, and aims to provide a heating and thawing container and a heating and thawing method that can easily and uniformly heat and thaw frozen foods without impairing their quality. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the present inventors have found that a heating and thawing container that combines a specific container with a heating device that generates heat through a chemical reaction between water and a heating agent can solve the above problems.

[0010] In other words, the present invention is as follows: (1) A heating and thawing container for heating and thawing frozen food, comprising: a container body; an inner tray placed on the container body and having a water-holding space capable of holding water; an upper tray placed on the inner tray and on which frozen food is placed; a lid; and a heating device housed between the container body and the inner tray, The heating device consists of a rectangular, dish-shaped box with an open top, in which a water bag containing water in a water-impermeable and easily tearable bag, and a heating agent bag containing a heating agent that generates heat upon contact with water in a bag-shaped container, are stacked from top to bottom on a support plate with an opening interposed between the bags, and are fixed to the support plate. Furthermore, one end is fixed to the support plate, and the other end is wrapped around the front and back of both the upper and lower surfaces of the water bag and the front and back of both the upper and lower surfaces of the heating agent bag, and a string for tearing the water bag and heating agent bag is attached, which is pulled out from the front of the box. A heating and thawing container, wherein, with the lid removed and water contained in the water-holding space of the inner tray, the tearing string is pulled from the outside, causing the water bag and the heating agent bag to tear open, the water in the water bag and the heating agent to chemically react and generate heat, and the water in the water-holding space of the inner tray is heated, thereby heating and thawing the frozen food placed on the upper tray. (2) The heating and thawing container according to (1), wherein the water in the water bag contains an antifreeze agent, and the heating and thawing container is capable of storing and transporting the frozen food with the frozen food placed on the upper tray under freezing conditions. (3) The frozen food is frozen sushi having a rice portion and a topping portion, and the rice portion of the frozen sushi is positioned below the topping portion and in contact with the bottom surface of the upper plate, The heating and thawing container according to (1) or (2), wherein the bottom surface of the upper plate has a groove formed thereon to prevent rice from sticking to the bottom surface of the upper plate when the frozen sushi is heated and thawed. (4) A heating and thawing container according to any of (1) to (3), wherein the bottom surface of the upper tray does not have holes for steam to pass through. (5) A method of thawing frozen food using a heating and thawing container for thawing any of the frozen foods described in (1) to (4), The steps include removing the lid and pouring a predetermined amount of water into the water storage space of the inner tray, The process involves pulling the tearing string from the outside to tear open the water bag and the heating agent bag, and causing a chemical reaction between the water in the water bag and the heating agent to heat the water in the water storage space of the inner tray, A step of heating and thawing the frozen food contained in the upper tray by heating the water in the aforementioned storage space. Includes, The heating and thawing step is performed with the lid removed, in a heating and thawing method. Heat thawing method. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a heating and thawing container and a heating and thawing method that can easily and uniformly heat and thaw frozen foods without impairing their quality. [Brief explanation of the drawing]

[0012] [Figure 1] This is an exploded perspective view showing the configuration of a heating and thawing container according to an embodiment of the present invention. [Figure 2] This is a plan view of the upper pan according to an embodiment of the present invention. [Figure 3] This is a plan view of the upper pan according to an embodiment of the present invention. [Figure 4]This is a plan view of the heat generating device according to an embodiment of the present invention. To facilitate understanding of the layer structure of the heat generating device, it is drawn as a plan view in which a part of the porous film attached to the upper surface of the heat generating device is removed. In addition, to avoid complication, the depiction of a part of the tearing strings for the water bag and the heat generating agent bag is omitted. [Figure 5] This is a cross-sectional view seen from the right side surface of the heat generating device shown in Figure 4. The cross-section seen from the left side surface has substantially the same shape. [Figure 6] This is a plan view (top view) clarifying the location of the inner bag enclosing the heat generating agent disposed in the divided region housed in the heat generating agent bag of the heat generating device shown in Figure 4. This plan view is drawn in a state where a part of the heat generating agent bag is cut away. [Figure 7] This is an explanatory diagram for explaining a heating and thawing method using the heating and thawing container according to the embodiment of the present invention. [Modes for Carrying Out the Invention]

[0013] Hereinafter, the heating and thawing container and the heating and thawing method according to the embodiment of the present invention will be described in detail. The description of the constituent elements set forth below is an example (representative example) as one embodiment of the present invention, and the present invention is not limited to these contents. In the following drawings, for the clarity of each configuration, the scale, number, etc. of each structure may differ from those of the actual structure in some cases.

