JPH07170954A - Production of hermetically sealed and packaged food - Google Patents

Abstract

PURPOSE:To provide a method for producing a hermetically sealed and packaged food to be distributed at normal temperatures in which a short time is sufficient for the thermal sterilization treatment with regard to the size, etc., of the packaged food and deterioration in quality such as nutrition, flavor and color tone due to the heating can thereby be suppressed to a slight extent. CONSTITUTION:This method is to regulate a food to be treated so as to provide pH 4.0-5.5 thereof after completing a production process, fill the regulated food in a microwave transmitting packaging container, keep the packaging container in a hermetically sealed state, irradiate the hermetically sealed and packaged food in the container with microwaves under pressurized conditions of 0.5-2.8 kg/cm<2>, thereby increase the temperature of the food to 100-130 deg.C and maintain the food at this temperature under this pressure for a prescribed time. The time for the thermal sterilization treatment can be shortened by regulating the pH to 4.0-5.5. The whole heating time can further be shortened by increasing the temperature to the sterilizing temperature according to the irradiation of the hermetically sealed and packaged food with the microwaves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an instant product which can be stored at room temperature for a long period of time by hermetically wrapping a food to be treated and sterilizing it by heating, or cooking and sterilizing it, and eating it by simple re-cooking. The present invention relates to a method for producing a sealed packaged food such as food or food for a microwave oven.

[0002]

2. Description of the Related Art Clostridium botulinum, Vibrio parahaemolyticus,
Due to the growth of bacteria such as Salmonella, food easily deteriorates,
Further, when the food has low acidity or contains a large amount of water, the food is suitable for the growth of these food spoilage-causing bacteria. For this reason, for example, the pH of the food product exceeds 5.5 and the water activity is 0.
When it exceeds 94, it is obliged to heat the central part of the package at 120 ° C. for 4 minutes or to heat sterilize it by a method having the same or higher efficacy. Since this condition is the heating condition for the center of the packaged food, the time required for the heat applied from the outside to reach the center must be taken into consideration, and the required heating time differs depending on the size of the package, etc. Further heating must be performed for a long time.

However, such heat sterilization treatment for a long time causes deterioration of quality such as nutritional components, flavor and color tone in food. According to Japanese Patent Publication No. 58-11831, the pH of the food after heat sterilization is 4.0.
Or 5.5 or a water activity of 0.94 or less, the food can be made into a bad environment for the growth of food spoilage-causing bacteria. It is disclosed that since the time can be shortened, a room temperature distribution sealed packaged food excellent in nutrition, flavor and color tone can be provided.

[0004]

However, although the heating time can be shortened by adjusting the pH or water activity of the food itself, the heat applied from the outside may be reduced depending on the size and packaging form of the food. It takes a long time to reach the center, and a long-time heat sterilization treatment cannot be avoided.

Therefore, the present invention is a method for producing a hermetically-sealed packaged food which is allowed to flow at room temperature, and the heat sterilization treatment time can be shortened regardless of the size of the packaged food, whereby nutrition, flavor and color tone due to heating can be obtained. It is an object of the present invention to provide a method for producing a hermetically-sealed food product capable of suppressing deterioration of quality such as the above.

[0006]

In the method for producing a hermetically sealed food of the present invention which solves the above-mentioned problems, the food to be treated is adjusted to have a pH of 4.0 to 5.5 after the completion of the production process. A step of filling the microwave permeable packaging container with the food and sealing the container, and 0.5-2.
The method is characterized by including a step of raising the temperature of the food to 100 to 130 ° C. by irradiating with microwaves under a pressure condition of 8 kg / cm ² , and a step of maintaining the temperature and pressure for a predetermined time.

The pH after the completion of the manufacturing process is 4.
Adjusting the pH value to 0 to 5.5 also includes directly adopting the pH value which becomes pH 4.0 to 5.5 after the heat treatment. In the above method, when the pH of the food to be treated exceeds 5.5, a pH adjusting agent is added to the food to lower the pH so that the pH after the production process is adjusted to 4.0 to 5.5. It is possible. p
Examples of the H modifier include citric acid, succinic acid, malic acid, gluconic acid, lactic acid, tartaric acid, phytic acid, acetic acid, adipic acid, fumaric acid, ascorbic acid and salts thereof, and edible acidulants combining these. be able to.

