JP3656775B2 - Methods for freezing, storing and thawing food - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION
The present invention relates to a method for freezing / preserving and thawing foods that are a combination of cooked rice and one or more other foods, the quality at the time of adjustment hardly changing even after long-term storage.
[0002]
[Prior art]
The sales of bento boxes, which are a combination of cooked rice and other foods, are subject to severe fluctuations from day to day and must be manufactured on the day they cannot be stored. It has become a big issue. In addition, the manufacturing time is often in the early morning, which is a big burden.
Therefore, there has been a long-awaited technology for temporarily storing products manufactured on average during the daytime and thawing them as much as necessary.
As regards a single processed food, although it is almost technically solved as can be seen from the fact that many frozen foods are sold, foods that are a combination of cooked rice and other foods are stored frozen in a known manner. Even if it thawed, it was not possible to satisfy the quality.
[0003]
[Summary of the Invention]
[Problems to be solved by the invention]
It is an object of the present invention to provide a method for storing a cooked rice food in which cooked rice and other foods are combined for a long period of time with the quality as prepared or higher.
[0004]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the inventors of the present invention frozen a target food product by spraying liquefied carbon dioxide gas until the center temperature became −15 to −30 ° C., and the atmosphere was −25 ° C. or lower. After carrying out cryopreservation in the above, the present inventors have found that the above problem can be solved by thawing in an atmosphere of about 40 to 60 ° C. for at least a part of the total thawing time, thereby completing the present invention.
That is, this invention consists of the process of freezing, preservation | save, and thawing | decompression of foodstuffs, and the central temperature of the foodstuffs of cooked rice is -15-- A food product characterized by being frozen to 30 ° C., cryopreserved in an atmosphere of −25 ° C. or lower, and then thawed in an atmosphere of about 40 ° C. to 60 ° C. for at least part of the thawing time. Freezing, storage and thawing methods.
In the present invention, a preferred embodiment relating to the thawing step is a method for freezing / preserving foods and thawing, wherein thawing at about 40 to 60 ° C. is performed at a stage where the center temperature of the cooked rice passes the melting temperature of ice crystals. .
In one preferred embodiment of the present invention, the pressed sushi is frozen by spraying liquefied carbon dioxide gas until the center temperature of the cooked rice reaches −15 to −30 ° C., and then frozen and stored in an atmosphere of −25 to −35 ° C. The food is frozen and thawed in a period where the center temperature is about −5 ° C. in an atmosphere of about 40 ° C., and thawed in an atmosphere of 14 to 25 ° C. for other thawing times. Storage and thawing method.
In another preferred embodiment of the present invention, a lunch box with prepared dishes and cooked rice is frozen until the center temperature of the cooked rice reaches −15 to −30 ° C. by spraying liquefied carbon dioxide, and then −25 to − This is a method for freezing / preserving and thawing a food, characterized by carrying out cryopreservation in an atmosphere at 35 ° C. and then thawing in an atmosphere at about 40 to 60 ° C.
[0005]
[Detailed Description of the Invention]
In the method for freezing / preserving and thawing food according to the present invention, the cooked rice food in which the cooked rice and one or more other foods are combined is frozen by spraying liquefied carbon dioxide gas until the center temperature becomes −15 to −30 ° C., As described above, it is characterized by thawing in an atmosphere of about 40 ° C. to 60 ° C. for at least part of the thawing time after cryopreservation in an atmosphere of −25 ° C. or lower. By combining the freezing process, storage process, and thawing process of the conditions, it is possible to store cooked rice foods that combine cooked rice and other foods for a long period of time with the quality as it was prepared or higher. It is.
[0006]
The food that is the subject of the present invention is a cooked rice food that is a combination of cooked rice and one or more other foods. As a preferred specific example, seafood such as mackerel, horse mackerel, and crab are placed on vinegared rice. Typical examples include pressed sushi that has been pressed and cooked rice, a grilled fish, fried egg, fried food, fried rice, tempura, and other dishes. However, the present invention is not particularly limited, and it goes without saying that it can be widely applied as long as it is a combination of cooked rice and one or more other foods such as rolled sushi and rice balls with ingredients.
[0007]
In the present invention, the cooked rice food as described above is first subjected to a freezing step by directly spraying liquefied carbon dioxide gas. At this time, the food is preferably unwrapped so that the liquefied carbon dioxide gas can be directly sprayed. However, if it is difficult to wrap without pressing like sushi, you can wrap it with a thin transparent film for food, and if it is like a bento box lunch, pack the food in a box and then do not cover it. What is necessary is just to take the method of freezing.
