JP7292867B2 - Food freeze aging method and cooling device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a food freeze-ripening method and a cooling device.

Conventionally, foods such as beef are known to be aged for the purpose of increasing flavor and umami. Dry aging methods and wet aging methods are available as methods for aging foods. In both aging methods, food is often held at a temperature above the freezing point for a predetermined period of time. Adopting such an aging method accelerates the ripening of the food.
Here, ripening means chemically reacting food, for example, increasing the content of amino acids in food. Amino acids are components that constitute proteins, and an increase in amino acids enhances the flavor and umami of foods.

JP 2016-112014 A

However, if the food is held at a temperature above the freezing point for a predetermined period of time as in the above-described prior art, although this is advantageous in terms of promoting ripening, the number of microorganisms in the food also increases. An increase in microorganisms shortens the shelf life of food.
On the other hand, when trying to extend the shelf life of food by suppressing the increase of microorganisms, it is necessary to sufficiently freeze the food. When food is frozen, aging does not proceed, and it is difficult to increase the flavor and umami of the food.
Thus, there is a trade-off between increasing the flavor and umami of food and extending the shelf life of food.

SUMMARY OF THE INVENTION Accordingly, the present invention provides a food freeze aging method and a cooling device capable of increasing the flavor and umami of food and extending the expiration date of the food.

In order to solve the above problems, the method for freezing and ripening food according to the present invention cools the food material in a temperature range lower than the freezing point of the food material and 8 ° C. lower than the freezing point. a cooling step, a holding step of holding the food material in the temperature range of the cooling step for a period of at least 7 days, and a temperature lower than the temperature of the cooling step by at least 5° C. for at least 4 days. and a preliminary step of cooling for a period of six months, and the cooling step is performed after the preliminary step .

By adopting such a method, the food can be aged, and the flavor and umami of the food can be increased. Moreover, since the food is held at a temperature lower than the freezing point, it is possible to suppress the increase of microorganisms in the food. Therefore, the expiration date of the food can be extended.
In addition, it becomes possible to further promote aging of the food in the cooling process.

A cooling device according to the present invention is a cooling device for performing the above freezing and ripening method for food, comprising: a cooling chamber for storing the food material and cooling the food material; and a control unit that controls the cooling chamber during the period.

By configuring in this way, the food can be appropriately subjected to the cooling process and the preparatory process.

ADVANTAGE OF THE INVENTION According to this invention, while being able to increase the flavor and umami of food, the expiration date of food can be extended.

1 is a schematic configuration diagram of a cooling device according to an embodiment of the present invention; FIG. 1 is a flow chart of a freeze ripening method according to an embodiment of the present invention; 4 is a graph showing changes in the temperature of salmon and the temperature in the cooling chamber in an embodiment of the present invention; BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram for explaining the mechanism of freeze concentration in an embodiment of the present invention, and (a) to (c) respectively show states of food materials. Graph showing the change in amino acid increase ratio when the temperature of salmon in the preliminary step in the embodiment of the present invention is −60° C. FIG. Graph showing the change in amino acid increase ratio when the temperature of salmon in the preliminary step in the embodiment of the present invention is -10°C. A graph showing changes in the general viable count in the embodiment of the present invention, comparing the case where the preliminary step is set to -60 ° C. and the case where the preliminary step is set to -10 ° C. FIG. The graph which shows the change of the increase ratio of the amino acid in embodiment of this invention. The graph which shows the change of the increase ratio of the amino acid in embodiment of this invention. The schematic block diagram of the cooling device in the modification of embodiment of this invention.

Next, embodiments of the present invention will be described based on the drawings.

(Cooling system)
FIG. 1 is a schematic configuration diagram of a cooling device 1. As shown in FIG.
As shown in FIG. 1, the cooling device 1 includes a cooling chamber 2 for storing food materials F and cooling the food materials F; 3 and .
The cooling chamber 2 is configured to be able to block outside air temperature. The cooling chamber 2 also includes a refrigerating device 4 . The refrigerating device 4 is a device that cools the interior of the cooling chamber 2 . The refrigerating device 4 includes, for example, a compressor, a condenser, an evaporator (none of which are shown), and the like. By arranging at least an evaporator in the cooling chamber 2, the inside of the cooling chamber 2 can be cooled. Note that the refrigerating device 4 is not limited to being composed of the compressor, condenser, evaporator, etc., and may be composed of, for example, a thermoelectric element (Peltier element).

The control unit 3 includes, for example, a processor such as a CPU, a ROM ((Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and an ECU (Electronic Control Unit) including an electronic circuit such as a timer. In addition, the control unit 3 includes a temperature detection unit 5 that detects the temperature in the cooling chamber 2. The control unit 3 detects the temperature in the cooling chamber 2 based on the detection result of the temperature detection unit 5 and the count signal of the timer. , control the temperature in the cooling chamber 2 and control the execution period of this temperature control.

