JPH0783698B2 - How to store food - Google Patents

Description

The present invention relates to a method for preserving food. For more details,
A container made of a material with an oxygen permeability of 200 ml / m ² · 24hr · atm or less, together with an oxygen scavenger package in which the packaging material has a conductive layer and has air permeability for food with a moisture content of 8% or more. The present invention relates to a method for preserving foods, which is characterized in that it is stored in a container, irradiated with microwaves, and then stored.

[Prior Art] In recent years, as one of food preservation techniques, a food preservation technique using an oxygen scavenger has been established, and its use is expanding to various and various foods.

Oxygen scavenger storage technology is the use of oxygen scavenger to keep the inside of the packaging container in an anaerobic state to prevent the oxidation of oil and fat in food,
The quality of foods is maintained by preventing discoloration and fading, maintaining flavor, preventing insect damage, and preventing aerobic bacteria from breeding.

However, it was pointed out that oxygen was not able to suppress the quality deterioration of oxygen and the growth of facultative anaerobic bacteria and obligate anaerobic bacteria, which was a problem in the storage technology of oxygen scavengers.

Also, when using oxygen absorber packaging as a pest control method, depending on the type of pest, the oxygen requirement is small, 100
% It may take 9 to 12 days to die, and the number of treatment days is longer than that of chemical treatment such as fumigation.

Here, for example, a packaging material in which paper and perforated polyethylene film are laminated and bonded, or a packaging material in which perforated plastic film, paper and perforated polyethylene film are laminated and bonded, are used for the conventional oxygen absorber packaging.

On the other hand, a food preservation technique using microwave irradiation has recently attracted attention for the purpose of sterilization, inactivation of enzymes, pest control and the like.

That is, by irradiation with microwaves, bacteria that are dielectrics,
It is a high frequency induction heating method for sterilizing and exterminating pests.

Since the food preservation technology using microwave irradiation can be irradiated with microwaves after packaging, its use is expanding due to reasons such as prevention of secondary contamination, high processing speed, and good working environment.

However, from the viewpoint of food storage, it was not possible to prevent adverse effects of oxygen in the air such as discoloration and fading and oxidation of oil and fat.

As described above, the food preserving technique using the oxygen scavenger and the food preserving technique using microwave irradiation each have some drawbacks.

[Problems to be solved by the invention]

Problems with food storage technology using oxygen scavengers: facultative anaerobic bacteria, obligate anaerobic bacteria growth, quality deterioration due to enzymes, and pest control period may be long, and food storage technology using microwave irradiation. It is of great importance to solve the above problems such as discoloration and fading and the inability to prevent the oxidation of fats and oils, and the like, and to provide an even better food preservation technique.

However, when both techniques are simply combined and the conventional oxygen absorber is housed in a container together with food and is irradiated with microwaves, the packaging material used for the conventional oxygen absorber package is microwave. Since it permeates this, the oxygen absorber content itself is heated, the bag containing the oxygen absorber content is damaged, and the oxygen absorber content is discharged from the bag and mixed into food. It was

The present invention has been made in view of such conventional problems, and an object thereof is to combine a food storage technology using an oxygen scavenger and a food storage technology using microwave irradiation without any safety and health problems. And to provide a better food preservation method.

[Means for solving problems]

In view of the above problems, the inventors of the present invention have conducted earnest research on the improvement of the oxygen absorber package, and as a result, the conductive material has the property of transmitting, reflecting and absorbing microwaves. Then, the present invention has been completed.

That is, according to the present invention, a food having a moisture content of 8% or more, a packaging material having an electrically conductive layer and an oxygen scavenger package having air permeability, and an oxygen permeability of 200 ml / m ² · 24 hr · atm or less are provided. The present invention provides a method for preserving food, which is characterized by storing in a container made of material, irradiating with microwaves, and then storing.

In the present invention, a packaging material for containing the oxygen scavenger is used which has a conductive layer and is breathable.

In the oxygen absorber package of the present invention, due to the presence of the conductive layer,
Even when irradiated with microwaves, most of the microwaves are reflected by this conductive layer, the energy is attenuated, and the contents below the conductive layer are not excited. Therefore, the oxygen absorber, which is the content, is not heated, so that the package itself is not damaged.

