JP3447199B2 - Manufacturing method of sealed packaged food - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to a subject food which is hermetically packaged and sterilized by heating, or cooked and sterilized, so that it can be stored for a long time at room temperature and can be eaten deliciously by simple re-cooking. The present invention relates to a method for manufacturing hermetically sealed food.

[0002]

2. Description of the Related Art Sealed packaged foods that are distributed at room temperature are required to prevent spoilage due to the growth of bacteria such as Clostridium, botulinum, Vibrio parahaemolyticus and Salmonella. Since the food contains a large amount of water or has a pH close to neutral is suitable for the growth of food spoilage bacteria, for example, the food has a pH of more than 5.5 and a water activity value of more than 0.85 is hermetically sealed. In the case of packaged foods, it is obligatory to heat the central part at 121 ° C for 4 minutes or more, or heat sterilize it by a method that has the same or higher effect. It is necessary that this temperature and time be achieved in the central portion of the packaged food, and generally, the larger the solid content or the higher the viscosity of the viscous material, the longer the heating time to the high temperature.

However, the longer the heat sterilization process is to the higher temperature, the less the freshness is, and the nutritional content, flavor, and color of foods.
Degradation of quality such as tone occurs. Recently, a sterilization method in which a shower retort is performed in an air-containing state after performing the cooking step extremely hygiene, and a method in which the temperature of the retort is performed at 125 to 130 ° C for a short time have been considered. There is a risk that bacteria will remain because the ₀ value cannot be taken sufficiently, and the latter is only about 3 to 5 minutes shorter than the retort, which does not improve the deterioration of quality. There are sterilizers that can be heated in a short time such as direct steam blow sterilization (VTIS, infusion), scraping heat exchangers, plate type sterilizers, etc. if it is a liquid type, but pasty foods or super high viscosity foods ( For sterilization of high-viscosity foods that cannot be pumped) and solid foods or solid-liquid coexisting foods, there is a strong demand for development of an apparatus having excellent workability and continuity.

Currently, Joule heat sterilizers, microwave heat sterilizers and the like using electromagnetic waves are in operation in the world, and utilization of these for short-time sterilization is being considered. However, these sterilizers have the problem of non-uniform heating peculiar to electromagnetic waves and electric currents, and it is difficult to uniformly heat flat or angular foods, and they are used only as auxiliary means. For example, in Japanese Unexamined Patent Publication (Kokai) No. 7-170954, a hermetically sealed low-pH food is irradiated with microwaves under a pressure of 0.5 to 2.8 kg / cm ² (gauge pressure) and heated to 110 to 130 ° C., and then the same pressure is applied. , The same temperature (relative humidity 30% or less). Further, in JP-A-7-255388, the above-mentioned JP-A-7-255388 is disclosed.
As if supplementing the contents of 170954, the microwave frequency is used in combination with 915 MHZ in addition to 2450 MHZ (megahertz) in an attempt to reduce uneven heating. These methods are not satisfactory because they require rather long microwave sterilization time rather than microwave heating in a pressurized atmosphere in the presence of water vapor, and may cause quality deterioration.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a hermetically-sealed food product which can be distributed at room temperature, and has a short heat sterilization treatment time regardless of the type of the content food product and the size and shape after packaging. It is an object of the present invention to provide a method for producing a hermetically-sealed packaged food, which can suppress deterioration of quality such as nutrition, flavor, and color tone due to heat treatment, heating, and heating.

[0006]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the inventors of the present invention have earnestly studied and, as a result, have sealed a food in a packaging material and placed it in a pressurized atmosphere in which steam is present. The present invention has been completed by finding that the above-mentioned problems can be solved by a method characterized by heating by microwaves and then lowering the temperature.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The specific conditions will be described below. The target food product of the present invention is a paste food product, a solid food product, or a solid-liquid coexisting food product, and is easily applied and prepared foods (boiled foods etc.), dairy products (cheese etc.), soybean processed foods (uhana flower etc.) It can be widely applied to simmered foods and side dishes, and can be easily applied even if the hermetically sealed state has a flat shape or a corner.

At least a part or all of the packaging material for sealing the target food is preferably microwave permeable and has heat resistance at a sterilization temperature. As the material, polyethylene, polyester, polyethylene terephthalate or the like may be used. Examples thereof include a polymer and an ethylene-vinyl alcohol copolymer. The sealing is performed by a bag-shaped material or a container and a lid made of almost the same material by a known means such as a heat seal.