[0014] As used in the present specification, "frozen food" refers to food in a frozen state. The frozen food may be subjected to sale, transfer, distribution, storage and the like in the frozen state. The frozen food is to be eaten after being thawed, and may be solid or liquid. The frozen food may optionally be cooked (e.g., baked or the like) together with thawing (in other words, simultaneously with thawing) or after thawing. Specific examples of the frozen food include frozen cooked rice including frozen rice such as frozen rice ball and frozen sushi, frozen noodles such as frozen udon and frozen pasta, frozen bread, frozen rice cake, frozen Japanese-style pancake, frozen confectionery such as frozen jelly and frozen cake, and the like. Among these, the container for heating and thawing of the present embodiment can be suitably used for the frozen cooked rice, and can be particularly suitably used for the frozen sushi. The form of the frozen sushi is not particularly limited, and examples thereof include hand-formed sushi, rolled sushi, pressed sushi and the like.

[0015] As used in the present specification, "heating and thawing" refers to heating a frozen food, which is food in a frozen state, while keeping the frozen state.

[0016] It is known that the white waxy change of cooked rice in frozen sushi becomes particularly prominent in slow thawing. In the present embodiment, it is presumed that the white waxy change can be eliminated by heating and thawing the cooked rice in a short time with water heated by a heat generating device. Furthermore, in the present embodiment, since the cooked rice is heated and thawed under a humidified condition, it is possible to prevent moisture from escaping from the cooked rice during thawing, and prevent the cooked rice from forming lumps and significantly deteriorating the texture, resulting in excellent taste.

[0017] On the other hand, the heat denaturation of the ingredients in frozen sushi is caused by prolonged exposure to high temperatures. In this embodiment, the rice portion of the frozen sushi is placed in the container so that it is below the ingredients and in contact with the bottom surface of the tray on which the frozen sushi is placed. The bottom surface of the tray in contact with the rice portion is heated by heat conduction from the heat generated by the heating device along with the heated water, so the rice portion in contact with the heated bottom surface of the tray is heated and thawed preferentially over the ingredients. Furthermore, in this embodiment, the container is heated with the lid removed, i.e., with the top open. Therefore, the steam from the water heated by the heating device does not strongly act on the top of the frozen sushi, i.e., the ingredients, and the heating of the ingredients is suppressed. Thus, using the heating and thawing container of this embodiment can suppress the heat denaturation of the ingredients in frozen sushi. Furthermore, because the container is heated and thawed with the lid removed, excessive water vapor does not adhere to the frozen sushi. As a result, the ingredients can be heated and thawed in a fresh and moist state without being boiled.

[0018] (Container for heating and defrosting) Figure 1 is an exploded perspective view showing the configuration of a heating and thawing container according to an embodiment of the present invention. The heating and thawing container 100 of this embodiment comprises a container body 10 arranged sequentially from the bottom in the height direction, a heating device 50, an inner tray 20, an upper tray 30, and a lid 40.

[0019] <Container body> The container body has a housing space inside for accommodating the heating device 50. The container body 10 has an open top and, in the example shown in Figure 1, is formed in a roughly rectangular shape in plan view. The shape of the container body 10 is arbitrary and may be a polygon, a circle, an ellipse, or the like. Furthermore, if the container body 10 is a polygon, each side may be straight or may bulge outwards in an arc shape. In addition, each corner may be arc-shaped, i.e., it may have a rounded corner shape.

[0020] The size of the container body 10 is not particularly limited, as long as it can accommodate the heating device 50. If the container body 10 is roughly rectangular in plan view, the dimensions of the container body 10 may be, for example, about 10 cm to 30 cm in the width and length directions, and about 3 cm to 10 cm in the height direction.

