WO2023190552A1 - Thawing device for frozen bread and thawing method for frozen bread - Google Patents

Abstract

Provided is a technology that makes it possible to return frozen bread to a state that is close to freshly baked bread.　According to the present invention, a thawing device comprises a steam generation device that supplies water vapor to the inside of a thawing chamber, a heater that radiates infrared light at frozen bread that has been introduced into the thawing chamber, and a microwave radiation device that radiates microwaves into the thawing chamber. When frozen bread is to be thawed, the steam generation device, the heater, and the microwave radiation device are all run for the entirety of a heating period of, for example, 300 seconds. When the steam generation device is run, the gas inside the thawing chamber is kept at normal pressure while being discharged from the thawing chamber to create a flow of gas inside the thawing chamber.

Description

Frozen bread thawing device, frozen bread thawing method

The present invention relates to a technique for thawing frozen bread, such as a thawing device for frozen bread and a method for thawing frozen bread.

In recent years, frozen bread has rapidly become popular. Note that "frozen bread" in the present application does not refer to bread that is made from frozen dough before baking, but refers to bread that is made from baked bread that is cooled to room temperature, for example, and then refrozen.
For example, by thawing frozen bread for home use, the bread can be returned to a freshly baked state. Bread obtained by thawing frozen bread may be closer to freshly baked bread than bread sold unfrozen (in short, regular bread), and generally tastes better. For such reasons, frozen bread for home use has become popular in recent years.
Frozen bread for commercial use is also becoming popular. As mentioned above, the taste of frozen bread is similar to that of freshly baked bread, so for example, a large chain bread manufacturing and sales company sells frozen bread mass-produced using a central kitchen method. There are an increasing number of cases in which frozen bread is being introduced by supplying it to stores, which then thaw it and sell it. In addition, in recent years, small-scale bread shops that sell freshly baked bread (so-called town bakeries) have been experiencing a shortage of bakers, who do hard labor, so we will reduce the burden on bakers. Frozen bread is increasingly being used for this purpose.

The general purpose of thawing frozen bread is to return it to a state as close to "freshly baked" bread (or "ready-to-eat" bread as described below) by thawing the frozen bread.
Several techniques are used to make it possible to restore frozen bread to a state similar to freshly baked bread.
The first step is to irradiate frozen bread with microwaves. When frozen bread is irradiated with microwaves in the same manner as in a microwave oven, the dough of the frozen bread generates heat and thaws.
Techniques have also been used to supply steam to frozen bread. When steam is supplied to the frozen bread using a steamer, the heat given from the steam to the frozen bread progresses the thawing of the frozen bread dough. In addition, water vapor enters the frozen bread dough, increasing the moisture content of the frozen bread dough, especially crumbs (described later). This generally improves the taste and aging resistance of frozen bread after thawing, although this is not the case if the moisture content is increased excessively.
Another technique used is to irradiate frozen bread with far-infrared rays. For example, by irradiating the frozen bread with far infrared rays using a heater, heat is applied to the frozen bread dough, which progresses the thawing of the frozen bread dough. Furthermore, by irradiating far infrared rays, the moisture content of the bread crust (described later) can be reduced and the crispy or crunchy texture of the bread crust can be increased. This also generally improves the taste of frozen bread after thawing, unless the moisture content of the crust is excessively reduced.
The three techniques described above for supplying microwaves, steam, and far infrared rays to frozen bread may be used individually or in combination.

JP2000-279148 JP2014-031948

However, when frozen bread is thawed using conventional techniques, it is difficult to return the thawed frozen bread to a state similar to freshly baked bread.
When frozen bread is thawed using conventional techniques, the moisture content of the thawed frozen bread is lower than that of ``freshly baked'' bread, and furthermore, the moisture content of the thawed frozen bread is lower than that of ``freshly baked'' bread, and even more so than that of ``freshly baked'' bread. In most cases, the temperature will be lower than that of bread that has been baked for about 20 minutes (temperature is around 38℃).
In addition, this problem can be solved to some extent by lengthening the heating time with the supply of water vapor, but if the time required for thawing becomes longer, it becomes difficult to use the product for both domestic and commercial purposes. Yes, frozen bread will not be as convenient to use.

Before discussing the detailed challenges of bread thawing technology, we will first explain the composition of bread and how its deliciousness comes about.
Bread is made of crumb and crust. Crumb is the inner layer of bread, which is generally milky white. The crust is the surface of bread, also called the skin or outer layer, and is generally brown in color. By baking bread dough, bread crumbs and crusts are produced as follows.
When baking bread, consider baking bread dough at room temperature, for example, about 24°C.
When baking bread, the bottom of the dough comes into contact with a bed at a temperature of over 200°C from the beginning of baking, and the heat conduction from there causes the dough to expand as a whole, and dries in a short period of time, causing the bottom of the dough to touch the floor. It is in a state of being insulated to some extent.
On the other hand, the parts of the bread dough other than the bottom are conductively heated from the surface by the air and water vapor present in the baking chamber. The air within the baking chamber may also contain water vapor generated from the dough over time. The bread expands greatly during baking because the carbon dioxide gas bubbles generated by the fermentation of the dough, which are distributed in large quantities inside the dough, contain water vapor generated from the hydrated starch. Some of the water escapes from the dough, but essentially remains inside the dough. In the crumb, the hydrated starch becomes gelatinized (gelatinized) and becomes sticky, which gives it a chewy texture. On the other hand, on the surface of bread dough, the pregelatinized starch dries and undergoes a Maillard reaction, resulting in a crust that is fragrant and has a crunchy or crunchy texture. Because the crust is dry and has little moisture, it has a low thermal conductivity and insulates the outside and inside of the dough. Therefore, the temperature at the center of the crumb is generally maintained at no more than 100° C. until the end of baking. Baking of the bread is completed while maintaining this state, and crumbs and crusts are produced.

As you can see from the above explanation, the taste of bread depends on ``having a well-dried crust'' to ensure the aroma and texture of the crust, and ``having a good crumb quality'' to ensure the texture of the crumb. It has a lot to do with the fact that it contains moisture.
All of these are related to the moisture content of bread. Of course, there are other factors that determine the deliciousness of bread, but in this application, the amount of water contained in bread is used as a factor for evaluating the deliciousness of bread.

The crust is dry, at least compared to the crumb. Therefore, mold does not grow on the crust, making it useful for making bread a preserved food. The crust also has the function of preventing moisture from escaping from the crumb. This prevents the crumb from drying out for a certain period of time.
The moisture contained in "freshly baked" bread immediately after baking is lost over time, but in general, bread that has cooled down about 20 minutes after baking is considered "ready to eat." ” is called.
However, as more time passes from the "ready-to-eat" state, the moisture contained in the crumb is gradually lost and the crumb ages. In the process of moisture being removed from the crumb, the moisture contained in the crumb first transfers to the crust, and a phenomenon occurs in which the moisture content of the crumb and crust becomes equal. When this phenomenon occurs, the texture of the crust deteriorates and the crumb becomes dry. Also, as the moisture is removed from the crust and the temperature drops, the starch that has been pregelatinized in the crumb becomes beta and hardens, resulting in a crumbly texture (this has been mentioned several times so far). (This is the meaning of the phrase "aging.") As the bread continues to dry further, both the crust and crumb become dry. As the crust, which has become overhydrated by receiving moisture from the crumb, dries, the texture of the crust temporarily recovers, but as the drying progresses further, the texture deteriorates again. In addition, the texture of the crumb deteriorates as the crumb dries, that is, as time passes from the "ready-to-eat" state.

Frozen bread is generally made by freezing bread whose temperature has dropped to a "ready-to-eat" level. Furthermore, when bread is frozen to produce frozen bread, some of the moisture in the bread is lost during the freezing process. Therefore, the amount of water contained in frozen bread is generally somewhat lower than that of "freshly baked" bread, and even more so than that of "ready-to-eat" bread.
If frozen bread can retain its original moisture content when thawed, thawed frozen bread will retain a somewhat lower moisture content than "freshly baked" bread. There should be. However, frozen bread thawed using conventional thawing methods does not retain the same moisture content as when it was frozen. This is because the moisture inside the frozen bread escapes to the outside due to the heating that is always performed during thawing.
As a result, the moisture content of frozen bread that has been thawed using the conventional thawing method is slightly lower than when it is freshly baked, and even lower than when it is ready to eat. The amount of water it contains is even lower.
Conversely, if the thawed frozen bread maintains the moisture content originally contained in the frozen bread before thawing, at least the amount of moisture contained in the frozen bread before thawing is If the moisture content is maintained very close to the moisture content, the bread should be delicious enough, although the moisture content is somewhat lower than that contained in "ready-to-eat" bread.
When you thaw frozen bread, if the amount of water contained in the thawed frozen bread is approximately the same as or more than the amount of water originally contained in the "freshly baked" bread, then it is considered "freshly baked". The taste is the same as or better than that of `` bread.'' In the first place, bread that has the same moisture content as ``freshly baked'' bread does not go through the distribution process, nor is it served at food and beverage establishments that have bread baking equipment. It can even be said that bread has the potential to have a new (and in some cases superior) taste that goes beyond conventional bread.
Bread obtained by thawing frozen bread with a moisture content exceeding the moisture content of the frozen bread may have such a new taste in some cases.