The method of adjusting the pH differs depending on the properties of the food.
In the case of liquid foods, it is considered that a predetermined amount of the pH adjusting agent or a solution of the pH adjusting agent is added and then stirred to make the entire pH uniform. For a solid food, a method of immersing the food in a solution of the pH adjusting agent, leaving it standing, immersing it, boiling it, or the like can be considered. Further, in the case of a food product in which a liquid substance and a solid substance are mixed, the pH of both the liquid portion and the solid portion is adjusted to a predetermined pH by separately adjusting the pH by the above method.

In the above method, the pH of the food to be treated is
May be filled in a packaging container and then sealed, or the pH may be adjusted and sealed after filling. At least a part or all of the packaging container used in the above method has microwave permeability and needs to have heat resistance according to heating conditions, and its material is polyethylene, polypropylene, polyester, polyethylene terephthalate. And the like, ethylene-vinyl alcohol copolymer, and the like.

The packaging container filled with the food to be treated is sealed by a known means such as heat sealing with a lid made of the same material as described above. The container itself may be partially overlapped and heat-sealed without using the lid. Not only one packaging container but also one having a plurality of storage units is conceivable, and the food to be sealed is not limited to one type (including stuffed food such as pilaf and cooked rice). Can also be considered. When there are a plurality of storage units, it is possible to store different types of food in each.

[0011] In the above method, the food sealed in the container is irradiated with microwaves to heat the food to be treated until the temperature of the central portion of the food reaches 100 to 130 ° C, but when the heating temperature is lower than 100 ° C. However, it becomes practically impossible to perform sufficient sterilization, and when the heating temperature is higher than 130 ° C., the heating time is shortened, but overheating is caused, and in any case, the quality of food is deteriorated. In addition, there may be a problem of heat resistance of the container due to overheating.

0.5 to 2.8 k during the microwave irradiation
Pressurization within the range of g / cm ² is to prevent bumping of the packaging contents and deformation of the packaging container due to temperature rise due to microwave irradiation, and pressure lower than 0.5 kg / cm ² In the case of 2, the sufficient effect due to pressurization cannot be obtained, and 2.
If the pressure is higher than 8 kg / cm ² , the packaging container and contents may be damaged.

In the above method, 0.5 to 2.8 kg /
By maintaining the pressure of cm ² and the temperature of 100 to 130 ° C. for a predetermined time according to the type of food to be treated, it is possible to sterilize the vegetative cells of the expected food spoilage causative bacteria. Further, it is considered that the relative humidity at this time is maintained at 0 to 30%, but this makes it possible to keep the oxygen permeability of the packaging container made of a material such as an ethylene-vinyl alcohol copolymer low, The tightness of the container can be improved.

In the above method, it is conceivable to use, for example, rice and water as the food to be treated and obtain aseptic cooked cooked rice after the completion of the process. Rice may be raw rice, or may be raw rice soaked in water, seasonings or the like and swollen. In addition, as the food to be treated, an uncooked food may be used and cooking and sterilization may be performed by the above method, or a cooked food may be used and only sterilization may be performed by the above method.

[0015]

According to the method for producing a hermetically sealed food of the present invention, the pH of the food to be treated is adjusted so as to be 4.0 to 5.5 after the production process, so that the bactericidal condition of the food spoilage causing bacteria ( Temperature, pressure, time, etc.) can be relaxed. Further, by heating the food directly from the inside by microwave irradiation, the temperature of the food can be raised to the sterilization temperature in a short time. Therefore, the heat sterilization processing time can be shortened as a whole. This reduces quality deterioration of the food such as nutrition, flavor, and color tone.