The extent to which water vapor is present depends on the relative humidity in the pressurized atmosphere (total pressure at atmospheric temperature (absolute pressure)
Calculated as a percentage of the water vapor partial pressure (absolute pressure) relative to
Abbreviated as RH. ), It is better to maintain above 30%. In this case, the atmosphere may contain other gas (for example, an inert gas such as air, nitrogen, carbon dioxide gas) in addition to water vapor.

The degree of pressurization is 0.5 kg / cm ² (gauge pressure expressed as a pressure difference from atmospheric pressure. Corresponding to 110 ° C., the same meaning hereinafter) to
3.0kg / cm ² (142 ° C), preferably 1.0kg / cm ² (119 ° C) ~
The range of 2.7 kg / cm ² (140 ℃) is good.

Microwave irradiation heating can be carried out uniformly under the above atmosphere so that the central temperature of the target food is 110 ° C to 140 ° C, preferably 119 ° C to 140 ° C in a short time.
The temperature can be raised to.

The holding time is inversely proportional to the set temperature, and the time required to achieve sterilization may be set. In the present invention, the central temperature is 110 ° C. for 10 minutes, or 121 ° C. for 7 minutes,
As a guide, 3 minutes at 130 ℃ or 1 minute at 140 ℃.
The microwave wavelength used was 2450 MHZ (megahertz), but it is not particularly limited.

When the heating temperature is lower than 110 ° C, sufficient sterilization cannot be performed. When the heating temperature is higher than 140 ° C, the time required for sterilization is shortened but the quality of food is deteriorated and the container It is easily deformed or torn. Further, in an atmosphere with a small amount of water vapor, micro-energy concentrates locally and only the edges and corners of the packaging material are burnt, which delays the temperature rise in the central portion.

This microwave heating has a relative humidity RH of 30%.
If it exceeds, the microwave output can be controlled so that the temperature difference between the central portion and the end portion is within 10 ° C.

The target food is sterilized and cooled. At this time, the center temperature of the target food is 70 ° C. or more from 70 ° C.
Cool the product to a temperature below ℃ within 3 minutes so that the quality (flavor, color tone, nutrition) of the food is not impaired.

For this reason, the temperature is preferably lowered in a pressurized atmosphere in order to prevent the destruction of the hermetically sealed material. Specifically, a part or all of the steam is replaced with a dry gas, and the internal pressure of the packaged food is reduced. Keep it.

A processing apparatus used in the present invention will be exemplarily described below for a target food in which a microwave permeable container having one or a plurality of accommodating parts is filled and sealed with one or a plurality of kinds of food. To do. The processing apparatus for the target food, which is the filled sealed food, is 1. 1. has a pressurized air port and / or a steam port and / or another gas port (nitrogen, carbon dioxide gas, etc.) for pressurization. 2. The target food is transported by an air-locked rotary valve, and 3. 3. A device for irradiating the sealed packaged food with microwaves from a waveguide provided on the belt conveyor or under the pressure after equalizing the pressure between inside and outside. It is possible to adjust the temperature under the pressure and the relative humidity to an ambient temperature of 145
A heat treatment device for maintaining a predetermined time in an atmosphere of ℃ or less,
5. It consists of a device that cools a sealed packaged food that has been sterilized by heating under pressure. With the manufacturing apparatus having all the apparatuses including the above main apparatuses (1 to 5), the following Example 1 and comparative examples
The following tests were conducted.

[0018]

EXAMPLES Examples of the present invention will be described below. However, the technical scope of the present invention is not limited to these examples.

Example 1 500 g of Unohana, which was prepared by adding soybean curd, carrot, bamboo shoot, green peas, chicken, seasoning, etc.
Was placed in a retort polypropylene bag of 300 mm in length and 200 mm in width (manufactured by Toppan Printing Co., Ltd., hereinafter referred to as retort bag) and heat-sealed. First, heat sterilization conditions are 121 ℃
× 7 minutes was set. 121 ° C = saturated vapor pressure 1.1 kg / cm ² Gauge pressure = saturated vapor 2.1 kg / cm ² Absolute pressure. After that, the absolute pressure is written in the parentheses, and the RH% calculated using the absolute pressure value as described above is shown.

