JP7489227B2 - Microwave Aging Equipment - Google Patents

Description

Patent Law Article 30, Paragraph 2 applied. Disclosed at the 12th Symposium of the Japan Society of Electromagnetic Energy Applications held at the Kitakyushu International Conference Center on November 15-16, 2018.

Patent Law Article 30, Paragraph 2 applied. Unveiled at the Microwave Exhibition MWE2018 held at Pacifico Yokohama from November 28 to 30, 2018.

Patent Law Article 30, Paragraph 2 applied. Exhibited at the 47th International Hotel & Restaurant Show held at Tokyo Big Sight from February 19 to 22, 2019.

Patent Law Article 30, Paragraph 2 applied. Disclosed at the 44th Meat Industry Exhibition 2019 held at Tokyo Big Sight from April 17 to 19, 2019.

The present invention relates to a microwave aging device and a microwave aging method for aging food by irradiating it with microwaves.

In recent years, so-called aged meat, which is beef that has been aged for a certain period of time to enhance its flavor, has become widely known, and demand for it is increasing. When aging beef, it is generally preferable to age it at about 40°C in order to bring out the flavor, but in order to prevent spoilage due to bacterial growth, it is usually aged at a low temperature of around 1°C (see Patent Document 1).

JP 2015-123057 A

Conventional technology has the problem that because maturation is carried out at such low temperatures, it takes a long time (in some cases 90 to 180 days) for the maturation to be complete. In addition, the longer the maturation period, the more bacteria will cause spoilage from the surface, even at low temperatures, which means more trimming needs to be done to remove the surface, resulting in poor yields.

The objective of the present invention is to provide a microwave aging device and a microwave aging method that can shorten the time required for aging food and improve yield.

The microwave aging device of the present invention is a microwave aging device comprising a aging chamber for storing food, a cooling section for cooling the aging chamber, a microwave oscillator section for irradiating microwaves to the aging chamber, and a control section, wherein the control section has an aging mode in which microwaves are irradiated to food in the aging chamber while cooling the aging chamber, as well as one or more cooking modes selected from the following (A) to (E).
(A) Ultra-low temperature preservation mode in which the food in the aging chamber is not frozen by irradiating microwaves into the aging chamber while cooling the aging chamber to a temperature lower than the freezing temperature. (B) Supercooling freezing mode in which the food in the aging chamber is supercooled by irradiating microwaves into the aging chamber while cooling the aging chamber to a temperature lower than the freezing temperature, and then the microwave irradiation is stopped to quickly freeze the food. (C) Thawing mode in which the aging chamber is cooled while controlling the microwave irradiation output into the aging chamber so that the surface and internal temperatures of the food are minimized. (D) Low temperature cooking mode in which low temperature cooking is performed by irradiating microwaves into the aging chamber while stopping the cooling of the aging chamber to heat the food to a temperature suitable for low temperature cooking. (E) Extraction mode in which the temperature of the food is maintained at 0 to 30°C by irradiating microwaves into the aging chamber while cooling the aging chamber.

The microwave aging device can be configured to have two or more of the above modes (A) to (E).

The microwave aging device can be configured to have the thawing mode (C) and to have a thawing/aging mode that automatically executes the aging mode after executing the thawing mode (C).

In the microwave aging device, the control unit can be configured to have the ultra-low temperature storage mode (A) and the thawing mode (C), and further to have a thawing/aging/ultra-low temperature storage mode that automatically executes the aging mode under predetermined conditions after executing the thawing mode (C) and automatically executes the ultra-low temperature storage mode (A) after the conditions have ended.

In the microwave aging device, the microwave oscillator can be configured to include a semiconductor microwave oscillator that irradiates microwaves of less than 50 W to the food in the aging chamber.

In the microwave aging device, the microwave oscillator is configured to include a first oscillator having a semiconductor microwave oscillator and a second oscillator having a magnetron, and the control unit can be configured to include a high-temperature cooking mode in which, in addition to the low-temperature cooking mode (D) performed using the first oscillator, the second oscillator is used to irradiate microwaves into the aging chamber while cooling of the aging chamber is stopped, thereby heating food to a temperature suitable for high-temperature cooking.

According to the present invention, the internal temperature of the food can be made higher than the surface temperature during maturation, which shortens the maturation period, inhibits bacterial growth on the food surface, and reduces the amount of trimming.

1 is a configuration diagram of a microwave aging device according to a first embodiment. FIG. FIG. 11 is a configuration diagram of a microwave aging device according to a second embodiment. FIG. 11 is a configuration diagram of a microwave aging device according to a third embodiment. FIG. 11 is a configuration diagram of a cavity according to a third embodiment. 1 is a table showing the measurement results of amino acid content for each aging day when continuously irradiated with microwaves. 6 is a graph showing the measurement results of FIG. 5 . 1 is a table showing the measurement results of amino acid content under each aging condition. 8 is a graph showing the measurement results of FIG. 7 . 1 is a graph showing the measurement results of glutamic acid content under each aging condition. FIG. 2 is a diagram for explaining test conditions for a sensory test. 1 is a graph showing the results of a sensory test. FIG. 13 is a diagram showing test results of the low-temperature cooking mode. FIG. 13 shows the test results of the extraction mode. FIG. 13 is a diagram showing test results in a defrosting mode.