(Method for freezing and maturing food materials)
Next, based on FIGS. 1 to 9, a freeze ripening method for the food material F using the cooling device 1 (hereinafter simply referred to as freeze ripening method) will be described in detail.
FIG. 2 is a flow chart of the freeze ripening method.
As shown in FIGS. 1 and 2, the freeze-ripening method includes a preliminary step S1 of storing the food material F in the cooling chamber 2 and cooling the food material F at a predetermined temperature; It has a cooling step S2 of cooling at a temperature higher than that of step S1, and a holding step S3 of holding the food material F at the temperature of this cooling step S2 for at least seven days.

First, the cooling step S2 will be described in detail.
In the cooling step S2, the food material S2 is cooled to a temperature lower than the freezing point of the food material F and 8°C lower than the freezing point. Here, the food material F contains not a little water. The freezing point is the point at which the water content changes from liquid to solid and the food material F appears to freeze. This freezing point will be explained more specifically by citing salmon as an example of the food material F.

FIG. 3 is a graph showing changes in the temperature of the salmon and the temperature in the cooling chamber 2 when the vertical axis is the temperature [° C.] and the horizontal axis is the cooling time T. As shown in FIG. Note that the salmon shown in FIG. 3 is a part of fillet, and the temperature change varies depending on the size of the salmon and the like. Also, in FIG. 3, the temperatures of two salmon are shown as the temperature of salmon "1" and the temperature of salmon "2" in order to average the temperatures of the salmon.

As shown in FIG. 3, as the temperature inside the cooling chamber 2 is lowered, the temperature of the salmon is also lowered. At this time, the water in the salmon is liquid at the start of cooling, and the sensible heat of the salmon decreases without changing its state (state 1 in FIG. 3). Subsequently, the water content in the salmon changes from liquid to solid (ice). Here, the latent heat of salmon changes. At the initial stage when the latent heat changes, the water in the salmon is in a state where liquid and solid are mixed (state 2 in FIG. 3). After this, the moisture inside the salmon is completely solidified (state 3 in FIG. 3). Once the moisture has completely solidified, the salmon will appear frozen. When the salmon freezes and the latent heat changes completely, the sensible heat begins to drop again. Here, the freezing point refers to the time point when the water in the salmon has completely solidified, that is, the boundary point between state 2 and state 3 in FIG. In Figure 3, the freezing point of salmon is -1.4°C.

Therefore, in the case of the salmon, the temperature range H in the cooling step S2 is
-1.4°C < H ≤ -9.4°C (1)
is a range that satisfies In the cooling step S2, the salmon (food material F) is cooled within the temperature range that satisfies the above formula (1).

Here, the freezing point of the food material F is below the freezing point, and the temperature of the food material F itself is minus temperature. At minus temperature, the microorganisms in the food material F do not propagate, so the increase of the microorganisms is suppressed.
On the other hand, when the temperature of the food material F is lower than the freezing point and 8° C. lower than the freezing point, the non-solidifying component (non-freezing component) of the food material F undergoes a chemical reaction. . That is, the protein contained in the food material F, for example, is not solidified (freezes) and the chemical reaction proceeds.
Therefore, in the holding step S3, the state of the cooling step S2 is held for at least seven days. As a result, for example, amino acids in the food material F are increased, and aging (chemical reaction) of the food material F is promoted.

Next, the preliminary step S1 will be described.
In the preliminary step S1, the food material F is cooled for a predetermined period at a temperature lower than that in the cooling step S2 by 5°C or more. By performing the preliminary step S1, the food material F is freeze-concentrated. The freeze-concentration of the food material F promotes maturation in the subsequent cooling step S2.
Here, freeze concentration means to concentrate the desired ingredients by solidifying water in the food material F (making it into ice) and removing the solidified ice. The mechanism of freeze concentration is specifically shown below.

FIG. 4 is a schematic diagram for explaining the mechanism of freeze concentration, and (a) to (c) show the state of the food material F, respectively.
As shown in FIG. 4(a), the food material F contains a solute Y such as protein. When the food material F is cooled below the freezing point, the water W in the food material F solidifies into ice as shown in FIG. 4(b). Further, ice (moisture W) grows as shown in FIG. 4(c). Then, the solute Y in the food material F is dehydrated and concentrated.
Proteins of solute Y are condensed so that the distance between molecules is reduced while they remain liquid. For this reason, even if the temperature is lowered, the chemical reaction proceeds, and the aging is further accelerated by the concentration.