The present invention is a technology that can return frozen bread to a state close to freshly baked bread, for example, by thawing frozen bread so that the moisture content of the bread is approximately the same as the moisture content of the frozen bread before thawing. The purpose of the present invention is to provide a technique for thawing frozen bread that has a higher moisture content.

The inventor of the present application has conducted repeated research on methods for thawing frozen bread. As a result, we obtained the following knowledge.
As mentioned above, when frozen bread is thawed using the conventional method, the water content in frozen bread is reduced by heating, so the amount of water contained in thawed frozen bread is lower than the amount of water contained in frozen bread before thawing. is common.
However, as a result of repeated experiments under various conditions, the inventor of the present application found that when steam is used to thaw frozen bread, and when steam is applied to the bread, a gas flow is generated in the thawing chamber. The amount of water contained in thawed frozen bread is either approximately the same as the amount of water contained in the frozen bread before thawing, or in most cases, the amount of water contained in the frozen bread before thawing is greater than the amount of water contained in the frozen bread before thawing. We obtained the knowledge that it is possible to increase the moisture content and shorten the time required for thawing.
The present invention is based on such knowledge.

The present invention includes a thawing chamber into which frozen bread can be placed and a door that can be opened and closed to take in and take out the frozen bread, and a steam generator that supplies water vapor into the thawing chamber when the thawing chamber is operated. , a heater that irradiates far infrared rays to the frozen bread placed in the thawing chamber when the heater is activated; a microwave irradiation device that irradiates the inside of the thawing chamber with microwaves when the heater is activated; A thawing device for frozen bread includes a steam generator, the heater, and a control device that controls the microwave irradiation device.
This frozen bread thawing device (hereinafter sometimes simply referred to as the ``defrosting device'') uses the three types of heating means used in the conventional thawing device described in the background art section, namely, a steam generator and a steam generator. , a heater, and a microwave irradiation device. The steam generator, heater, and microwave irradiation device themselves may be the same as the conventional ones.
The control device controls a steam generator, a heater, and a microwave irradiation device as follows when thawing the frozen bread placed in the thawing chamber. Specifically, when the continuous time during which any one of the steam generator, the heater, and the microwave irradiation device is in operation is defined as a heating time period, the control device controls the heating time period at the beginning of the heating time period. The steam generator is operated from a predetermined timing in the heating time period to a predetermined timing in the heating time period, the heater is operated from a predetermined timing in the heating time period to the last timing in the heating time period, and The microwave irradiation device is operated from a predetermined timing to a predetermined timing after the heating time period.
Further, when the steam generator is operating during the heating time period, the air pressure inside the thawing chamber becomes normal pressure, and a gas flow from the thawing chamber to the outside of the thawing chamber occurs. It is configured.

The control device in the thawing device of the present application controls the steam generation device, the heater, and the microwave irradiation device during the heating time period, that is, the time period when any one of the steam generation device, the heater, and the microwave irradiation device is in operation. control the irradiation device. The control device operates the steam generator from the first timing of the heating time zone to a predetermined timing of the heating time zone, operates the heater from the predetermined timing of the heating time zone to the last timing of the heating time zone, and The microwave irradiation device is operated from a predetermined timing during the heating time period to a predetermined timing after the heating time period.
As is well known, microwaves efficiently heat moisture by starting the steam generator from the beginning of the heating period and supplying steam into the thawing chamber from the beginning of the heating period. On the other hand, it is not possible to efficiently heat frozen water, so if water vapor adheres to the surface of a very cold bread (for example, around -18°C or lower), the water vapor condensed on the surface of the bread will condense on the bread. This is because it provides latent heat of condensation, which is convenient for quickly thawing bread.
In addition, operating the heater from the predetermined timing of the heating time period to the final timing of the heating time period, in other words, irradiating the frozen bread with far infrared rays by the heater at the last timing of the heating time period is Of course, the increase in temperature caused by infrared rays has the effect of thawing frozen bread, but it is also effective in reducing the moisture content of the crust, which has become higher than the appropriate moisture content due to exposure to steam, to the appropriate moisture content. This is because in order to lower the temperature to 100%, it is necessary to irradiate the frozen bread with far infrared rays at the end of the heating period.
The microwave irradiation device operates from a predetermined timing during the heating time period to a predetermined timing thereafter. Microwaves irradiated to frozen bread during the heating period usually play a larger role than water vapor or far infrared rays when considering the amount of heat given to frozen bread as a standard. Conversely, the microwave irradiation device is designed to irradiate the frozen bread with microwaves within the time range in which the frozen bread is irradiated with microwaves sufficient to generate enough heat to thaw the frozen bread. Good too. The microwave may be irradiated from the beginning of the heating time period, may be irradiated until the last timing of the heating time period, or may be irradiated during the entire heating time period. Note that the microwave may be irradiated intermittently, for example, repeating 3 seconds of irradiation and 7 seconds of rest, or 5 seconds of irradiation and 5 seconds of rest. Nevertheless, even if such intermittent irradiation is repeated (or even if the microwave irradiation device operates intermittently), in the present application the microwave is continuously irradiated (the microwave irradiation device is operated intermittently). (operating continuously). Note that this situation is the same for the steam generator and the heater, and even if they operate intermittently, in this application, the steam generator and the heater are treated as operating continuously.
In the thawing device of the present invention, when the steam generator is operating during the heating time period, the air pressure inside the thawing chamber becomes normal pressure, and gas flows from the thawing chamber to the outside of the thawing chamber. It is configured as follows.
Prior to filing the present application, the applicant of this application reported that if the air pressure inside the thawing chamber was maintained higher than normal pressure when the steam generator was in operation, the steam generator would generate electricity, although the detailed mechanism is unknown. The water vapor that has been thawed penetrates into the frozen bread while it is thawing, and the amount of moisture contained in the frozen bread after thawing is significantly higher than the amount of moisture contained in the frozen bread that has been thawed using the conventional thawing method. I was discovering what would happen.
However, as a result of further research into thawing technology for frozen bread, we found that if a flow of gas, that is, air and water vapor, is created in the thawing chamber while the steam generator is operating, the pressure of the gas in the thawing chamber will rise to normal pressure. Even if the water vapor generated by the steam generator easily enters the frozen bread that is being thawed, the amount of water contained in the frozen bread after thawing will be lower than that of the frozen bread that was thawed using the conventional thawing method. It was found that the water content was significantly higher than that of bread. The amount of water contained in thawed frozen bread is approximately the same as the amount of water contained in frozen bread before thawing, or in most cases exceeds the amount of water contained in frozen bread before thawing.
The detailed mechanism by which such an effect occurs is unknown. However, during thawing, fresh water vapor continues to hit the frozen bread one after another, condensing on the surface of the frozen bread, and continuing to impart latent heat of condensation to the frozen bread. It seems that the amount of water contained in bread increases.
Moreover, the fact that the pressure inside the thawing chamber can be normal pressure eliminates the need for the casing containing the thawing chamber in the thawing device for frozen bread to be airtight to withstand high pressure, which reduces the manufacturing cost of the thawing device for frozen bread. can. In addition, if the moisture content of the bread obtained by thawing frozen bread becomes too high, for example, the crust may become sticky and the taste of the bread may deteriorate. While the moisture content can sometimes be excessive, frozen bread that is thawed using steam while creating a gas flow under normal pressure rarely has an excessively high moisture content. In other words, even if the technology of thawing frozen bread using water vapor while creating a gas flow under normal pressure can only perform rough control, it is possible to control the amount of moisture in the thawed bread by controlling the amount of water contained in the frozen bread. The water content can be kept in the category of approximately the same as or slightly higher than the water content that was previously used, and also has the effect that there is little risk of excess water content.
In addition, it is thought that the total amount of thermal energy given to the frozen bread by far infrared rays from the heater should be larger as the crust is thicker, or as the crust is drier, or as the crust is thicker and drier. . As mentioned above, the crust has the function of preventing moisture from escaping from the crumb. Therefore, when attempting to supply frozen bread with more water vapor derived moisture, thicker, drier, or thicker and drier crusts impede this. In this case, it is necessary, for example, to increase the flow of gas in the thawing chamber to pass through the crust and forcibly introduce moisture into the crumb. In this case, the thick, dry, or thick and dry crust becomes softer than it was originally, and there is a strong possibility that the taste of the frozen bread after thawing will deteriorate. Therefore, in order to make the crust drier, the total amount of thermal energy imparted by far infrared rays from the heater to the frozen bread can be reduced the thicker the crust, or the drier the crust, or the thicker and drier the crust. , it should be made larger.