The gauge pressure of the air in the can of the above-mentioned apparatus is used.
Over 20 seconds with steam of 6 kg / cm ² was sufficiently replaced and immediately with the water vapor partial pressure gauge pressure ^{0.3kg / cm 2 (1.3kg / cm} 2).
Next, air was injected to make the total pressure 1.1 kg / cm ² (2.1 kg / cm ² ). In this case, 1.3% against 2.1 or RH = 62%
Is. To check for local heating of the retort bag,
Optical fiber-thermometer sensors were previously attached to the center and edges of the food-filled retort pouch. Microwave irradiation was started on the bag with an electric output of 1 KW. In addition,
In the following Examples and Comparative Examples, the above-mentioned temperature sensor was similarly attached to the packaging material in which the target food was sealed, and the operation was performed.

At the initial stage of heating, the temperature tends to rise faster at the end portion than at the center portion of the bag, and variations in temperature were observed.
However, from the time when the core temperature exceeded 100 ℃, the difference in the difference narrowed, it did not rise after the end reached the target 121 ℃, and there was a state of waiting until the core temperature reached 121 ℃. . After the central temperature reached 121 ° C, the temperature was maintained for 7 minutes while controlling the microwave, and then in a cold water shower at 10 ° C in a pressurized atmosphere of less than 1.1 kg / cm ^2, which was lower than when the temperature was raised. After cooling, the temperature was lowered to 70 ° C within 1 minute. In terms of quality, there is no peeling of the seal of the retort bag,
No burnt charcoal is seen (appearance evaluation)
The flavor and texture were also excellent (sensory evaluation). Also, implemented products (
A storage test was also performed using the unopened product). After the cooking (filling), we used 10 ⁴ / g of Uranus flowers,
After 3 days of storage at 0 ° C, the number of bacteria was 0 × 10 ⁰ / g.
It was 0 × 10 ⁰ / g even after a month (measurement of the number of bacteria), so that aseptic condition was established.

Example 2 In Example 1, the steam partial pressure was 0.5 kg / cm ² (1.5 kg / cm ² ), and RH
This was set as Example 2 under the same conditions except that = 71% was set. As a result of the increase in the amount of water vapor in the can, a slight difference was observed in the temperature rising rate at the center, but the appearance of the retort pouch was better than in Example 1 in the appearance evaluation after the implementation. Moreover, the results of the sensory evaluation and the storage test were as good as those in Example 1.

Comparative Example 1 In Example 1, the water vapor partial pressure was 0.0 kg / cm ² (absolute pressure was 0.0 kg / cm 2).
² ) and 1.1 kg / cm ² (2.1 kg / cm ² )
cm ² ), therefore the same conditions were used except that RH = 0%, and this was set as Comparative Example 1. As a result, the temperature of the retort pouch was different between the center and the end, and the temperature at the end was higher than the set temperature of 121 ℃ by 3 to 5 ℃. The reason for this is considered to be that, as is generally said, the microwave effect is concentrated at the edge and the temperature rises, which is the tip effect. As a result, the seal of the retort pouch was easily peeled off, but unlike the later microwave irradiation with an electric output of 5 KW, no scorching of the retort pouch was observed. Although it is considered that the seal of the bag was peeled off, the bacterial count after holding at 37 ° C for 3 days was 10 ⁶ or more / g (thus, the observation after 1 month was stopped), and the sterilization did not occur.

Example 3 Example 3 was carried out under the same conditions except that the electric output of microwave irradiation was 5 KW. RH = 71%. The microwave was irradiated with an electric power of 5 KW until the core temperature rose to 121 ° C, and after reaching 121 ° C, the output was controlled to 1 KW. Initially, in this case as well, there was a difference in the initial temperature between the center and the end of the bag, and the end temperature was 123 to 124 ° C.
It increased by ~ 3 ° C, but it did not rise any further, and the core temperature
The condition of waiting until 121 ° C was observed. 12 at this time
The heating rate up to 1 ℃ was about 4 times faster than that at 1 KW. It was cooled in the same manner as in Example 1. In terms of quality, there is no peeling of the seal of the retort bag, and there is no scorching (appearance evaluation).
In addition, the flowers of Uto were excellent in color tone, flavor, and texture (sensory evaluation). The results of the storage test also showed that the number of bacteria was 0 after storage at 37 ° C for 3 days.
It was × 10 ⁰ / g, and it was 0 × 10 ⁰ / g even after one month under the same conditions (bacteria number measurement).