First Embodiment
FIG. 1 is a configuration diagram of a microwave aging device according to the first embodiment. The microwave aging device 1 according to this embodiment is an apparatus capable of dry aging and wet aging, and includes a cooling section 10, a microwave oscillator section 20, a microwave aging section 30, a control section 40, and a UV lamp 50, as shown in FIG. 1. The microwave aging device 1 incorporates the microwave aging section 30, the control section 40, and the UV lamp 50 inside the cooling section 10. In the microwave aging device 1 according to this embodiment, foods to be aged include meats (including processed meat foods such as ham), seafood, dairy products such as cheese, beans such as coffee beans, vegetables, fruits, noodles, breads, alcoholic beverages such as wine, fermented foods (including fermented seasonings such as miso and soy sauce), etc.

The cooling unit 10 is a device that cools the internal space of the cooling unit 10 with cold air. As shown in FIG. 1, the cooling unit 10 has a cooler 11, a first fan 12, a cooling chamber 13, and a cooling chamber door 14 (not shown). In this embodiment, the cooler 11 generates cold air by exchanging heat with the outside, and the generated cold air is blown into the cooling chamber 13 inside the cooling unit 10 by the first fan 12. This makes it possible to keep the temperature inside the cooling chamber 13 low. As will be described later, the control unit 40 appropriately controls the operation of the microwave oscillator 20 and the temperature inside the cooling chamber 13 so that the surface temperature of the food to be aged is lower than the internal temperature. In addition, the user can put food to be aged in and take it out of the microwave aging unit 30 installed in the cooling chamber 13 by opening the cooling chamber door 14.

The microwave oscillator 20 generates microwaves to be irradiated to the food M. Although an oscillator using a magnetron can be used as the microwave oscillator 20, in this embodiment, a solid-state oscillator using a semiconductor element (semiconductor microwave oscillator) is used, which can obtain a higher frequency and output stability than a magnetron. A magnetron can only reduce its output to about 400 W, but a semiconductor microwave oscillator can stably output microwaves of less than 50 W, which are suitable for irradiation during aging. The microwave oscillator 20 oscillates microwaves by continuously changing the frequency between 2.4 and 2.5 GHz. The microwaves oscillated by the microwave oscillator 20 are irradiated from the irradiation port 31 of the microwave aging section 30 via the cable 21. Note that by continuously changing the microwave frequency between 2.4 and 2.5 GHz, the distribution of the electromagnetic field in the microwave aging section 30 is uniformed, so that the microwaves are irradiated to the food M with a uniform distribution, which can promote uniform heating (uniform aging) of the food M.

As shown in FIG. 1, the microwave aging section 30 includes an irradiation port 31, a second fan 32, an aging chamber 33, and an aging chamber door 34 (not shown). A user can put food M to be aged in and take it out of the aging chamber 33 by opening the aging chamber door 34.

The aging chamber 33 is a cavity in which reflectors are installed on all of the inner surfaces (inner walls) to reflect microwaves. An irradiation port 31 is installed on the upper inner surface of the aging chamber 33, which irradiates the microwaves generated by the microwave oscillator 20 into the aging chamber 33. In this embodiment, a small, high-gain patch antenna (flat antenna) is attached to the irradiation port 31, and the microwaves generated by the microwave oscillator 20 are irradiated into the aging chamber 33. A shelf of any shape made of a microwave-transparent material such as Teflon (registered trademark) or polypropylene may be installed in the aging chamber 33. When using a metal material such as stainless steel, a lattice-shaped shelf with an interval of 20 mm or more or a punched metal-shaped shelf with an opening with a diameter of 20 mm or more may be installed.

The second fan 32 blows the cold air in the cooling chamber 13 into the aging chamber 33. The second fan 32 can be one that can blow air at a volume suitable for dry aging (for example, 0.5 to 10.0 m/sec). In wet aging, the second fan 32 can also be stopped. In this embodiment, as shown in FIG. 1, the second fan 32 is attached to the outside of the aging chamber 33, and a first micro-opening 35 is provided on the side wall of the aging chamber 33 to which the second fan 32 is attached. The first micro-opening 35 is opened with a size shorter than the wavelength of the microwave, and for example, in this embodiment, the size of the first micro-opening 35 is set to a diameter of 10 mm or less. The microwave irradiated into the aging chamber 33 is blocked by the first micro-opening 35, and only the cold air blown by the second fan 32 passes through. In addition, a second micro-opening 36 with the same diameter as the first micro-opening 35 is provided on the side wall of the aging chamber 33 facing the first micro-opening 35. The second micro-opening 36 blocks the microwaves irradiated into the ripening chamber 33, but the air in the ripening chamber 33 that has been heated by heat exchange with the food M passes through the second micro-opening 36 and is discharged into the cooling chamber 13. The first micro-opening 35 and the second micro-opening 36 may be provided in an area that occupies a large portion of one or more side walls to improve ventilation. The ripening chamber 33 may also be constructed using a punched metal in which the first micro-opening 35 and the second micro-opening 36 are formed in advance, and a stainless steel plate with a diameter of 10 mm may be used as such a punched metal.