In the present invention, the conductive layer, gold, silver, copper, aluminum, a metal foil made of a metal such as iron, a metal net,
Plastic film with a metal coating of silver, copper, etc. formed by a chemical reduction method, metal film formed with a vacuum deposition method, etc., conductive coating, plating, etc., metal powder, particles A layer having conductivity by various methods, such as one in which fibers or the like are added to, dispersed in, or contained in the plastic film by various methods, is used. Among these conductive layers, when a metal foil is used, or as a metal in the case of forming various metal coatings, etc., aluminum or one mainly composed of aluminum from the viewpoint of safety and hygiene when used for food is used. preferable. A more specific preferable example is aluminum foil. When using aluminum foil, if the thickness of the aluminum foil is too thick, it will interfere with the suitability for automatic filling and packaging, and if it is too thin, it will interfere with the manufacturing of packaging material.
Is preferred, and 5 to 25 μ is most preferred. Furthermore, as the aluminum foil, a soft aluminum foil is preferable in view of suitability for packaging machines. Further, as a conductive layer such as aluminum foil, EVA, polyethylene, polybutadiene, for the purpose of imparting various characteristics,
A film coated with a resin such as a film made of polyvinyl chloride or an ionomer, latex, hot melt, emulsion or hot melt emulsion may be used.

This conductive layer may be arranged at any position except the innermost sealing layer of the packaging material of the oxygen absorber package, and may be arranged at any position such as the outermost layer and the intermediate layer.

Further, the conventional oxygen scavenger package may be double-wrapped with a breathable packaging material having a conductive layer. Alternatively, the oxygen absorber packaging body having a conductive layer may be doubly packaged using a breathable packaging material.

It is also possible to use a packaging material having a conductive layer on only one side of the bag of the oxygen absorber package, and use a water resistant packaging material such as a microporous film that has been conventionally used on the other side. is there. However, in this case, it is necessary to use the microwave so that the microwave hits the surface of the packaging material having the conductive layer.

There are various possible packaging materials containing such a conductive layer, and the following are examples. Here, the conductive layer is shown as an aluminum foil.

(1) A laminate in which polyester, aluminum foil, and polyethylene having a trademark printed on the back surface are laminated and adhered in this order.

(2) A product obtained by laminating polyester, aluminum foil, polyethylene, western paper, and polyethylene, which are printed with a trademark or the like on the back surface, in this order.

(3) Polyester, polyethylene, Japanese paper, polyethylene, aluminum foil, EVA (ethylene vinyl acetate copolymer, the same applies below) laminated and adhered in this order on the back side of which a trademark or the like is printed.

(4) Laminated and adhered polyester, polyethylene, Japanese paper, polyethylene, aluminum foil, EVA with a trademark printed on the back in this order.

(5) Laminated and laminated aluminum foil and polyethylene with a trademark printed on the surface.

(6) Oil-resistant paper with printed surface, polyethylene, aluminum foil, EVA laminated and adhered in this order.

In addition, as a method for laminating and bonding these packaging materials,
Various methods such as dry laminating, extrusion laminating, thermocompression laminating and hot melt laminating can be adopted.

Further, polyethylene, EVA or the like may be dry laminated or thermocompression laminated as a film, or may be adhered as a film at the time of extrusion laminating.

Preferably, the outermost layer of the packaging material is transparent from the viewpoint of ensuring the safety and hygiene by preventing the direct contact between the printing ink and food etc. while being visible from the surface even when the back printing of the trademark etc. is performed. It is better to use a plastic film.

Needless to say, packaging materials having various configurations other than the above examples can be adopted.

Next, an aspect of providing air permeability to the packaging material in the present invention will be described with reference to the drawings.

First, in the embodiment shown in FIG. 1, the packaging material designated by reference numeral 10 is an outer film layer 12 such as polyester, a conductive layer 14 such as aluminum foil, and an adhesive film layer such as polyethylene.
16, a breathable layer 18 such as paper, and a heat sealing film layer 20 such as polyethylene are laminated,
By stacking two sheets of the packaging material 10 so that the heat-sealing film layers 20 are overlapped with each other and heat-sealing only the peripheral portion thereof, a packaging body containing the oxygen absorber 22 is formed.
The heat-sealing film layer 20 is provided with a plurality of vent holes 24 in advance at appropriate intervals. A plurality of small holes 26 are formed in the outer layer except the innermost heat-sealing film layer 20 by cold needles, hot needles, punching or the like, and the small holes 26 are adhered to the film layer 20. When forming the vent holes 24 in the film layer 20, it is also possible to form the vent holes 24 with a cold needle, a hot needle or the like after adhering the outer laminate other than the film layer 20 to the film layer 20. Is. Further, since the breathable layer 18 itself has breathability, it is not always necessary to form the small holes 26.

The vent holes 24 and the small holes 26 provide air permeability to the oxygen scavenger 22.

The second embodiment shown in FIG. 2 is different from the first embodiment in that the first packaging material 28 including the outer film layer 12, the conductive layer 14, and the heat-sealing film layer 16, the breathable layer 18, and the heat A second wrapping material 30 composed of the sealing film layer 20 is provided separately, and the first wrapping material 28 and the second wrapping material 30 are not adhered to each other but leave a gap 32 between them. Only the peripheral edge is heat-sealed. Further, the small holes 26 are not formed in the breathable layer 18.