Comparative Example 2 This Comparative Example 2 is the same as Comparative Example 1 except that the microwave electric output is 5 KW.
In Example 3, the water vapor partial pressure is 0.0 kg / cm.
² (0.0 kg / cm ² ) and the internal pressure of the can is 1.1 kg /
It is also in cm ² (121 ° C). RH = 0%. 12
After reaching 1 ℃, the sterilization temperature was controlled by the output of 1 KW. There was a difference in temperature between the center and the end of the bag, and the end was higher than the set temperature of 121 ℃ by 5 to 8 ℃, and the temperature rise due to the tip effect was observed. In terms of quality, peeling of the seal from the retort bag and burning were seen. Uno's flower had a slightly darker color tone at the end of the retort pouch, and I felt awkward in flavor and texture. In the storage test, the number of bacteria after storage at 37 ° C for 3 days was 10 ⁶ or more / g, and it was not sterile.

Example 4 1,000 g of cooked Uno flowers (twice the weight of 500 g of the above four examples)
Example 4 was carried out under the same conditions as in Example 2 except that the sample was placed in a retort bag having a length of 350 mm and a width of 200 mm. RH
= 71%. The heating rate was twice as much as the weight when the internal volume was 500 g, and it took twice as long to reach 121 ° C. Initially, there was a variation in temperature, and the end of the retort pouch tended to heat up faster than the center. However, in the same manner as in Example 2, 121 ° C. could be controlled in both the central part and the end part. In terms of quality, even if the content of the flower of Ubo was doubled, the heating time was extended and the quality and fungus were the same as in Example 2. That is, it became sterile.

Example 5 In Examples 1 to 4 and Comparative Examples 1 to 2, a retort bag was used to test a flower of Usu, but in Comparative Examples 1 and 2 where RH = 0%, it is due to the above-mentioned tip effect. The following tests were conducted because heat tends to accumulate at the ends and cause charring and peeling off of the seal, and this tendency is likely to appear at a sterilization temperature of 121 ° C or higher.

[0028] A cheese prepared by emulsifying, heating, and stirring natural cream by adding cream, sugar, etc.
30) A round polypropylene base with round base (Sumitomo Bakelite Co., Ltd. capacity 300 ml, hereafter referred to as oval cup)
After adding 0 g and heat-sealing, microwave irradiation was performed so that the sterilization temperature was 130 ° C. The internal pressure of the can is 1.8 kg / cm ² (2.8 k
g / cm ² . (Corresponding to 130 ° C), first add 1.0k of steam.
The pressure was adjusted to g / cm ² (2.0 kg / cm ² ), and then air was pressure-fed to make the total pressure 1.8 kg / cm ² . RH = 71%. In the same manner as in Example 1, optical fibers-sensors of a thermometer-were installed in the central portion and the end portion of the elliptical cup and irradiated with microwaves at an electric output of 1 KW. There was a variation in the temperature rise at the center and the end of the cup, and the temperature at the end tended to rise faster than at the center. However, from the point where the temperature exceeds 100 ℃, the speed slows down, and the temperature at the center approaches the temperature at the edge, that is, after the temperature at the edge reaches the target value of 130 ℃, the temperature does not rise any further and the core temperature reaches 130 ℃. There was a tendency to wait until. After the central temperature reaches 130 ℃, hold the temperature for 3 minutes by microwave control, and after the holding time, pressurize with air at less than 1.8 kg / cm ^{2 and} cool it to 70 ℃ within 2 minutes with a cold water shower at 10 ℃. ℃ was made. In terms of quality, the oval cup did not peel off, no scorching was observed (appearance evaluation), and the color, flavor and texture of this cream cheese preparation were excellent (sensory evaluation). Number of bacteria after 3 days maintained at 37 ° C. The results of the storage test is ⁰ × 10 0 / g, 1 month after ⁰ × 10 0 / g becomes the same conditions (number of cells measured)
Sterility was confirmed.