The control unit 40 is equipped with a program including an aging mode, an ultra-low temperature storage mode, a supercooling freezing mode, a thawing mode, a low temperature cooking mode, and an extraction mode, which control the temperature so that the surface temperature and the internal temperature of the food M to be aged are each at a predetermined temperature. Specifically, the control unit 40 controls the operation of the microwave oscillator 20, the cooler 11, the first fan 12, and the second fan 32, thereby controlling the microwave output by the microwave oscillator 20, the temperature of the cold air by the cooler 11, and the air volume of the first fan 12 and the second fan 32 to perform temperature control. For example, when the aging mode is executed, the control unit 40 can increase the internal temperature of the food M by increasing the microwave output of the microwave oscillator 20, and can age the food M with the surface temperature of the food M lowered by lowering the temperature of the cold air by the cooler 11 or increasing the air volume of the first fan 12 and the second fan 32.

The control unit 40 can also control the microwave oscillation by the microwave oscillator 20. For example, in addition to fixed irradiation that fixes the microwave oscillator 20 to oscillate at a constant output value and a constant frequency, the control unit 40 can perform intermittent irradiation that causes the microwave oscillator 20 to repeat oscillation and stop in a short period (for example, a period of several milliseconds), sweep irradiation that changes the frequency of the microwave oscillator 20 over time, and continuous irradiation that changes the output value of the microwave oscillator 20 over time. The control unit 40 can also be configured to control the microwave oscillator 20 in the aging mode so as to switch the microwave irradiation ON-OFF every certain time (for example, several hours) (in the case of intermittent irradiation, to switch between a period in which intermittent irradiation is performed and a period in which intermittent irradiation is not performed every certain time). For example, in the maturation mode, the control unit 40 can control the microwave oscillator unit 20 to irradiate microwaves for three hours, then stop irradiating microwaves for three hours, and similarly repeat the process of irradiating and stopping microwaves every three hours for, for example, the entire maturation period of seven days.

In the ultra-low temperature storage mode, the control unit 40 cools the aging chamber 33 to a temperature lower than the freezing temperature of the food M (for example, -2 to -10°C) while irradiating microwaves into the aging chamber 33, thereby storing the food M in the aging chamber 33 in an unfrozen state. For example, beef is normally frozen at -2°C, but by controlling the output of the microwave oscillator 20 so that heating occurs within a range that does not exceed the cooling capacity of the cooling unit 10, the food M can be placed in a supercooled state in which it does not freeze even when the temperature of the food M reaches the freezing temperature (for example, -2°C for beef), and by storing it in such a state, it is possible to store the food M deliciously without freezing it while maintaining the surface of the food M at a temperature at which microorganisms do not grow. In addition, in the ultra-low temperature storage mode, the internal temperature of the food M is approximately the same as the surface temperature, but lower than the freezing temperature at which microorganisms do not grow, but by continuously irradiating weak microwaves (for example, about a few watts), it is possible to expect the effect of aging the food deliciously while maintaining the entire meat at a temperature at which microorganisms do not grow.

In the supercooling freezing mode, the control unit 40 irradiates microwaves into the aging chamber 33 while cooling the aging chamber 33 to a temperature lower than the freezing temperature (for example, -5 to -10°C), thereby putting the food M in the aging chamber 33 into a supercooled state, and then stops the microwave irradiation to rapidly freeze the food M, thereby improving the freshness retention of the food M. At this time, the output of the cooler 11 may be increased together with the stopping of the microwave irradiation, and the freezing speed may be shortened by lowering the temperature inside the aging chamber 33 (for example, -15°C or lower).

In the defrosting mode, the control unit 40 performs dripless defrosting by blowing cold air into the aging chamber 33 to cool the food M while controlling the microwave irradiation output into the aging chamber 33 so that the surface and internal temperatures of the food M are minimized. The reason for blowing cold air into the aging chamber 33 for cooling even in the defrosting mode is to prevent the surface and edges of the food M from thawing first, causing the thawed parts to absorb the microwaves intensively, resulting in temperature unevenness. The control unit 40 may be provided with a defrosting/aging program that automatically transitions to the aging mode after defrosting in the defrosting mode, and further with a defrosting/aging/ultra-low temperature preservation program that automatically transitions to the aging mode after defrosting in the defrosting mode, and automatically transitions to the ultra-low temperature preservation mode after aging.

In the low-temperature cooking mode, the control unit 40 performs low-temperature cooking by irradiating microwaves into the aging chamber 33 with the cooling of the aging chamber 33 stopped, thereby raising the surface temperature of the food M to a temperature suitable for low-temperature cooking (for example, 57 to 80°C). Note that in the low-temperature cooking mode, the internal temperature of the food M can be made lower than the surface temperature, for example, 40 to 80°C, for low-temperature cooking. Also, the low-temperature cooking mode may be executed for food M in a frozen state without going through the thawing mode.

