JP7590816B2 - Method and apparatus for aging food using microwaves - Google Patents

Description

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

Application of Article 30, Paragraph 2 of the Patent Act Announced at the MWE2018 Microwave Exhibition held at Pacifico Yokohama from November 28 to 30, 2018

Application of Article 30, Paragraph 2 of the Patent Act Announced at the 47th International Hotel & Restaurant Show held at Tokyo Big Sight from February 19 to 22, 2019

Application of Article 30, Paragraph 2 of the Patent Act Announced 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 method for aging food by shortening the time it takes for food to become aged after 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).

On the other hand, microwaves directly heat molecules with polar groups and compounds with large dipole moments. For example, in the drying and distillation of agricultural products, microwaves directly heat the water inside the agricultural products and break down the cell walls from the inside, which is excellent in terms of drying efficiency and extraction of useful components. Since it heats from the inside, the thermal effect due to conduction is small. For example, when used to dry fresh leaves, it is possible to obtain dried leaves with high nutritional value because there is little thermal decomposition of nutritional components such as vitamin C inside. In addition, since the inside of the plant is heated, it is easy to extract components. For example, it is known that the useful component tryptanthrin contained in indigo leaves can be quickly extracted by solvent extraction under microwave irradiation (Patent Document 2).
Also, as a microwave irradiation device, a microwave irradiation device (Patent Document 3) is known in which the internal structure of the kettle can be changed according to the properties and amount of the object and which has a stirring function, making it suitable for multiple uses.Furthermore, in a microwave irradiation device (Patent Document 4) that irradiates microwaves from multiple directions that do not face each other and uses a rotating reflector plate to suppress microwave interference and ensure high thermal uniformity, it is possible to control the output of microwaves irradiated from three irradiation units based on the detection values of multiple sensors that can measure the temperature of the irradiated object.

JP 2015-123057 A JP 2009-149596 A JP 2014-196896 A International Publication No. 2015/199005

The range of foodstuffs that can be aged is expanding beyond beef, and as the food aging market expands, there is a demand for a highly useful food aging method that can be widely applied to various foods. Conventionally, aged flavor is usually achieved by mixing raw materials, subjecting them to a heating process, and then leaving them for a certain period of time, i.e., by passing through a aging period. By passing through a aging period, foods and beverages with a desirable aged flavor are obtained, which is a flavor in which the harsh taste and odor of, for example, harsh vinegar or saltiness is mellowed and the richness and aroma are enhanced. In conventional technology, there was a problem that it took a long time (in some cases 90 to 180 days) to complete the aging. In addition, the longer the aging period, the more bacteria will spoil from the surface even at low temperatures, and the greater the amount of trimming that needs to be removed from the surface, resulting in a problem of poor yield. The time required to complete aging is shortened.

The present invention aims to provide a microwave maturation method that improves the maturation sensation so that the flavor specific to a food is a combination of aroma, taste, and texture, and that these elements play a role in the deliciousness of the food in a ratio specific to the food, and further that the components that make up these elements are present in a well-balanced manner and the physical, chemical, and physiological interactions between the components form the subtle flavor of the food, and that can shorten the time required for maturation and improve the yield.
Another object of the present invention is to provide a microwave maturation method that improves the maturation feeling and produces foods and beverages with a flavor that is unique to each food and has a unified overall flavor, without requiring a long maturation period. Still another object of the present invention is to provide a maturation method that can sufficiently develop umami components by the maturation operation using a microwave maturation device.

The objective of this invention is to provide a method for aging food in which the proteins, fats, carbohydrates, etc. in the food are broken down appropriately by the action of enzymes, fungi, salts, etc. without spoiling, and the aroma, taste, texture, color, chemical components, etc. that constitute the flavor are changed. This method is intended to be widely applied to a wide range of foods, including fish eggs, fermented foods, brewed products, confectionery, as well as dairy products such as cheese, beans such as coffee beans, vegetables, fruits, noodles, bread, etc. More specifically, the objective is to provide an aging method for fermented foods, including brewed alcoholic beverages such as sake and wine, that completes aging in a short period of time without compromising quality.

The present invention relates to the following microwave aging methods (1) to ( 3 ).
(1) A method for microwave aging of food, which improves the sense of maturity so that the components constituting the delicious elements of aroma, taste, and texture are present in a balanced manner and the physical, chemical, and physiological interactions between each component form a subtle flavor unique to the food, and which targets foods in which the flavor is formed by the action of enzymes and/or microorganisms and/or salt, and which is characterized in that the method irradiates the food with microwaves while simultaneously heating the inside of the food and cooling the surface of the food by blowing cold air, while keeping the internal temperature of the food at 25°C or less and making the internal temperature of the food higher than the surface temperature of the food, and in that if the food is a food selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, noodles, bread, alcoholic beverages, and fermented foods, the internal temperature of the food is 5°C or higher, if the food is a vegetable, the internal temperature of the food is 15°C or higher, and if the food is a fruit, the internal temperature of the food is 20°C or higher, thereby shortening the time it takes for the sense of maturity to be improved.
(2) A microwave aging method as described in (1) above, in which microwaves are irradiated and cold air is blown so that the internal temperature of the food is 5°C or higher, the surface temperature of the food is less than 5°C, and the temperature difference between the surface temperature and the internal temperature of the food is 3°C or higher.
( 3 ) The microwave maturation method according to (1) or (2) above, wherein the food is selected from the group consisting of roe, cheese, yogurt, sour cream, fermented butter, natto, tempeh, coffee beans, cacao, shio - koji, miso, soy sauce, mirin, vinegar, noodle dough, pasta dough, pizza dough, sake, shochu, beer, amazake, wine, bonito flakes, kusaya, shiokara, funazushi, anchovies, salami, black tea, goishicha , oolong tea, and fermented tea.