[0021] The material of the container body 10 is not particularly limited and includes resin materials such as polyethylene resin and polypropylene resin, and paper materials such as cardboard and corrugated cardboard sheets. Paper materials such as cardboard and corrugated cardboard sheets are preferably treated to be water-resistant (e.g., by applying or impregnating with wax) to suppress the decrease in strength due to contact with water vapor generated by the heating device 50. In addition, to improve water resistance, a metal foil such as aluminum foil or a resin film can be laminated onto the surface of the paper material.

[0022] <Medium Plate> The middle tray 20 is placed on the container body 10, supporting the upper tray 30 (described later), and is into which water is poured. The inner tray 20 has an open top, and its shape in plan view corresponds to the shape of the container body 10. As mentioned above, the container body 10 is roughly rectangular in plan view, so the inner tray 20 is also roughly rectangular in plan view. The inner tray 20 has a water storage space 21 for storing water.

[0023] The shape of the inner tray 20 is not particularly limited. In this embodiment, for example, the peripheral wall portion of the inner tray 20 rises upward from the periphery of the bottom surface of the inner tray 20, expanding outwards as a whole (towards the opening side of the inner tray 20). The width and length dimensions of the bottom surface of the inner tray 20 are smaller than the width and length dimensions of the opening of the container body 10. The width and length dimensions of the opening of the inner tray are larger than the width and length dimensions of the opening of the container body 10. With the above configuration, when the inner tray 20 is placed on the container body 10, the peripheral wall portion of the inner tray is pressed against the opening of the container body 10, and the inner tray 20 can be stacked on the container body 10. That is, when the inner tray 20 is placed on the container body 10, the bottom surface of the inner tray 20 is floating above the bottom surface of the container body. The heating device 50 is housed in the space (storage space of the container body 10) formed by the floating state. Furthermore, the opening of the inner tray 20 is closed by fitting the lid 50, which will be described later, into the inner tray.

[0024] The size of the inner tray 20 is not particularly limited, as long as it can support the upper tray 30, have a water-holding space 21 into which water can be poured, and be placed on the container body 10. For example, if the inner tray 20 is roughly rectangular in plan view, the size of the inner tray 20 can be the same as that of the container body 10.

[0025] The material of the inner tray 20 is not particularly limited, and the same material as that used for the container body 10 can be used.

[0026] <Top plate> The upper tray 30 is placed on top of the middle tray 20 and functions as a food tray for arranging frozen foods. The upper tray 30 has an open top and, in the example shown in Figure 1, is formed in a roughly rectangular shape in plan view, but there are no restrictions on its shape as long as frozen foods can be placed on it. Preferably, the upper tray 30 has divider members that can hold frozen foods individually during storage and transport, and that indicate where the frozen foods should be placed.

[0027] Figures 3 and 4 are examples of plan views of the upper tray according to an embodiment of the present invention. In Figures 3 and 4, frozen sushi is used as the frozen food. In the example shown in Figure 3, a partition plate 31 is provided as a dividing member. The partition plate 31 is a protruding portion that extends upward from the bottom surface of the upper tray 30 and is made of the same material as the upper tray 30. The partition plate 31 allows for the individual separation and holding of frozen foods during storage and transport, and also indicates where the frozen foods should be placed. The number, shape, size, etc. of the partition plates 31 can be appropriately designed according to the frozen foods to be placed.

[0028] Furthermore, as shown in Figure 3, it is preferable that the bottom surface of the upper tray 30 on which the frozen food is placed is provided with uneven surfaces 32 to prevent thawed rice from sticking to it. In addition, by providing the uneven surfaces 32, if a small amount of drip occurs during heating and thawing, the drip can be contained in the recesses of the uneven surfaces 32. This is preferable because it is possible to separate the drip from the thawed food and maintain a non-contact state between the thawed food and the drip. The number, shape, size, etc. of the uneven surfaces 32 can be appropriately designed according to the frozen food being placed.