In the extraction mode, the control unit 40 performs extraction by blowing cold air into the aging chamber 33 to cool it, while irradiating microwaves into the aging chamber 33 to set the temperature of the food to be extracted (food M) at 0 to 30°C. For example, in coffee extraction, it is known that by extracting coffee beans with cooling water at 10°C, many aromatic components are dissolved, while the components that cause bitterness and astringency are not easily dissolved, resulting in an overall mellow taste with few unpleasant flavors. However, when extracting at a low temperature of 10°C, there is a problem that the extraction takes a long time. In contrast, in the extraction mode according to the present embodiment, microwaves are irradiated to the coffee beans and water, which are the food M, so that the coffee beans can be heated evenly to the inside, and the coffee extraction speed can be increased even at a low temperature of 10°C.

The microwave oscillator 20 may be configured to include a first oscillator having a semiconductor microwave oscillator and a second oscillator having a magnetron, and the control unit 40 may be capable of executing a low-temperature cooking mode using the first oscillator and a high-temperature cooking mode (e.g., 250 to 350°C) using the second oscillator. With this configuration, it is possible to bake the surface of the food M in the high-temperature cooking mode and then cook it thoroughly in the low-temperature cooking mode. A grill plate (e.g., a grill plate made of a ferrite material) that absorbs microwaves and generates heat may be placed on the back side, and microwaves from the first oscillator may be irradiated from the back side, and microwaves from the second oscillator may be irradiated from the front side on which the food M is directly placed.

The control unit 40 can also be configured to be connected to a temperature sensor that measures the internal temperature and surface temperature of the food M (for example, a fluorescent fiber optic thermometer (manufactured by Anritsu Keiki Co., Ltd.) that can measure temperature by contact even in a microwave environment, or a radiation type temperature sensor that measures the intensity of infrared or visible light by non-contact), and to perform appropriate temperature control based on the measurement results of the temperature sensor.
Furthermore, the control unit 40 may be configured to store, through testing in advance, the relationship between the weight and moisture content of the food M and the microwave output of the microwave oscillator 20, the temperature of the cold air from the cooler 11, and the air volume of the first fan 12 and the second fan 32 for setting the surface temperature and internal temperature of the food M to a predetermined temperature, and to control the microwave output of the microwave oscillator 20, the temperature of the cold air from the cooler 11, and the air volume of the first fan 12 and the second fan 32 according to the weight and moisture content of the food M obtained from a weighing scale or a non-contact moisture meter installed in the aging chamber 33. In this case, the control unit 40 may be equipped with an input device such as an operation button or a touch panel, and is disclosed to automatically control the surface temperature of the food to be aged to be higher than the internal temperature by inputting information on the food to be aged, such as the type of food (e.g., beef, pork, chicken) and size.

Here, microwaves heat the inside of food through dielectric heating, so when microwaves are irradiated from the microwave aging section 30, the inside of the food M can be heated in addition to the surface of the food M. Heating the inside of the food M can promote aging of the food M, but heating the surface of the food M promotes the growth of bacteria attached to the surface of the food M. In contrast, in the microwave aging device 1 according to this embodiment, the surface of the food M is cooled by the operation of the cooling mechanism, i.e., the cooling section 10 and the second fan 32, thereby suppressing the growth of bacteria attached to the surface of the food M.

In particular, in the microwave aging device 1 according to this embodiment, the heating mechanism (microwave oscillator 20 and microwave aging unit 30) heats the food M and the cooling mechanism (cooling unit 10 and second fan 32) cools the surface of the food M simultaneously, and the operation of the heating mechanism and the cooling mechanism is controlled by the control unit 40 so that the internal temperature of the food M is higher than the surface temperature. More specifically, the control unit 40 controls the temperature so that the internal temperature of the food M is 5°C or higher and the surface temperature of the food M is less than 5°C, and more preferably controls the output of the microwave oscillator 20, the temperature of the cold air from the cooler 11, and the air volume from the first fan 12 and the second fan 32 so that the difference between the internal temperature and the surface temperature of the food M is 3°C or higher. As a result, in the microwave aging device 1, the aging of the food M can be promoted during the aging of the food M, and the proliferation of bacteria on the surface of the food M can be suppressed. It is not necessary to continuously irradiate the microwaves throughout the aging of the food M, but the microwaves can be irradiated for at least 1 hour (preferably 3 hours or more, more preferably 5 hours or more).

The UV lamp 50 is a device that generates ultraviolet light. In this embodiment, by irradiating the cold air circulating in the cooling chamber 13 and the aging chamber 33 with ultraviolet light, bacteria floating in the cold air can be sterilized, and the growth of bacteria present on the surface of the food M and in the cooling chamber 13 and the aging chamber 33 can be further suppressed. In addition, it is also possible to configure the wall of a part of the aging chamber 33 (at least a part on the UV lamp 50 side) so that ultraviolet light passes through, or to install the UV lamp directly in the aging chamber 33. In that case, during the aging of the food M, the ultraviolet light generated by the UV lamp 50 can be directly irradiated onto the surface of the food M placed in the aging chamber 33. In this way, by irradiating the surface of the food M with ultraviolet light during aging, the growth of bacteria present on the surface of the food M can be further suppressed. The control unit 40 can also control the operation of the UV lamp 50. For example, the control unit 40 can control the UV lamp 50 to irradiate ultraviolet light for a certain period of time (for example, several hours) from the timing when aging begins or the timing when the aging chamber door 34 is closed (after being opened).