The present invention also relates to a microwave aging apparatus for foods selected from the group consisting of fish eggs, dairy products, coffee beans, cacao, vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods as set forth below in ( 4 ) to (13).
( 4 ) A microwave aging device for foods selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods, for use in the microwave aging method described in (1) or (2) above, comprising an aging chamber for storing the foods, a microwave oscillator for emitting microwaves to be irradiated into the aging chamber, a cooler for cooling the air in the aging chamber, and a control unit , wherein the control unit controls the operation of the microwave oscillator so that the internal temperature of the food is 25°C or lower and is higher than the surface temperature of the food, and so that the internal temperature of the food is 5°C or higher when the food is a food selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, noodles, breads, alcoholic beverages, and fermented foods, 15°C or higher when the food is a vegetable, and 20°C or higher when the food is a fruit .
( 5 ) A microwave aging apparatus as described in ( 4 ) above, in which a large number of minute openings that block microwaves but allow air to pass through are provided on the inner wall of the aging chamber.
( 6 ) The microwave aging apparatus according to ( 5 ) above, wherein a large number of the minute openings are provided on each of a plurality of inner walls of the aging chamber.
( 7 ) The microwave aging apparatus according to any one of ( 4 ) to ( 6 ) above, wherein the aging chamber comprises a plurality of aging chambers.
( 8 ) A microwave aging apparatus described in any one of (4) to (7) above, wherein the control unit automatically controls the operation of the cooler and/or the blower fan so that the surface temperature of the food is kept below 5°C during aging.
( 9 ) A microwave aging apparatus as described in any one of (4) to (8) above, wherein the control unit automatically controls the operation of the microwave oscillator, the cooler, and the blower fan so that the temperature difference between the surface temperature and the internal temperature of the food during aging is 3 ° C or more.
( 10 ) The microwave aging device according to any one of ( 4 ) to ( 9 ) above, wherein the microwave oscillator irradiates microwaves for one hour or more during aging.
( 11 ) A microwave aging device according to any one of ( 4 ) to ( 10 ) above, wherein the control unit repeats, during aging, irradiating the microwave oscillator with microwaves for a certain period of time and then stopping the irradiation of microwaves for a certain period of time.
( 12 ) The microwave aging apparatus according to any one of ( 4 ) to ( 11 ) above, further comprising a UV lamp.
( 13 ) The microwave maturation apparatus according to any one of (4) to (12) above, wherein the food selected from the group consisting of fish eggs, dairy products , vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods is selected from the group consisting of manko, cheese, yogurt, sour cream, fermented butter, natto, tempeh, shio-koji , miso, soy sauce, mirin, vinegar, noodle dough, pasta dough, pizza dough, sake, shochu, beer, amazake, wine, bonito flakes, kusaya, shiokara, funazushi, anchovies, salami, black tea, goishi tea, oolong tea, and fermented tea.

The present invention is aimed at foods that have an inherent flavor that is a combination of aroma, taste, and texture, and in which these elements play a role in the deliciousness of the food in a ratio that is inherent to the food, and further in which the components that make up these elements are present in a well-balanced manner and in which the physical, chemical, and physiological interactions between the components form the subtle flavor of the food, thereby improving the sense of maturation, and the maturation period of the food maturation method can be shortened.
According to the present invention, it is possible to prepare food and drink with a well-balanced flavor overall, which has the aged flavor obtained by long-term aging, without going through a long aging period. During aging, the internal temperature of the food can be made higher than the surface temperature, so that the aging period can be shortened, and the growth of bacteria on the food surface can be suppressed and the amount of trimming can be reduced. In this way, the excellent feature of the present invention is that the flavor of food and drink can be improved in a short time and at low cost.
The food aging method, in which proteins, fats, carbohydrates, etc. in food are appropriately decomposed by the action of enzymes, fungi, salts, etc. without spoilage, and the aroma, taste, texture, color, chemical components, etc. are changed, can be widely applied to various foods, such as fermented foods, brewed products, confectionery, as well as meat, fish, fruit, etc., as a processing method. For example, it is possible to check the flavor improvement of food and drink by using tasty low molecular peptides and amino acids that contribute to the flavor of brewed foods such as miso, soy sauce, and sake, and to confirm that the aged feeling of the food and drink has been improved. In addition, pickles and salted foods originally use salt as an element, but by promoting the aging of food, it is possible to bring out the flavor improvement effect on the food, such as softening the salty taste of salted products and pickles, and giving them a strong, deep, and rounded flavor, which can be confirmed by sensory testing.

1 is a configuration diagram of a microwave aging device according to a first embodiment. FIG. FIG. 6 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 microwaves were continuously irradiated in Reference Example 1. 6 is a graph showing the measurement results of FIG. 5 . 1 is a table showing the measurement results of amino acid content for each aging condition in Reference Example 2. 8 is a graph showing the measurement results of FIG. 7 . 1 is a graph showing the measurement results of glutamic acid content for each aging condition in Reference Example 3. FIG. 13 is a diagram for explaining the test conditions for the sensory test in Reference Example 4. 1 is a graph showing the test results of a sensory test in Reference Example 4. FIG. 2 is a diagram showing the measurement results of the elongation resistance of pizza dough before baking in Example 1. FIG. 13 is a diagram showing the measurement results of the first derivative value of the stress of the pizza dough after baking in Example 2. 1 is a graph showing the results of a sensory test of amazake in Example 6. 1 is a graph showing the test results of a sensory test of the yogurt drink in Example 7. FIG. 13 shows test results after aging of Shio-Koji in Example 9.

[Foods to be aged]
The present invention is directed to foods in which the flavor inherent to the food is a combination of aroma, taste, and texture, and these elements play a role in the deliciousness of the food in a ratio inherent to the food, and further, the components that make up these elements are present in a good balance, and the physical, chemical, and physiological interactions between the components form the subtle flavor of the food, thereby improving the sense of maturity.

Specifically, the subject foods are those whose flavor is formed by the action of enzymes and/or microorganisms and/or salt, more specifically, foods selected from the group consisting of fish eggs, dairy products such as cheese, beans such as coffee beans, vegetables, fruits, noodles, bread, alcoholic beverages such as wine, and fermented foods (including fermented seasonings such as miso and soy sauce).