[0029] On the other hand, in the example shown in Figure 4, a surrounding portion 33 is provided as a partitioning member, conforming to the shape of the frozen food. The surrounding portion 33 is a recess protruding downward from the bottom surface of the upper tray 30, which accommodates multiple frozen foods side by side, surrounding each frozen food item completely. The surrounding portion 33 prevents the frozen food from shifting position and allows it to maintain its normal shape when thawed. The number, shape, size, etc., of the surrounding portions 33 can be appropriately designed according to the frozen food being placed.

[0030] In this embodiment, the bottom surface of the upper tray 30 does not have holes for allowing steam (water vapor) generated by the heating device 50 to pass through. If holes are formed, it tends to overheat the frozen food, which is undesirable.

[0031] The size of the upper tray 30 is not particularly limited as long as it can be placed on the upper tray and on which frozen food can be arranged, and can be designed as appropriate. If the upper tray 30 is roughly rectangular in plan view, its size can be, for example, the same as the size of the container body 10 or the inner tray 20.

[0032] The material of the upper tray 30 is not particularly limited, and resin materials such as polyethylene resin and polypropylene resin, and paper materials such as cardboard and corrugated cardboard sheets can be used. In particular, it is preferable that the upper tray 30 is formed from a resin material such as polyethylene resin or polypropylene resin.

[0033] <Lid> The lid 40 fits onto the container body 10 or the inner tray 20 and has the function of preventing the frozen food placed on the upper tray 30 from being exposed to the outside air until it is heated and thawed. The lid 40 is formed to fit the container body 10 or the inner tray 20, and is therefore shaped and sized to match the container body 10 or the inner tray 20. For example, the lid 40 mainly consists of a top portion and an outer lid surface portion that is suspended along the periphery of the top portion. The fitting structure between the container body 10 or the inner tray 20 and the lid 40 can be any shape or configuration as long as it enables the fitting of the container body 10 or the inner tray 20 and the lid 40. For example, when the lid 40 is placed over the inner tray 20, the outer lid surface portion of the lid 40 may be fitted and supported by the upper edge of the peripheral wall portion of the inner tray 20.

[0034] The lid 40 is preferably made of a translucent resin material, and more preferably is colorless and transparent, so that the frozen food placed on the top tray 30 can be seen from the outside. However, it may also be made of a material that is not translucent.

[0035] <Heating device> The heating device 50 is housed in the container body 10 and generates heat through a chemical reaction between water and a heating agent, heating the water contained in the inner tray 20.

[0036] Figure 4 is a plan view of a heating device according to an embodiment of the present invention. Figure 5 is a cross-sectional view of the heating device shown in Figure 4, viewed from the right side. The basic configuration of the heating device 50 in this embodiment is the same as that of a heating device 50 using a heating agent that has been known to date. The heating device 50 is arranged on a support plate 55 with an opening between two bags, with a water bag 53 containing water in a water-impermeable, easily tearable bag and a heating agent bag 54 containing a heating agent that generates heat upon contact with water in a bag-shaped container, stacked inside the support plate 52. One end of the string 56 is fixed to the support plate 55, and the other end is wrapped around the front and back of both the upper and lower surfaces of the water bag 53 and the front and back of both the upper and lower surfaces of the heating agent bag, and is pulled out from the front side of the box 52. The top surface of the dish-shaped box 52 is usually covered with a porous plastic film 57 to prevent the water bag 53 and heat-generating agent bag 54 housed inside from falling out, and to efficiently raise the thermal energy generated by the exothermic reaction.

[0037] The rectangular, dish-shaped box 52 with an open top that houses the heat-generating laminate, which includes the water bag 53, the heat-generating agent bag 54, the support plate 55, and the tear-off string 56, is preferably a water-resistant container made of synthetic resin, which is commonly used in conventional heating devices of the same type 50. However, there are no particular limitations on the depth of the dish-shaped box 52. Also, cardboard or corrugated cardboard with enhanced water resistance can be used. Furthermore, it is preferable that a notch is formed along the edge of the box body 52 that allows the tearing string 56 to be pulled out to the outside. However, this notch is not necessarily required, and instead of a notch, a hole may be provided in the front side (side wall) of the box body 52.

[0038] It is preferable to provide a recess or a V-shaped depression on the bottom surface of the square, dish-shaped box 52 in order to collect the water that diffuses to the bottom surface of the box 52 when the water bag 53 ruptures.