The heating time period may be within 300 seconds, and the control device may operate the heater at least from a central timing of the heating time period to a final timing of the heating time period. In other words, the control device may control the heater in this manner. By operating the heater at least during the second half of the heating period of 300 seconds or less, the crust of thawed bread can be dried to the extent that the taste does not deteriorate, regardless of the type of bread. .
The heating time period may be within 300 seconds, and the control device may operate the steam generator from the first timing to the last timing of the heating time period. That is, the control device may control the steam generator in this manner. If the steam generator is operated during the entire heating period of 300 seconds or less, the moisture content of the thawed bread will be approximately the same as or greater than that of frozen bread, regardless of the type of bread. You will be able to do this.
Regardless of whether the heating time period is within 300 seconds, the control device controls all of the steam generator, the heater, and the microwave irradiation device from the first timing of the heating time period to the heating time period. It may be configured to operate until the last timing of the band. That is, the control device may control the heater, the microwave irradiation device, and the steam generator in this manner. If the heater, microwave irradiation device, and steam generator are all operated during the entire heating time period, it is useful to shorten the heating time period, for example, to within 300 seconds.
Note that, as is common to all the cases described in this paragraph, a relatively short heating time of 300 seconds or less is particularly suitable for operations in food and beverage establishments that provide thawed frozen bread to customers. The lower limit of the heating time period of 300 seconds or less is about 30 seconds (for example, 30 seconds), although it depends on the capabilities of the heater, microwave irradiation device, and steam generator. On the contrary, there is no particular upper limit to the heating time period.

As mentioned above, when the steam generator is operating during the heating period, the thawing device maintains the atmospheric pressure inside the thawing chamber at normal pressure, and gas flows from the thawing chamber to the outside of the thawing chamber. It looks like this.
In order to create a gas flow from the inside of the thawing chamber to the outside of the thawing chamber while maintaining normal pressure inside the thawing chamber, the following procedure may be used. For example, the thawing chamber may be provided with an exhaust pipe that communicates from the thawing chamber to the outside of the thawing chamber, and gas may flow from the thawing chamber to the outside of the thawing chamber via the exhaust pipe. Alternatively, when the door is closed to the thawing chamber, a gap is created at an appropriate position around the door to communicate the space inside and outside the thawing chamber, and the door is opened through the gap. A gas flow may occur from inside the thawing chamber to outside the thawing chamber.

The inventor of the present application also proposes a method performed by the frozen bread thawing apparatus described above as one aspect of the invention of the present application. The effects of this invention are equivalent to the effects of a thawing device for frozen bread.
An example method includes a thawing chamber having a door that can be opened and closed to take frozen bread in and out, and a steam generator that supplies water vapor into the thawing chamber when the thawing chamber is operated. a heater that irradiates the frozen bread placed in the thawing chamber with far infrared rays when the apparatus is operated; and a microwave irradiation device that irradiates the inside of the thawing chamber with microwaves when the apparatus is operated. , a control device for controlling the steam generator, the heater, and the microwave irradiation device. ).
In this thawing method, when the frozen bread placed in the thawing chamber is thawed, the control device is configured to continuously operate one of the steam generator, the heater, and the microwave irradiation device. When time is defined as a heating time period, the steam generator is operated from the first timing of the heating time period to a predetermined timing of the heating time period, and from the predetermined timing of the heating time period to the heating time period. The heater is operated until the last timing of the heating time period, and the microwave irradiation device is operated from a predetermined timing of the heating time period to a subsequent predetermined timing of the heating time period, and When the steam generator is in operation, the atmospheric pressure inside the thawing chamber is maintained at normal pressure, and a gas flow is caused from the thawing chamber to the outside of the thawing chamber.
The inventor of the present application also proposes, as an aspect of the invention of the present application, a method that can be executed using the above-described frozen bread thawing apparatus that does not have the above-mentioned control device. The method also includes manually controlling the steam generator, heater, and microwave irradiation device, or controlling the air pressure inside the defrosting chamber. Other than that point, the effects of the present invention are equivalent to those of a defrosting device for frozen bread.
An example of the method includes a thawing chamber having a door that can be opened and closed to take frozen bread in and out, and a steam generator that supplies water vapor into the thawing chamber when the thawing chamber is operated. a generator, a heater that irradiates far infrared rays to the frozen bread placed in the thawing chamber when the generator is operated, and a microwave irradiator that irradiates microwaves into the thawing chamber when the generator is operated. A method for thawing frozen bread carried out using a thawing device for frozen bread, comprising:
In this thawing method, when thawing the frozen bread placed in the thawing chamber, the continuous period during which any of the steam generator, the heater, and the microwave irradiation device is operating is defined as a heating time period. In this case, the steam generator is operated from the first timing of the heating time slot to a predetermined timing of the heating time slot, and the heater is operated from the predetermined timing of the heating time slot to the last timing of the heating time slot. and the microwave irradiation device is operated from a predetermined timing in the heating time zone to a predetermined timing after the heating time zone, and the steam generator is operated within the heating time zone. When the thawing chamber is in the thawing chamber, the atmospheric pressure inside the thawing chamber is set to normal pressure, and a gas flow is caused from inside the thawing chamber to outside the thawing chamber.
With the thawing method of the present application, thawed frozen bread can contain a moisture content greater than the moisture content of the frozen bread before thawing. As a result, the resulting thawed bread has better taste and is less susceptible to staleness than frozen bread thawed by conventional methods.

FIG. 1 is a perspective front view of a frozen bread thawing apparatus according to an embodiment. FIG. 2 is a perspective right side view of the frozen bread thawing device shown in FIG. 1; 2 is a perspective plan view of the frozen bread thawing device shown in FIG. 1. FIG. A timing chart showing the operating status of the steam generator, heater, and magnetron during the heating time period. Table showing the results of Test Example 1. Table showing the results of Test Example 2. Table showing the results of Test Example 3.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
In the description of each embodiment, common objects will be given the same reference numerals, and redundant descriptions will be omitted as the case may be.

A frozen bread thawing apparatus 1 according to this embodiment is as shown in FIGS. 1 to 3. FIG. 1 is a front view, FIG. 2 is a right side view, and FIG. 3 is a plan view.
The configuration of the frozen bread thawing device 1 may be the same as an existing thawing device including a steam generator, a heater, and a microwave irradiation device, except for the functions of a control device and valves, which will be described later. Therefore, the configuration of the decompressing device 1 will be explained in a relatively simple manner.

The defrosting device 1 includes a housing 10. The housing 10 is made of metal, for example, and has a substantially rectangular parallelepiped shape in this embodiment, although it is not limited thereto. A thawing chamber 11 is provided inside the housing 10. The thawing chamber 11 is a space in which frozen bread to be thawed can be placed. Although not limited to this, the thawing chamber 11 has a substantially rectangular parallelepiped shape. Although not limited to this, the size of the thawing chamber 11 in this embodiment is 405 mm in width x 645 mm in depth x 245 mm in height, and its volume is approximately 0.064 m ³ (64 l).
The inner wall surface of the thawing chamber 11 is designed to withstand water vapor or water supplied from a steam generator, which will be described later, and to withstand the heat of a heater, which will be described later. It is designed to reflect the microwaves emitted from the microwave irradiation device. Further, it is advantageous for the inner wall of the thawing chamber 11 to have a large heat storage capacity.
A door 12 is provided at the front of the housing 10. The door 12 is for opening and closing the thawing chamber 11. In FIG. 1, the door 12 is in a closed state, and in FIG. 3, the door 12 is in an open state. The door 12 is hinged to, for example, the housing 10 on the left side in FIG. 1, and can be opened and closed with respect to the housing 10.
Although not limited to this, the door 12 is rectangular, and in this embodiment, a glass window 12A for looking into the thawing chamber 11 from the outside is provided in the center thereof, although the shape is not limited to this. However, if there is a risk of heat radiation or microwave leakage from the glass window 12A, the glass window 12A can be omitted. When the door 12 is closed, the space between the edge of the door 12 and the housing 10 may be airtight, or a gap may be formed between the edge of the door 12 and the housing 10. This point will be discussed later.
Although not limited to this, an operation panel 13 is provided on the right side of the front surface of the casing 10 in FIG. 1 . The operation panel 13 is used to perform desired input to a control device, which will be described later. The operation panel 13 is provided with an input device for inputting input to the control device, but is not shown. As the input device, a known one such as a push button, a rotary dial, a touch panel, or any other known appropriate device may be used.

The thawing device 1 includes a steam generator 20 that supplies water vapor into the thawing chamber 11 when the thawing device 1 operates, and a steam generator 20 that irradiates far infrared rays to the frozen bread placed in the thawing chamber 11 when the thawing device 1 operates. It includes a heater 30, a microwave irradiation device that irradiates microwaves into the thawing chamber 11 when the heater 30 is operated, and a control device 50 that controls the steam generator 20, the heater 30, and the microwave irradiation device. . In this embodiment, the steam generator 20, the heater 30, the microwave irradiation device, and the control device 50 are all provided within the casing 10, but the control device 50 may be provided outside the casing 10. do not have.