Preferred examples include roe such as dried mullet roe, cheese, yogurt, sour cream, fermented butter, natto, tempeh, coffee beans, cacao, shio-koji, miso, soy sauce, mirin, vinegar, noodle dough, pasta dough, pizza dough, sake, shochu, beer, amazake, wine, bonito flakes, kusaya, shiokara, funazushi, anchovies, salami, black tea, Goishicha (registered trademark), oolong tea, and fermented tea. The above list is merely an explanation of the wide range of applications of the present invention, and does not limit the application of the present invention to the foods listed here.
That is, the present invention is characterized by simultaneously heating the inside of a food by irradiating it with microwaves and cooling the surface of the food by blowing cold air, while keeping the inside temperature of the food higher than the surface temperature, and can be widely applied to the large-scale maturation of various foods, but is excellent in cooling the surface of the food, and is suitable for meat, poultry, fish, shellfish, shrimp, crab and other seafood, paste products such as ham, sausage, chikuwa and kamaboko, salted poultry, seafood and vegetables, dried fish such as dried fish, boiled fish, salted fish, grilled fish and seasoned fish, as well as raw dried foods, pickles, Japanese and Western fresh sweets, fresh cakes, fruits, vegetables, various fermented foods, brewed products, etc.
Furthermore, any food for which an improvement or improvement in the sense of maturation is desired, such as Japanese seasonings, processed marine products, processed livestock products, and cooked foods, which are made by appropriately mixing ingredients such as miso, soy sauce, mirin, vinegar, salt, and sugar, and heating them as necessary and then allowing them to stand for a period of time to mature the flavor, can be targeted, and it is possible to produce in a short period of time a food or drink with a favorable taste and aroma that would be obtained by long-term maturation. The maturation method of the present invention can be advantageously applied to the mass production of food or drink for which an improvement in the flavor of maturation, which requires a long period of time, is desired in as short a time as possible.

This microwave maturation method for foods improves the sense of maturation by ensuring that the components that make up the delicious aroma, taste, and texture of such foods are present in a balanced manner and that the physical, chemical, and physiological interactions between the components create a subtle flavor unique to the food.The method targets foods whose flavor is formed by the action of enzymes and/or microorganisms and/or salt, and is characterized in that the method heats the inside of the food by irradiating it with microwaves and cools the surface of the food by blowing cold air simultaneously, while keeping the internal temperature of the food higher than the surface temperature.

[Aging mechanism, etc.]
Foods whose flavor is formed by the action of enzymes and/or microorganisms and/or salt are foods in which the aroma, taste, texture, color, chemical components, etc. that make up the flavor change. Examples include fermented foods, which are foods that have become tastier through the action of microorganisms, and brewed products that use the fermentation process to produce alcoholic beverages (alcoholic beverages) and other foods (mainly liquid seasonings).
Generally, fermented foods (brewed foods) are shipped as products after a certain period of maturation after fermentation. There are many types of fermented or brewed foods, including sake, shochu, soy sauce, and miso. It is also well known that different types of koji mold are used depending on the type of brewed food. For sake, koji mold with strong enzymes that convert starch into sugar is used, while for miso, koji mold with strong enzymes that break down protein and create amino acids that give it umami flavor is used. That is, for sake, enzymes are produced by sprinkling spores of yellow koji mold (Aspergillus oryzae) on steamed rice as seed koji and cultivating for about two days. This is an important process in sake brewing, which requires delicate control according to the growth of koji mold. In the fermentation process of moromi, the enzymes stored in the koji break down the starch in the rice and supply the glucose necessary for alcoholic fermentation. At the same time, the enzymes break down the protein in the rice into amino acids, which form the flavor of the sake. Lactic acid bacteria also produce lactic acid to help the yeast grow.
For example, after fermentation, sake, wine, and other brewed alcoholic beverages are stored in low-temperature maturation tanks and aged for about six months before being shipped after adjusting the flavor and alcohol content. Such brewed (fermented) foods are stored at low temperatures because the oxidation of ingredients can cause quality deterioration such as flavor deterioration and coloring. The smell of aged sake is called hineka (old aroma), and this smell is caused by the enzymes contained in the sake, and it is a smell that becomes noticeable when it is stored at high temperatures during storage or after bottling. The hineka is a smell that seems to have aged strangely too far, and is similar to the "aged aroma" found in aged sake. If it is judged to be unpleasant, it is called "old aroma," and if it is judged to be pleasant, it is called "aged aroma." It cannot be said that there is a boundary between the evaluation of such luxury goods.

Foods that are made by the action of a single type of microorganism include bread, beer, and natto, while miso and soy sauce, like sake, are made by the collaboration of mold, yeast, and bacteria. Yogurt is made from milk with the help of lactic acid bacteria and yeast. Cheese is also made by lactic acid bacteria, but blue cheese and camembert have different flavors and textures depending on the mold used. In the past, the enzyme (rennet) that solidifies cheese was extracted from cows, but nowadays the enzyme is made from a mold called Mucor. Also, bread rises due to the action of yeast and proteins contained in wheat. Mushrooms are also microorganisms, and are eaten as food as they are.

Regarding aging vegetables and fruits, first of all, there are methods for aging vegetables, such as drying, pickling in oil, letting it sit, salting, etc. To ripen vegetables by salting, the basic steps are to cut the vegetables to be used, pack them into a container, add salt (5% salt concentration) to about half the container, seal the container, and let it sit at room temperature for about a week. This is the same procedure as for pickles and sauerkraut.
Traditionally, pickles have been produced by methods such as pickling vegetables with seasonings such as salt, brewed vinegar, sugar, mirin, soy sauce, and seasonings. This is a method for producing so-called lightly pickled pickles, which are obtained in a short period of time using a simple production method, and the freshness, color, and shape of the vegetables are utilized, giving them a fresh taste. On the other hand, as vegetable pickles, old pickles and rice bran pickles, which have a rich sour taste and flavor, are produced with a lot of effort by steeping for a long period of time using fermentation by microorganisms, deepening the sense of maturity. It is said that it is difficult to obtain a sense of maturity in lightly pickled foods, such as old pickles and rice bran pickles. Similarly, it is difficult to obtain a sense of maturity even in seasoned umeboshi, which have a short shelf life and a short pickling time. As a method for enhancing the sense of maturity of pickles in a short period of time and in a simple manner, there is the microwave maturation method of the present invention, which can enhance the sense of maturity of fermented foods. Even so-called lightly pickled foods can be produced in a short period of time, with pickles having the flavor of old pickles and rice bran pickles. Recently, a food called black garlic, which is made by fermenting garlic, has become known, but when fermentation begins, the sulfur components in the raw garlic react to produce sulfurous acid gas, so the odor is a major problem that must be overcome in order to ferment garlic. The present invention can also be applied to the production of black garlic.
Next, regarding fruits, ripening or maturing fruits after harvest is a fine line between ruining the deliciousness of the fruit and spoiling it, and even a slight mistake can lead to spoilage. The ripening of any food requires delicate and difficult management of temperature, humidity, oxygen, and time, so research and improvements are being made every day. Ripening refers to further maturing harvested fruit, and there are many fruits that are not tasty unless they are ripened. Ripening is an act that can be explained scientifically, and is done on fruits with specific properties. Melons, kiwi fruits, pears, plums, and bananas are fruits that ripen after harvest. When this type of fruit is formed on the tree, the seeds inside are in a mature state, and the surrounding flesh is sufficiently nutritious, but the flesh itself stops growing to store this nutrition. After a suitable time, the starch stored in the flesh is broken down into glucose and fructose (which tastes sweet), and the pectin that connects the cell walls is broken down and the flesh becomes soft. In addition, aromatic components are released, and the fruit becomes sweet, soft, and fragrant for the first time. By carrying out the same operations as for ripening on fruits that are not ripened, the fruits can be made to taste even more delicious.

