JP2001061650A - Rice cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the increase in thermophilic bacillus regardless of a quantity of cooked rice being kept hot to surely prevent the generation of nasty smell, in a rice cooker wherein, when the time set by a timer for heating is up, a heating process is conducted to allow a heating source for cooking rice to generate heat until the temperature inside a pot monitored by a temperature sensor becomes one which can suppress the increase in thermophilic bacillus, and thereafter, a heat reserving process is continued. SOLUTION: This rice cooker is provided with a quantity-of-rice judgement means (ST30)-(ST36) and a heat reserving temperature correction means (ST37). The quantity-of-rice judgement means (ST30)-(ST36) judges a quantity of cooked rice being kept hot based on the magnitude of a gradient of a temperature detected by a temperature sensor which changes during a heating process. When the quantity of cooked rice being kept hot judged by the quantity-of-rice judgement means (ST30)-(ST36) is larger than a reference value, the heat reserving temperature correction means (ST37) raises the heat reserving temperature to a fungistatic temperature at which the increase in thermophilic bacillus can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to suppress the generation of offensive odor from cooked rice irrespective of the amount of cooked rice by changing the keeping temperature according to the amount of cooked rice.

[0002]

2. Description of the Related Art The temperature at which rice cooker is kept warm by a rice cooker is usually set at 70 ° C. in order to ensure good taste and prevent early drying of cooked rice.

[0003] On the other hand, rice cooked during warming is generally contaminated with various bacteria called thermophilic bacilli. The thermophilic bacillus is an organism that produces spores and reproduces them.
It has the property of germinating and growing when nutrients are present at a temperature of 70 ° C.

For this reason, when the cooked rice is kept at 70 ° C. for a long time, the thermophilic bacillus grows. When the number of bacteria multiplies to about 10 ⁷ cells / g, off-flavors are released from the cooked rice.

[0005] Therefore, when the thermophilic Bacillus bacterium proliferates and emits an offensive odor after the start of the heat retention, the inside of the kettle is filled with, for example, 85%.
Heating to about ° C, thereby providing a rice cooker having a function of heating a thermophilic Bacillus bacterium to suppress a subsequent odor. Specifically, Japanese Patent Application Laid-Open No. 9-276
In the invention of No. 134, when 5 hours have passed since the start of heat retention after cooking rice, the number of thermophilic Bacillus bacteria is reduced by burning the gas burner until the temperature in the pot rises to 80 ° C. or more. Like that.

[0006]

However, simply heating heated rice to reduce thermophilic Bacillus bacteria as in the invention of Japanese Patent Application Laid-Open No. 9-276134 described above cannot be used when the amount of heated rice is large. The cooked rice near the wall of the pot is heated sufficiently, but the cooked rice located in the center of the pot does not conduct enough heat and may not rise to a temperature that can suppress the growth. Therefore, in such a case, the thermophilic Bacillus bacteria breeding on the rice located in the center of the pot cannot be sufficiently reduced, and thereafter, when the rice is kept at 70 ° C. again, the rice has already propagated in the rice in the center of the pot. There is a problem that some thermophilic Bacillus bacteria grow more and an off-flavor is generated at an early stage.

[0007] The present invention has been made in view of the above points,
"A rice cooker that sequentially executes a rice cooking step of heating a pot with a heating source for rice to cook rice, and a heat keeping step of heating the pot with a heat keeping heat source to maintain the inside of the pot at a keeping temperature after the rice cooking step. A heating timer that starts after the rice cooking process is completed and that time-ups when thermophilic Bacillus bacteria multiply to the number of bacteria that emits an offensive odor from the heated rice, the heating timer comprising: When the time is up, the rice cooker executes a heating step of causing the heating source for rice cooking to generate heat until the temperature in the pot monitored by the temperature sensor reaches a temperature that can suppress the growth of the thermophilic bacillus, and then further continues the heat retention step. The object of the present invention is to suppress the growth of thermophilic Bacillus bacteria regardless of the amount of warm rice and to surely suppress the generation of offensive odor.

[0008]

Means for Solving the Problems <1> The technical means of the present invention for solving the above-mentioned problem is based on a technique based on "the magnitude of the temperature gradient of the temperature detected by the temperature sensor which changes during the execution of the heating step. Means for determining the amount of cooked rice by using
In the case where the amount of warm rice cooked by the rice amount determining means is larger than a reference amount, there is provided a warming temperature correcting means for raising the warming temperature to a bacteriostatic temperature at which the growth of thermophilic Bacillus bacteria can be suppressed. " .

The above technical means operates as follows.