The steam generator 20 is a so-called boiler. The steam generator 20 is capable of supplying water from the outside of the housing 10 to the inside thereof using a known or well-known method. The steam generator 20 is configured to boil the water therein using thermal power or electric power to generate water vapor. Although not limited to this, the steam generator 20 of this embodiment is a boiler that is equipped with a large 2 kW heater and has a small volume in order to improve responsiveness. Although the upper limit of the pressure of the steam supplied by this boiler is unlimited by design, the pressure of the steam supplied by the boiler is set to the pressure necessary to bring the pressure in the thawing chamber 11 to the predetermined pressure. . Further, the temperature of the steam supplied by the steam generator 20 is about 99°C at normal pressure, but it can rise to about 103°C when the pressure increases.
The steam generator 20 may operate intermittently.
The steam generator 20 has one end connected to the other end of a steam pipe 21 , which is a metal pipe, for example, and communicates with the thawing chamber 11 . The steam generator 20 is capable of supplying the steam generated therein into the thawing chamber 11 via the steam pipe 21.
Although not limited to this, the equivalent evaporation amount of the steam generator 20 in this embodiment, which is a boiler, can be determined by the following formula and is approximately 3.30 kg/h.
Equivalent evaporation amount = electricity consumption (2kw) x electric heating value (3.6MJ/kw) x boiler efficiency (95%) ÷ 2257kJ/kg

The heater 30 generates far infrared rays and irradiates the frozen bread placed in the thawing chamber 11 with the far infrared rays. As long as this is possible, the heater 30 may be an existing heater 30, and a known heater 30 may be used.
Although not limited to this, the heater 30 in this embodiment can be, for example, a sheathed heater, and is used in this embodiment, although it is not limited thereto. It is made of a metal tube filled with silica, and is highly insulating and waterproof, so it can be used even in an atmosphere filled with water vapor.
Although not limited to this, the heaters 30 in this embodiment are rod-shaped, and there are four heaters located directly below the ceiling and four directly above the floor (directly below the hearth plate 60) of the thawing chamber 11, and their length direction It is installed horizontally so as to match the front-rear direction of the device 1. That is, although not limited thereto, the heater 30 in this embodiment applies far infrared rays to the frozen bread from both above and below. In this embodiment, the upper heater 30 has a total power of 1500 W, and the lower heater 30 has a total power of 1000 W, but this is not limited to this either.
The sheathed heater can also be processed by bending. Therefore, the heater 30 does not have to be rod-shaped, and can be appropriately designed, for example, the upper heater 30 can be a series of W-shapes, and the lower heater 30 can be a series of U-shapes.
The heater 30 may operate intermittently.

The microwave irradiation device is composed of a magnetron 41 that generates microwaves and a waveguide 42 that guides the microwaves generated by the magnetron 41 into the thawing chamber 11, as is known or known.
The magnetron 41 may be, for example, a known or well-known device as long as it is a device capable of generating microwaves, and is constituted by, for example, an oscillation vacuum tube also called a magnetron tube. Although not limited to this, in this embodiment, the number of magnetrons 41 is two, and in this embodiment, the magnetrons 41 are provided at the rear of the thawing chamber 11 within the housing 10, although the number is not limited to this. Although not limited to this, the frequency of the microwaves generated by each magnetron 41 in this embodiment is 2450 MHz, which is a planned frequency that can be used in Japan, and its output is 1.1 kW.
The magnetron 41 may operate intermittently.
The waveguide 42 is a tube that guides the microwaves generated by the magnetron 41 to the thawing chamber 11. The configuration of the waveguide 42 may also be publicly known or known. Although not limited thereto, the waveguide 42 in this embodiment is a metal tube with a rectangular cross section, with its base end below each magnetron 41 and its tip extending horizontally toward the front of the thawing device 1. be. The upper surfaces of both waveguides 42 are flush with the floor of the thawing chamber 11 and are exposed within the thawing chamber 11. A large number of slits 42A, which are cuts extending in the left-right direction, are provided on the upper surface of the waveguide 42. The microwaves that have reached the inside of the waveguide 42 from the magnetron 41 go from the base end to the tip end of the waveguide 42, exit through a number of slits 42A in the middle, and enter the thawing chamber 11 or the inside of the thawing chamber 11. It is designed to irradiate frozen bread placed in a container. If the magnetron 41 operates intermittently, the microwave irradiation will also be intermittently.

In the thawing chamber 11, a hearth plate 60, which is a rectangular plate corresponding to the horizontal cross section of the thawing chamber 11, is laid horizontally just above the heater 30 directly above the floor surface.
The hearth plate 60 is a plate that prevents water vapor guided into the thawing chamber 11 from the steam generator 20 from entering the inside of the waveguide 42, and does not allow water vapor to pass through, but allows microwaves and far infrared rays to pass through. It stores heat. Therefore, although water vapor does not enter the waveguide 42, the microwave and far infrared rays from the heater 30 can heat the frozen bread that is being thawed without any problem.
As the hearth plate 60, "Bethermo F (trademark)", which is a heat-resistant board manufactured and sold by Nikko Kasei Co., Ltd., can be used.

As described above, the control device 50 controls the steam generator 20, the heater 30, and the microwave irradiation device (more precisely, the magnetron 41 included in the microwave irradiation device). The control device 50 is connected to each of the steam generator 20, the heater 30, and the magnetron 41 by signal lines (not shown) to enable this.
The control device 50 can be configured by a known or well-known device, and can be configured by a known or well-known computer or microcomputer. If the control device 50 is a computer, the computer includes, for example, a CPU (central processing unit) which is an arithmetic unit, a ROM (read only memory) which is a non-rewritable recording medium, and a RAM (RAM) which is a rewritable recording medium. random access memory) and an interface for connecting with the steam generator 20, heater 30, magnetron 41, and operation panel 13 via signal lines.
The steam generator 20, heater 30, and magnetron 41 are each operated by a signal sent from the control device 50 through a signal line (of course, as is well known, the operating status of each can also be controlled by the signal). ), it has started to stop again.
The control device 50 is also connected to the operation panel 13 by a signal line (not shown) so that it can receive input from the operation panel 13. The control device 50 generates signals for controlling the steam generator 20, the heater 30, and the magnetron 41 based on signals input from the operation panel 13 via the signal line.

The thawing device 1 in this embodiment is configured such that when the steam generator 20 is operating during the heating time period, the air pressure inside the thawing chamber becomes normal pressure, and the gas flow from the thawing chamber to the outside of the thawing chamber is controlled. It's starting to happen.
In order to satisfy such conditions, although not limited thereto, in this embodiment, an exhaust pipe 71, which is, for example, a metal pipe, is provided to connect the defrosting chamber 11 and the outside of the defrosting apparatus 1. When the pressure of the gas (mainly air and water vapor) in the thawing chamber 11 is about to rise, the gas in the thawing chamber 11 flows from the inside of the thawing chamber 11 communicating with each other via the exhaust pipe 71 to the outside of the thawing chamber 11. It starts to flow. As a result, the pressure of the gas within the thawing chamber 11 is maintained at normal pressure, and a gas flow is generated within the thawing chamber 11. The cross-sectional area of the exhaust pipe 71 is large enough to keep the pressure of the gas in the thawing chamber 11 at normal pressure, but small enough to prevent the temperature in the thawing chamber 11 from dropping too much.
Although not limited thereto, a valve 72 is provided at the opening of the exhaust pipe 71 on the outer surface of the defrosting device 1 in this embodiment. The valve 72 is conveniently provided in order to perform a test in which the pressure of the gas in the thawing chamber 11 is increased in Test Examples 1 to 3, which will be described later. If you don't have it, you don't need it.
In this embodiment, the valve 72 is provided on the left side of the housing 10 in FIG. 1, but of course this is not limited to this.
The valve 72 may be of a known or well-known type. The pressure within the thawing chamber 11 when the valve 72 discharges the gas within the thawing chamber 11 to the outside can be adjusted by its operation. The pressure inside the thawing chamber 11 when the valve 72 discharges the gas inside the thawing chamber 11 to the outside may be adjusted manually with respect to the valve 72, or it may be controlled by operating the operation panel 13. The device 50 may also perform this. In the latter case, the control device 50 will be connected to the valve 72 via a signal line.
As described above, the door 12 and the housing 10 may be configured such that a gap is left between the edge of the door 12 and the housing 10 when the door 12 is closed. If such a gap exists, the gap fulfills the function of the exhaust pipe 71 described above, that is, exhausts the gas in the thawing chamber 11 from the inside of the thawing chamber 11 provided in the housing 10 to the outside of the thawing chamber 11. If the exhaust pipe 71 is capable of performing the functions described above, it is also possible to omit the exhaust pipe 71 described above. The gap can be provided at an appropriate portion between the edge of the door 12 and the housing 10. For example, the gap may exist around the edge of the door 12, or it may exist only at an appropriate position on a part of the edge of the door 12, such as only on the upper side of the door 12, or only on the upper side and on the right side when viewed from the front. You can leave it there. Further, the width of the gap may or may not be the same at all positions in the length direction. In this embodiment, since the exhaust pipe 71 is present, there is no gap between the edge of the door 12 and the casing 10 when the door 12 is closed. As a technique for preventing the formation of a gap, a known or well-known technique such as using packing may be used.