In addition, many foods undergo a drying process for aging. Conventionally, saltwater-pickled foods, in which fish such as salmon are soaked in saltwater, have been provided on the market. This soaking in saltwater is intended to prevent the progression of putrefaction while preventing quality deterioration, thereby improving quality. Soaking in saltwater at room temperature and low temperature can prevent the progression of putrefaction due to salt, but there is a limit to how long it can be done, and soaking and aging in saltwater cannot be done for a long time. Therefore, a aging method has been adopted in which food is kept in an unfrozen state in the ice temperature range from 0°C to the freezing point and aged. This food aging method allows aging to be performed while preventing the progression of putrefaction. The present invention improves the problem that "umami components" are not sufficiently developed as drying progresses, while taking advantage of the characteristics of the microwave aging device, which has a fast drying processing speed for cold air drying and is suitable for industrial drying. Although drying can increase the surface layer containing a large amount of umami components, the drawback that natural cold air drying requires a long time can be significantly improved. Foods that easily spoil, such as meat, fresh cakes, and fish and shellfish, can be aged in an extremely hygienic manner without spoilage, and the method of the present invention is also highly superior in terms of food hygiene.
According to the method of the present invention, the cold air does not wet or humidify the food, so the appearance and quality of the food are not damaged, and the food is aged in a physically and biologically clean state. One of the major features of the aging method of the present invention is that it can be applied to any type of food.

The microwave aging apparatus for foods selected from the group consisting of fish eggs, dairy products, beans, vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods to be used in the microwave aging method of the present invention will be described with reference to the drawings.
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 a device 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, the food to be aged is a food selected from the group consisting of fish eggs, dairy products, beans, vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods.

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 is used, which can obtain a higher frequency and output stability than a magnetron. The microwave oscillator 20 generates microwaves by continuously changing the frequency between 2.4 and 2.5 GHz. The microwaves generated 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 made uniform, so that the microwaves are irradiated to the food M with a uniform distribution, which promotes 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). By opening the aging chamber door 34, the user can put food M to be aged in and take it out of the aging chamber 33.

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 for controlling the temperature so that the surface temperature and 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 to control the microwave output from 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 to control the temperature. For example, 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 decrease the surface temperature of the food M by decreasing the temperature of the cold air from 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, the control unit 40 can perform fixed irradiation, which fixes the microwave oscillator 20 to oscillate at a constant output value and a constant frequency, as well as intermittent irradiation, which causes the microwave oscillator 20 to repeat oscillation and stop in a short period (for example, a period of several milliseconds), sweep irradiation, which changes the frequency of the microwave oscillator 20 over time, and continuous irradiation, which 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 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, 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 aging period of seven days.

In addition, the control unit 40 can 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 maturation 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 automatically control the surface temperature of the food to be maturated so that it is higher than the internal temperature by inputting information on the food to be maturated, such as the type of food (for example, fish eggs, dairy products, beans, vegetables, fruits, noodles, bread, alcoholic beverages, and fermented foods) 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 irradiate the food M with microwaves continuously throughout the maturation process, but the food M can be configured to be irradiated with microwaves 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 rays. In this embodiment, by irradiating the cold air circulating in the cooling chamber 13 and the aging chamber 33 with ultraviolet rays, 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 aging chamber 33 so that ultraviolet rays pass through a part of the wall (at least a part on the UV lamp 50 side) or to install the UV lamp 50 directly in the aging chamber 33. In that case, the ultraviolet rays generated by the UV lamp 50 can be irradiated onto the surface of the food M placed in the aging chamber 33 during aging of the food M. In this way, by directly irradiating the surface of the food M with ultraviolet rays 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 rays 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 method 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, 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 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, the microwave maturation method according to this embodiment can improve the maturation sensation not only of meat and seafood, but also of fish eggs, dairy products, beans, vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods, by ensuring that the components that make up the delicious elements of aroma, taste, and texture are present in a balanced manner and that the physical, chemical, and physiological interactions between each component form a subtle flavor unique to the food, and can also shorten the time it takes for the maturation sensation to improve.

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 exchanged 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.

<Reference 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 Reference Examples 1 to 3, about 300 g of beef ham meat (about 700 g in Reference Example 4) was placed in the microwave aging section and irradiated with microwaves of 100 W or less to conduct the tests. 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.

(Reference 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 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.

(Reference Example 2)
Next, in Reference Example 2, the amino acid content after aging for 7 days (for (A), the amino acid content of beef thigh meat before aging) was 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) was measured. Figure 7 shows the measurement results of the amino acid contents of (A) to (D) in 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.

(Reference 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 the amount (range of increase) of glutamic acid tended to increase with the aging period.

(Reference 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 Reference Example 4. As shown in FIG. 10, in beef thigh meat (E) aged for 7 days by continuous microwave irradiation, the temperature was controlled so that the cooling chamber temperature was -2°C, the surface temperature of the beef thigh meat was 2°C, and the internal temperature of the 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 the beef thigh meat was -2°C, and the internal temperature of the 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 the beef thigh meat was 8°C, and the internal temperature of the beef thigh meat was 8°C.

Figure 11 shows the results of the sensory test for 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, including 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. The evaluation points in Figure 11 show the average evaluation points of the three experts.

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. In addition, 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 Reference 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).

The foods that can be aged in the microwave aging device of the present invention are not limited to beef, as shown in Reference Examples 1 to 4, but can also be aged in foods in which the proteins, fats, carbohydrates, etc. in the food are appropriately decomposed without spoilage by the action of enzymes, fungi, salts, etc., and the aroma, taste, texture, color, chemical components, etc. that constitute the flavor are changed, as will be explained in the following examples. The technical scope of the present invention is not limited to the description of these examples. Various modifications and improvements can be made to these examples, and forms with such modifications or improvements are also included in the technical scope of the present invention.