Freezing is continued until the center temperature of the food that is most difficult to cool (usually the cooked rice portion) is in the range of -15 to -30 ° C. Even if the temperature condition exceeds the predetermined range or the condition is less than that, it is not preferable because the quality after thawing is deteriorated. If the storage period is about half a year, the food can be stored almost as it is prepared without deterioration in quality. The freezing step may be performed using a normal liquefied carbon dioxide spraying device in a small scale, and can be performed using a tunnel type liquefied carbon dioxide spraying device or the like at a large scale level.
[0008]
After reaching the predetermined freezing temperature condition as described above, the cooked rice food is transferred to a storage process and stored for a necessary period until it is used for the next thawing process. Storage is performed at -25 ° C or lower, preferably in the range of -25 to -35 ° C. In this preservation | save process, since the quality after thawing | decompression will fall when it exceeds the said predetermined temperature range, it is unpreferable. In addition, this preservation | save process can be performed using a normal food freezer.
[0009]
The frozen rice food is stored in the final thawing process. The thawing step includes a thawing process performed in an atmosphere of about 40 ° C. to 60 ° C. (specifically, 38 ° C. to 62 ° C.) for at least a part of the total thawing time. That is, in the thawing step, thawing under this specific temperature range condition is essential, and other thawing temperature conditions may be used in combination as necessary. Specifically, it is not necessary to perform the entire thawing process in the above-mentioned specific temperature range, and in the specific stage, the center temperature of the food that is most difficult to warm passes the melting temperature of ice crystals (generally around −5 ° C.). When thawing, it is indispensable to perform thawing (rapid thawing treatment) within the range of melting time of ice crystals at a temperature of about 40 ° C. to 60 ° C., but at other times, the lower limit is set as necessary. The thawing may be performed gently at a temperature lower than about 40 ° C. (specifically, 38 ° C.).
Therefore, in the thawing process according to the present invention, depending on the type or nature of the food, the combination of the rapid thawing under the specific temperature condition and the slow thawing under the lower temperature condition is preferable, or only the rapid thawing. It may be able to thaw efficiently. For example, at the melting temperature of ice crystals (around -5 ° C), there is almost no change in the product temperature with only a change in state. In the case of cooked rice foods that require freshness using raw fish, such as pressed sushi In order to maintain the quality of raw fish, it is rapidly thawed at about 40 ° C. (specifically 38 to 42 ° C.) when the center temperature is around −5 ° C., and 14 to 25 ° C. when the center temperature is otherwise. It is desirable to thaw slowly at about 20 ° C. (specifically, 18 to 22 ° C.). The rapid thawing time is a time within the range of the melting time of ice crystals, and this time varies depending on the amount of cooked rice food, etc., but is specifically about 20 to 60 minutes, for example. In addition, cooked rice food such as a bento lunchbox that does not use raw fish can be quickly thawed only at a temperature of about 40 to 60 ° C. during the entire thawing time or process.
In the thawing step, a normal thermostatic device that can be set to a constant temperature can be used, but natural thawing during storage at room temperature or transportation at room temperature is also used for thawing in the present invention depending on the desired temperature conditions. It is included.
[0010]
The food finally thawed through the frozen storage step by the method of the present invention as described above, as shown in the examples below, that the quality of all foods, including cooked rice, can be maintained as prepared. I understood. Moreover, regarding the pressed sushi, a panelist result was obtained that the taste was improved when the frozen storage and thawing treatment was performed according to the method of the present invention compared to the one immediately after the preparation.
[0011]
【Example】
The following examples further illustrate the present invention.
[Example 1]
A pressed sushi roll (a rectangle with a long side of 5 cm and a short side of 3 cm × a length of 25 cm) manufactured by a normal method was wrapped with a transparent film for food and then frozen by spraying liquefied carbon dioxide. The temperature change at the center of the sushi rice at that time is shown in FIG.
Then, after wrapping with bamboo skin and packaging with a pillow packaging machine, it was transferred to a −30 ° C. freezer and stored as it was.
One week later, the product was taken out from the freezer, heated for 180 minutes in a constant temperature chamber at 20 ° C. until the center temperature reached about −5 ° C., and then heated at 40 ° C. for 40 minutes. After that, it was again defrosted by heating at 20 ° C. The temperature change at that time is shown in FIG.
[0012]
[Comparative Example 1-1]
The freezing method was performed in the same manner as in Example 1 except that a method of putting in a -60 ° C air blast type freezer instead of spraying liquefied carbon dioxide was used. In this case, the internal temperature was almost the same as when liquefied carbon dioxide was sprayed, but the freezing time was long.
[0013]
[Comparative Example 1-2]
The freezing method was performed in the same manner as in Example 1 except that a method of putting in a -25 ° C. air blast type freezer instead of blowing liquefied carbon dioxide was used. In this case, the freezing time was longer than 1-1.
[0014]
[Comparative Example 1-3]
The thawing method was performed in the same manner as in Example 1 except that the center temperature was about −5 ° C. and the inside temperature was 65 ° C. for 40 minutes.