The usage and operation of the thawing device 1 as described above, specifically, the usage and operation when thawing frozen bread will be explained.

When thawing frozen bread using the thawing device 1, the door 12 of the thawing device 1, which was in the closed state, is opened, and the frozen bread to be thawed is put into the thawing chamber 11. There may be more than one type of frozen bread. Next, the door 12 is closed. As a result, the thawing chamber 11 becomes airtight except for the valve 72.
Next, the user operates the operation panel 13 to determine the method for defrosting the frozen bread. Note that the operation panel 13 may be operated before putting the frozen bread into the thawing chamber 11 and closing the door 12.
What is determined is at least a heating time period (heating time period means a time period in which any of the steam generator 20, the heater 30, and the magnetron 41 of the microwave irradiation device is in operation). .) At which timing should the steam generator 20, the heater 30, and the magnetron 41 of the microwave irradiation device be operated, and at which timing should they not be operated. In addition to these, it is also possible to first determine the length of the heating time period.
Furthermore, in addition to these, the outputs of the steam generator 20, heater 30, and magnetron 41 may be determined. For example, the amount and temperature of water vapor generated by the steam generator 20, the amount of heat dissipated by the heater 30 (it is also possible to set different operating temperatures for the upper and lower heaters 30), and the amount of water vapor generated by the magnetron 41. The user can set the strength of the microwave to be used. The outputs of the steam generator 20, heater 30, and magnetron 41 can also be made to change over time during the heating time period.
In this embodiment, it is assumed that the outputs of the steam generator 20, heater 30, and magnetron 41 are all constant when they are in operation, and the inputs from the operation panel 13 are the length of the heating time period, It is assumed that the information indicates at what timing during the heating time zone the steam generator 20, heater 30, and magnetron 41 should be operated and at what timing they should not be operated.
Note that the length of the heating time period and the timing during the heating time period when the steam generator 20, the heater 30, and the magnetron 41 should be operated and when they should not be operated are determined as described below. This embodiment has limitations. If an input exceeding the limit is made from the operation panel 13, the control device 50 can, for example, treat the input as an error and not accept the input.
Furthermore, there may be a limit to the types of bread that can be thawed using a certain thawing device 1, and the same settings may be applicable to multiple types of frozen bread. Therefore, according to the user's advance settings or from the time of shipment by the manufacturer of the thawing device 1, the length of the heating time period and the timing during the heating time period are stored in the control device 50, for example, in the RAM, and the steam generator 20 and the timing during the heating time period are specified. It is also possible to record, for example, a plurality of pieces of data specifying all of the information regarding when the heater 30 and the magnetron 41 should be operated and when they should not be operated. If this has been done in advance, by selecting one of the multiple pieces of data, the user can input all of the above-mentioned information included in the selected data at once. It's convenient.
In this embodiment, before and after operating the operation panel 13, the pressure inside the thawing chamber 11 is adjusted when the valve 72 discharges the gas inside the thawing chamber 11 to the outside. As already mentioned, this adjustment may be performed by operating the operation panel 13 if it is possible.
In addition, regardless of the setting method, the total amount of thermal energy given to the frozen bread by far infrared rays from the heater 30 increases as the crust becomes thicker, or as the crust becomes drier, or as the crust becomes thicker and drier. It is thought that it should be made larger. In order to increase the total amount of thermal energy given to the frozen bread by far infrared rays, for example, the set temperature of the heater 30 may be increased, or the ratio of the operating time of the heater 30 to the heating time may be increased.

When the user operates the operation panel 13 and performs the above-mentioned input, the information is sent to the control device 50 via the signal line. For example, when a user operates a start switch on the operation panel 13, the control device 50 sends control signals to the steam generator 20, the heater 30, and the magnetron 41, respectively. Thereby, a heating time period is started, and thawing of the frozen bread in the thawing chamber 11 is started.
The heating time period means a time period in which any one of the steam generator 20, the heater 30, and the magnetron 41 of the microwave irradiation device is operating.

The length of the heating time period can be longer than that, but in this embodiment it is 300 seconds or less. The lower limit of the length of the heating time period is approximately 30 seconds. Although not limited to this, in this embodiment, the length of the heating period is 300 seconds.
Regardless of the length of the heating time slot, the steam generator 20 is operated at least during the heating time slot from the first timing of the heating time slot to a predetermined timing of the heating time slot. However, the length of time that the steam generator 20 operates is set so that the amount of moisture contained in the thawed frozen bread is approximately the same as or exceeds the amount of moisture contained in the frozen bread before thawing. . In this embodiment, although not limited thereto, the amount of water contained in the thawed frozen bread is set to be approximately the same as or greater than the amount of water contained in the frozen bread before thawing.
Regardless of the length of the heating time slot, the heater 30 is operated at least during the heating time slot from a predetermined timing of the heating time slot to the last timing of the heating time slot. However, the length of time that the heater 30 operates is set to be long enough for the crust in the thawed frozen bread to be in a sufficiently dry state.
Regardless of the length of the heating time slot, the magnetron 41 in the microwave irradiation device is operated during the heating time slot from a predetermined timing in the heating time slot to a predetermined timing after the heating time slot. However, the length of time during which the magnetron 41 operates is determined to be long enough to generate enough heat to thaw the frozen bread.

In this embodiment, the length of the heating time period is 300 seconds, but if the heating time period is within 300 seconds, the control device 50 controls the heater 30 at least from the center timing of the heating time period to the heating time period. Operate until the last timing. If the heater 30 is operated at least during the second half of the heating period of 300 seconds or less, the crust of the thawed bread can be dried to the extent that the taste does not deteriorate, regardless of the type of bread. can.
In this embodiment, the length of the heating time period is 300 seconds, but if the heating time period is within 300 seconds, the control device 50 controls the steam generator 20 from the first timing to the last timing of the heating time period. operate until. If the steam generator 20 is operated during the entire heating period of 300 seconds or less, the moisture content of the thawed bread can be kept within the range of "freshly baked" bread, regardless of the type of bread. can be accommodated in
FIG. 4A shows a timing chart showing ON and OFF of the steam generator 20, the heater 30, and the magnetron 41, which satisfy such conditions. The shaded time periods are the time periods when the steam generator 20, heater 30, and magnetron 41 are ON, and the non-shaded time periods are the time periods when they are OFF. be. In this example, the steam generator 20 operates for the first 150 seconds of a 300-second heating period and then stops, and the heater 30 stops for the first 150 seconds of the heating period. The magnetron 41 operates for the next 150 seconds, and the magnetron 41 operates from 37.5 seconds into the heating time period until 250 seconds have elapsed, and stops for the remaining time.
Regardless of the length of the heating time period, the steam generator 20, heater 30, and magnetron 41 may all remain ON during the entire heating time period. A timing chart showing this is shown in FIG. 4(B). In FIG. 4(B), the length of the heating time period is 300 seconds. If an attempt is made to shorten the heating time period, such as 30 seconds, the timing chart will become as shown in FIG. 4(B).

If the valve 72 is not provided, the air pressure in the thawing chamber 11 will become higher than normal pressure even if the air in the thawing chamber 11 expands as the temperature inside the thawing chamber 11 rises due to heating by the heater 30 and magnetron 41. There are cases. In the heating time zone, the atmospheric pressure in the thawing chamber 11 when the steam generator 20 is operating may become higher than normal pressure if the valve 72 is not provided. The valve 72 is adjusted so that the atmospheric pressure within the defrosting chamber 11 remains at a desired level even when such situations occur. In the case of the present invention in which the pressure of the gas in the thawing chamber 11 is set to normal pressure, the valve 72 may be left fully open if it exists.
Note that "when the steam generator 20 is operating" does not include when the steam generator 20 is changing from a stopped state to an operating state and when it is changing from an operating state to a stopped state. . This is common throughout this application.
For example, if the valve 72 is not activated, the steam generator 20 is activated so that the pressure of the gas in the thawing chamber 11 is higher than the pressure at which the valve 72 is activated and the gas in the thawing chamber 11 is discharged to the outside. may be supplied into the thawing chamber 11. Even in such a case, if the valve 72 is fully open, the gas (mainly air and water vapor) in the thawing chamber 11 will be discharged to the outside of the thawing chamber 11 through the valve 72. The internal pressure will be maintained at normal pressure. Further, by appropriately adjusting the degree of operation of the valve 72, it is also possible to maintain the pressure of the gas in the thawing chamber 11 at a desired pressure. When the gas in the thawing chamber 11 is exhausted to the outside of the thawing chamber 11 via the exhaust pipe 71 and the valve 72, a flow of gas is created within the thawing chamber 11.