The sense of maturation of foods evaluated after maturation is related to the fullness of flavor, a concept centered on flavor and taste, and within the fullness of flavor, foods that have a stronger sense of unity, breadth, and depth are evaluated as having a sense of maturity. Unity is evaluated as a smooth, well-balanced flavor, breadth is evaluated as a state in which the flavor and taste spreads in the mouth, and depth is evaluated as a state in which a solid taste can be felt as the base of the flavor, and is shown according to evaluation criteria unique to each food.

Example 1
Pizza dough maturation Physical properties were measured for pizza dough that had been aged for 6 hours by continuous microwave irradiation, pizza dough that had been aged for 8 days without microwave irradiation, and pizza dough that had not been aged immediately after forming.
Specifically, wheat flour, water, salt, and natural yeast were mixed, and the mixture was ground into crumbs over a period of 2 hours, and then kneaded for 10 to 30 minutes. After the final kneading, each was wrapped or vacuum packed to prepare the raw material (pizza dough that had not been aged immediately after molding). The raw material thus produced was continuously irradiated with microwaves, and the temperature was controlled so that the cooling chamber temperature was 0°C and the internal temperature of the dough was 10°C, and the raw material was aged for 6 hours, to obtain a pizza dough aged for 6 hours by continuous microwave irradiation. Furthermore, for comparison, the raw material thus produced was not irradiated with microwaves, and the temperature was controlled so that the cooling chamber temperature was 0°C and the internal temperature of the dough was 0°C, and the raw material was aged for 8 days, to obtain a pizza dough aged for 8 days without microwave irradiation. The obtained pizza dough was divided into portions of 150 g each and molded.

The elongation resistance of the pizza dough before baking was measured using an Extensograph (manufactured by Brabender) for pizza dough aged for 6 hours by continuous microwave irradiation, pizza dough aged for 8 days without microwave irradiation, and pizza dough that was not aged immediately after forming the pizza dough. Figure 12 shows the measurement results of the elongation resistance of the pizza dough before baking, where (A) is pizza dough aged for 8 days without microwave irradiation, (B) is pizza dough aged for 6 hours by continuous microwave irradiation, and (C) is pizza dough that was not aged immediately after forming the pizza dough. As shown in Figure 12, the maximum energy and elongation resistance of the pizza dough aged for 6 hours by continuous microwave irradiation (B) was significantly smaller than the pizza dough that was not aged immediately after forming the pizza dough (C), and was equivalent to the energy and elongation resistance of the pizza dough aged for 8 days without microwave irradiation (A). This shows that pizza dough aged for 6 hours under continuous microwave irradiation (B) can produce a dough equivalent to pizza dough aged for 8 days without microwave irradiation (A) by maturing for just 6 hours.

Furthermore, the stress of the pizza dough was measured after heating for 2 minutes in a wood-fired oven at 400 to 450 °C for pizza dough aged for 6 hours by continuous microwave irradiation, pizza dough aged for 8 days without microwave irradiation, and pizza dough that was not aged immediately after forming the pizza dough, and the first derivative value of the measured stress was calculated. Figure 13 is a graph showing the first derivative value of the measured stress, where (A) shows pizza dough aged for 8 days without microwave irradiation, (B) shows pizza dough aged for 6 hours by continuous microwave irradiation, and (C) shows pizza dough that was not aged immediately after forming the pizza dough. In addition, in the example shown in Figure 13, the average number of times the first derivative value of the stress became negative during the target time shown in the figure was counted. The fewer the number of times the first derivative value of the stress of the pizza dough after baking becomes negative, the less the change in stress, and it is considered that the pizza dough after baking has high elasticity and is chewy. In the example shown in FIG. 13, in the pizza dough (A) that was aged for 8 days without microwave irradiation, the average number of times that the first differential value of the stress became negative was 1, in the pizza dough (B) that was aged for 6 hours with continuous microwave irradiation, the average number of times that the first differential value of the stress became negative was 4, and in the pizza dough (C) that was not aged immediately after forming the pizza dough, the average number of times that the first differential value of the stress became negative was 10. From this, it was found that the pizza dough (B) that was aged for 6 hours with continuous microwave irradiation had a more chewy texture than the pizza dough (C) that was not aged immediately after forming the pizza dough, and that by aging for 6 hours, the chewy texture became closer to that of the pizza dough (A) that was aged for 8 days without microwave irradiation.

Example 2
Aging of Mozzarella Cheese Commercially available mozzarella cheese was used as the raw material. The concentration of free L-glutamic acid was measured for mozzarella cheese that was aged for 5 days by continuous microwave irradiation at a surface temperature of 5°C and an internal temperature of 15°C, and for mozzarella cheese that was aged for 5 days without microwave irradiation at a surface temperature and an internal temperature of 5°C. Specifically, 200 ml of distilled water was added to about 30 g of cheese, homogenized with a mixer, and the resulting suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 15 minutes. After centrifugation, the supernatant was taken out and the volume was constant, which was used as a sample solution, and the concentration of free L-glutamic acid was measured. The concentration of free L-glutamic acid was measured using an L-glutamic acid measurement kit "Yamasa" NEO (manufactured by Yamasa Shoyu Co., Ltd.).

The procedure for measuring L-glutamic acid is as follows:
(1) Dispense 10 μL of the prepared sample solution, the L-glutamic acid standard solution included in the L-glutamic acid measurement kit, and distilled water into each test tube.
(2) Dispense 450 μL of the R1 enzyme reagent solution contained in the L-glutamic acid measurement kit into each test tube, mix, and leave to stand at 20° C. to 30° C. for 20 minutes.
(3) 450 μL of the R2 enzyme reagent solution contained in the L-glutamic acid measurement kit was dispensed into each test tube and mixed. After standing at 20° C. to 30° C. for 20 minutes, the absorbance at 555 nm was measured using distilled water as a control.
(4) In addition, since the color of the sample may affect the absorbance, 900 μL of distilled water was dispensed into 10 μL of the sample as a sample color specimen, and the mixture was mixed. The sample was then allowed to stand at 20° C. to 30° C. for 20 minutes, and the absorbance at 555 nm was measured using distilled water as a control.
(5) Based on the measured absorbance, the concentration of free L-glutamic acid in each sample was calculated according to the following formula 1.
Concentration of L-glutamic acid (mg/L) = (A-B-R) ÷ (S-R) × 250 × dilution ratio ... (1)
In the above formula 1, A is the absorbance of the sample, S is the absorbance of the L-glutamic acid standard solution, R is the absorbance of distilled water, and B is the absorbance of the sample color.