By the time the heating timer started after the rice heating step has timed out, the thermophilic bacillus bacteria in the cooked rice approaches the state where the odor is released, as in the case of the above-described conventional one. come. However, when the heating timer has timed out, the temperature in the pot detected by the temperature sensor is equal to the temperature (for example, 80 ° C. to 110 ° C.) at which the temperature of the kettle detected by the temperature sensor suppresses the growth of thermophilic bacilli.
The heating step of heating the kettle with a heating rice cooker is performed until the temperature of the rice cooker is reduced, whereby the number of thermophilic Bacillus bacteria in the cooked rice is reduced.

On the other hand, according to the above technical means, the amount of warm rice is determined by the rice amount determining means during the execution of the heating step. That is, the temperature of the cooked rice is determined based on the temperature gradient of the temperature detected by the temperature sensor that detects the temperature in the pot during the execution of the heating step. Since the temperature may not rise to a temperature that suppresses the growth of the thermophilic Bacillus bacterium at the time of performing the heating step, in such a case, the subsequent warming temperature is set to a high temperature by the warming temperature correcting means. That is, in this case, in order to further prevent the thermophilic Bacillus bacteria from growing and emitting an unpleasant odor, the heat retention temperature is raised to a bacteriostatic temperature at which the growth and metabolism of the thermophilic Bacillus bacteria can be inhibited to suppress the growth. Thus, the thermophilic Bacillus is prevented from growing to such an extent that an unpleasant odor is emitted from the cooked rice. <2> The method according to the above item 1, wherein the bacteriostatic temperature is 70 ° C.
Above 80 ° C. or lower ”, it is possible to suppress the growth of thermophilic Bacillus bacteria while suppressing the drying speed of cooked rice during heat retention. <Claim 3> In the above paragraph 1 or 2, if the “heating timer has a set time of 6 to 8 hours”, the proliferation of thermophilic Bacillus bacteria after rice cooking is completed. The thermophilic bacillus can be effectively heated by heating the inside of the kettle at the time of its most prosperous.

[0012]

According to the above invention, when the amount of warm rice is too large to reduce thermophilic Bacillus bacteria,
Since the heat retention temperature is raised to a temperature at which the growth and metabolism of the thermophilic Bacillus bacterium is inhibited and the proliferation thereof is suppressed, the thermophilic bacillus bacterium involved in the generation of offensive odor can be further inhibited from growing. Therefore, according to the present invention, it is possible to surely suppress the generation of offensive odor at the time of keeping the temperature regardless of the amount of the kept rice.

In the items 2 and 3, the specific effects described in the respective items are further obtained in addition to the above effects.

[0014]

Next, embodiments of the present invention will be described.

FIG. 1 is a sectional view showing a configuration of a rice cooker according to an embodiment of the present invention.

As shown in FIG. 1, the rice cooker (1) comprises a kettle (2).
, An outer lid (4) attached to the inner body (3) so as to be openable and closable, and a gas burner (6) as a heating source for cooking rice for heating the bottom of the kettle (2). A heater (7) as a heat source for heating provided to surround the burner head of the gas burner (6), and a temperature sensor (8) contacting the bottom of the shuttle (2).
And an ignition device (9) for igniting the gas burner (6).

The gas burner (6) and the heater (7)
Is controlled by a control device (10) including a microcomputer, and a rice cooking process of cooking rice by controlling the amount of combustion of the gas burner (6) according to a set rice cooking pattern is executed. Further, when the rice cooking operation is completed, a warming step is performed in which the warming heater (7) is energized to keep the cooked rice in the pot (2) warm.

A microcomputer incorporated in the control device (10) stores a control program having the contents shown in the flowcharts of FIGS.

The operation of the rice cooker according to the present embodiment will be described below with reference to the flowcharts shown in FIGS.

When it is confirmed in step (ST1) that the rice cooker switch (12) provided in the operation section of the rice cooker (1) has been operated, the rice cooking process is executed in step (ST2). That is, the ignition device (9) is operated and gas is supplied to the gas burner (6) so that the gas burner (6) is burned according to a predetermined rice cooking pattern, and the temperature in the cooking pot (2) detected by the temperature sensor (8) indicates the rice cooking temperature. When the temperature reaches a completion temperature of 145 ° C., the rice cooking gas burner (6) is extinguished and a predetermined steaming operation is executed, thereby ending the rice cooking process. Next, in step (ST3), the heat retaining heater (7) is heated to start the heat retaining step. Next, in step (ST4), the heating timer (T) incorporated in the microcomputer is reset. From this point, the heating timer (T) is started, and the temperature H of the cooked rice is set to 70 ° C. I do. Next, when it is confirmed in step (ST5) that the temperature detected by the temperature sensor (8) for judging the temperature in the shuttle (2) is 70 ° C. or more, which is the warming temperature H, the temperature is maintained in step (ST6). The heater (7) is maintained in the OFF state, and thereafter, in step (ST7), it is monitored that the measurement time of the heating timer (T) has elapsed for 6 hours. That is, after the rice cooking process is completed, the heating timer (T) finishes measuring 6 hours, which is a time required for the thermophilic Bacillus bacteria to grow to a viable count enough to emit an unpleasant odor from the heated rice. Watch out for.

