JPH0764367B2 - Microwave cooked food - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a microwave-heated cooked food product in which the contents are visible and can be stored at room temperature for a long period of time, and in particular, it has high microwave gas and water vapor barrier properties and microwave permeability. The present invention relates to a microwave cooked food using the transparent packaging material of.

[Prior Art] Currently, food is sterilized by a retort sterilization method in order to circulate a sealed food package at room temperature for a long time. However, the retort sterilization method sterilizes in a pressurized state using a heating medium of 100 ° C or more, but the temperature reached to the center is mainly due to the heat conduction of food, so it is determined by the nature of food (especially food containing solid matter). 120 to meet the sterilization conditions of
It took an extremely long time, such as 15 to 60 minutes at ℃.
Therefore, packaging materials and foods are exposed to high temperatures for a long time, and packaging materials are inevitably of high quality and high price, and the biggest drawback is that the texture, taste, color, etc. of foods are impaired. On the other hand, the packaging material that is transparent and has a low content of oxygen has a low oxygen gas barrier property, and it is impossible to store the food for a long time after sterilization.
Since these retort sterilization methods perform sterilization under pressure, a high level of technology is required to adjust the pressure for preventing the package from bursting.

Instead of this retort sterilization method, attention has been paid to a sterilization method using microwaves that can be heated in a short time.As with the retort sterilization method, a method of sterilizing by irradiating microwaves under pressure was announced by the United States Army Research Institute. However, since this method is a method of irradiating microwaves under pressure, it is difficult to adjust the pressure like the retort sterilization method, and the sterilization device is complicated and expensive, and thus it is difficult to be used widely.

In addition, as a sterilization method using microwaves, Japanese Patent Publication No. 58-26
As shown in Japanese Patent No. 949, a method of sterilizing a package in which an object to be sterilized is packaged in a pressure container made of a microwave permeable material and irradiating with microwaves from the outside of the pressure container is proposed. ing. According to this method, it is possible to sterilize by sealing the package in a pressure-resistant container and irradiating with microwaves, but since microwaves are radiated at one time, heating unevenness is likely to occur, and especially moisture content In the case of low-priced foods, there were drawbacks such as frequent burns.

Furthermore, although a method and an apparatus for continuously performing microwave sterilization under normal pressure have been proposed, it is difficult to use a transparent and high-barrier packaging material on the apparatus, and an appropriate food package for long-term storage can be obtained. It was the current situation.

[Object of the Invention and Problems to be Solved] An object of the present invention is to provide a microwave-heated and cooked food product in which the contents are visible and which can be stored at room temperature for a long time.

In other words, microwave irradiation under normal pressure and continuous, efficient sterilization without degrading the quality of food, the contents are visible, and sealed microwave cooking that can prevent quality deterioration during storage at room temperature It is about manufacturing finished foods.

Therefore, oxygen and water vapor that efficiently transmit microwaves, do not cause physical damage to the packaging material in the sterilization / cooling process, and the process of circulating as a product at room temperature, and are transparent and do not cause changes in the components of the food product, etc. It is necessary to be sealed with a packaging material having a barrier property against.

[Means for Solving Problems] The present invention provides a heat-resistant synthetic resin film base material alone, or a heat-resistant synthetic resin film that can be heat-sealed with a laminated product as an innermost layer, or a metal as an intermediate layer of the laminated product. Microwave permeable provided with a thin film of an oxide simple substance or a mixture, and a packaging bag made of a transparent laminated packaging material, filled with food in any of a molded container or a can, and a sealed package is stored in a support, The conventional problems were solved by using microwave-cooked foods whose contents can be seen by heating and sterilizing them in a microwave irradiation oven at a temperature of 100 ° C or higher and which can be stored at room temperature for a long time.

[Function] Microwaves have a function of permeating food to some extent and directly heating from the inside, and it is possible to raise the central temperature of food in a short time. At this time, by using a microwave permeable support, it is possible to prevent the package from bursting due to water vapor pressure. In addition, by using a heat-resistant synthetic resin film / metal oxide thin film / heat-sealable synthetic resin film structure that can be heat-sealed as a packaging material, microwaves can be transmitted, and the contents can be seen. Allows long-term storage of food at room temperature without deterioration of gas barrier properties after irradiation.

[Examples] The present invention will be specifically described below.