Example 6 Example 6 was carried out under the same conditions except that the electric power of microwave irradiation was 5 KW. The cooked cheese was placed in an elliptical cup, and after heat-sealing, the partial pressure of water vapor in the can was adjusted to 1.0 kg / cm ² (2.0 kg / cm ² ). Then, air was fed under pressure so that the total pressure was 1.8 kg / cm ² (2.8 kg / cm ² ). RH = 7
It is 1%. Next, microwave irradiation was performed with an electric output of 5 KW.
After reaching 130 ℃, the sterilization temperature was controlled by the electric output of 1 KW. There was a variation in the initial temperature at the center and the end of the cup, and at the beginning, the end tended to heat up faster than the center. However, from the point where the temperature exceeds 100 ° C, the speed slows down, the temperature at the center approaches the temperature at the edge, and the temperature at the edge becomes 2-3 ° C higher than the target temperature of 130 ° C, but the temperature does not rise further and the temperature at the center The tendency was to wait until the temperature reached 130 ° C. At this time, the heating rate up to 130 ℃ is
It was about 4 times faster than at 1 KW. After the central temperature reaches 130 ℃, hold the temperature for 3 minutes by controlling the microwave, and after the holding time, pressurize with air at 1.8 kg / cm ² and cool it to 70 ℃ within 2 minutes with a cold water shower at 10 ℃. And In terms of quality, the oval cup did not peel off, no scorching was observed (appearance evaluation), and the color, flavor and texture of this cream cheese preparation were excellent (sensory evaluation). Number of bacteria after 3 days maintained at 37 ° C. The results of the storage test is ⁰ × 10 0 / g, 1 month after ⁰ × 10 0 / g becomes the same conditions (number of cells measured)
Sterility was confirmed. From the above results, it was found that the target processing can be performed without being affected even by the elliptical cup.

Example 7 Example 7 was carried out under the same conditions except that the partial pressure of water vapor was changed to 1.8 kg / cm ² (2.8 kg / cm ² ). That is, the total pressure was 1.8 kg / cm ² and the steam was pressurized only with 1.8 kg / cm ² .
At this time, RH = 100%. Using the same amount of cooked cheese and elliptical cups as in Example 6, microwave irradiation was performed at a power of 5 KW so that the sterilization temperature was 130 ° C. After the sterilization temperature reached 130 ° C, the sterilization temperature was controlled by the output of 1 KW. The temperature rising situation tended to be the same as in Example 6, and the temperature at the edge reached 130 ° C, but there was a state in which the temperature did not rise any further and waited until the central temperature reached 130 ° C. After the central temperature reached 130 ° C, the temperature was maintained for 3 minutes while controlling the microwave, and the temperature was lowered in the same manner as in Example 6 to 70 ° C within 2 minutes. In terms of quality, there is no peeling of the oval cup seal, no scorching (appearance evaluation), and the color tone, flavor, and
The texture was also excellent (sensory evaluation). The result of the preservation test is also 37
The number of bacteria after storage for 3 days at 0 ° C was 0 × 10 ⁰ / g.
After one month also ⁰ × 10 0 / g next to (the number of bacteria measurement) sterility could be confirmed. From the above results, it was found that the elliptic cup can also serve the purpose of retort sterilization.

Comparative Example 3 In Example 6 and Example 7, the partial pressure of water vapor was 0.0 kg / cm ² (0.0 kg / cm ² ).
cm ² ) and 1.8 kg / cm ² (2.
(8 kg / cm ² ) except that the same conditions were used, and this was compared to Comparative Example 3
And RH = 0%. This was irradiated with microwaves at an output of 5 KW, and the temperature rise at the center and the edge of the cup was uneven, and the temperature at the edge rose faster than at the center. However, from the time when the temperature exceeded 100 ° C, the velocity became slow and the temperature at the center tended to be close to the temperature at the edges. The temperature at the edge will be 5-8 ° C higher than the target 130 ° C.
Until the core temperature reaches 130 ℃ without further increase in temperature,
The state of waiting was seen. At this time, the heating rate up to 130 ℃ was about 4 times faster than that at 1 KW. After the central temperature reached 130 ° C, the temperature was held for 3 minutes by controlling the microwave, and after the holding time, it was cooled by the above method of 10 ° C to 70 ° C within 2 minutes. In terms of quality, the peeling of the oval cup seal and charring of the edges were also seen. Storage test at 37 ℃
The number of bacteria after holding for 3 days is 10 ⁶ or more / g, it does not become aseptic,
The flavor and texture were not good enough to withstand eating.