If the measurement time of the heating timer (T) is less than 6 hours, the temperature sensor is set at step (ST8).
The temperature inside the pot (2) detected by (8) is 70
The temperature is monitored to be less than ℃. If the temperature is less than the heat retention temperature H, the temperature sensor (8) detects the temperature in steps (ST9), (ST10) and (ST11).
(2) The heat retention heater (7) is heated until the internal temperature reaches the heat retention temperature H, and it is monitored whether the measurement time of the heating timer (T) does not exceed 6 hours.

As described above, while monitoring the measurement time of the heating timer (T) for 6 hours in steps (ST7) and (ST10), the heater (7) is turned on in steps (ST6) and (ST9).・ O
FF is performed and the heat retention process is performed. And a timer for heating
Step (T8) is when the measurement time of (T) exceeds 6 hours
If it can be confirmed in (ST10), the control shifts to the control in FIG. 3, and in steps (ST30) to (ST42) in FIG. 3, a heating step of heating and heating the pot (2) to 85 ° C. is executed.

That is, first, in step (ST30), the temperature sensor
Detection to pot the temperature (8) after storing the first temperature memory of the microcomputer (S ₁₎ as a first detection temperature, only 30 seconds the gas burner (6) in step (ST31) (ST32) (ST33) Burn. Next, the process waits for one minute to elapse in step (ST34), and the heat stored in the constituent wall of the pot (2)
(2) Wait for the rice to spread inside. Thereby, the pot (2)
And the temperature of the heated rice inside it are almost equal,
The temperature sensor (8) is in a state of substantially detecting the temperature of the cooked rice in the pot (2).

Next, in step (ST35), the temperature inside the shuttle (2) detected by the temperature sensor (8) is stored in the second temperature memory (S ₂ ) of the microcomputer as the second detected temperature. ), The second temperature memory (S ₂ ) and the first temperature memory (S
₁ ) The temperature difference (the temperature gradient of the detected temperature of the temperature sensor (8)) between the second detected temperature and the first detected temperature stored in (1) and the reference value S
0 (corresponding to the “reference amount” of the above-mentioned invention specific matter). If the former is smaller than the latter, the step (ST32)
(ST34) Hook during the total of 1 minute and 30 seconds of standby time
This means that the temperature rise (temperature gradient) in (2) was small, so in such a case, it was determined that the amount of warm rice in the kettle (2) was large, and the warming temperature H was set in step (ST37). Correct the temperature to 74 ° C. That is, the heat retention temperature set at 70 ° C. in step (ST4) is corrected to 74 ° C. Therefore, in the present embodiment, the functional unit of the microcomputer that raises the temperature of the warming temperature H to 74 ° C. when the amount of the warming cooked rice is large corresponds to the warming temperature correcting means as the above-described invention specific matter. Further, in the present embodiment, a control step (ST30) is performed until a temperature gradient corresponding to a temperature difference between the second detected temperature detected by the temperature sensor (8) and the second detected temperature is obtained and compared with the reference value S0. The functional part of the microcomputer that executes the instructions of (ST36) to (ST36) corresponds to the rice quantity determination means as the above-mentioned invention specific matter.

Next, in step (ST38), the gas burner (6) is burned, and in steps (ST39) and (ST40), the temperature sensor
Gas burner (6) until the detected temperature of (8) rises to 85 ° C
In the pot (2) in step (ST41) for 8 minutes only for 1 minute.
Maintain at 5 ° C. In step (ST41), the inside of the hook (2) is
When maintaining the temperature in ° C, the gas burner (6) may be intermittently burned while monitoring the temperature in the pot (2) with the temperature sensor (8), or the pot (2) may be heated with the heat retaining heater (7). Is also good. Then, when the pot (2) is heated in this way, if the amount of heat-retained rice is small, the heat is transferred to the rice located at the center of the pot (2), and the rice rises to 85 ° C. as a whole. In this way, by heating the pot (2) so that the temperature inside the pot (2) detected by the temperature sensor (8) becomes 85 ° C., vegetative thermophilic Bacillus bacteria grown in the heated rice can be removed. Heating reduces the number of viable bacteria and suppresses the generation of off-flavors during the subsequent heat retention.