First, the packaging material according to the present invention will be described.

The packaging material of the present invention provides heat resistance for high temperature sterilization, physical strength for normal pressure and high temperature sterilization, transparency of visible contents, microwave transparency for microwave sterilization, and room temperature long-term storage stability. Therefore, a minimum gas barrier property against oxygen and the like, and a water vapor barrier property are required. Therefore, laminated materials made of the following materials and methods are required.

That is, as the heat resistant synthetic resin film substrate, a single or laminated product of a heat resistant film such as a polyester film, a nylon film or a polypropylene film is used. As the heat-sealable film capable of being heat-sealed, a heat-resistant polyolefin such as unstretched polypropylene is used as the innermost layer, and a single product thereof or a laminated product with a heat-resistant film such as a polyester film, a nylon film or a polypropylene film, for example, a polyester film. / Unstretched polypropylene film laminate, stretched nylon film / unstretched polypropylene film laminate, stretched polypropylene film / unstretched polypropylene film and the like are used.

Next, as a metal oxide to be provided in the intermediate layer between these base material and the sealable film, titanium oxide, zinc oxide,
Aluminum oxide, silicon oxide, magnesium oxide, manganese oxide, and other microwave-permeable metal oxides can be used, but aluminum oxide, silicon oxide, etc. are the most suitable, and aluminum oxide / silicon oxide,
Mixtures are also effective.

The metal oxide thin film used in the present invention can be coated on the surface of the synthetic resin film by a vacuum vapor deposition method or a sputtering method, and the film thickness is preferably 500 to 1000Å.
Table 1 shows examples of vapor deposition film thickness and barrier properties.

Table 1 shows 500-1000 silicon oxide thin film on 25μ polyester.
Å This is an example of the barrier property when it is provided by the vacuum deposition method.

The method for laminating these films is not particularly limited, but it is possible to improve the adhesive strength by providing a modified polyolefin (for example, a carboxyl group-containing polyolefin) layer between the heat resistant sealant layer and the metal oxide thin film layer. Is known.

Next, the microwave heating cooking method of the present invention will be described.

The present invention has heat resistance and a barrier property against oxygen and water vapor in which the metal oxide thin film as described above is provided in the intermediate layer,
And a laminated material having a property of transmitting microwaves is formed into a bag shape, and foods, in particular, cooked foods containing solid matter are filled from the opening, and after sealing with leaving a vent hole in a part of the opening, A microwave-permeable material having a storage space of substantially the same shape and having a volume capable of storing a food filling package, for example, synthetic resin such as Teflon, polycarbonate, polyphenylene sulfide, polyacetal, or various ceramics After being stored in a support, continuously put into the first microwave irradiation oven and heated up to around 100 ° C to seal the ventilation hole, and then continuously to the second
It is a microwave-cooked food that can be stored for a long period, characterized by being placed in a microwave irradiation oven and heated to a predetermined temperature exceeding 100 ° C, and immediately cooling the support together with the package. As compared with the conventional heat sterilization, a cooked food was obtained which has less loss during sterilization such as texture, taste, color and texture of food and can be stored at room temperature for a long time.

The above method was performed by filling the cooked food and performing the primary heating in a state where the vent hole was left in a part of the opening and sealing, but after sealing without leaving the vent hole in the opening, the primary heating microwave was used as it was. You may heat in an irradiation oven. Further, the heating may be carried out not only in two steps by using a microwave irradiation oven but also once. By reversing or rocking the package during heating, it is possible to more effectively sterilize even by heating once by microwave irradiation.

Then, in addition to the packaging body, a container body in which a laminated material is deep-drawn is used, and after filling the contents, a molded container configured to be sealed by the same laminated material, the body is made of the laminated material, and the top and bottom are sealed by a lid material. The cans are also treated in the same manner as described above to obtain cooked foods that can be stored for a long time at room temperature.

[Test Example 1] After cooking or processing each of the foods described below, after performing heat sterilization by the conventional retort sterilization method and the method of the present invention, respectively,
The results of taste and sensory properties immediately after heat sterilization and immediately after heat sterilization and after storage for 6 months are shown. Taste and sensory were examined by 10 panelists regarding changes in appearance, scent, taste, texture and presence of offensive odors, etc., and were indicated by scores and special notes. For each food item, the highest level was given as a maximum of 5 points for relative comparison. The criteria for rating are as follows.