As described above, in the microwave aging device 1 according to the present embodiment, the inside of the food is heated by microwaves irradiated from the microwave oscillator 20, and the surface of the food is cooled by the cooling unit 10 and the second fan 32 at the same time, and the internal temperature of the food M is made higher than the surface temperature of the food M to ripen the food M, thereby suppressing the growth of bacteria present on the surface of the food M and promoting the aging of the food M. That is, in the past, the food M was aged at a low temperature (for example, 1°C) to suppress the growth of bacteria present on the surface of the food M, but since microwaves were not irradiated, the internal temperature of the food M became the same as the surface temperature, and there was a problem that the aging took a long time (for example, about 30 to 180 days). In addition, because spoilage by bacteria progresses from the surface even at low temperatures, the amount of trimming to remove the surface increases as the aging takes longer, resulting in a poor yield. However, in the microwave aging device 1 according to the present embodiment, the food M is aged while being irradiated with microwaves, so that the inside of the food M can be heated as uniformly as the surface. By simultaneously heating the inside of the food with the microwave oscillator 20 and cooling the surface of the food with the cooling unit 10 and the second fan 32, it is possible to increase only the internal temperature of the food M while keeping the surface temperature of the food M low. This makes it possible to suppress the growth of bacteria present on the surface of the food M and promote the aging of the food, compared to conventional methods.

In addition, in the microwave maturation device 1 according to this embodiment, in addition to the maturation mode in which microwaves are irradiated onto the food M in the maturation chamber 33 while the maturation chamber 33 is cooled, the device can also perform (A) an ultra-low temperature preservation mode in which microwaves are irradiated into the maturation chamber 33 while the maturation chamber 33 is cooled to a temperature lower than the freezing temperature, thereby keeping the food M in the maturation chamber 33 in an unfrozen state; (B) a supercooling freezing mode in which microwaves are irradiated into the maturation chamber 33 while the maturation chamber 33 is cooled to a temperature lower than the freezing temperature, thereby bringing the food in the maturation chamber 33 into a supercooled state, and then the microwave irradiation is stopped to rapidly freeze the food; (C) a thawing mode in which the maturation chamber 33 is cooled while controlling the microwave irradiation output into the maturation chamber 33 so that the surface temperature and internal temperature of the food M are minimized, thereby thawing the food; and (D) a low temperature cooking mode in which microwaves are irradiated into the maturation chamber 33 while the cooling of the maturation chamber 33 is stopped, thereby heating the food to a temperature suitable for low temperature cooking, thereby cooking the food at low temperature. In this way, in addition to maturing the food M, the microwave aging device 1 according to this embodiment utilizes the characteristic of microwaves, which allows the food M to be heated uniformly from the inside as well as the surface, making it possible to preserve, freeze, thaw, and cook the food M in a way that was not possible before.

Second Embodiment
Next, a microwave aging device 1a according to the second embodiment will be described. Fig. 2 is a configuration diagram showing an example of the microwave aging device 1a according to the second embodiment. As shown in Fig. 2, the microwave aging device 1a according to the second embodiment is similar to the microwave aging device 1 according to the first embodiment, except that the aging chamber door 34 of the aging chamber 33 has a choke structure and can be opened and closed from the outside. The same components as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 2, in the microwave aging device 1a according to the second embodiment, the aging chamber door 34 of the aging chamber 33 can be opened and closed directly from the outside. In addition, in the second embodiment, the aging chamber door 34 of the aging chamber 33 has a choke structure to prevent microwaves from leaking to the outside. The choke structure can be a known structure.

In this way, in the microwave aging device 1a according to the second embodiment, food M can be put in and taken out of the aging chamber 33 directly from the outside. In addition, in the second embodiment, the aging chamber door 34 is provided with a choke structure, which effectively prevents microwaves from leaking to the outside.

Third Embodiment
Next, a microwave aging device 1b according to the third embodiment will be described. Fig. 3 is a perspective view showing an example of the microwave aging device 1b according to the third embodiment, and Fig. 4 is a perspective view showing an example of the microwave aging section 30a according to the third embodiment. As shown in Fig. 3, the cooling section 10 has two cooling chambers 13, and a microwave aging section 30a (aging chamber 33) is installed in each cooling chamber 13.

As shown in FIG. 4(A), the microwave maturation section 30a has a two-tier structure with the maturation chamber 33 divided into upper and lower sections by a mesh plate 37, and food M can be placed on both the upper and lower sections. In addition, in the microwave maturation section 30a according to the third embodiment, as shown in FIG. 4(B), a second fan 32 is attached to the back of each tier, and the cold air in the cooling chamber 13 is blown into the maturation chamber 33 by the operation of the second fan 32. In addition, small openings 36 are opened in most of both sides of the microwave maturation section 30a, and the air blown from the cooling chamber 13 into the maturation chamber 33 and exchanges heat with the food M is discharged from the small openings 36 into the cooling chamber 13, thereby efficiently lowering the surface temperature of the food M.