[0039] The water bag 53 and the heat-generating agent bag 54 are fixed to the support plate 55 in a stacked state, with an opening interposed between the bags. Preferably, the water bag 53 and the heat-generating agent bag 54 are fixed by joining and fixing the rear edge of the water bag 53 and the rear edge of the heat-generating agent bag 54 by sandwiching the rear edge of the support plate.

[0040] The water contained in the water bag 53 may be ordinary tap water or industrial water, but it is preferable to add an antifreeze agent to the water. This allows the frozen food to be transported and stored under freezing conditions (a temperature at which the food remains frozen, for example, -18°C or below) while placed in the heating and thawing container 100 until heating and thawing.

[0041] The type of antifreeze that can be used in this embodiment is not particularly limited, but examples include acetates, formates, urea, chlorides, low molecular weight alcohols, etc.

[0042] Examples of acetate salts include sodium acetate, magnesium acetate, potassium acetate, and calcium acetate. Examples of formate salts include sodium formate, potassium formate, and magnesium formate. Examples of chlorides include sodium chloride, calcium chloride, and magnesium chloride. Examples of low molecular weight alcohols include glycerin, propylene glycol, ethylene glycol, methyl alcohol, and ethyl alcohol.

[0043] The amount of antifreeze added can be determined appropriately considering the freezing conditions of the heating and thawing container 100. Although not particularly limited, the amount of antifreeze added to the water is preferably in the range of 5 to 30% by weight, and particularly preferably in the range of 10 to 20% by weight. Within this range, the fluidity of the water tends not to be significantly hindered under the frozen storage temperature conditions.

[0044] As the heating agent, it is preferable to use a known quicklime or a highly heating agent obtained by adding a heat-enhancing agent such as metallic aluminum powder to quicklime. The heating agent is usually used in the form of a known powder or granules, but it may also be in the form of fragments or plate-shaped molded bodies.

[0045] The heating device 50 is particularly preferably configured such that: a) the bag-shaped container for the heating agent is made of a water-impermeable and easily tearable metal film; b) the heating agent is contained inside the bag-shaped container made of metal film, divided into left and right halves by a gap; and c) a string 56 for tearing the water bag 53 and the heating agent bag 54 is wound around the water bag 53 and the heat-generating agent bag 54, spanning the upper and lower sides of the gap. The blank area described above is positioned so that the heating agent is located approximately in the center of the bag-shaped container.

[0046] Typically, a bag made of a water-impermeable, easily tearable metal film is used as a container for housing the heating agent, by joining the edges of each of the four sides of two sheets of aluminum foil. The heating agent to be incorporated into the heating laminate is divided into approximately equal parts beforehand, and each part is packed into a water-permeable inner bag made of nonwoven fabric or the like. These inner bags are then placed inside the water-impermeable, easily tearable metal film bag (outer bag) of the heating agent, on the left and right sides. In this case, the "left and right" arrangement refers to a positional relationship where the heating agent is on the left and right sides of the tearing string 56, which is set in the heating laminate, so as not to overlap with the string 56, and the arrangement is based on the pulling direction of the string 56. Furthermore, the left and right arrangement does not need to strictly coincide with the pulling direction of the tearing string 56.

[0047] Figure 6 is a plan view showing a typical positional relationship in which the heating agents are packed into two inner bags (54a, 54b) and arranged on the left and right sides of the metal film outer bag, with empty spaces left inside.

[0048] The heat-generating laminate is typically housed in a dish-shaped (with no particular limit on depth, and materials such as synthetic resin or cardboard are used) water-resistant box 52, as can be seen from Figures 4 and 5.

[0049] In the heat-generating laminate housed in this box 52, the tearing string 56 pulled out or removed from the front of the box 52 causes the water bag 53 and the heat-generating agent bag 54 to rupture and open. As a result, water flows out of the water bag 53 into the container, and a similar rupture and opening causes the heat-generating agent exposed in the heat-generating agent bag 54 to come into contact with it, causing a chemical reaction that generates heat and high-temperature steam, i.e., the generation of thermal energy, and continuous heat generation thereafter is achieved.