The outline of the conventional method and the present invention is as follows.

Conventional method After cooking and processing each food, it is filled and sealed in a pouch made of polyester (12μ) / vinylidene chloride (20μ) / unstretched polypropylene (70μ), then hot water at 125 ° C, static retort sterilization (cooling time is Included). Immediately after retort sterilization and indoor (20-30 ° C)
After leaving it to stand for 6 months, the taste and sensory evaluations were performed for each.

After cooking and processing each food of the present invention, a pouch made of polyester (25μ) / silicon oxide (600Å) / unstretched polypropylene (70μ) is filled and oscillated at room temperature with some ventilation holes sealed. Is radiated for 3 minutes in the first microwave oven with 3kw, heated to 95 ℃, then sealed for 3 minutes while keeping the vent hole sealed, and put into the second microwave oven with oscillation output of 1kw. Irradiate for 6 minutes at 125 ℃
Hold for 3 minutes and cool for 3 minutes. For these items, as in the conventional method, immediately after heat sterilization and in the room (20 to 30
After left to stand naturally for 6 months, the taste and sensory evaluations were performed for each. The amount filled in each package is 150 g
Met.

[Test Example 2] The conventional method was performed in the same manner as Test Example 1, but the present invention was performed as follows.

After cooking each food, fill the pouch made of polyester (25μ) / silicon oxide (600Å) / unstretched polypropylene (70μ), seal it, and then invert it with the support in a 4kw microwave irradiation oven. After irradiation for 4 minutes
Heat sterilization was performed by holding and heating at 125 ° C. for 3 minutes and then cooling for 4 minutes. Similar to the conventional method, these were subjected to taste and sensory evaluation immediately after heat sterilization and after being naturally left in a room (20 to 30 ° C.) for 6 months. The tested foods were 1,2,3,8,9,10 in Table-2. As a result, both the conventional method and the present invention are shown in Table-2.
The results were similar to 1,2,3,8,9,10.

[Test Example 3] In the conventional method, after the whiskey and edible wild plants were cooked, unstretched nylon film (20μ) / vinylidene chloride film (20μ) / unstretched polypropylene film (70)
0μ) laminated material is vacuum formed to 80 × 100 × 20mm (volume 16
A tray of 0 cm ³ ) is made, and a polyester film (25μ) / vinylidene chloride film (20μ) / is used as a lid material.
Using a laminated material made of unstretched polypropylene (50μ), 150g each of the above foods was filled and packaged.
Heat sterilization was performed using a hot water / static retort device at 125 ° C.

The taste and sensory evaluation before and after sterilization were performed in the same manner as in Test Example 1.

The present invention vacuum-molds the same food as in the above conventional method into a laminated material of unstretched nylon film (20μ) / silicon oxide (1000Å) / unstretched polypropylene (700μ) to obtain 80 × 100 ×
Create a tray of 20 mm (volume 160 cm ³ ), use a laminated material consisting of polyester film (25 μ) / silicon oxide (600 Å) / unstretched polypropylene film (50 μ) as the lid material, and fill and pack 150 g of each food The test piece was mounted on a retainer in the same manner as in Test Example 1, irradiated with microwaves for 4 minutes in a 4 kw microwave oven, held for 3 minutes, cooled for 3 minutes, and then heat sterilized to similarly perform taste and sensory evaluation. It was

The results are shown in Table 3.

[Test Example 4] The results of taste and organoleptic properties after cooking or processing each of the following foods, heat sterilized by the conventional method and the present invention, respectively, and immediately after the heat sterilization and after storage for 6 months are shown. The test methods for taste and sensory and the criteria for rating are the same as in Test Example 1.

Conventional method After cooking and processing each food, 160g of food c was filled into the cup-shaped container d shown in Fig. 7 of polypropylene single layer of thickness 300μ which was pressure molded to 80mmφ × 40mm, and polypropylene single layer of thickness 80μ The film was sealed with a film e and then sterilized by hot water at 125 ° C. in a static retort. Immediately after retort sterilization and after being left to stand in a room (20 to 30 ° C.) for 6 months, the taste and sensory evaluations were performed on each of these.