In the third embodiment shown in FIG. 3, the oxygen scavenger 22 is packaged by a conventional packaging material, for example, a packaging material 34 in which paper and perforated polyethylene film are laminated and adhered, and the packaging material 34 is further packaged in the outer film. It is wrapped with a first packaging material 28 comprising a layer 12, a conductive layer 14 and a heat-sealing film layer 16.

It goes without saying that these three modes are merely examples, and other modes are conceivable. In addition, the thickness of the packaging material is preferably 20 to 300 µ, more preferably 20 to 200 µ in view of suitability for an automatic filling and packaging machine. The air permeability of the packaging material can be freely adjusted by the diameter and number of the small holes to be punched, the material of the paper, and the like. Since the conductive layer 14 has a microwave shielding effect, the size of the holes formed therein has a major axis in the range of 0.02 to 3 mm, and the open area ratio (total area of holes / total area of bag). Should be selected within the range of 30% or less.

As a method for imparting air permeability to the packaging material in the present invention, various methods other than the generally practiced punching, opening with a cold needle, hot needle, and the like can be adopted. When air permeability is imparted to a conductive layer such as aluminum foil among these methods, after lamination with an outer film layer and a film layer for heat-sealing, a small amount such as a cold needle or a hot needle having a sharp tip is used. It is preferable to drill holes. This is because aluminum foil and the like have higher heat resistance than plastic films that have been conventionally used for oxygen scavenger packaging materials, and it is difficult to heat-melt open holes with a hot convex roll or the like. In addition, cold hands on aluminum foil beforehand,
When a small hole is formed with a hot needle or the like, irregularities are easily formed, it becomes difficult to stack the film on another film, and the small hole is easily closed during lamination. Therefore, it is preferable to form small holes after laminating and adhering the other film material and the aluminum foil.

Next, in the present invention, as an oxygen scavenger, an oxygen absorber, sulfite, bisulfite, dithionite, ferrous salt, hydroquinone, catechol, resorcin, pyrogallol, gallic acid, rongalit, ascorbic acid and / Or a salt thereof, isoascorbic acid and / or a salt thereof, a deoxidizer containing sorbose, glucose, lignin, dibutylhydroxytoluene or butylhydroxyanisole, or a deoxidizer containing a metal powder such as iron powder, An oxygen gas generating type oxygen absorber or a carbon dioxide gas absorbing type oxygen absorber is used as the material. Of these oxygen absorbers, oxygen absorbers containing ascorbic acid and / or a salt thereof, or metal powder such as iron powder are preferably used.

In the present invention, the container has an oxygen permeability of 200 ml / m ²
It is made of a material of 24 hr · atm or less, preferably 100 ml / m ² · 24 hr · atm or less, and can be used regardless of its form as long as it can be completely sealed. The simplest containers used in the present invention are, for example, KON / PE (polyvinylidene chloride coated nylon / polyethylene), KOP / PE.
(Polyvinylidene chloride coated polypropylene / polyethylene) or various polyvinylidene chloride coated laminated films exemplified by KPET / PE (polyvinylidene chloride coated polyethylene terephthalate / polyethylene) etc., laminated layers such as EVAL (trade name, manufactured by Kuraray Co., Ltd.) It is a bag made of film or the like, and is usually sealed by heat sealing.

In the present invention, the container is made of a material that does not easily transmit microwaves, such as an aluminum vapor deposition film,
The one made of a laminated film or the like laminated with aluminum foil is not preferable because the preserved food contained in the container is not effectively irradiated with microwaves.

Examples of the foods to be stored according to the present invention include foods having a water content of 8% or more in order to make sterilization by microwave irradiation, pest control, enzyme deactivation and the like effective.

Also, specific foods that can be applied include rice, wheat, beans,
Cereals such as gen soba, yakitori, hamburger,
Stir-fried items such as nuggets, kotsuke, american dog, bite cutlet, various fried foods, processed meats such as ham, sausage, etc., grilled fish, fried foods, steamed foods, boiled fish etc. Processed seafood products or seafood paste products, steamed foods such as yoyoza, shimai, etc., Japanese confectioneries exemplified by ten thousand heads, dorayaki, kuzumochi, daifuku, abe river mochi, natto etc., cakes, cream, castella, baumkuchen, Western confectionery exemplified by pancakes, processed rice and wheat products exemplified by red rice, chewy rice, mixed rice, etc., exemplified by boiled udon, boiled buckwheat, raw buckwheat, raw udon, yakisoba, spaghetti, yaki udon, etc. Various noodles, delicacies, seaweed such as kelp and wakame, side dishes, tofu, natto, fish meat, livestock meat, miso, cut rice cake, and the above examples Other retort foods with food product, sterilization with microwave, pest control, combination of the enzyme-inactivating or the like and the oxygen scavenger include a valid food.