When frozen bread is thawed during the heating period, the following phenomena generally occur.
Steam is supplied into the thawing chamber 11 from a steam generator 20. Water vapor condenses on the surface of the crust, and the latent heat of condensation heats the frozen bread from the surface. As a result, heat or hot water penetrates toward the center of the frozen bread while melting the ice crystals.
Microwaves are irradiated from a microwave irradiation device simultaneously with the start of supply of water vapor or after a delay. Microwaves heat the moisture near the center of frozen bread. The resulting heat helps the frozen bread defrost.
The frozen bread is heated by the heater 30 from the beginning, or from the middle to the end of the heating time period. As a result, the crust dries, and a Maillard reaction occurs in the crust, creating a fragrance. The Maillard reaction occurs when the temperature of the crust exceeds 160°C, and when the temperature exceeds 180°C, the crust turns brown. By drying the crust, the thickness and strength of the crust are maintained, and the shrinkage (deflation) of the frozen bread after thawing, which is caused by the crust becoming soft due to water vapor, is prevented.
Since the crust dries while adding moisture from steam, most of the moisture added to the thawed frozen bread (moisture in excess of the moisture content of the frozen bread before thawing) ends up in the crumb.
As mentioned above, there is a gas flow within the defrosting chamber 11. Therefore, the steam supplied from the steam generator 20 into the thawing chamber 11 is well absorbed by the frozen bread.

Thawing of frozen bread is completed in the above manner.
The user only has to open the door 12 and take out the thawed frozen bread from the thawing chamber 11.
≪Test example≫
The test results will be explained below. The test contents and test results of Test Examples 1 to 3 will be explained.
Using the above-described thawing device 1, a butter roll was thawed in Test Example 1, a loaf of bread was thawed in Test Example 2, and a French bread (mini-France) was thawed in Test Example 3.
In Test Examples 1 to 3, frozen bread was thawed using 10 different methods. All of the 10 methods adopted in Test Example 1 were also adopted in Test Examples 2 and 3.
The length of the heating period is 180 seconds. Further, the steam generator 20, the heater 30, and the magnetron 41 were turned ON (operating state) during all the heating time periods according to the timing chart shown in FIG. 4(B).
The output of the magnetron 41 was set to 500 W instead of the maximum output, and the operation was repeated for 3 seconds and stopped for 7 seconds during the entire heating period.
The set temperatures of the heaters 30 are 170°C for the upper heater 30 and 170°C for the lower heater 30, and 30 minutes in advance with the upper heater 30 at 170°C and the lower heater 30 at 170°C. After preheating, the frozen bread to be thawed was placed in the thawing chamber 11 of the thawing device 1 and thawed.
The steps up to this point are common to all 10 thawing methods adopted in Test Examples 1 to 3, respectively.

On the other hand, in Test Examples 1 to 3, the pressure of the gas in the thawing chamber 11 during the heating time period was set to two types. One is normal pressure, 0 kpa, and the other is 3 kpa.
In Test Examples 1 to 3, when the gas pressure in the thawing chamber 11 is 0 kpa, the gas flow in the thawing chamber 11 is 0, and from a weak state to a strong state. A total of six tests were conducted under five conditions in which gas flow existed.
In addition, in Test Examples 1 to 3, when the pressure of the gas in the thawing chamber 11 is 3 kpa, the gas flow in the thawing chamber 11 is in a state of 0 and a state from a weak state to a medium state. A total of four tests were conducted under three conditions in which gas flow existed within the thawing chamber 11.
In Test Examples 1 to 3, there are five different gas flow strengths when the gas pressure in the thawing chamber 11 is 0 kpa, and three different gas flow strengths when the gas pressure in the thawing chamber 11 is 3 kpa. A test was conducted on thawing frozen bread. Here, the strength of the gas flow was adjusted as follows.
The equivalent evaporation amount of the steam generator 20, which is a boiler in the thawing device 1 described in the above embodiment, that is, the thawing device 1 used in Test Examples 1 to 3, is approximately 3.30 kg/h. This means that the maximum amount of water vapor that the steam generator 20 can supply is 3.30 kg per hour. Although not shown in the figure, the steam generator 20 has a rotary handle that determines the amount of water vapor supplied at an appropriate position in the middle of the steam pipe 21 that connects the steam generator 20 and the thawing chamber 11. We are prepared. The handle can rotate the steam pipe 21 about 10 times from a completely closed state, but the steam pipe 21 will be fully open after 5 turns.
Naturally, when the handle is not rotated and the steam pipe 21 is completely closed, the amount of water vapor supplied from the steam generator 20 to the thawing chamber 11 is zero. On the other hand, when the steam pipe 21 is completely closed and the handle is rotated once, the steam pipe 21 is slightly opened, and 1/5 of the equivalent evaporated water vapor is released from the steam generator 20 into the thawing chamber 11. It will be supplied via pipe 21. Similarly, when the steam pipe 21 is completely closed, turning the handle twice will produce 2/5 of the equivalent evaporated water vapor, and rotating the handle 3 times will produce 3/5 of the equivalent evaporated water vapor, making 4 turns. 4/5 of the equivalent amount of evaporation, and when the steam is rotated five times, the amount of water vapor equivalent to the equivalent amount of evaporation is supplied from the steam generator 20 to the thawing chamber 11 via the steam pipe 21.
On the other hand, as already explained, the outer end of the exhaust pipe 71 that connects the inside and outside of the thawing chamber 11 in the thawing device 1 described in the above embodiment, that is, the thawing device 1 used in Test Examples 1 to 3 A valve 72 is present.
When maintaining the gas pressure in the thawing chamber 11 at 0 kpa, the valve 72 is kept fully open regardless of the amount of water vapor supplied from the steam generator 20 to the thawing chamber 11. As a result, regardless of the amount of water vapor supplied to the thawing chamber 11, the gas in the thawing chamber 11 easily leaks out to the outside, and the pressure of the gas in the thawing chamber 11 is maintained at 0 kpa.
Roughly speaking, the amount of gas leaking out from the thawing chamber 11 per unit time roughly corresponds to the amount of water vapor supplied from the steam generator 20 to the thawing chamber 11. Therefore, when the steam pipe 21 is completely closed (when the handle is rotated 0 times), the flow of gas in the thawing chamber 11 is virtually zero; When the handle is rotated, a gas flow occurs in the thawing chamber 11 due to the gas inside the thawing chamber 11 flowing out from the inside of the thawing chamber 11 to the outside of the thawing chamber 11, and the flow becomes larger each time the handle is rotated once. go.
When maintaining the gas pressure in the thawing chamber 11 at 3 kpa, the degree of opening of the valve 72 is adjusted so that the gas pressure in the thawing chamber 11 becomes 3 kpa. As described above, depending on how the handle is rotated, the amount of water vapor supplied from the steam generator 20 to the thawing chamber 11 changes from 0 to an amount equivalent to the equivalent amount of evaporation.
Roughly speaking, in order to maintain the gas pressure in the thawing chamber 11 at 3 kpa, the steam generator 2 The amount of water vapor supplied from the inside of the thawing chamber 11 to the thawing chamber 11 and the amount of gas exhausted from the inside of the thawing chamber 11 to the outside may be matched to balance the two. By adjusting the opening of the valve 72 to maintain such a balance, the pressure of the gas in the thawing chamber 11 can be controlled regardless of the amount of water vapor supplied from the steam generator 20 to the thawing chamber 11. It becomes possible to maintain the pressure at 3kpa.
Even when the pressure of the gas in the thawing chamber 11 is 3 kpa, the flow of gas in the thawing chamber 11 is virtually 0 when the steam pipe 21 is completely closed (the handle is rotated 0 times). Each time the handle is rotated once from the completely closed state of the steam pipe 21, the flow of gas in the thawing chamber 11 increases.
In the explanation of the results of Test Examples 1 to 3 detailed below, the phrases "Flow 0" to "Flow 5" appear, but they each refer to the state in which the handle is rotated 0 times to 5 times. and the valve 72 is adjusted as described above. This is the same whether the pressure of the gas in the thawing chamber 11 is 0 kpa or 3 kpa.
In addition, the measurement of the moisture content of each bread in Test Examples 1 to 3 was performed on crumbs and crusts collected according to the proportion of both in each bread, so it refers to the moisture content of the entire bread. .