[0016]

EXAMPLES Examples of the present invention will be described below. According to one embodiment, a packaging step (A) of filling and sealing one or more kinds of food to be treated in a microwave permeable packaging container having one or a plurality of accommodating parts, and the sealed food packaging container. And (b) supplying at least one of each of the above to the transport line, and the food packaging from the waveguide provided on the transport line under a pressure condition of 0.5 to 2.8 kg / cm ^2. A microwave irradiation step (C) of irradiating the container with microwaves to raise the temperature of the food in the packaging container to 100 to 130 ° C., and the temperature under the pressurized condition and relative humidity of 0 to 30%. Then, a heat treatment step (D) of maintaining a dry heat heating atmosphere at an ambient temperature of 130 ° C. or lower for a predetermined time is sequentially performed to produce a heat and pressure sterilized product or a heat and pressure cooked and sterilized sealed packaged food product. Also, the heat treatment step (D)
After that, a cooling step (E) of cooling the sealed packaged food and returning it to the atmospheric pressure is adopted.

The above will be described in more detail below. FIG. 1 shows a schematic structure of a continuous microwave heating and pressurizing sterilizer used for manufacturing the sealed packaged food of the present invention.
This apparatus is provided with a first pressure adjusting chamber 1, a microwave irradiation chamber 2, a dry heat heating chamber 3, a cooling chamber 4 and a second pressure adjusting chamber 5 continuously in this order, and each of the chambers 1, 2, 3, Gate valves b, c, d, e, a, and f are provided between the chambers 4 and 5, and between the chamber 1 and the outside, and between the chamber 5 and the outside. In addition, this device is a food transport conveyor line L that extends from one outside of the device through each gate valve and each room interior to the outside of the other.
Is equipped with. Each chamber 1, 2, 3, 4, 5 has a pressure gauge 1A, 2A, 3A, 4A, 5A and a pressure regulating valve 1B, respectively.
One compressor 6 via 2B, 3B, 4B, 5B
To each of the chambers, so that each chamber can have a predetermined air pressure. Although the compressor 6 common to each room is used here, a separate compressor or the like for each room may be provided. If the temperature control of the chambers 3 and 4 is not hindered, the gate valves c and d are not necessarily installed, and the microwave irradiation chamber 2, the dry heat pressurizing chamber 3 and the cooling chamber 4 are It does not matter if the pressure is always the same.
The microwave irradiation chamber 2 is provided with three microwave waveguides 21 in each of the upper part and the lower part inside thereof, and the waveguides 21 are connected to the microwave generator 22 outside the chamber 2. The number of the installed waveguides 21 is not limited to this, and an appropriate number can be installed according to the size and properties of the packaged food, the shape of the packaging container, the material, the heating conditions, and the like. Dry heat heating chamber 3
Is equipped with a hot air circulation type heater 31, and the cooling chamber 4 is equipped with a cooler 41.
Is equipped with.

With the microwave heating and pressure sterilization apparatus described above, the above-mentioned sealed packaged food is manufactured as follows. First, the cooked or uncooked food to be treated 8 has a pH of 4.
After being adjusted to be 0 to 5.5, the microwave permeable packaging container 7 is filled and sealed with the lid 71. The food 8 to be treated may be filled in the packaging container 7 and then adjusted in pH and sealed. Next, the gate valve a is opened, and the sealed food is fed to the processed food transfer line L through the first pressure adjusting chamber 1
After being carried in and closing the gate valve a, the inside of the chamber 1 is brought to a predetermined pressure for sterilization (and cooking) by operating the compressor 6 and adjusting by the pressure adjusting valve 1B. Next in advance valve 2
By the operation of B, the gate valve b of the microwave irradiation chamber 2 set to the same atmospheric pressure as the inside of the chamber 1 is opened, the food 8 to be treated is carried into the chamber 2 together with the container 7, and the gate valve b is closed. Further, the microwave generated by the microwave generator 22 is applied to the waveguide 21.
The food 8 to be treated is irradiated for a predetermined time to raise the temperature of the food to a predetermined temperature for sterilization (and cooking). Then, the gate valve c of the dry heat heating chamber 3 which was previously set to the same atmospheric pressure as the inside of the chamber 2 by operating the valve 3B and was set to substantially the same temperature as the food whose temperature was raised by the heater 31 was heated. The food to be treated is carried into the chamber 3, the gate valve c is closed, and the temperature and pressure are maintained for a predetermined time. The time for maintaining the temperature and pressure is, for example, 5 to 10 minutes, preferably 6 to 8 minutes when cooked polished rice and sterilized to obtain cooked rice. Next, the valve 4B is set in advance to the same atmospheric pressure as the chamber 3, and the gate valve d of the cooling chamber 4 cooled by the cooler 41 is opened to carry in the heat-sterilized (and cooked) food. And close the food to room temperature. Then, the gate valve e of the second pressure adjusting chamber 5 which is set to the same pressure as the chamber 4 in advance by operating the valve 5B is opened to carry in the heat-treated food, the gate valve e is closed, and the chamber 5 is gradually removed. Reduce the pressure to 0 and return to normal pressure. After that, the gate valve f
Open and remove the food from the device. As described above, the operation of loading the food to be processed into the device, passing through each room, and unloading it outside the device is all performed by the food transport conveyor line L.