[0050] As described above, in the heat-generating agent bag 54 used in this embodiment, a water-permeable inner bag is prepared in which the heat-generating agent is enclosed in a water-permeable bag body such as a nonwoven fabric (note that the heat-generating agent pack itself, which contains the heat-generating agent enclosed in a water-permeable bag body such as a nonwoven fabric, is commercially available as a component of the heating device 50 or as a heat-generating agent pack for use for other purposes), and this heat-generating agent inner bag is placed inside a moisture-resistant outer bag (a bag body in which the permeation of water vapor is significantly suppressed, and which has a structure in which a metal layer is formed on the surface of a metal film or synthetic resin film by means of vapor deposition or the like, for example) that is larger than the separately prepared heat-generating agent inner bag, with the two bags placed approximately equally on the left and right sides. It is preferable that the cutting position of the heat-generating agent bag 54 by the tearing string 56 is set so as not to overlap with the position of any of the heat-generating agent inner bags placed inside the box body 52.

[0051] By configuring the heating agent bag 54 of the heating device 50 as shown in Figures 4 to 6, the water bag 53 and the moisture-resistant outer bag of the heating agent bag 54 can be easily and reliably ruptured and opened by pulling the tearing string 56, even with a relatively weak tensile force. Furthermore, if each of the heating agents, which are divided and arranged on the left and right sides, is packed into an inner bag made of nonwoven fabric or the like, even if the heating agent bag (outer bag 54) is ruptured or opened, the heating agent inner bag containing the heating agent within the water-permeable bag will not rupture or open, and the heating agent will remain enclosed within the water-permeable bag. Therefore, scattering of the heating agent to the outside of the water-permeable bag and rising due to the rise of water vapor are unlikely to occur. As a result, contamination of the food to be heated by heating agent residue, which is often a problem with conventional heating devices, is effectively prevented.

[0052] <Other Embodiments> The above describes an example of the heating and thawing container 100. However, the embodiments of the present invention are not limited thereto. Other embodiments of the heating and thawing container 100 will be described below.

[0053] In the above embodiment, water was contained in the water-holding section 21 of the inner tray 20, but any liquid other than water may be used as long as it does not hinder the effects of the present invention. For example, a viscous gel-like liquid may be used. If a gel-like liquid is used, even if the heating and thawing container 100 is accidentally tilted, it is possible to effectively prevent the heating water from spilling out of the container. In addition, by adjusting the amount of gelling additive, it tends to be easier to adjust the heating and thawing temperature and heating and thawing time for frozen foods.

[0054] Furthermore, a water-absorbing sponge-like insert or the like may be provided within the water-holding space 21 of the inner tray 20, to the extent that it does not hinder the effects of the present invention. This effectively prevents heating water from spilling out of the container even if the container is accidentally tilted. In addition, by adjusting the amount of sponge relative to the water, it tends to become easier to adjust the heating and thawing temperature and heating and thawing time for frozen foods.

[0055] Furthermore, the peripheral wall of the inner tray 20 may have markings indicating the approximate amount of water to be poured into the inner tray, or the maximum permissible amount of water.

[0056] (Method of using a heating and thawing container and a heating and thawing method using the same) Next, the method of using the heating and thawing container 100 of this embodiment and the heating and thawing method using it will be described.

[0057] Figure 7 is an explanatory diagram illustrating a thawing method using a heating and thawing container according to an embodiment of the present invention. Figure 7 shows an example in which frozen sushi is used as the frozen food X. First, as a preparatory step for heating and thawing, the lid 40 is removed and the heating device 50 is placed in the storage space of the container body 10. After the heating device 50 is placed, the inner tray 20 is placed on top of the container body 10. At this time, the string 56 for tearing the heating device 50 is extended outside the heating and thawing container 100 so that it can be pulled from the outside between the container body 10 and the inner tray 20. If the frozen sushi, which is the frozen food X, is not placed on the upper tray 30, the frozen sushi is placed using the partition section of the upper tray 30 (partition plate 31 in the example of Figure 7) as a guide. At this time, the frozen sushi is placed so that the rice portion of the frozen sushi is below the topping portion and in contact with the bottom surface of the upper tray 30 on which the frozen sushi X is placed. In the example of Figure 7, the rice portion of the frozen sushi is placed in contact with the uneven portion 32 of the upper tray 30.