Example 8 In Example 5, the water vapor partial pressure was 0.8 kg / cm.²(1.8kg / cm²), Can body
Pressure is 2.7kg / cm²(3.7kg / cm². (Corresponding to 140 ℃)
The conditions were the same except for the above, which was set as Example 8. At this time
R.H. = 49%. In the same manner as in Example 5, steam was fed in and empty.
After pumping the air, it was irradiated with microwaves at an output of 1 KW.
Example 5 Similarly, the temperature rises upward at the center and end of the cup.
There was some variation, but the difference was not close as the temperature increased.
The tip temperature reached the target temperature of 140 ° C,
Wait until the center temperature reaches 140 ° C without increasing the temperature
It was observed. 1 minute from when the core temperature reaches 140 ° C
After holding the temperature for a while under microwave control,
It was cooled in the same manner as above and brought to 70 ° C. within 3 minutes. quality
There is no peeling of the seal of the elliptical cup, and you can see the burnt charcoal.
Not (appearance evaluation)
The color tone, flavor, and texture were also excellent (sensory evaluation). Save test
The number of bacteria was 0 x 10 after 3 days of storage at 37 ° C. ⁰at / g
Under the same conditions, 0 × 10 even after 1 month⁰/ g (measurement of bacterial count)
Sterility was confirmed.

Example 9 300 g of Chikuzen simmered carrots, bamboo shoots, green peas, chicken, seasonings, etc., which were heated and stirred, were placed in the oval cup of Example 5 and heat-sealed to a sterilization temperature of 140 ° C. It was irradiated with microwaves. First, the can body pressure was adjusted so that water vapor had a pressure of 1.3 kg / cm ² (2.3 kg / cm ² ), and the pressure was 2.7 kg / cm ² (3.7 kg / cm ² ) with air. RH = 6 at this time
2%. Next, microwave irradiation was performed with an electric output of 1 KW. There was a difference in temperature between the center and the end of the oval cup, and there was a tendency for the temperature to rise above the sterilization temperature at the end, but the temperature was controlled at 140 ° C immediately. After that, hold the temperature for 1 minute while controlling the microwave,
It was cooled in the same manner as above and brought to 70 ° C. within 3 minutes. In terms of quality, neither the oval cup seal broke nor the charring was observed (appearance evaluation). This Chikuzen-ni was also excellent in color tone, flavor, and texture (sensory evaluation). Storage test results also 3 at 37 ℃
Day the number of bacteria after holding is ⁰ × 10 0 / g, 1 after the month also ⁰ × 10 0 / g next to (the number of bacteria measurement) sterility could be confirmed under the same conditions.

Example 10 Compared to Example 9, the same procedure as in Example 9 was performed except that 500 g of cooked Uranami was used as a target food, placed in a retort bag, and the microwave electric output was set to 5 KW. Example 10 is set. Water vapor pressure 1.3 kg / cm ² (2.3 kg / cm ² ), total pressure 2.7 kg / cm
² (3.7 kg / cm ² ), RH = 62%. Initially, in this case as well, there was a difference in the temperature rise between the center and the edge of the bag, and the temperature increased by 2-3 ° C from the center of the bag, but it did not rise any further and the center temperature was
The state of waiting until 0 ° C was observed. Center temperature is 14
After the temperature was maintained at 0 ° C. for 1 minute under the control of microwaves, the temperature was cooled by the same method as described above. In terms of quality, the retort pouches tended to peel off slightly, but there was no tear, no scorching was observed (appearance evaluation), and this union flower was also excellent in color tone, flavor, and texture (sensory evaluation). The result of the storage test is that the number of bacteria is 0 after storage at 37 ℃ for 3 days.
× 10 ⁰ / g, which is 0 × 10 ⁰ / g even after 1 month under the same conditions.
(Measurement of bacterial count) Sterility was confirmed.