Next, in steps (ST42) and (ST43), the temperature sensor
The heater (7) is heated until the temperature in the pot (2) detected by (8) reaches the temperature H, and the heater (7) is turned off until the temperature in the pot (2) becomes lower than the temperature H. (Refer to steps (ST44) and (ST45)), and turn on the heat retaining heater (7).
-Keep the inside of the hook (2) at the heat retention temperature H by repeating the OFF operation. At this time, if the amount of the cooked rice is large, the warming temperature H is corrected to 74 ° C. in step (ST37), so that when the warmed cooked rice is heated in steps (ST38) to (ST41), the central portion of the warmed cooked rice is heated. If the temperature does not rise to 85 ° C., which is the temperature that suppresses the growth of thermophilic Bacillus bacteria (when the amount of warm rice is large), the bacteriostatic temperature (70 ° C.) at which the growth of thermophilic Bacillus bacteria during subsequent warming can be suppressed. Since the cooked rice is kept at a temperature of 74 ° C., the generation of off-flavors can be suppressed as compared with the case where the cooked rice is kept at a normal keeping temperature H of 70 ° C., and this fact was experimentally confirmed. .
In addition, it was confirmed that when the bacteriostatic temperature is in the temperature range of more than 70 ° C. and 80 ° C. or less, the growth rate of thermophilic Bacillus bacteria can be suppressed while suppressing the drying speed of cooked rice. On the other hand, as a result of executing steps (ST30) to (ST36), when it is determined that the amount of warm rice is small (in the case of branching to “N” in step (ST36)), the warm temperature H is corrected without being corrected. ° C, but in such a case, when the heating step is performed in steps (ST38) to (ST41), the rice in the kettle (2) is heated to 85 ° C to its center and heated to 85 ° C. Since the number of thermophilic Bacillus bacteria is suppressed, even if thermophilic Bacillus bacteria grow by keeping rice cooked at 70 ° C thereafter, the time required for the thermophilic Bacillus bacteria to grow until they emit an off-odor becomes longer, and an off-odor occurs. Can be further delayed.

In the above-described embodiment, the heating step of heating the inside of the pot (2) to 85 ° C. is performed only once when six hours have passed since the completion of the rice cooking. However, the step (ST41) in FIG.
After the above control is executed, the control may be returned to the step (ST4) in FIG. 2 so that the heating step may be intermittently repeated during the heat retaining operation.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rice cooker according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a rice cooker control program according to the embodiment of the present invention.

FIG. 3 is a flowchart illustrating a rice cooker control program according to the embodiment of the present invention.

[Explanation of symbols]

 (2) ・ ・ ・ Hook (6) ・ ・ ・ Gas burner (8) ・ ・ ・ Temperature sensor (T) ・ ・ ・ Heating timer

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takashi Oya 2-26, Fukuzumi-cho, Nakagawa-ku, Nagoya-shi Rinnai Corporation (72) Inventor Atsushi Komuro 2-26, Fukuzumi-cho, Nakagawa-ku Nagoya-shi 72) Inventor Takahiro Kawachi 2-26 Fukuzumi-cho, Nakagawa-ku, Nagoya Rinnai F-term (reference) 4B055 AA02 BA51 BA62 CB03 CD22 GA13 GB06 GB08 GB12 GB18 GC05 GC06 GC26 GD02

Claims (3)

[Claims] 1. A rice cooking process in which a rice cooker is heated by a rice cooker to cook rice, and a heat-retention process in which the rice cooker is heated by a heat-retention heat source to maintain the inside of the rice cooker at a heat retaining temperature after the rice cooking process. A rice cooker to be executed, comprising a heating timer that starts after the end of the rice cooking process and that time-ups when thermophilic Bacillus bacteria multiply to a number of bacteria that emits an unpleasant odor from the heated rice. When the timer for heating has timed out, a heating step of causing the heating source for rice cooking to generate heat until the temperature in the pot monitored by the temperature sensor reaches a temperature that suppresses the growth of thermophilic Bacillus bacteria is performed, and then the heat retaining step is further performed. In the rice cooker to be continued, the rice quantity determining means for determining the amount of warm rice based on the magnitude of the temperature gradient of the temperature detected by the temperature sensor that changes when the heating step is performed, and the rice quantity determining means determines A rice cooker provided with a temperature-maintaining temperature correcting means for raising the temperature of the heated rice to a bacteriostatic temperature at which the growth of thermophilic Bacillus bacteria can be suppressed when the amount of the heated rice is larger than a reference amount. 2. The rice cooker according to claim 1, wherein the bacteriostatic temperature is more than 70 ° C. and 80 ° C. or less. 3. The rice cooker according to claim 1, wherein the heating timer has a set time of 6 to 8 hours.