The measurement results of L-glutamic acid are shown in the following Table 1. As shown in the following Table 1, it was found that the concentration of free L-glutamic acid in the mozzarella cheese of the example aged using the microwave aging device according to the present embodiment was about four times higher than that in the mozzarella cheese of the comparative example aged at 12° C. using a low-temperature incubator.

Furthermore, an external expert conducted a sensory test on mozzarella cheese that had been aged for three days by continuous microwave irradiation and mozzarella cheese that had been aged for three days without microwave irradiation. As a result of tasting each type of mozzarella cheese, it was concluded that in the mozzarella cheese of the embodiment, whey had dissolved into the water placed in the same container as the mozzarella cheese as a result of the aging process, and that the elasticity of the mozzarella cheese was completely different before and after aging.

Example 3
Maturation of green soybeans In Example 3, a ripening test was performed by microwave irradiation on green soybeans, green soybeans (black soybeans), and green soybeans (frozen). Specifically, about 500 g of green soybeans were placed in a petri dish with the pods still on, and a thermocouple was inserted into one of the green soybeans with the pods still on to measure the internal temperature of the green soybeans. Then, while controlling the temperature so that the temperature of the cooling chamber was 10°C and the internal temperature of the green soybeans was 25°C, the green soybeans were aged for one or two days by continuous irradiation with microwaves. For comparison, the green soybeans were aged for one or two days without irradiating with microwaves, while controlling the temperature so that the temperature of the cooling chamber was 10°C and the internal temperature of the green soybeans was 10°C. Then, the contents of sucrose, alanine, and glutamic acid were analyzed for each aged green soybean sample. The analysis was performed by the Japan Food Research Center, a general incorporated foundation, and sucrose was measured by high performance liquid chromatography, and free alanine and free glutamic acid were measured by an automatic amino acid analysis method. The ripening conditions and results of each sample are shown in Table 2 below.

As shown in Table 2 above, when edamame beans still in the pods were aged for one day at a surface temperature of 10°C and an internal temperature of 25°C, sucrose increased by 24%, alanine decreased by 11%, and glutamic acid increased by 109%. Similarly, when aged for two days, sucrose increased by 47%, alanine increased by 71%, and glutamic acid increased by 310%. Furthermore, as shown in Table 2 above, when edamame beans (black beans) were aged for one day while still in the pods at a surface temperature of 10°C and an internal temperature of 25°C, sucrose increased by 75%, alanine increased by 200%, and glutamic acid increased by 288% compared to before aging.

Although not shown in the table, when beans removed from the pods were aged for one day at a surface temperature of 0°C and an internal temperature of 15°C, sucrose increased by 15%, alanine increased by 32%, and glutamic acid increased by 31% compared to before aging. Furthermore, when edamame beans still in the pods were aged for three days at a surface temperature of 0°C and an internal temperature of 15°C, the sample analyzed on the first day showed no change in sucrose, alanine decreased by 33%, but glutamic acid increased by 20% compared to before aging. Furthermore, the sample analyzed on the third day showed a 15% increase in sucrose, a 29% decrease in alanine, and an 80% increase in glutamic acid.

Example 4
Aging of Ponkan As Example 4, chemical analysis was performed on Ponkan (immature before the start of aging) aged for 3 days by continuous microwave irradiation and Ponkan (immature before the start of aging) aged for 3 days without microwave irradiation. Specifically, one immature Ponkan with the skin still attached was cut in half, and a thermocouple was inserted into one of the Ponkan. Then, temperature control (temperature condition 1) was performed so that the temperature of the cooling chamber was -5°C and the internal temperature of the Ponkan was 20°C, and microwaves were continuously irradiated to mature for 3 days. In addition, temperature control (temperature condition 2) was performed so that the temperature of the cooling chamber was -20°C and the internal temperature of the Ponkan was 25°C, and microwaves were continuously irradiated to mature for 3 days. Furthermore, for comparison, without microwave irradiation, temperature control was performed so that the temperature of the cooling chamber was 0°C and the internal temperature of the Ponkan was 0°C, and aging was performed for 3 days.

Each Ponkan was frozen and stored, and the sugars sucrose, glucose, and fructose were analyzed, as well as the aroma components. The analysis was carried out by the Kagawa Industry Support Foundation, a public interest incorporated foundation, and sucrose, glucose, and fructose were measured using high performance liquid chromatography, while the aroma components were measured using headspace GC/MS. The analytical conditions are explained below.

Analysis conditions:
GC-MS (HS) device: GCMS-QP2010 + HS-20
Headspace sampler conditions
Oven temperature: 50°C
Sample line temperature: 150°C
Transfer line temperature: 150°C
Vial pressurization gas pressure: 50 kPa
Vial warming time: 20 minutes <GC conditions>
GC column: DB-5 (length 30 m, 0.25 mm ID, df=1.00 μm)
Injection mode: Split (1:50)
Control mode: constant pressure (100 kPa)
Column oven temperature: 50°C (3 min) → 10°C/min → 150°C → 20°C/min → 250°C (10 min)
<MS Conditions>
Interface temperature: 250°C
Ion source temperature: 200° C.
Ionization method: EI
Measurement mode: Scan
MS measurement time: Start time 1.5 min → End time 29 min MS measurement range: Start m/z = 41.00, End m/z = 700.00

The results of the analysis of the sugars sucrose, glucose, and fructose are shown in Table 3 below.

As shown in Table 3 above, unripe Ponkan oranges were used and aged for three days under temperature condition 1, with a surface temperature of -20°C and an internal temperature of 20°C. As a result, compared to the comparative example, in the example in which microwaves were irradiated, fructose increased by 11%, glucose increased by 14%, and sucrose increased by 4%. Also, compared to the comparative example, in the example in which microwaves were irradiated, sucrose decreased slightly, but fructose increased by 20% and glucose increased by 21%.

