JP3180064B2 - How to defrost food - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Background of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for thawing food, wherein the quality at the time of preparation hardly changes even when thawing after freezing.

[0002]

2. Description of the Related Art Techniques of freezing foods for long-term storage and thawing and ingesting the foods for use have long been used. However, when the conventional technology is used, it is unavoidable that the quality has deteriorated when compared with the food before storage by freezing and defrosting the food. Therefore, various techniques have been proposed for the purpose of preventing the deterioration. Most of these technologies are described in Table 9-
Although it relates to a device in the step of freezing a food as disclosed in Japanese Patent No. 500542, the effect of preventing a sufficiently satisfactory quality deterioration has not been obtained by itself.

[Summary of the Invention]

DISCLOSURE OF THE INVENTION The present invention provides foods after frozen, in the same quality as they were when they were prepared or in a higher quality, and in particular, various kinds of foods which originally have different thawing conditions under the same conditions. It is an object of the present invention to provide a decompression method capable of processing a large number.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems, and as a result, after freezing a food, a suitable air layer has been secured around the food, and the food has been packaged in a substantially sealed state. Heating at a temperature of about 40 ° C. or more in a warm air atmosphere for at least a part of the total thawing time to increase the temperature, and then rapidly lowering the temperature of the hot air so that the surface of the food does not exceed 25 ° C. and thawing. As a result, the inventors have found that the above problem can be solved, and have completed the present invention. That is, the present invention relates to a method for thawing food, wherein the food is heated with warm air of about 40 ° C. or more for at least a part of the thawing time in a state where the food is frozen and packaged in a substantially sealed state with a space around the food. The temperature of the hot air is rapidly lowered so that the surface of the food does not exceed 25 ° C., and then thawed. A preferred embodiment of each condition in the present invention is that the volume of the space is 5% or more of the volume of the food, the packaging is a pillow package, and the thawing condition is that the thawing at a temperature of about 40 ° C. or more is performed. Is performed at a stage where the center temperature passes through the melting temperature of the ice crystal. One preferred embodiment of the present invention is that at about 40 ° C for at least a portion of the thawing time.
In the step of heating with the above warm air, the frozen food,
After heating with low-temperature air of 14 to 25 ° C, heating with high-temperature air of about 40 to 60 ° C.

DETAILED DESCRIPTION OF THE INVENTION In a method for thawing food according to the present invention, the food is frozen at about 40 ° C. or more for at least a part of the thawing time in a state where a space is secured around the food after freezing and the package is substantially sealed. The temperature is raised by heating with hot air, and then the temperature of the hot air is rapidly lowered so that the surface of the food does not exceed 25 ° C. and then thawed. By the way, in particular, the food is prepared at the time of preparation by combining the packaging which is almost sealed, which secures a space around the food, the warm air for maintaining the uniform temperature and the maintenance of a certain temperature or less (25 ° C or less) on the food surface. It is possible to provide a thawing method suitable for the purpose of providing various types of foods with different thawing conditions under the same thawing conditions, while providing the same quality or higher quality. .

The foods to be used in the present invention are cooked rice, one or more other foods, and cooked rice foods in which cooked rice is combined with one or more other foods. Or a combination of two or more of them can be subjected to thawing treatment. Preferable specific examples of other foods include prepared foods such as grilled fish, fried egg, fried, and tempura. Preferable examples of cooked rice foods include a boxed lunch box of a curtain combining one or more of the above prepared dishes and cooked rice, and a press formed by placing seafood such as mackerel, aji, crab on vinegared rice and pressing. Sushi is a typical example. However, the present invention is not particularly limited, and it goes without saying that the present invention is widely applicable as long as it is a combination of rice and at least one other food, such as rolled sushi and rice balls.

[0007] In the present invention, the above-mentioned food is first subjected to a freezing step. In this case, the cooked rice, one or more other foods, and the cooked rice foods can be subjected to the same freezing step alone or in combination of two or more. The freezing condition of the food is not particularly limited as long as the food is frozen. Freezing by a normal freezer, spraying of liquefied carbon dioxide, or air blast type multiple (normally two).
Freezing by a refrigerant compressor freezer (−45 to −75 ° C.) is possible. In the freezing process, the food may be unwrapped or wrapped in a thin transparent film for food, but in the case of no packaging, the method using liquefied carbon dioxide is suitable, and the food is tightly wrapped and packed. In this case, an air blast type freezer is also possible. Freezing is usually continued until the central temperature of the food falls in the range of -15 to -30C, preferably -20C or lower. In addition, the freezing step by spraying liquefied carbon dioxide gas may be performed using a normal liquefied carbon dioxide gas spraying device in a small scale, and can be performed using a tunnel type liquefied carbon dioxide gas spraying device or the like in a large scale. .