As described above, by adjusting the pH of the food to be treated so as to be 4.0 to 5.5 after the production process, the sterilization conditions such as temperature, pressure and time can be relaxed. Further, by heating the food to be treated directly from the inside by microwave irradiation to raise the temperature in a short time, the heat sterilization treatment time can be further shortened. As a result, it is possible to reduce deterioration in quality of the food to be treated such as nutrition, flavor and color tone due to heat sterilization.

Next, a specific example of the practice of the present invention in which cooked rice sterilized from polished rice and water is produced will be described. Example 1 After washing 90 g of polished rice with water, soaking it for 1 hour and soaking it in water 11
2 g was obtained. This water-immersed rice was filled in a polypropylene-made packaging container having a capacity of 350 ml, and then citric acid was added in an amount of 0.
88 g of an aqueous solution in which 135 g was dissolved was filled and sealed with a polypropylene lid. Then, in the chamber 2 of the microwave heating and pressure sterilizer, the temperature of the packed rice was raised to 120 ° C. under the pressure of 2.1 kg / cm ^{2 with} the microwave irradiation output of 0.18 kW, and then the chamber 3 was heated. Sterilization and cooking are performed by maintaining the temperature of 120 ° C and the pressure of 2.1 kg / cm ² for 7.2 minutes in a dry heat heating atmosphere with relative humidity of 0%, and further cooling in the cooling chamber 4 and the pressure adjusting chamber 5. And the pressure was adjusted to obtain 200 g of cooked rice. Example 2 In Example 1, 89 g of polished rice was used instead of 112 g of water-immersed rice.
88 g of an aqueous solution containing 0.135 g of citric acid dissolved in
Instead of the above, an aqueous solution 111 in which 0.135 g of citric acid was dissolved
g, and other conditions are the same as in Example 1
g was obtained. Comparative Example 1 Aqueous solution 8 in which 0.135 g of citric acid was dissolved in Example 1
2.1k in the room 2 using 88g of normal water instead of 8g
Microwave irradiation was performed at a power of 0.18 kW under a pressure of g / cm ² to raise the temperature to 120 ° C., and then the same temperature and the same pressure were maintained in the chamber 3 for 13.5 minutes. Other conditions were the same as in Example 1 to obtain 200 g of cooked rice. Comparative Example 2 Aqueous solution 1 in which 0.135 g of citric acid in Example 2 was dissolved
200 g of cooked rice was obtained in the same manner as in Comparative Example 1 except that 111 g of normal water was used instead of 11 g. Comparative Example 3 In Example 1, instead of the microwave heating and pressure sterilizer,
The temperature of the rice packaged using a retort sterilizer using hot water is raised to 120 ° C., and then the temperature 120
Sterilization and cooking were carried out by maintaining the temperature of 2.1 ° C. and the pressure of 2.1 kg / cm ² for 7.2 minutes to obtain cooked rice 200. Comparative Example 4 After 450 g of polished rice was washed with rice and left to soak for 1 hour, water was added to make the total amount 1125 g, and then rice was cooked using a commercially available gas rice cooker.
I got g of cooked rice.