[0058] Next, a predetermined amount of water Y is poured into the water-holding space 21 of the inner tray 20. The water Y may be at room temperature. The amount of water Y to be poured can be adjusted as appropriate depending on the size of the inner tray 20, the type and number of frozen sushi to be heated and thawed, etc.

[0059] Next, the upper tray 30, on which the frozen food X is placed, is placed on the middle tray 20. Alternatively, the frozen food X may be placed on the upper tray 30 after it has been placed on the middle tray 20. Alternatively, after the upper tray 30 has been placed on the middle tray 20, a predetermined amount of water Y may be poured into the water storage space 21 of the middle tray 20. After placing the upper tray 30, the tearing cord 56 of the heating device 50 is pulled from the outside to tear open the water bag 53 and the heating agent bag 54, causing a chemical reaction between the water in the water bag 53 and the heating agent to generate heat and steam.

[0060] The heat and steam generated by the heating device 50 heat the water Y injected into the water storage space 21 of the middle tray 20. Since the frozen food X placed on the upper tray 30 is surrounded by the heated water Y in the water storage space 21 of the middle tray 20, the frozen food X is thawed uniformly and evenly from the inside out under humid conditions by the heated water Y.

[0061] The following is an example of how frozen food X was uniformly thawed without uneven heating using the heating and thawing method described above.

[0062] The lid 40 was removed, a predetermined amount of water Y was poured into the inner tray 20, and the cooked rice from 8 rolls of frozen sushi (as frozen food X) was placed on the upper tray 30 shown in Figure 3. Then, the tensioning string 56 was pulled from the outside, and the temperature of the cooked rice and the water in the inner tray 20 was measured. For comparison, the temperature after natural thawing for 30 minutes was also measured. The results are shown in Table 1.

[0063] [Table 1]

[0064] The rice positions 1-8 in Table 1 represent the eight positions of the rice separated by the partition plate 31 on the upper tray 30 in Figure 3. In other words, if the temperature of each rice at positions 1-8 is generally similar, it indicates that the rice has been thawed uniformly without uneven heating. As shown in Table 1, after 25 minutes from the start of heating and thawing, all the rice reached 20°C or higher, confirming that the rice was uniformly heated to approximately body temperature without uneven heating. The temperature of the water Y in the middle tray 20 reached approximately 75°C after 5 minutes and then gradually decreased. The optimal heating and thawing time can be adjusted by appropriately designing the amount of water Y injected, the material of the upper tray 30, the thickness of the bottom surface, etc. It is preferable to measure the optimal heating and thawing time according to the material and shape of the container, the type of sushi, etc., and indicate it on the container or packaging.

[0065] Furthermore, when the cooked rice shown in Table 1 above was consumed, no whitening of the rice was observed, and it had excellent taste without compromising its quality before thawing. This is presumed to be because, in this embodiment, the rice is heated and thawed under humid conditions, which suppresses the loss of moisture from the cooked rice during heating and thawing, thus preventing the rice from clumping together and significantly degrading its texture.

[0066] Furthermore, when frozen sushi is used as the frozen food X, as described above, the rice portion of the frozen sushi is positioned below the topping portion and in contact with the upper tray 30 on which the frozen sushi is placed, and is then heated and thawed. Here, the heat generated by the heating device 50, along with the water Y poured into the middle tray 20, also heats the upper tray 30 (especially the bottom surface) in contact with the water Y through heat conduction. That is, the rice portion in contact with the upper tray 30 is heated and thawed by heat conduction from the upper tray 30 along with the heated water Y. On the other hand, the topping portion is heated and thawed by heat conduction from the frozen rice portion along with the heated water Y in the middle tray 20, instead of from the heated upper tray 30. As a result, the rice portion is heated and thawed preferentially over the topping portion, and the heating of the topping portion is suppressed. Moreover, in this embodiment, the heating and thawing method is performed with the lid 40 removed, that is, with the top of the container 100 open. As a result, the steam generated by the heated water Y does not strongly act on the top of the frozen sushi, i.e., the topping portion, and the heating of the topping portion is suppressed. Therefore, the heating and thawing method of this embodiment can suppress the heat-induced denaturation of the ingredients in frozen sushi. Furthermore, because the lid is removed during heating and thawing, excessive steam does not adhere to the frozen sushi. As a result, the ingredients can be heated and thawed in a fresh and moist state without being overcooked.