[0008] After reaching the above-mentioned predetermined freezing temperature condition, the food is usually transferred to a preservation step, and stored for a necessary period until it is used for the next thawing step. Storage is performed at -25 ° C or lower, preferably in the range of -25 to -35 ° C. In this preservation step, if the temperature exceeds the above-mentioned predetermined temperature range, the quality after thawing deteriorates, which is not preferable. This storage step can be performed using a normal food freezer.

In the present invention, the frozen food is subjected to a packaging step before the storage step or before the next freezing step, preferably before the storage step. The packaging of the frozen food is carried out in a space between the outer surface of the food and the surrounding space, usually 5% or more of the food volume, preferably 5%.
% To 200%, more preferably 30% to 100%, and is packaged in a substantially sealed manner. This closed space provided around the food by packaging is to prevent the food from directly touching the thawed environment in the next thawing process, and is usually wrapped in the surrounding environment and contains an air space, It may be packaged in another ambient environment such as in N ₂ gas and include the gas layer.

As the packaging material, a packaging material ordinarily used for hermetic packaging can be used, and examples thereof include a plastic film such as polypropylene and polyethylene, a laminated paper of paper and plastic, and the like. preferable. The sealing of the packaging material can be performed by a usual method such as heat fusion, high frequency adhesion, adhesion with an adhesive or the like according to the properties of each material. Depending on the packaging material, it may be sealed by bending, twisting, or the like without performing sealing. As a specific example of the substantially sealed packaging having a closed space around the food, bag-like packaging (for example, pillow packaging, three-side seal packaging, four-side seal packaging, bag-making, etc.) Packaging using finished bags), box-shaped packaging, packaging with a combination of trays and lids, wrap packaging (if the food is in a container with adequate strength and heat insulation comparable to the packaging material), Shrink packaging and the like can be used. Among them, pillow packaging is preferred mainly from the viewpoint of operability, sealing property and the like. Specifically, one or a plurality of foods are set in a packaging material, and the hermetically sealed packaging is carried out under a normal ambient environment or an N ₂ gas environment so that an appropriate space is secured around the foods. If necessary, the food in the package may be in a state of being contained in an open container made of plastic (such as styrene foam). In the present invention, the substantially hermetically sealed package means a package having such a degree of hermeticity that the effect of the present invention (mild heat conduction to food) can be exhibited by the hot air heating treatment in the next thawing step, Specifically, for example, a state in which there is substantially no circulation with the outside air environment while maintaining the predetermined surrounding space in a warm air atmosphere in the next thawing step (flow rate 50
(% By volume or less), and any type of packaging material may be used as long as it satisfies this condition, and it is desirable that the sealing property is also perfect, but it may be incomplete.

[0011] The food packaged as described above is transferred to a final thawing step, which has the greatest feature of the present invention. The thawing step is at least about 40 ° C., for example, about 40 ° C. to 80 ° C., preferably about 40 ° C. to 60 ° C. (specifically, 38 ° C. to 62 ° C.) warm air for at least a part of the total thawing time. This includes an operation of performing a heat treatment in an atmosphere, and a subsequent thawing treatment by an operation of rapidly lowering the temperature of hot air so that the surface of the food does not exceed 25 ° C. That is, in the thawing step, thawing under these specific temperature range conditions and in a warm air atmosphere is essential, and other thawing temperature conditions may be used in combination as needed. Specifically, it is not necessary to carry out the entire thawing process in the above-mentioned specific temperature range, and in a specific stage, preferably, the center temperature of the food which is hardly warmed passes the melting temperature of ice crystals (generally around -5 ° C). When performing, about 40 ℃ or more, usually about 40 ℃ ~ 80
It is essential to perform thawing (rapid thawing treatment) within the range of the melting time of the ice crystals at a temperature of 0 ° C. (preferably about 40 ° C. to 60 ° C.). Gently at temperatures below about 40 ° C. (specifically 38 ° C.).