In addition, the analysis of aroma components using headspace GC/MS showed that no significant difference was observed between the peak areas in unripe Ponkans aged for three days while irradiating microwaves under temperature condition 1, with a surface temperature of -20°C and an internal temperature of 20°C. However, Ponkans aged for three days while irradiating microwaves under temperature condition 2, with a surface temperature of -5°C and an internal temperature of 25°C, contained higher amounts of the components Ethyl acetate, Propanoate <ethyl->, Isoamylalcohol, 2-Methyl-1-butanol, and Butyrate <2-methyl-, ethyl->, compared to Ponkans aged for three days without microwave irradiation, with a cooling room temperature of 0°C and an internal temperature of 0°C (comparison example). However, the amount of L-linalol was reduced compared to the comparison example. The detailed mechanism of action is unknown, but it is thought to be due to aging.

Example 5
Miso Aging In Example 5, a maturation test was carried out using commercially available miso (product name "Shikomi Miso", manufactured by Tachibana Honpo) as a raw material. The concentration of free L-glutamic acid was measured for miso that was aged for 24 days by continuous microwave irradiation at a surface temperature of 0°C and an internal temperature of 10°C, and for miso that was aged for 24 days without microwave irradiation at a surface temperature and internal temperature of 0°C. Specifically, 50 ml of distilled water was added to about 1 g of miso, homogenized in a mixer, and the resulting suspension was transferred to a centrifuge tube and centrifuged at 8000 rpm for 15 minutes. After centrifugation, the supernatant was taken out and the volume was adjusted to a constant value, which was used as a sample solution, and the concentration of free L-glutamic acid was measured. The concentration of free L-glutamic acid was measured using an L-glutamic acid measurement kit "Yamasa" NEO (manufactured by Yamasa Shoyu Co., Ltd.). The measurement results of L-glutamic acid showed that the concentration of free L-glutamic acid in the miso matured using the microwave maturation device according to this embodiment was about 36% higher than that of the miso of the comparative example matured at 0°C using a low-temperature incubator.

Example 6
Aging of Amazake In Example 6, a aging test was conducted using commercially available amazake (product name "Honmamon no Amazake", manufactured by Inaka Ii-naa Company) as the raw material. Sensory tests were conducted on amazake (Example) that was aged for 24 hours by continuously irradiating microwaves at a surface temperature of 0°C and an internal temperature of 10°C, and on amazake (Comparative Example) that was aged for 24 hours without irradiating microwaves at a surface temperature and an internal temperature of 5°C. Each sample was placed in a plastic cup in an amount of about 45 ml (3 tablespoons) and served with mineral water for rinsing the mouth. The sensory tests were conducted by a panel of 10 people with extensive eating experience at the Institute of Taste Science, a general incorporated foundation.

Specifically, the participants were asked to compare and evaluate the "sweetness" and "thickness" of the amazake of the Example that was aged for 24 hours with microwave irradiation, using the amazake of the Comparative Example that was aged for 24 hours without microwave irradiation as a control. They were also asked to comprehensively evaluate the amazake of the Comparative Example and the amazake of the Example, and to choose the one that they felt was "tastier." Furthermore, each panelist was asked to freely comment on each amazake.

Figure 14 shows the results of a sensory test on the "sweetness" and "thickness" of the Example aged for 24 hours with microwave irradiation, compared to the Comparative Example aged for 24 hours without microwave irradiation. The results show the results of the evaluation of "sweetness" and "thickness" on a five-point scale, "strong," "slightly strong," "same as Comparative Example," "slightly weak," and "weak," compared to the Comparative Example. As shown in Figure 14, the percentage of people who felt the "sweetness" was stronger, such as "strong" or "slightly strong," than the Comparative Example. On the other hand, the percentage of people who felt the "thickness" was stronger, such as "slightly weak," than the Comparative Example. In addition, seven out of ten panelists selected the Amazake of the Example as tastier than the Amazake of the Comparative Example. In addition, comments on the Amazake of the Example aged for 24 hours with microwave irradiation included "The sweetness still came out even after a while," "I felt a deep sweetness," and "It feels smooth."

(Example 7)
Aging of Yogurt Drink A aging test was carried out using a commercially available yogurt drink (product name "Meiji Probio Yogurt R-1 Drink Type", manufactured by Meiji Co., Ltd.) as a raw material. Specifically, a sensory test was carried out on a yogurt drink (Example) that was aged for 1 hour by continuous irradiation with microwaves at a surface temperature of 0°C and an internal temperature of 10°C, and a yogurt drink that was aged for 1 hour at a surface temperature and internal temperature of 5°C without irradiating with microwaves. The sensory test was carried out by a panel of 10 people with extensive food experience at the Institute of Science of Taste, a general incorporated foundation. First, the yogurt drinks of the Examples were compared and evaluated for "sourness,""sweetness," and "mouthfeel" with the Comparative Example as a control. Furthermore, each panelist was asked to freely comment on each yogurt drink. The samples were each placed in a plastic cup at about 45 ml (3 tablespoons) and served with mineral water for rinsing the mouth.

Figure 15 shows the results of a sensory test on "sourness," "sweetness," and "mouthfeel" for the Example aged for one hour with microwave irradiation, compared to the Comparative Example aged for one hour without microwave irradiation. As shown in Figure 15, no difference was observed in "mouthfeel" before and after aging, but the percentage of people who felt that the "sweetness" was "slightly strong" was higher than in the Comparative Example. On the other hand, the percentage of people who felt that the "sourness" was "weak" or "slightly weak" was higher than in the Comparative Example. In addition, comments on the Example aged for one hour with continuous microwave irradiation included "The sourness was mild and easy to drink," "The sweetness was felt immediately after drinking, and there was a slight aftertaste," and "The mouthfeel was mellow, so the sweetness felt a little strong."

(Example 8)
Production of mullet roe In Example 8, 1.2 kg of raw mullet roe (roe) was soaked in 1 L of Saumur liquid or powdered rock salt, and irradiated with microwaves so that the surface temperature was 0°C and the center temperature was 10°C. The Saumur liquid was prepared by adding 30 g of salt, 10 grains of white pepper, sliced onions, sliced lemons, sliced ginger, and bay leaves to 1 L of water, boiling it, and then cooling it. After irradiating with microwaves, the roe was further immersed in white wine for 1 to 2 days. The roe was taken out and weighted down, and 20 to 30% of the moisture was removed in 2 days. Furthermore, the roe was irradiated with microwaves for 3 to 4 days while adjusting the air volume in the range of 0 to 0.5 m/s so that the surface temperature was 0°C and the center temperature was 10°C, and mullet roe was obtained. This process may be performed in combination with microwave irradiation and sun drying. Tasting the resulting dried mullet roe revealed that the dried mullet roe aged under microwave irradiation for 3-4 days was equivalent to that aged for 3 years. In this way, by aging dried mullet roe under microwave irradiation, not only can the aging period be shortened, but it also has beneficial effects in terms of hygiene.