Next, the results of subjecting salmon to the freeze aging method as an example of the food material F will be described with reference to FIGS. 5 to 7. FIG. 5, 6, 8 and 9 below show the increase ratio of amino acids as an index of the results of the freeze ripening method, and the results of the freeze ripening method will be explained based on this increase ratio.
FIG. 5 is a graph showing the change in amino acid increase ratio when the vertical axis is the amino acid increase ratio and the horizontal axis is the period during which the freeze ripening method is performed. 5, 6, 8 and 9 below show aspartic acid, threonine, serine, asparagine, glutamic acid, glutamine, proline, glycine, alanine and valine as amino acids.

As shown in FIGS. 2 and 5, the temperature of the salmon in the preliminary step S1 was set to −60° C., and the period of the preliminary step S1 was set to 4 months as the freeze-ripening method. After that, the temperature of the salmon was set to -4°C in the cooling step S2. Thereafter, in the holding step S3, the temperature of the salmon (-4°C) in the cooling step S2 was held for one month.
As a result, as shown in FIG. 5, it was confirmed that the increasing ratio of amino acids remained almost unchanged in the preliminary step S1. After that, through the cooling step S2, in the holding step S3, it was confirmed that the amino acid increased rapidly. Specifically, in the holding step S3, it was confirmed that the amount of amino acids in the preparatory step S1 was more than doubled. In addition, in the holding step S3, it was confirmed that the amino acids rapidly increased immediately after starting the holding step S3, and that the amino acids increased sufficiently after about 7 days.

FIG. 6 is a graph showing the change in amino acid increase ratio when the vertical axis is the amino acid increase ratio and the horizontal axis is the period during which the freeze ripening method is performed. FIG. 6 corresponds to FIG. 5 described above.
6 differs from FIG. 5 described above in that the temperature of the salmon in the preliminary step S1 is different. In FIG. 6, the salmon temperature in the preliminary step S1 was -10°C.
As shown in FIG. 6, even when the temperature of the salmon in the preliminary step S1 is -10 ° C., the increase gradient is smaller than the increase ratio than in the case of -60 ° C., but in the holding step S3, the amino acid is A rapid increase was confirmed. Specifically, in the holding step S3, it was confirmed that the amount of amino acids in the preparatory step S1 was more than doubled. In addition, in the holding step S3, it was confirmed that the amino acids rapidly increased immediately after starting the holding step S3, and that the amino acids increased sufficiently after about 7 days.

Next, based on FIG. 7, the breeding state of microorganisms during the period of performing the freeze ripening method will be described.
FIG. 7 is a graph showing changes in the general viable count when the vertical axis is the general viable count [CFU/g] and the horizontal axis is the period during which the freeze ripening method is performed. In FIG. 7, the case where the preliminary step S1 is set at -60°C (-60°C→-4°C) is compared with the case where the preliminary step S1 is set at -10°C (-10°C→-4°C). ing. In addition, in FIG. 7, the period during which the freezing and ripening method is performed on the horizontal axis corresponds to FIG. 5 and FIG. 6 described above.
As shown in FIG. 7, during the period in which the freeze ripening method is performed, the general viable cell count changes in both cases when the preliminary step S1 is set to -60 ° C. and when the preliminary step S1 is set to -10 ° C. was not found.

Here, in order to explain the difference between the case where the above freeze aging method is performed and the case where it is simply frozen without performing the freeze aging method, salmon as the food material F is shown in FIGS. A case of simply freezing will be described.
FIGS. 8 and 9 are graphs showing changes in amino acid increase ratio when the vertical axis is the amino acid increase ratio and the horizontal axis is the period of simple freezing. 8 shows salmon simply frozen to -60.degree. C., and FIG. 9 shows salmon simply frozen to -10.degree. The period during which simple freezing is performed on the horizontal axis corresponds to FIGS. 5 and 6 described above.
As shown in FIGS. 8 and 9, it was confirmed that when salmon was simply frozen, the increase ratio of amino acids hardly changed during the freezing period.

As described above, the above-described freeze-ripening method includes the cooling step S2 of cooling the food material S2 in a temperature range lower than the freezing point of the food material F and 8° C. lower than the freezing point, and the cooling step S2. and a holding step S3 of holding the food material F at a temperature of at least 7 days. Therefore, the food material F can be aged, and the flavor and taste of the food material F can be increased. Moreover, since the food material F is held at a temperature lower than the freezing point, it is possible to suppress the increase of microorganisms in the food material F. Therefore, the expiration date of the food material F can be extended.

Moreover, the freeze-ripening method has a preparatory step S1 as a step preceding the cooling step S2. In the preliminary step S1, the food material F is cooled for a predetermined period at a temperature lower than that in the cooling step S2 by 5°C or more. By performing the preliminary step S1, the food material F is freeze-concentrated. As a result, aging is promoted in the subsequent cooling step S2.