The present invention 600 Å silicon oxide on a 25μ thick polyester film
Was vacuum deposited by applying a urethane-based adhesive 4.5 g / m ² stuck unstretched polypropylene film 70micro, it was applied a urethane-based adhesive 4.5 g / m ² on the other side further to the deposition surface , 30μ unstretched polypropylene film is attached,
Laminated film J was made. This film is shown in Figs.
The spiral can body shown in the figure was used.

The can body has a shape as shown in FIG. 4 which is an enlarged partial sectional view and FIG. 5 which is an overall view showing an enlarged sectional view. That is, the laminated material J used in the present invention, which has a silicon oxide vapor deposition layer as an intermediate layer, is an unstretched polypropylene layer A 70 μm from the inside, a urethane adhesive B of 4.5 g / m ² , a 600 Å silicon monoxide vapor deposition film. Layer C, 25μ polyester layer D, 4.5g
/ m ² urethane adhesive layer B, 30μ unstretched polypropylene layer H, outer layer material K is 4.5g / m ² urethane adhesive layer B through 200μ unstretched polypropylene layer E, 5
It consists of a polypropylene layer F of 00μ and a polypropylene layer G of 30 to 50μ.

A bottom lid b made of an injection-molded plastic laminated material is attached to such a can body a, and a 52.3 mmφ × 90 mm shown in FIG. 6 is attached.
Make a container of H, cook and process each food c, fill 160 g, attach an upper lid b made of the same plastic laminated material as the bottom lid and seal it, then rotate integrally with the support in the microwave irradiation oven Or, oscillating while irradiating, output 4kw for 4 minutes →
Holding for 2 minutes → irradiation for 2 minutes → holding for 2 minutes was repeated until a predetermined sterilization, and then heat sterilization was performed by cooling. Taste and sensory evaluations were carried out on these products immediately after heat sterilization as in the conventional method and after naturally left in a room (20 to 30 ° C.) for 6 months. The results are shown in Table 4.

[Effects of the Invention] The microwave-cooked food that can be stored for a long time with the contents of the present invention has a shorter heating time than conventional retort sterilization. By using a packaging material with a high gas barrier property, the contents can be seen and the high quality after heat sterilization can be maintained as it is, enabling long-term storage at room temperature.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing an embodiment of a packaging material used for the microwave cooked food of the present invention, and FIG. 2 is a cross section showing a state in which a package is filled with the microwave cooked food of the present invention. Explanatory drawing, FIG. 3 is a sectional explanatory drawing when a tray is used, FIG. 4 is an enlarged partial sectional view of a plastic can body which is one embodiment of the present invention, and FIG. 5 is an enlarged sectional view thereof. General view, FIG. 6 is a cross-sectional view of the can-shaped container of the present invention, FIG.
The figure is a cross-sectional view of a polypropylene single-layer container having a thickness of 300 μ used in the conventional method. 1 ... Polyester film 2 ... Silicon oxide thin film 3 ... Unstretched polypropylene film 4 ... Package, 5 ... Contents 6 ... Tray, 7 ... Lid A ... Unstretched polypropylene layer B ... Polyurethane type Adhesive layer C: Silicon oxide vapor deposition film layer D: Polyester layer E: 200μ unstretched polypropylene layer F: 500μ polypropylene layer G: 30-50μ polypropylene layer H: 30μ unstretched polypropylene layer J …… Laminated material with a silicon oxide vapor deposition film layer in the middle K …… Exterior material, a …… Can barrel b …… Lid, c …… Contents food

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Sasaki 1-1, Suzuki-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Ajinomoto Co., Inc., Kawasaki Plant (56) Reference JP-A-58-23774 (JP, A) Special features Open Sho 52-68785 (JP, A) Actual Open Sho 60-193077 (JP, U)

Claims (2)

[Claims] 1. A microstructure in which a metal oxide simple substance or a mixture thin film is provided in an intermediate layer of a simple substance or a laminated product having a heat resistant synthetic resin film as an innermost layer capable of heat-sealing with a heat resistant synthetic resin film substrate simple substance or a laminated product. A microwave-cooked food that can be stored for a long period of time and is made by filling the contents of a package made of a transparent laminated packaging material capable of transmitting waves, and then irradiating with microwaves and sterilizing by heating. 2. A microwave-cooked food which can be stored for a long period with visible contents and is characterized in that the metal oxide alone or the mixture is an oxide or mixture of silicon.