Example 11 In Example 8, water vapor pressure 0.1 kg / cm²(1.1kg / cm²), Can body pressure
0.5 kg / cm²(1.5kg / cm ². (Equivalent to 110 ℃)
This was carried out under the same conditions, and this was set as Example 11. R.H. at this time
= 73%. First, cooked cheese (pH = 5.3
It was ) Put 300 g into an oval cup, heat seal, and sterilize
Irradiate microwaves with an electric output of 1 kW so that the temperature reaches 110 ° C.
Shot Increased temperature at the center and edges of the elliptical cup
Fluctuations are observed, and the temperature rises faster at the edges than at the center.
There was a tendency, but the speed became slow from the point of exceeding 100 ℃.
Temperature at the center approaches that at the edges, and the temperature at the edges
After reaching the target of 110 ℃, the temperature does not rise any further and the core temperature
There was a tendency to wait until the temperature reached 110 ° C. Core temperature
When the temperature reaches 110 ° C, the temperature is set to microwave for 10 minutes.
Hold while controlling, and after the holding time, same as above
And cooled to 70 ° C within 1 minute. Elliptical in quality
There was no peeling of the seal on the cup, and there was no burning.
(Appraisal), the color tone and wind of this cream cheese mixture
The taste and texture were also excellent (sensory evaluation). Storage test results
The number of bacteria after storage at 37 ° C for 3 days was 0 × 10⁰/ g and the same conditions
After 1 month, 0x10⁰/ g (measurement of bacterial count)
I was able to recognize it.

[0036] In Example 12 Example 9, the water vapor pressure ^{0.3kg / cm 2 (1.3 kg /} cm 2), ( equivalent to 4.0kg / cm ² .140 ℃) the can body pressure 3.0 kg / cm ^2, Micro Example 12 was carried out under the same conditions except that the wave electric output was 5 KW. At this time, RH = 33%. As in the previous example, put 300 g of cooked Chikuzen in an oval cup, heat-seal, put in a can under the above conditions, and irradiate with microwaves. After the temperature at the center reaches 140 ° C, 1 KW The output controlled the temperature. There was a difference in temperature between the center and the end of the cup, and there was a tendency for the temperature to rise above the sterilization temperature at the end, and the temperature at the end tended to be 1 to 2 ° C higher than the center temperature. After the central temperature reached 140 ° C, the temperature was maintained for 1 minute, and then cooled in the same manner as above to 70 ° C within 3 minutes. In terms of quality, the oval cup did not peel off, no scorching was observed (appearance evaluation), and the color, flavor and texture of this cream cheese preparation were excellent (sensory evaluation).
The results of the storage test also showed that the number of bacteria was 0 × 10 ⁰ / after being kept at 37 ° C for 3 days.
It was g, and it was 0 × 10 ⁰ / g even after 1 month under the same conditions (bacteria number measurement), and sterility was confirmed.

Comparative Example 4 300 g of cooked Chikuzen-ni was placed in an elliptical cup, heat-sealed, and then irradiated with microwaves so that the sterilization temperature was 140 ° C. First, the can body pressure is 5.0 kg / cm ² (6.0 kg / cm ²⁾ only with air.
² . Adjust so that the pressure is equivalent to 140 ℃ (R.
H. = 0%), and the microwave was irradiated with an electric output of 1 KW. There was a variation in the temperature rise at the center and the end of the elliptical cup, and there was a tendency for the temperature to rise above the sterilization temperature at the end, and the center tended to be 5 to 8 ° C higher than the temperature at the end. After the central temperature reached 140 ° C, the temperature was held for 1 minute by controlling the microwave, and after the holding time was completed, it was cooled by the same method as above to 70 ° C within 3 minutes. In terms of quality, peeling of the elliptical cup and burning were seen (appearance evaluation),
Chikuzen-ni had poor color tone, charred flavor, and texture was unbearable. The number of bacteria was 3 days after storage at 37 ℃.
It was 10 ⁶ or more / g and was not aseptic.

Comparative Example 5 Comparative Example 5 was carried out under the same conditions as Comparative Example 4 except that the microwave electric output was changed to 5 KW. Water vapor pressure ^{0.0kg / cm 2 (0.0kg / cm} 2), the can body pressure 5.0kg / cm ² (6.0k
g / cm ² . (Equivalent to 140 ℃), at this time RH = 0%. The microwave was irradiated with an electric output of 5 KW, and after the sterilization temperature reached 140 ° C, the sterilization temperature was controlled by the output of 1 KW. There was a variation in the initial temperature at the center and the end of the elliptical cup, and there was a tendency for the end to rise above the sterilization temperature, and the temperatures at the center and the end could not be controlled at all. When the core temperature reaches 140 ° C, the temperature at the end is 160
Exceeded ℃. After the central temperature reached 140 ° C, the temperature was held for 1 minute by controlling the microwave, and after the holding time, it was cooled by the same method as above to 70 ° C within 3 minutes. In terms of quality, peeling of the elliptical cup and burnt charcoal were observed (appearance evaluation), and Chikuzen-ni had poor color tone, burnt flavor and texture, and was not edible to eat and was poor. 37 ° C
After 3 days of storage, the bacterial count was 10 ⁶ or more / g, and it was not aseptic.