Next, Examples 1 and 2 and Comparative Examples 1, 2, 3, 4
With respect to the cooked rice, the taste, aroma, and color tone were evaluated and comprehensively evaluated by a sensory test by 10 panelists. The results are shown in Table 1. The numerical values in Table 1 are relatively shown with the evaluation of each item relating to Comparative Example 4 as a maximum of 100 points.

[0022]

[Table 1]

The cooked rice of Examples 1 and 2 had the same aroma as the cooked rice of Comparative Examples 1 and 2, but were excellent in taste, color tone, and overall evaluation. 0
It is considered that the heating time was shortened by adjusting so as to be ~ 5.5. Also, the cooked rice according to Examples 1 and 2 is
Compared with the cooked rice according to Comparative Example 3, the taste, aroma, color tone, and overall evaluation are excellent. This is because the heating time is shortened by rapidly heating the rice and water to the sterilization temperature by microwave irradiation. It is thought to be a tame. Thus, the quality of the cooked rice of Examples 1 and 2 was the closest to the ideal cooked rice of Comparative Example 4 obtained by ordinary cooking, as compared with the cooked rice of Comparative Examples 1, 2, and 3.

In order to verify the bactericidal effect of Examples 1 and 2 and Comparative Examples 1, 2 and 3, 1 × 10 ³ spores of Bacillus coagulans were preliminarily stored in the packaging container before sealing.
Prepare 60 samples each of the cooked rice obtained by inoculation so that each of the samples will have a volume of 1 and 40 ° C. in a hermetically sealed state.
After leaving it for two months, it was examined whether or not the rice had deteriorated.

Further, Examples 1, 2 and Comparative Examples 1, 2, 3,
The pH of cooked rice according to No. 4 and the sterilization value Fo in each case were measured. The results are shown in Table 2.

[0026]

[Table 2]

It can be seen that the rice and water inoculated with the bacterium were able to withstand normal temperature circulation by all the methods according to Examples 1 and 2 and Comparative Examples 1, 2 and 3. In addition, the pH of the cooked rice according to the above 5 examples was lower than 5.5 in Examples 1 and 2 and Comparative Example 3, and higher than 5.5 in Comparative Examples 1 and 2.

[0028]

As described above, according to the present invention,
A method for producing a sealed packaged food that is distributed at room temperature,
It is possible to provide a method for producing a hermetically sealed packaged food, which requires a short heat sterilization treatment time regardless of the size of the packaged food and thereby can suppress deterioration of quality such as nutrition, flavor and color tone due to heating. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a microwave heating and pressure sterilizer used in one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st pressure adjustment chamber 2 Microwave irradiation chamber 21 Waveguide 22 Microwave generator 3 Dry heat heating chamber 31 Hot air circulation heater 4 Cooling chamber 41 Cooler 5 Second pressure adjustment chamber 6 Compressors 1A, 2A, 3A, 4A, 5A Pressure gauge 1B, 2B, 3B, 4B, 5B Pressure adjustment valve a, b, c, d, e, f Gate valve L Conveyor conveyor line

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichimaro Okamoto 463 Kagasuno, Kawauchi Town, Tokushima City, Tokushima Prefecture Otsuka Chemical Co., Ltd. Food Research Institute

Claims (4)

[Claims] 1. A step of: (a) adjusting the food to be treated so that the pH thereof after the production step is 4.0 to 5.5.
(B) filling the microwave permeable packaging container with the food and sealing it; and (c) 0.5 to 0.5 for the food sealed in the container.
Includes a step of raising the temperature of the food to 100 to 130 ° C. by irradiating with microwaves under a pressurized condition of 2.8 kg / cm ² , and (d) a step of maintaining the temperature and pressure for a predetermined time. A method for producing a hermetically sealed food product, which comprises: 2. In the step (a), the pH is 5.5.
The method for producing a hermetically sealed food according to claim 1, wherein the food to be treated exceeding the above is adjusted to have a pH of 4.0 to 5.5 after completion of the production process by using a pH adjuster. 3. The method for producing a hermetically sealed packaged food according to claim 1, wherein the step (d) is performed in a dry heat heating atmosphere having a relative humidity of 30% or less. 4. The method for producing a hermetically sealed food according to claim 1, 2 or 3, wherein the food to be treated is rice and water.