[0067] Furthermore, in this embodiment, the heating and thawing container 100 contains an antifreeze in the water bag 53 of the heating device 50. Therefore, the water bag 53 does not freeze even under freezing conditions, and the frozen food X can be stored and transported as is with the container 100 placed inside under freezing conditions. In addition, the heating and thawing container 100 of this embodiment is lightweight and compact, making it highly portable. It does not require commercial power, so it can be used anywhere and anytime quickly. Moreover, since the heating and thawing container 100 of this embodiment is made of paper or resin material, it can be used as a disposable container.

[0068] In other words, using the heating and thawing container 100 of this embodiment, for example, multiple frozen sushi portions, each consisting of frozen rice topped with frozen ingredients, can be sold in the heating and thawing container 100. The buyer can then simply pour water Y into the container 100 and pull the tearing string 56 from the outside to enjoy delicious sushi anytime, anywhere.

[0069] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence. [Explanation of Symbols]

[0070] 10...Container body, 20...Inner tray, 21...Water storage space, 30...Top tray, 31...Partition plate, 32...Rubbered section, 33...Enclosing section, 40...Lid, 50...Heating device, 52...Box body, 53...Water bag, 54...Heating agent bag, 55...Support plate, 56...Tear-off string

Claims

1. A heating and thawing container for heating and thawing frozen food, comprising: a container body; an inner tray placed on the container body and having a water-holding space capable of holding water; an upper tray placed on the inner tray and on which frozen food is placed; a lid; and a heating device housed between the container body and the inner tray, The heating device consists of a rectangular, dish-shaped box with an open top, in which a water bag containing water in a water-impermeable and easily tearable bag, and a heating agent bag containing a heating agent that generates heat upon contact with water in a bag-shaped container, are stacked from top to bottom on a support plate with an opening interposed between the bags, and are fixed to the support plate. Furthermore, one end is fixed to the support plate, and the other end is wrapped around the front and back of both the upper and lower surfaces of the water bag and the front and back of both the upper and lower surfaces of the heating agent bag, and a string for tearing the water bag and heating agent bag is attached, which is pulled out from the front of the box. A heating and thawing container, wherein, with the lid removed and water contained in the water-holding space of the inner tray, the tearing string is pulled from the outside, causing the water bag and the heating agent bag to tear open, the water in the water bag and the heating agent to chemically react and generate heat, and the water in the water-holding space of the inner tray is heated, thereby heating and thawing the frozen food placed on the upper tray.

2. The heating and thawing container according to claim 1, wherein the water in the water bag contains an antifreeze agent, and the heating and thawing container is capable of storing and transporting the frozen food with the frozen food placed on the upper tray under freezing conditions.

3. The frozen food is frozen sushi having a rice portion and a topping portion, and the rice portion of the frozen sushi is positioned below the topping portion and in contact with the bottom surface of the upper plate. The heating and thawing container according to claim 1, wherein the bottom surface of the upper plate has a groove formed thereon to prevent rice from sticking to the bottom surface of the upper plate when the frozen sushi is heated and thawed.

4. The heating and thawing container according to claim 1, wherein no holes for steam to pass through are formed on the bottom surface of the upper tray.

5. A method for thawing frozen food according to claims 1 to 4, using a heating and thawing container, The steps include removing the lid and pouring a predetermined amount of water into the water storage space of the inner tray, The process involves pulling the tearing string from the outside to tear open the water bag and the heating agent bag, and causing a chemical reaction between the water in the water bag and the heating agent to heat the water in the water storage space of the inner tray, A step of heating and thawing the frozen food contained in the upper tray by heating the water in the aforementioned storage space. Includes, The heating and thawing step is performed with the lid removed, in a heating and thawing method.

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