Comparative Example 6 Comparative Example 6 was carried out under the same conditions as Comparative Example 5 except that the partial pressure of water vapor was 0.8 kg / cm ² (1.8 kg / cm ² ). At this time, RH = 30%. Then, the microwave was irradiated with an electric output of 5 KW, and after the sterilization temperature reached 140 ° C, the sterilization temperature was controlled by the output of 1 KW. There is a variation in the initial temperature between the center and the end of the elliptical cup, and the end tends to rise above the sterilization temperature, and the center tends to be 5 to 8 ° C higher than the end temperature. It was After the central temperature reached 140 ° C, the temperature was held for 1 minute by controlling the microwave, and after the holding time, it was cooled by the same method as above to 70 ° C within 3 minutes. In terms of quality, peeling of the oval cup and burnt charcoal were observed (appearance evaluation), and Chikuzen-ni had poor color tone, slightly charred flavor and texture. After kept at 37 ° C for 3 days, the number of bacteria became 10 ⁶ or more / g, and it was not aseptic.

From the results of Examples 1 to 12 and Comparative Examples 1 to 6 as described above, the following was revealed. That is, if the internal pressure of the can is only air, local heating due to the concentration of microwaves at the end of the packaging material is observed (tip effect), but the air inside the can is replaced by water vapor and the internal pressure of the can is 0.5 kg / Under the conditions of cm ^{2 to} 3 kg / cm ² (4 kg / cm ² ) and relative humidity RH of more than 30%, it was found that abnormal microwave concentration at the end could be prevented and uniform heating could be performed. It was Under the above conditions, the pressure inside the can was increased only by water vapor, and even at a relative humidity of RH 100%, the rate of temperature rise was only slow, and the quality and sterility were not affected at all, which was good.

[0041]

According to the present invention, unlike the conventional retort sterilization, the sterilization of the target food is carried out by adjusting the conditions such as gas pressurization including steam pressure and microwave irradiation heating as described above, and continuous sterilization. The processable manufacturing equipment enabled continuous production of uniform sterilized foods without deterioration of quality (flavor, color tone, nutrition, etc.) of target foods and charring or damage of packaging materials and containers. .

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadahisa Shimoda 1 Sumiyoshi-cho, Izumisano-shi, Osaka Fuji Oil Co., Ltd. Hannan factory (56) References JP-A-56-119259 (JP, A) JP-A-56 -142124 (JP, A) JP-A-60-120970 (JP, A) JP-B-36-18133 (JP, B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) A23L 3/00- 3/24 A23L 1/01

Claims (5)

(57) [Claims] 1. A packaging material (having a microwave transmission property and a sterilization temperature
Heat resistant polyethylene, polyester,
Polyethylene terephthalate polymer and ethylene vinyl
Alcohol copolymer or polypropylene) , seal the food , put the sealed packaging container inside the can, and put water inside the can.
Substituting with steam, pressurization (1.1-2.7 in the presence of steam )
kg / cm ² (gauge pressure)) 2450 MHZ (mega)
Hertz) microwave heating, followed by cooling down, a method for producing a hermetically sealed food product. 2. A method of displacing air with steam is a method for evacuating air in a can.
The method according to claim 1, wherein the steam pressure is 6 kg / cm ² . 3. Relative humidity in the atmosphere during microwave heating,
The method according to claim 1 or 2, which is maintained at more than 30%. 4. From the temperature range of 120 ℃ or more after completion of sterilization to 70 ℃
The manufacturing method according to claim 1, wherein the temperature is reduced to the following within 3 minutes in a pressurized atmosphere . 5. The food in a hermetically-sealed state is flat and young.
5. The shape is a shape having corners.
The method according to any one of 1.