In the third embodiment, the front of the microwave maturation section 30a is an opening, and a choke structure 38 is formed on the edge of the opening. As shown in FIG. 3, the cooling chamber door of the cooling chamber 13 is also used as the maturation chamber door 34 of the maturation chamber 33, and the choke structure 38 can effectively prevent microwaves from leaking to the outside. By making the door surface a double structure of a punched metal plate and a transparent plate, it is possible to make it possible to check the maturation progress of the food M inside the maturation chamber 33 without opening the door while maintaining the microwave leakage prevention and heat insulation function. There is no particular restriction on the material of the transparent plate, and for example, glass or polycarbonate resin is good. In addition, by making a structure in which two transparent plates are stacked so that an air layer is formed, it is possible to make a structure with improved heat insulation function.

In the third embodiment, an irradiation port 31 and an illumination unit 39 are arranged on the upper surface of the microwave maturation unit 30a. As in the first embodiment, the irradiation port 31 irradiates microwaves into the maturation chamber 33. The illumination unit 39 has an LED light source that illuminates the interior of the maturation chamber 33, and illuminates the interior of the maturation chamber 33 when, for example, the maturation chamber door 34 is opened.

As described above, the microwave aging device 1b according to the third embodiment has two cooling chambers 13 and two aging chambers 33, so that it is possible to increase the amount of food M that can be aged at one time. In addition, the aging chambers 33 are divided into two levels, an upper one and an lower one, and by providing a second fan 32 for each level, it is possible to appropriately lower the surface temperature of the food M even when a large amount of food M is to be aged. Furthermore, in the third embodiment, a commercially available refrigerator can be used as the cooling section 10, so that it is also possible to reduce manufacturing costs.

<Test Example>
The inventors conducted the following tests to confirm the aging effect of food by the microwave aging device according to the present invention. Specifically, a prototype with the same configuration as the microwave aging device 1 according to the first embodiment was manufactured and each test was conducted. In the following test examples 1 to 3, about 300 g of beef ham meat (about 700 g in test example 4) was placed in the microwave aging section and irradiated with microwaves of 100 W or less. In addition, the tests were conducted by controlling the microwave output of the microwave oscillator, the temperature of the cooler, and the airflow of the first and second fans so that the temperature inside the cooling section 10 was -2°C, the temperature on the surface of the beef ham meat was -1 to +2°C, and the temperature inside the beef ham meat was +8°C. The airflow of the second fan was controlled in the range of 0.5 to 1.0 m/sec.

(Test Example 1)
First, microwave irradiation was continued until the 9th day of aging, and the amino acid content was measured for each aging day. The measurement results are shown in Figures 5 and 6. Figure 5 shows the measurement results of the amino acid content for each aging day in Test Example 1, and Figure 6 is a graph of the measurement results shown in Figure 5. Focusing on the total amount of amino acids, the total amount of amino acids at the beginning (day 0) was 375.4 mg/100 g, the total amount of amino acids on the 6th day of aging was 745.9 mg/100 g, and the total amount of amino acids on the 9th day of aging was 1128.1 mg/100 g. As can be seen from these results, by irradiating microwaves to beef thigh meat, the total amount of amino acids increased by about 2 times after 6 days of aging and about 3 times after 9 days of aging.

(Test Example 2)
Next, in Test Example 2, the amino acid contents after aging for 7 days (for (A), the amino acid content of beef thigh meat before aging) were measured for (A) beef thigh meat before aging, (B) beef thigh meat aged for 7 days without microwave irradiation, (C) beef thigh meat aged for 7 days and irradiated with microwaves for only 6 hours from the start of aging, and (D) beef thigh meat aged for 7 days and irradiated with microwaves for only 20 hours from the start of aging were measured. Figure 7 shows the measurement results of the amino acid contents of (A) to (D) in Test Example 2, and Figure 8 is a graph of the measurement results shown in Figure 7.

As shown in Figures 7 and 8, when focusing on the total amount of amino acids, the total amount of amino acids increased by 44.9 mg/100 g in beef thigh meat (B) aged for 7 days without microwave irradiation compared to (A) beef thigh meat before aging. On the other hand, the total amount of amino acids increased by 96.5 mg/100 g in beef thigh meat (C) aged for 6 hours with microwaves compared to (A) beef thigh meat before aging, and the total amount of amino acids increased by 232.5 mg/100 g in beef thigh meat (D) aged for 20 hours with microwaves compared to (B) aged for 7 days without microwave irradiation. Thus, it was found that the total amount of amino acids increased significantly in (C) aged for 6 hours with microwaves compared to (B) aged for 7 days without microwave irradiation, and in (D) aged for 20 hours with microwaves compared to (B) aged for 7 days. It was also found that the total amount of amino acids tends to increase as the microwave irradiation time increases.

(Test Example 3)
Next, the glutamic acid content was measured for each aging day in a normal aging method without microwave irradiation and in the aging method of the present invention with microwave irradiation, and the results are shown in Figure 9. Glutamic acid is an amino acid related to umami, and is also an indicator of the umami of beef. Note that since beef aged by a normal aging method and beef aged by microwave irradiation according to the present embodiment are different types of meat, the glutamic acid content at the beginning of aging is different, as shown in Figure 9.

As shown in FIG. 9, when microwaves were irradiated, the glutamic acid content increased significantly compared to when microwaves were not irradiated. Specifically, in the conventional aging method without microwave irradiation, the glutamic acid content increased by 1.52 times after 7 days of aging, whereas in the aging method according to the present embodiment in which microwaves were irradiated, the glutamic acid content increased significantly by 2.60 times after 7 days of aging. It was also found that when microwaves were irradiated, the increase in glutamic acid (the increase in the amount of glutamic acid) tended to increase with the aging period.