In a preferred embodiment of the present invention, at the melting temperature of the ice crystal (around -5 ° C.), only a change in the state is observed, and almost no change in the product temperature is observed. Slowly thaw at 25 ° C, more preferably about 20 ° C (specifically 18-22 ° C), and about 40 ° C (specifically 38-42 ° C) when the center temperature is around -5 ° C.
It is desirable to defrost rapidly at or above C). According to such a method of the present invention, cooked rice food (for example, pressed sushi) using fresh fish or the like that requires freshness can be simultaneously defrosted under the same defrosting conditions as other various foods. After the rapid thawing, the operation of rapidly reducing the hot air temperature to maintain the food surface temperature at 25 ° C. or lower (preferably 18 ° C.) or less is actually about 15 to 20 ° C., preferably about 18 ° C. Switch to low-temperature air. The thawing step is performed with warm air of about 40 ° C. or more for at least a part of the entire thawing time as described above,
Thereafter, the surface temperature is basically adjusted so that the temperature of the food is raised so that the surface of the food does not exceed 25.degree.

In the present invention, in order to carry out the thawing process under the warm air atmosphere as described above, any suitable constant temperature device, that is, a temperature which can be set to a constant temperature and varies depending on the location in the device. A constant-temperature device equipped with a hot air blower for eliminating (keeping a uniform temperature) can be used. Further, in the present invention, since it is suitable for simultaneously defrosting a large number of foods, the thermostatic apparatus may have a structure in which a large amount of foods can be installed and the hot air can be uniformly sent to the entire inside of the apparatus. desirable.

As a constant temperature apparatus having the above-mentioned functions, specifically, for example, a defroster (A) for mass processing as shown in FIG. 3 can be used. This thawing room (A)
A multi-stage movable shelf (3) equipped with a fan (1) that can be adjusted to a constant temperature and can uniformly send hot air into the refrigerator, and in which a large number of frozen foods (2) can be placed. Can be put in and out multiple times. The fan (1) circulates warm air through the space between the food rows on the tray (4) of each stage of the shelf (3), and sends uniform warm air to the whole food (2) in the refrigerator. It is supposed to be. Each frozen food (2) is packed with packaging material (5) as shown in FIG.
Thus, it is hermetically sealed in a state where a certain surrounding space (6) composed of an air layer is secured, and is arranged on the tray (4) of each stage of the plurality of movable shelves (3) (FIG. 2). The tray preferably has a structure through which warm air can be easily transmitted. For example, a plastic net-shaped tray is a preferred example. The moving shelves (3) in which the foods (2) are arranged as described above are moved and arranged in the thawing cabinet (A) as shown in FIG. ), The uniform hot air is continuously sent, so that the gentle heat conduction through the surrounding space (the bottom part is due to the gentle heat conduction through the packaging material and the tray part), the surface temperature of the food and the core temperature Thawing can be performed with little difference from the food.

According to the thawing method of the present invention as described above, it has been found that various foods can be simultaneously thawed in a large quantity with the quality as prepared at the same time, as shown in Examples described later.

[0016]

The following examples illustrate the present invention in more detail. [Example 1] A plastic container (17 cm long x 25 cm wide x 3.5 cm thick) used as an inner box of a lunch box
Rice and prepared dishes, frozen without lids (-50 ° C with a liquefied carbon dioxide combined compression refrigerator)
(Thickness: 0 μm). At this time, as shown in FIG. 1, the inside of the pillow package was sealed by heat fusion in an air-containing state (air content = about 100% of the total volume of the food) such that there was a distance between the inner box of the lunch box and the film. After pillow packaging, those stored at −25 ° C. or lower are arranged on a plastic mesh tray, as shown in FIG. I put it in a wind thawing room. After starting thawing, circulate warm air of about 20 ° C for about 2 hours and heat until the central temperature of the lunch box becomes about -5 ° C.
For 40 minutes. Thereafter, the temperature in the refrigerator was lowered to 18 ° C. in 20 minutes so that the temperature of the lunch box did not exceed 18 ° C., and the thawing was performed.

[Evaluation Example 1] Nine panelists evaluated the taste of Example 1 and the inner lunch box of a curtain that was not frozen by nine panelists. As a result, 9 persons in Example 1 answered that there was no difference compared to those not frozen and thawed. Rather, the inner lunch box of a curtain that has not been frozen and thawed, which is several hours after production, rather than immediately after thawing, Example 1
The inside lunch box of the curtain was evaluated as having a good taste.