<Test Example 1>
In Test Example 1, butter rolls were thawed. The butter rolls used in Test Example 1 were butter rolls manufactured and sold by Yamazaki Baking Co., Ltd. (12 Yamazaki butter rolls, JAN code: 4903110152934). The butter rolls were individually packaged to prevent moisture evaporation, and then frozen to produce frozen bread before thawing. The moisture content of the butter roll after freezing was 35% (35.00%). Therefore, in Test Example 1, the goal was set to make the moisture content of the butter roll after thawing 35%, which is the same as the moisture content of the bread before thawing, although it is not limited to this. In other words, the lower limit of the allowable moisture content of the butter roll after thawing is 35%.
Then, the butter roll, which is frozen bread, was thawed using the thawing device 1.
There are six types of thawing conditions: Flow 0 to Flow 5 when the gas pressure in the thawing chamber 11 is 0 kpa, and Flow 0 to Flow 3 when the gas pressure in the thawing chamber 11 is 3 kpa. There are 10 types in total including the previous 4 types.
The test results are shown in Figure 5.
When the pressure of the gas in the thawing chamber 11 is 0 kpa and the flow is 0 (when "0 kpa flow 0", the same notation will be used below by combining the pressure and flow of the gas in the thawing chamber 11), after thawing The moisture content of the butter roll was 34.41%, which was 0.59% lower than the moisture content of the butter roll before thawing, which was 35%.
Next, 0kpa flow 1, 0kpa flow 2, 0kpa flow 3, 0kpa flow 4, and 0kpa flow 5 all exceed the target lower limit of 35%, ranging from 35.61% for 0kpa flow 1 to 37.6% for 0kpa flow 5. Up to 72%, each time the flow of gas in the thawing chamber 11 increased, the moisture content of the thawed butter roll increased.
What should be noted is the difference between 0kpa flow 0 and 0kpa flow 1. The difference between the two is significantly larger than the difference between the other two arranged above and below, and even the existence of a small gas flow in the thawing chamber 11 called Flow 1 greatly contributes to the increase in the moisture content of the butter roll after thawing. I found out that it is.
All 3kpa data is for reference only.
When the 3kpa flow was 0, the moisture content of the butter roll after thawing was 34.76%, which was 0.24% lower than the moisture content of the butter roll before thawing, which was 35%. Next, at 3kpa flow 1, 3kpa flow 2, and 3kpa flow 3, all of them exceed the target lower limit of 35%, and from 36.07% of 3kpa flow 1 to 36.92% of 3kpa flow 3, the inside of the thawing chamber 11 As the gas flow increased, the moisture content of the thawed butter roll increased. However, when comparing butter rolls with the same flow rate after thawing, the moisture content of butter rolls at 3 kpa is generally higher than at 0 kpa. This indicates that when the pressure of the gas in the thawing chamber 11 is increased, more water vapor enters the inside of the butter roll that is being thawed.
When the gas pressure in the thawing chamber 11 is 3 kpa, the behavior of the butter roll after thawing with respect to the water content with respect to the flow is the same as when the gas pressure in the thawing chamber 11 is 0 kpa. Further, the result that the difference between 3 kpa flow 0 and 3 kpa flow 1 is significantly larger than the difference between the other two arranged above and below also corresponds to the case when the gas pressure in the thawing chamber 11 is 0 kpa. The amount of water contained in the butter roll after thawing is higher at 0 kpa flow 4 (37.47%) and 0 kpa flow 5 (37.72%) than at 3 kpa flow 3 (36.92%). many. This means that if the flow of gas in the thawing chamber 11 is made sufficiently large, even if the pressure of the gas in the thawing chamber 11 is set to normal pressure, the amount of water contained in the butter roll after thawing can be reduced. This shows that it is possible to sufficiently increase the size to the same extent as when pressurized. Also, for the same flow, the amount of moisture in the butter roll after thawing is higher when the pressure of the gas in the thawing chamber 11 is normal pressure than when the gas in the thawing chamber 11 is pressurized. small. This is thought to prevent the butter roll from having an excessive amount of moisture after thawing, which would cause the taste to deteriorate and the crust to become sticky.

<Test Example 2>
In Test Example 2, bread was thawed. The bread used in Test Example 2 was bread (Seven the Price bread, 8 slices) manufactured by Fujipan Co., Ltd. and sold by York Co., Ltd. at York Mart. Then, by freezing the bread, it was made into frozen bread before thawing. The moisture content of the bread after freezing was 41% (41.00%). Therefore, in Test Example 2, the target was set to make the moisture content of the bread after thawing to 41%, which is the same as the moisture content of the bread before thawing, although it is not limited to this. In other words, the lower limit of the allowable moisture content of bread after thawing is 41%.
Then, the frozen bread was thawed using the thawing device 1.
The thawing conditions are the same as in Test Example 1: 6 types from flow 0 to flow 5 when the gas pressure in the thawing chamber 11 is 0 kpa, and 6 types when the gas pressure in the thawing chamber 11 is 3 kpa. There were 10 types in total, including 4 types from flow 0 to flow 3 in certain cases.
The test results are shown in Figure 6.
At 0kpa flow 0, the moisture content of the bread after thawing was 40.30%, which was 0.70% lower than the moisture content of the bread before thawing, which was 41%.
Next, 0kpa flow 1, 0kpa flow 2, 0kpa flow 3, 0kpa flow 4, and 0kpa flow 5 all exceed the target lower limit of 41%, ranging from 41.77% for 0kpa flow 1 to 43.0% for 0kpa flow 5. Up to 76%, each time the flow of gas in the thawing chamber 11 increased, the moisture content of the thawed bread increased.
What should be noted is the difference between 0kpa flow 0 and 0kpa flow 1. The difference between the two is significantly larger than the difference between the other two arranged above and below, and even the existence of a small gas flow in the thawing chamber 11 called Flow 1 contributes greatly to the increase in the moisture content of the bread after thawing. I found out that
Even in Test Example 2, all data for 3 kpa are for reference.
When the 3kpa flow was 0, the moisture content of the bread after thawing was 41.09%, which was 0.09% higher than the moisture content of the bread before thawing, which was 41%. In this way, even if there is no flow, depending on the type of bread, by pressurizing the gas in the thawing chamber 11, the moisture content of the thawed bread can be made larger than the moisture content of the frozen bread before thawing. There are cases where it is possible. However, as mentioned above, this phenomenon occurs depending on the type of bread, and because sliced bread has a large exposed crumb area, it is easier for water vapor to penetrate inside compared to other breads, so the above phenomenon occurs. It is thought that this will occur.
Next, 3kpa flow 1, 3kpa flow 2, and 3kpa flow 3 all exceeded the target lower limit of 41%, and from 42.16% of 3kpa flow 1 to 44.17% of 3kpa flow 3, the inside of the thawing chamber 11 As the flow of gas increased, the moisture content of the thawed bread increased. However, when comparing breads with the same flow rate after defrosting, the moisture content of bread at 3 kpa is generally higher than at 0 kpa. This indicates that when the pressure of the gas in the thawing chamber 11 is increased, more water vapor enters the inside of the bread being thawed.
When the gas pressure in the thawing chamber 11 is 3 kpa, the behavior of the moisture content of the thawed bread with respect to the flow is the same as when the gas pressure in the thawing chamber 11 is 0 kpa. Further, the result that the difference between 3 kpa flow 0 and 3 kpa flow 1 is significantly larger than the difference between the other two arranged above and below also corresponds to the case when the gas pressure in the thawing chamber 11 is 0 kpa. The amount of water contained in the thawed bread is higher when 0 kpa flow 2 (42.63%) to 0 kpa flow 5 (43.76%) than when 3 kpa flow 1 (42.16%). . This means that if the flow of gas in the thawing chamber 11 is made sufficiently large, even if the pressure of the gas in the thawing chamber 11 is set to normal pressure, the amount of moisture contained in the thawed bread can be reduced by increasing the pressure inside the thawing chamber 11. This shows that it is possible to increase the amount of water obtained when compressed to a certain level. In addition, for the same flow, the moisture content of the bread after thawing is smaller when the pressure of the gas in the thawing chamber 11 is normal pressure than when the gas in the thawing chamber 11 is pressurized. . More specifically, when the pressure of the gas in the thawing chamber 11 is normal pressure, the increase in the moisture content of the bread after thawing is gradual when the flow is increased. This is thought to prevent the bread from having too much water content after thawing, resulting in a loss of flavor and a sticky surface.