(Test Example 4)
Next, a sensory test was performed on beef thigh meat (E) aged for 7 days by continuous microwave irradiation, and beef thigh meat (F) and (G) aged for 7 days without microwave irradiation. FIG. 10 is a diagram for explaining the aging conditions of each sample in Test Example 4. As shown in FIG. 10, in beef thigh meat (E) aged for 7 days by continuous microwave irradiation, aging was performed by controlling the temperature so that the cooling chamber temperature was −2° C., the surface temperature of beef thigh meat was 2° C., and the internal temperature of beef thigh meat was 8° C. In addition, among beef thigh meat aged for 7 days without microwave irradiation, (F) was aged by controlling the temperature so that the cooling chamber temperature was −2° C., the surface temperature of beef thigh meat was −2° C., and the internal temperature of beef thigh meat was −2° C., and (G) was aged by controlling the temperature so that the cooling chamber temperature was 8° C., the surface temperature of beef thigh meat was 8° C., and the internal temperature of beef thigh meat was 8° C.

Figure 11 shows the results of the sensory test for Test Example 4. The sensory test was conducted by three experts at the Meat Science and Technology Research Institute, a general incorporated association. In the sensory test, unaged beef round meat was used as the standard (zero point), and each item, unpleasant odor, off-flavor, aged flavor, richness, umami, juiciness, tenderness, and overall, was rated on a seven-point scale from -3 points to +3 points.

As a result, compared to unaged beef thigh meat (standard), (E) beef thigh meat aged for 7 days by continuous microwave irradiation, and (F) and (G) beef thigh meat aged for 7 days without microwave irradiation, had higher aged flavor, richness, umami, and juiciness, and also had a higher overall evaluation. Also, when comparing (E) beef thigh meat aged for 7 days by continuous microwave irradiation with (F) and (G) beef thigh meat aged for 7 days without microwave irradiation, (E) beef thigh meat aged for 7 days by continuous microwave irradiation was rated higher in richness, umami, juiciness, and tenderness, and also had a higher overall evaluation. In particular, (E) beef thigh meat aged for 7 days by continuous microwave irradiation was rated significantly higher in richness and umami, compared to unaged beef thigh meat (standard).

As such, (E) beef thigh meat aged for 7 days by continuous microwave irradiation had improved sensory flavor, umami, juiciness, and tenderness, making the beef thigh meat more delicious, compared to (F) and (G) beef thigh meat aged for 7 days without microwave irradiation.

The beef rump meat (E) to (G) aged in Test Example 4 was subjected to a bacterial test, and it was confirmed that the E. coli count was less than 30 (per 100 g) and the Enterobacteriaceae count was less than 10 (cfu/g).

(Test Example 5)
In Test Example 5, salmon was cooked at low temperature in the low temperature cooking mode. FIG. 12(A) is a diagram for explaining a temperature control method in the low temperature cooking mode in Test Example 5, and (B) is a diagram showing a photograph of salmon cooked at low temperature in Test Example 5. In Test Example 5, as shown in FIG. 12(A), an internal temperature sensor for measuring the internal temperature of salmon was installed. In addition, in order to suppress the influence of microwaves, the sheath length of the sheath part (thermocouple) of the internal temperature sensor was set to less than 48 mm, and the sheath diameter was set to less than φ2.5 mm. Then, microwaves were irradiated into the aging chamber 33 with the cooling of the aging chamber 33 stopped so that the internal temperature of the salmon was 40° C. As a result, the salmon could be cooked at a low temperature as shown in FIG. 12(B).

(Test Example 6)
In Test Example 6, coffee was extracted using the extraction mode. Specifically, in Test Example 6, 16 g of coffee beans were immersed in 50 ml of a 25% ethanol aqueous solution, and coffee was extracted for 72 hours using the 25% ethanol aqueous solution as a solvent. Here, FIG. 13(A) shows an example of extraction performed in the extraction mode of this embodiment, in which the temperature of the aging chamber 33 (external temperature) was set to 0° C. and the temperature of the 25% ethanol aqueous solution containing coffee beans was maintained at 10° C. by continuously irradiating microwaves into the aging chamber 33 while cooling the aging chamber 33. FIG. 13(B) shows an example of extraction performed without irradiating microwaves, with the temperature of the aging chamber 33 at 10° C. (the temperature of the 25% ethanol aqueous solution containing coffee beans also set at 10° C.). As shown in FIGS. 13(A) and (B), it can be seen that the coffee extraction speed is faster in the example (A) extracted using the extraction mode of this embodiment than in the example (B) extracted without irradiating microwaves. In addition, in Example 6, the extraction mode was tested using coffee beans, but the extraction mode is not limited to the extraction of coffee, and can also be used for the extraction of tea leaves or fruit liquor, for example.