(Example 9)
In Example 9, a maturation test of Shio-Koji was carried out by soaking 5 go of commercially available raw koji (product name "Tsukumo Koji", Tsukumo Fermentation Works) and 150 g of salt in 700 ml of water. A comparison was made between Shio-Koji that was aged for 24 hours by continuous microwave irradiation at a surface temperature of 0°C and an internal temperature of 10°C (Example) and Shio-Koji that was aged for 24 hours without microwave irradiation at a surface and internal temperatures of 5°C (Comparative Example).

Figure 16 shows the state of salt koji after aging, with (A) salt koji aged for 24 hours without microwave irradiation at a surface and internal temperature of 5°C (Comparative Example), and (B) salt koji aged for 24 hours with continuous microwave irradiation at a surface temperature of 0°C and an internal temperature of 10°C (Example). As shown in Figure 16, in (B) salt koji aged for 24 hours with continuous microwave irradiation at a surface temperature of 0°C and an internal temperature of 10°C (Example), the rice koji has absorbed water and become soft, and aging is nearly complete, compared to (A) salt koji aged for 24 hours without microwave irradiation at a surface and internal temperature of 5°C (Comparative Example). Shio-koji is generally completed in one week (summer) to two weeks (winter) at room temperature, so by continuously irradiating microwaves (B) to a surface temperature of 0°C and an internal temperature of 10°C and aging for 24 hours (Example), it was found that by aging for only 24 hours, it was possible to obtain Shio-koji equivalent to that aged for one to two weeks.

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.

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 (13)

A microwave maturation method for foods that improves the sense of maturation so that the components that make up the delicious elements of aroma, taste, and texture are present in a balanced manner and the physical, chemical, and physiological interactions between the components form a subtle flavor unique to the food, and the method is targeted at foods in which the flavor is formed by the action of enzymes and/or microorganisms and/or salt, and the microwave irradiation is performed by simultaneously heating the inside of the food and cooling the surface of the food by blowing cold air, while keeping the internal temperature of the food at 25°C or less and making the internal temperature of the food higher than the surface temperature , and
In the case where the food is a food selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, noodles, bread, alcoholic beverages, and fermented foods, the internal temperature of the food is set to 5° C. or higher;
When the food is a vegetable, the internal temperature of the food is set to 15° C. or higher;
When the food is fruit, the microwave aging method is characterized in that the time required for the aged sensation to improve is shortened by setting the internal temperature of the food to 20°C or higher. The microwave aging method according to claim 1, in which microwaves are irradiated and cold air is blown so that the internal temperature of the food is 5°C or higher, the surface temperature of the food is less than 5°C, and the temperature difference between the surface temperature and the internal temperature of the food is 3°C or higher. 3. The microwave maturation method according to claim 1 or 2, wherein the food is selected from the group consisting of roe, cheese, yogurt, sour cream, fermented butter, natto, tempeh, coffee beans, cacao, shio-koji, miso, soy sauce, mirin, vinegar, noodle dough, pasta dough, pizza dough, sake, shochu, beer, amazake, wine , bonito flakes, kusaya, shiokara, funazushi, anchovies, salami, black tea, goishicha, oolong tea and fermented tea. A microwave aging apparatus for foods selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, vegetables, fruits, noodles, bread, alcoholic beverages, and fermented foods, for use in the microwave aging method according to claim 1 or 2,
A maturation chamber for storing the food;
A microwave oscillator that radiates microwaves to be irradiated into the aging chamber;
A cooler for cooling the air in the aging chamber;
A control unit .
The control unit controls the temperature of the food so that the internal temperature of the food is 25° C. or lower and the internal temperature of the food is higher than the surface temperature of the food,
A microwave aging device that controls the operation of the microwave oscillator so that the internal temperature of the food is 5°C or higher when the food is selected from the group consisting of meat, fish eggs, dairy products, coffee beans, cacao, noodles, bread, alcoholic beverages, and fermented foods, so that the internal temperature of the food is 15°C or higher when the food is vegetables, and so that the internal temperature of the food is 20°C or higher when the food is fruits . 5. The microwave aging apparatus according to claim 4 , wherein an inner wall of said aging chamber is provided with a large number of minute openings which block microwaves but allow air to pass through. 6. The microwave aging apparatus according to claim 5 , wherein a large number of the minute openings are provided on each of a plurality of inner walls of the aging chamber. 7. The microwave aging apparatus according to claim 4 , wherein the aging chamber comprises a plurality of aging chambers. 8. The microwave aging apparatus according to claim 4, wherein the control unit automatically controls the operation of the cooler and/or the blower fan so that the surface temperature of the food is kept below 5° C. during aging. A microwave aging apparatus as described in any one of claims 4 to 8, wherein the control unit automatically controls the operation of the microwave oscillator, the cooler and the blower fan so that the temperature difference between the surface temperature and the internal temperature of the food during aging is 3°C or more. 10. The microwave aging apparatus according to claim 4 , wherein the microwave oscillator irradiates microwaves for one hour or more during aging. 11. The microwave aging apparatus according to claim 4 , wherein the control unit causes the microwave oscillator to repeatedly irradiate microwaves for a certain period of time and stop irradiating microwaves for a certain period of time during aging. 12. The microwave aging apparatus according to claim 4 , further comprising a UV lamp. 13. The microwave maturation apparatus according to any one of claims 4 to 12, wherein the food selected from the group consisting of fish eggs, dairy products , vegetables, fruits, noodles, breads, alcoholic beverages, and fermented foods is selected from the group consisting of manko, cheese, yogurt, sour cream, fermented butter , natto, tempeh, shio-koji, miso, soy sauce, mirin, vinegar, noodle dough, pasta dough, pizza dough, sake , shochu, beer, amazake, wine, bonito flakes, kusaya, shiokara , funazushi, anchovies, salami, black tea, goishicha, oolong tea, and fermented tea.