<Test Example 3>
In Test Example 3, French bread was thawed. The French bread used in Test Example 3 was French bread (trade name: Ishigama Mini France (8)) manufactured and sold by Takaki Bakery Co., Ltd. By freezing the French bread, it was made into frozen bread before thawing. The moisture content of the French bread after freezing was 37% (37.00%). Therefore, in Test Example 3, the target was set to make the moisture content of the French bread after thawing 37%, which is the same as the moisture content of the bread before thawing, although it is not limited to this. In other words, the lower limit of the allowable moisture content of French bread after thawing is 37%.
Then, the frozen bread, French bread, was thawed using the thawing device 1.
There are six types of thawing conditions: Flow 0 to Flow 5 when the gas pressure in the thawing chamber 11 is 0 kpa, and Flow 0 to Flow 3 when the gas pressure in the thawing chamber 11 is 3 kpa. There are 10 types in total including the previous 4 types.
The test results are shown in Figure 7.
At 0kpa flow 0, the moisture content of the French bread after thawing was 36.67%, which was 0.33% lower than the moisture content of the French bread before thawing, which was 37%.
Next, 0kpa flow 1, 0kpa flow 2, 0kpa flow 3, 0kpa flow 4, and 0kpa flow 5 all exceed the target lower limit of 37%, ranging from 37.05% for 0kpa flow 1 to 39.0% for 0kpa flow 5. Up to 20%, each time the flow of gas in the thawing chamber 11 increased, the moisture content of the thawed French bread increased.
In Test Example 3, unlike Test Examples 1 and 2, the difference in the moisture content of French bread after thawing at 0 kpa flow 0 and 0 kpa flow 1 was greater than the difference in the moisture content of French bread after thawing at 0 kpa flow 1 and 0 kpa flow 2. The difference in the moisture content of French bread was greater. This difference from other breads is thought to be related to the thickness and dryness of the crust.
However, when the flow is made larger than that, the increase in moisture content of French bread after thawing is suppressed. From this, it has been found that even the presence of at least the small flow of gas in the thawing chamber 11, called flow 2, greatly contributes to the increase in the moisture content of the French bread after thawing.
Even in Test Example 3, the data for 3 kpa are for reference only.
When the 3kpa flow was 0, the moisture content of the French bread after thawing was 36.83%, which was 0.17% lower than the moisture content of the French bread before thawing, which was 37%. Next, at the time of 3kpa flow 1, 3kpa flow 2, and 3kpa flow 3, all exceeded the target lower limit of 37%, and from 38.24% of 3kpa flow 1 to 38.83% of 3kpa flow 3, the inside of the thawing chamber 11 As the flow of gas increased, the moisture content of the thawed French bread increased. However, when comparing French breads with the same flow rate after thawing, the moisture content of French bread is generally higher at 3 kpa than at 0 kpa. This indicates that when the pressure of the gas in the thawing chamber 11 is increased, more water vapor enters the interior of the French bread being thawed.
When the pressure of the gas in the thawing chamber 11 is 3 kpa, the behavior with respect to the flow regarding the moisture content of the French bread after thawing is generally the same as when the pressure of the gas in the thawing chamber 11 is 0 kpa. However, when the pressure of the gas in the thawing chamber 11 is 0 kpa, the upward jump in the moisture content in the thawed French bread between 0 kpa flow 1 and 0 kpa flow 2 causes the gas pressure in the thawing chamber 11 to increase. If the pressure is 3kpa, it is between 3kpa flow 0 and 3kpa flow 1. It is assumed that this is because French bread has a thick dry layer of crust, so if the gas in the thawing chamber 11 is pressurized, water vapor will more easily enter the crumb, and the effect of the flow of water vapor will be stronger.
The amount of water contained in French bread after thawing is higher at 0 kpa flow 4 (39.15%) and 0 kpa flow 5 (39.20%) than at 3 kpa flow 3 (38.83%). many. This means that if the flow of gas in the thawing chamber 11 is made sufficiently large, even if the pressure of the gas in the thawing chamber 11 is set to normal pressure, the amount of moisture contained in the thawed French bread can be reduced. This shows that it is possible to sufficiently increase the size to the same extent as when pressurized. Furthermore, for the same flow rate, the amount of moisture in the French bread after thawing is higher when the pressure of the gas in the thawing chamber 11 is normal pressure than when the gas in the thawing chamber 11 is pressurized. small. This is thought to prevent the French bread from having too much moisture after thawing, resulting in poor taste and sticky or soft crust.

[Summary of test examples]
Generally similar results were obtained for the three types of bread.
Regardless of the type of bread, by creating a gas flow in the thawing chamber 11 at normal pressure, the moisture content of the thawed bread can be made to be approximately the same as or greater than the moisture content of the frozen bread before thawing. That's what I found out. In any of the three types of bread according to Test Examples 1 to 3, by creating a gas flow in the thawing chamber 11 at normal pressure, the moisture content of the bread after thawing is equal to the moisture content of the frozen bread before thawing. exceeded.
Even if the flow is relatively weak such as Flow 1 and Flow 2, if there is a gas flow in the thawing chamber 11, the moisture content of the frozen bread after thawing will increase dramatically compared to when there is no gas flow. Understood.
Moreover, the increase in moisture content in the thawed bread by creating a gas flow in the thawing chamber 11 at normal pressure can be achieved by creating a gas flow in the thawing chamber 11 and pressurizing the gas in the thawing chamber 11. It turned out to be more restrained. This is thought to help prevent the moisture content of the bread from becoming excessive after thawing.

1 thawing device 11 thawing chamber 20 steam generator 30 heater 41 magnetron 42 waveguide 50 control device 72 valve

Claims (9)

a thawing chamber into which frozen bread can be placed and which has a door that can be opened and closed to take in and take out the frozen bread;
a steam generator supplying water vapor into the thawing chamber when it is activated;
a heater that irradiates far infrared rays to the frozen bread placed in the thawing chamber when the heater is operated;
a microwave irradiation device that irradiates microwaves into the thawing chamber when it is operated;
a control device that controls the steam generator, the heater, and the microwave irradiation device;
A frozen bread thawing device comprising:
When thawing the frozen bread placed in the thawing chamber, the control device defines a continuous period during which any of the steam generator, the heater, and the microwave irradiation device is operating as a heating time period. In this case, the steam generator is operated from the first timing of the heating time slot to a predetermined timing of the heating time slot, and the heater is operated from the predetermined timing of the heating time slot to the last timing of the heating time slot. and the microwave irradiation device is operated from a predetermined timing in the heating time period to a predetermined timing after the heating time period,
When the steam generator is in operation during the heating time period, the air pressure inside the thawing chamber becomes normal pressure, and a gas flow is generated from the thawing chamber to the outside of the thawing chamber. ing,
Frozen bread thawing device. The heating time period is within 300 seconds, and the control device operates the heater at least from a central timing of the heating time period to a final timing of the heating time period.
The apparatus for defrosting frozen bread according to claim 1. The heating time period is within 300 seconds, and the control device operates the steam generator from the first timing to the last timing of the heating time period.
The apparatus for defrosting frozen bread according to claim 1. The control device operates all of the steam generator, the heater, and the microwave irradiation device from the first timing of the heating time period to the last timing of the heating time period.
The apparatus for defrosting frozen bread according to claim 1. A discharge pipe is provided which is a pipe communicating from the thawing chamber to the outside of the thawing chamber, and gas flows from the thawing chamber to the outside of the thawing chamber through the discharge pipe.
The apparatus for defrosting frozen bread according to claim 1. When the door is closed to the thawing chamber, a gap is created at an appropriate position around the door to communicate the space inside and outside the thawing chamber, and the thawing chamber is opened through the gap. A gas flow is generated from the thawing chamber to the outside of the thawing chamber.
The apparatus for defrosting frozen bread according to claim 1. a thawing chamber into which frozen bread can be placed and which has a door that can be opened and closed to take in and take out the frozen bread;
a steam generator supplying water vapor into the thawing chamber when it is activated;
a heater that irradiates far infrared rays to the frozen bread placed in the thawing chamber when the heater is operated;
a microwave irradiation device that irradiates microwaves into the thawing chamber when it is operated;
a control device that controls the steam generator, the heater, and the microwave irradiation device;
A method for thawing frozen bread carried out in a frozen bread thawing device comprising:
In the control device, when defrosting the frozen bread placed in the thawing chamber, a continuous period in which any of the steam generator, the heater, and the microwave irradiation device is in operation is defined as a heating time period. In this case, the steam generator is operated from the first timing of the heating time slot to a predetermined timing of the heating time slot, and the heater is operated from the predetermined timing of the heating time slot to the last timing of the heating time slot. and operating the microwave irradiation device from a predetermined timing in the heating time period to a predetermined timing after the heating time period,
When the steam generator is operating during the heating time period, the atmospheric pressure in the thawing chamber is set to normal pressure, and a gas flow is caused from the thawing chamber to the outside of the thawing chamber.
How to thaw frozen bread. a thawing chamber into which frozen bread can be placed and which has a door that can be opened and closed to take in and take out the frozen bread;
a steam generator supplying water vapor into the thawing chamber when it is activated;
a heater that irradiates far infrared rays to the frozen bread placed in the thawing chamber when the heater is operated;
a microwave irradiation device that irradiates microwaves into the thawing chamber when it is operated;
A method for thawing frozen bread carried out using a frozen bread thawing device comprising:
When thawing the frozen bread placed in the thawing chamber, if the continuous time during which any of the steam generator, the heater, and the microwave irradiation device is in operation is defined as the heating time period, the The steam generator is operated from the first timing of the heating time slot to a predetermined timing of the heating time slot, and the heater is operated from the predetermined timing of the heating time slot to the last timing of the heating time slot, , operating the microwave irradiation device from a predetermined timing in the heating time period to a subsequent predetermined timing in the heating time period;
When the steam generator is operating during the heating time period, the atmospheric pressure in the thawing chamber is set to normal pressure, and a gas flow is caused from the thawing chamber to the outside of the thawing chamber.
How to thaw frozen bread. To make thawed frozen bread contain more moisture than the frozen bread had before thawing.
The method for thawing frozen bread according to claim 7 or 8.

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