Moreover, the cooling device 1 is used in order to implement such a freeze ripening method. The cooling device 1 includes a cooling chamber 2 that stores food materials F and cools the food materials F, and a control unit 3 that controls the temperature in the cooling chamber 2 and the execution period of this temperature control. . Therefore, the food material F can be subjected to the cooling step S2 and the preliminary step S1 accurately.

(Modified example of cooling device)
Next, a modified example of the cooling device 1 will be described based on FIG. 10 .
FIG. 10 is a schematic configuration diagram of a cooling device 1 in a modified example. In addition, the same code|symbol is attached|subjected to the same aspect as above-mentioned embodiment, and description is abbreviate|omitted.
Here, in the cooling device 1 according to the above-described embodiment, the case where all the three steps of the preliminary step S1, the cooling step S2, and the holding step S3 are performed in one cooling chamber 2 has been described. However, as shown in FIG. 10, the preliminary step S1, the cooling step S2 and the holding step S3 may be performed in separate rooms.

That is, the cooling device 1 in the modification includes two cooling chambers 11 and 12 (first cooling chamber 11 and second cooling chamber 12) instead of the single cooling chamber 2 in the above embodiment. The first cooling chamber 11 and the second cooling chamber 12 are provided with a controller 3, a refrigerator 4, and a temperature detector 5, respectively.
Under such a configuration, first, the food material F is subjected to the preliminary step S1 in the first cooling chamber 11 . Thereafter, the food material F is transferred to the second cooling chamber 12, and the food material F is subjected to the cooling step S2 and the holding step S3 in the second cooling chamber 12.

Therefore, according to the modified example described above, in addition to the same effect as the above-described embodiment, by providing the two cooling chambers 11 and 12, it is possible to efficiently perform the steps S1 to S3. For example, a first cooling chamber 11 in which the temperature of the food material F needs to be lowered to a low temperature and a second cooling chamber 12 in which the temperature of the food material F2 is maintained higher than that of the first cooling chamber 11 are provided. 12 cooling performance can be changed. Therefore, in addition to performing the steps S1 to S3, the cost of the cooling device 1 for realizing the freeze ripening method can be reduced as compared with the above-described embodiment.

It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications of the above-described embodiments within the scope of the present invention.
For example, salmon is used as an example of the food material F in the above freeze aging method. However, the method is not limited to this, and the freeze aging method described above can be applied to various food materials F. Examples of food materials F include salmon, beef, chicken, vegetables, milk, yogurt, cheese, and bread.
When the above freeze aging method is performed with a food material F other than salmon, the freezing point of the food material F is actually investigated, and the cooling step S2 and the holding step S3 are performed at a temperature -3 to -4 ° C lower than the freezing point. I do. In addition, the aging of the food material F is considered to be faster for the food material F with more fat, and slower for vegetables and the like having a moisture content of 90% or more. Also, for bread dough (processed food), etc., after aging only the chemical components in frozen dough, there is also a usage such as raising the temperature to 1 ° C in the sensible zone to raise the yeast and ripening.

Further, in the above-described embodiment, the case where the freeze-ripening method has three steps, the preliminary step S1, the cooling step S2, and the holding step S3, has been described. However, it is not limited to this, and the freeze ripening method may have at least two steps, the cooling step S2 and the holding step S3. By these two steps S2 and S3, the aging of the food material F can be promoted, the flavor and taste of the food material F can be increased, and the expiration date of the food material F can be extended.

Further, in the above-described embodiment, the case where the period of the preparatory step S1 of the freeze-ripening method was set to four months and the period of the holding step S3 was set to one month was described as an example. However, the period of the preliminary step S<b>1 is not limited to this, and can be changed according to the cooling performance of the cooling device 1 . The period of the holding step S<b>3 may also be at least seven days, and the period of the holding step S<b>3 can be controlled according to the cooling performance of the cooling device 1 .

REFERENCE SIGNS LIST 1 cooling device 2 cooling chamber 3 control unit 5 temperature detection unit 11 first cooling chamber 12 second cooling chamber F food material S1 preliminary step S2 cooling step S3: Holding step

Claims (2)

a cooling step of cooling the food material in a temperature range lower than the freezing point of the food material and 8° C. lower than the freezing point;
a holding step of holding the food material in the temperature range of the cooling step for a period of at least 7 days;
a preliminary step of cooling the food material for a period of at least 4 months at a temperature that is 5°C or more lower than the temperature in the cooling step;
has
After the preliminary step, the cooling step is performed.
A method for freezing and aging a food, characterized by: A cooling device for performing the method for freezing and ripening food according to claim 1,
a cooling chamber that stores the food material and cools the food material;
and a control unit that controls the cooling chamber at each of the temperatures and for the period in each of the steps .

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