[0015]
[Comparative Example 1-4]
The preservation method was performed in the same manner as in Example 1 except that a freezer having an internal temperature of 0 to -5 ° C was used.
[0016]
[Comparative Example 1-5]
The preservation method was performed in the same manner as in Example 1 except that a freezer having an internal temperature of about −20 ° C. was used.
[0017]
[Evaluation Example 1]
About the pressed sushi of Example 1 and Comparative Examples 1-1 to 5 and those not cryopreserved, the taste was evaluated by seven skilled panelists.
As a result, compared with the thing which is not cryopreserved, 5 people replied that the food of Example 1 was good in taste, and 2 replied that there was no difference, whereas Comparative Example 1-1. About 6 people, all 7 people recognized the drip from the strawberry, and especially 1-2 about the aging of sushi rice. As for Comparative Example 1-3, five panelists pointed out discoloration of cocoons, and responded that the taste was impaired.
Moreover, the reply that the taste of Example 1 was mellow was obtained from four people.
Regarding Comparative Example 1-4, all pointed out that the sushi rice was hard and aged, and both 1-4 and 1-5 responded that the vinegar taste of the sushi rice became weak and the taste changed. It was.
[0018]
[Example 2]
A box lunch box (vertical 17 cm × width 25 cm × thickness 3.5 cm) manufactured by a normal method was packed in a box, and then frozen by blowing liquefied carbon dioxide gas without a top cover. The temperature change at the center of the white rice at that time is shown in FIG. Thereafter, the upper lid of the transparent film was covered so as to cover the upper surface of the lunch box, transferred to a −30 ° C. freezer, and stored as it was.
After one week, it was taken out from the freezer and heated for 100 minutes in a thermostatic chamber with an internal temperature of 60 ° C. The temperature change at the center of the white rice at that time is shown in FIG.
The inner lunch box consists of white rice and grilled salmon, fried chicken, egg roasted, kamaboko, shrimp tempura, university salmon, marinade, cherry pickles, boiled beans, plum dried, pineapple or cherry canned food.
[0019]
[Evaluation Example 2]
About Example 2 and the inner lunch box of the curtain which is not cryopreserved, the taste was evaluated by seven skilled panelists.
As a result, as for the thing of Example 2, compared with what was not cryopreserved, 3 persons answered that the taste was good, and 4 persons answered that there was no difference.
According to the panelists' individual responses, grilled salmon and fried chicken have no difference in the texture of the meat and are not preserved at all, the eggs are plump, the marinade, pickles, plum dried, crisp crunchy pineapple Things were obtained. The tempura was preserved with the clothes in a dry state.
[0020]
【The invention's effect】
As described above, according to the method of the present invention, by combining the freezing step, the storage step, and the thawing step of specific conditions, the cooked rice food in which the cooked rice and other food are combined can be obtained with the quality as it is at the time of adjustment. With the above quality, it can be stored for a long time.
[Brief description of the drawings]
FIG. 1 is a graph showing changes in temperature at the center of sushi rice due to freezing treatment of pressed sushi (Example 1).
FIG. 2 is a graph showing a temperature change at the center of sushi rice by the thawing process in Example 1;
FIG. 3 is a graph showing a temperature change in the central portion of white rice by the freezing process of the inner lunch box of the curtain (Example 2).
4 is a graph showing the temperature change in the center of white rice by the thawing process in Example 2. FIG.

Claims (3)

  It consists of a process of freezing / preserving food and thawing, and the cooked rice food, which is a combination of cooked rice and one or more other foods, is frozen by spraying liquefied carbon dioxide gas until the center temperature becomes −15 to −30 ° C., − Frozen food under freezing in an atmosphere of 38 ° C. to 62 ° C. after being frozen and stored in an atmosphere of 25 ° C. or lower and then at a stage where the central temperature of the cooked rice passes the melting temperature of ice crystals Storage and decompression methods.   The frozen sushi was frozen by spraying liquefied carbon dioxide gas until the center temperature became -15 to -30 ° C, and then cryopreserved in an atmosphere of -25 to -35 ° C, and then the center temperature was -5 ° C. The method for freezing / preserving and thawing food according to claim 1, wherein the food is rapidly thawed in an atmosphere of 38 ° C to 42 ° C for a period of time, and thawed in an atmosphere of 14 to 25 ° C for other thawing times.   The lunch box with side dishes and cooked rice was frozen until the center temperature of the cooked rice reached −15 to −30 ° C. by spraying liquefied carbon dioxide gas, and then cryopreserved under an atmosphere of −25 to −35 ° C. The method for freezing / preserving and thawing food according to claim 1, wherein the food is thawed in an atmosphere of 38 ° C to 62 ° C.

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