(Test Example 7)
In Test Example 7, frozen fish meat (sea bass) was thawed in the thawing mode. Specifically, about 150 g of raw sea bass sashimi was divided into two, frozen at -20°C, and then thawed. Here, Fig. 14(A) shows a photograph of the thawed fish meat when the thawing was performed in the thawing mode of this embodiment by continuously irradiating the aging chamber 33 with 1 W of microwaves while cooling the temperature (external temperature) of the aging chamber 33 to -5°C, and Fig. 14(B) shows a photograph of the thawed fish meat when the thawed fish meat was placed in a plastic bag with a zipper and thawed over one day at a temperature of 0°C without irradiating microwaves. Table 1 shows the weight of the sea bass before and after thawing and the amount of drips that flowed out.

As shown in Table 1, in the example where the thawing was performed using the thawing mode of this embodiment, the thawing speed was faster and the amount of dripping was smaller than in the comparative example where the thawing was performed without irradiating microwaves. Specifically, when the temperature of the ripening chamber 33 was set to 0°C and the thawing took about one day, the thawing was completed in about 6.5 hours when the thawing was performed using the thawing mode of this embodiment. Also, as shown in Table 1, when the temperature of the ripening chamber 33 was set to 0°C and the thawing amount was 0.7 g, which was about 1% of the total weight. On the other hand, when the thawing was performed using the thawing mode of this embodiment, the thawing amount was 0.1 g, which was suppressed to about 0.1% of the total weight. In addition, in the thawing mode of this embodiment, the frozen sea bass was not placed in a plastic bag with a zipper, which also has the effect of evaporating excess water contained in the sea bass.

The above describes preferred embodiments of the present invention, but the technical scope of the present invention is not limited to the above description of the embodiments. Various modifications and improvements can be made to the above embodiments, and such modifications or improvements are also included in the technical scope of the present invention.

For example, in addition to the above-described embodiment, an activated carbon filter can be further provided in the maturation chamber 33 or the cooling chamber 13. The activated carbon filter can remove odors from the maturation chamber 33 or the cooling chamber 13.

In addition to the above-described embodiment, a measuring device for measuring the weight of the food M placed in the maturation chamber 33 may be provided at the bottom of the maturation chamber 33. In this case, the degree of maturation of the food may be determined based on the change in the weight of the food and presented to the user. A non-contact moisture meter may also be provided, and the degree of maturation of the food may be determined based on the change in the weight and moisture content of the food.

Furthermore, in the above-described embodiment, a configuration in which the microwave frequency is 2.4 to 2.5 GHz (ISM frequency band) is exemplified, but this is not limited to this configuration, and it is also possible to use a frequency in the range of, for example, 300 MHz to 300 GHz.

Reference Signs List 1, 1a, 1b...Microwave maturation device 10...Cooling section 11...Cooler 12...First fan 13...Cooling chamber 20...Microwave oscillator section 21...Cable 30, 30a...Microwave maturation section 31...Irradiation port 32...Second fan 33...Maturation chamber 34...Maturation chamber door 35...First minute opening 36...Second minute opening 37...Grain plate 38...Choke structure 39...Illumination section 40...Control section 50...UV lamp

Claims (5)

a maturation room for storing food;
A cooling section for cooling the maturation chamber;
A microwave oscillator for irradiating microwaves into the aging chamber;
A microwave aging apparatus comprising:
The control unit of this microwave aging device has an aging mode in which microwaves are irradiated to food in an aging chamber while cooling the aging chamber so that the internal temperature of the food in the aging chamber becomes higher than the surface temperature, as well as an irradiation mode in which microwaves are irradiated into the aging chamber while cooling the aging chamber, thereby maintaining the temperature of the food in the water or aqueous solution at 0 to 30°C and extracting it . a maturation room for storing food;
A cooling section for cooling the maturation chamber;
A microwave oscillator for irradiating microwaves into the aging chamber;
A microwave aging apparatus comprising:
The control unit executes an aging mode in which microwaves are irradiated onto food in the aging chamber while cooling the aging chamber so that the internal temperature of the food in the aging chamber becomes higher than the surface temperature, and then automatically executes an irradiation mode in which microwaves weaker than those in the aging mode are irradiated into the aging chamber while cooling the aging chamber, thereby aging and preserving the food in the aging chamber in a supercooled state that does not freeze. a maturation room for storing food;
A cooling section for cooling the maturation chamber;
A microwave oscillator for irradiating microwaves into the aging chamber;
A microwave aging apparatus comprising:
The control unit of this microwave aging device executes an irradiation mode in which food is thawed by irradiating microwaves into the aging chamber while cooling the aging chamber, and then automatically executes an aging mode in which microwaves are irradiated to the food in the aging chamber while cooling the aging chamber so that the internal temperature of the food in the aging chamber becomes higher than the surface temperature. The microwave aging device according to any one of claims 1 to 3, wherein the microwave oscillator is equipped with a semiconductor microwave oscillator that irradiates the food in the aging chamber with microwaves of less than 50 W. the microwave oscillator unit is configured to include a first oscillator unit having a semiconductor microwave oscillator and a second oscillator unit having a magnetron,
A microwave aging device as described in any one of claims 1 to 4, wherein the control unit has an irradiation mode in which food is cooked at low temperatures by irradiating microwaves into the aging chamber using a first oscillating unit while cooling of the aging chamber is stopped, and an irradiation mode in which food is cooked at high temperatures by irradiating microwaves into the aging chamber using a second oscillating unit while cooling of the aging chamber is stopped.