Comparative Example 1 An inner lunch box of a frozen curtain was thawed in the same manner as in Example 1 without pillow packaging. In this case, the surface of both the cooked rice and the prepared food was dried, and the original quality of both taste and texture was impaired. In addition, since the surface temperature of the food was about 30 ° C., which was higher than the appropriate temperature for storage at room temperature, there was a concern about deterioration of quality due to propagation of bacteria.

[Comparative Example 2] An inner lunch box of a frozen curtain was wrapped with the inside of the pillow package in a degassed state, and thawed as in Example 1. The part near the outlet of the hot air thawed faster than the other parts, resulting in uneven thawing with other parts.

[0020]

As described above, according to the method of the present invention, a plurality of foods such as raw fish, cooked rice, cooked prepared foods, etc. are prepared by a combination of the closed space provided in the foods and the thawing process under specific conditions. It is possible to defrost a large amount at a time in the same defroster with the quality as it is or better. Further, according to the present invention, the following effects are specifically obtained. In a series of freezing and thawing systems, providing a closed space around the packaging material and the food can greatly improve quality degradation. This space transmits the warm air heat mildly, so that the influence of drying and dew condensation due to the temperature rise and fall of the external environment is small, and therefore, the difference between the surface temperature of the food and the core temperature is small, and drip can be prevented. Foods that were conventionally handled as products such as lunch boxes can be handled in the same way as frozen materials, so even if the shipment volume is large, even if they are made in large quantities, there is no danger such as bacterial proliferation Food can be provided. In this case, the effect is further enhanced by freezing the food immediately after production (preferably continuous freezing). Since it is stored in a substantially hermetically sealed package, contamination during storage can be prevented.
By packing in an atmosphere close to the saturation humidity at the temperature at the time of unpacking (usually room temperature), the effect of preventing drying of the food is enhanced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state of a pillow package of food in Example 1.

FIG. 2 is a perspective view showing an arrangement state of an inner lunch box (pillow wrapping) on a shelf in the first embodiment.

FIG. 3 is a front view showing an arrangement state of an inner lunch box (arranged on a shelf) of the curtain in the thawing chamber in the first embodiment.

[Explanation of symbols]

 A Thaw storage 1 Fan 2 Food 3 Shelf 4 Tray 5 Packaging material 6 Space around food

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takaaki Nakamura 1-1-25 Shinurashima-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Within Kirin Engineering Co., Ltd. (72) Inventor Seishi Kasutani Shinura, Yokohama-shi, Kanagawa 1-1-25 Shimamachi Kirin Engineering Co., Ltd. (72) Inventor Mikiyuki Kano 1-1-25 Shinurashimacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Kirin Engineering Co., Ltd. (56) References JP-A-8-126465 ( JP, A) JP-A-5-336878 (JP, A) JP-A-9-252755 (JP, A) JP-A-5-284920 (JP, A) JP-A-56-131172 (JP, A) Sho-59-33342 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) A23L 3/36-3/54 A23L 1/10-1/105 A23B 4/00-5/22 B65D 67/00-79/02 B65D 81/18-81/3 0 B65D 81/38

Claims (6)

(57) [Claims] 1. A method for thawing food, wherein when thawing a substantially hermetically packaged food while securing a space around the food after freezing, the food is heated with hot air at a surface temperature not exceeding 25 ° C. When the temperature of the food exceeds the melting temperature of the ice crystals, the temperature is increased by heating at a temperature of about 40 ° C. or more, and then the temperature of the hot air is maintained so that the surface of the food does not exceed 25 ° C. A method for thawing food, characterized by rapidly lowering and thawing. 2. The thawing method according to claim 1, wherein the frozen food is heated with a low-temperature air of 14 to 25 ° C. and then heated with a high-temperature air of about 40 to 60 ° C. to raise the temperature. 3. The thawing method according to claim 1, wherein the volume of the space is at least 5% of the volume of the food. 4. The food packaging according to claim 1, wherein the packaging is a pillow packaging.
4. The thawing method according to any one of claims 1 to 3. 5. The thawing method according to claim 1, which is used for thawing a large number or variety of foods. 6. The thawing method according to claim 1, wherein the food is a food selected from cooked rice, one or more other foods, and a cooked rice food in which both are combined.