Among these foods, Japanese confectionery, Western confectionery, noodles, rice cakes, miso, fried foods, steamed foods, processed rice and wheat products, and cereals are particularly effective foods.

As a method for carrying out the preservation of the food according to the present invention, the food and the oxygen absorber are stored in a container made of a material having an oxygen permeability of 200 ml / m ² , 24 hr, atm or less, and a microwave for about 10 seconds to 10 minutes. It is performed by irradiating.

At this time, either method can be adopted, even if the container is sealed and then microwave-irradiated, or even if the container is microwave-irradiated in the opened state and then sealed.

However, when microwave irradiation is performed after sealing, the irradiation time is limited because the container expands due to evaporation of water from food. If the irradiation after sealing is not sufficiently effective, the irradiation time can be extended while the container is left open.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 (Manufacture of oxygen absorber package having conductive layer) A 12 μm thick polyethylene terephthalate film and a 9 μm thick aluminum foil, each of which has a character printing and a white solid printing on the back, are dry-laminated. A laminated sheet 1 was obtained.

Next, a sheet (A) was obtained by extruding and laminating 15 µ of polyethylene between the aluminum foil side of the laminated sheet 1 and an oil resistant pure white roll paper having a basis weight of 40 g / m ² .

Holes having a hole diameter of 0.2 mm were formed in this sheet (A) by being distributed at intervals of 5 mm in length and width. (Opening rate 0.12%) After laminating polyethylene with a thickness of 30μ on this, small holes with a hole diameter of 0.2 mm are made in this polyethylene layer at intervals of 2.5 mm in the vertical direction and 1.5 mm in the horizontal direction for air permeability ( A laminated packaging material having a conductive layer having a width of 100 mm, which was provided with a heat-sealing film having a porosity of 0.83%), was prepared.

This packaging material is guided to a three-sided seal automatic filling and packaging machine, and while filling 3.0 g of iron-based oxygen scavenger inside the heat sealing film, seal it with a bar heater from the outside film side,
It was cut to obtain a breathable oxygen scavenger package having dimensions of 50 × 50 mm.

As Comparative Example 1, 15 μm of polyethylene was extruded and laminated between a polyethylene terephthalate film and an oil-resistant pure white roll paper having a basis weight of 40 g / m ² without using an aluminum foil in place of the laminated sheet 1. A sheet (A ') was obtained.

Hereinafter, prepare a laminated packaging material having no conductive layer in the same manner as in the above-mentioned example, and fill with 3.0 g of an iron-based oxygen absorber 50 ×
A 50 mm oxygen absorber package was obtained.

These oxygen absorber packages were sealed in a KOP / PE (polyvinylidene chloride-coated polypropylene / polyethylene) bag together with 500 CC of air, stored at 25 ° C, and analyzed for oxygen concentration after 2 days.

Next, the KOP / PE bag containing these oxygen absorber packages was microwave-heated in a microwave oven (frequency 2450 ± 50MHz, 500W) made by Mitsubishi Electric for 5 minutes to check the appearance of the oxygen absorber package. The change was observed. The results are shown in Table-1.

Example 2 A laminated sheet 1 was obtained by dry-laminating a polyethylene terephthalate film having a thickness of 12 μ and a 9 μ-thick aluminum foil, each having a character printing and a white solid printing on the back.

Next, 30 μm of polyethylene was extruded and laminated on the aluminum foil side of the laminated sheet 1 to obtain a laminated sheet (A).

Small holes with a hole diameter of 0.2 mm are distributed in this sheet at intervals of 5 mm in the vertical and horizontal directions (perforation rate 0.12%), and after imparting air permeability,
A laminated packaging material (1) having a conductive layer slit to a width of 140 mm was prepared.

On the other hand, a packaging material (2) was prepared by laminating pure white paper (basis weight: 50 g / m ² ) and a perforated polyethylene film having small holes each having a hole diameter of 0.2 mm at intervals of 2.5 mm in length and 1.5 mm in width.

Guide this packaging material (2) to a three-sided seal automatic filling and packaging machine, fill and package 3.0g of iron-based oxygen scavenger, cut and cut 50 ×
A 50 mm oxygen absorber package was obtained.

Further, the laminated packaging material (1) is guided to another three-way seal filling and packaging machine, and the oxygen absorber packaging body made of this packaging material (2) is double-wrapped with the laminated packaging material (1) to obtain a 70 × 70 mm An oxygen absorber package made of a packaging material having a conductive layer was obtained.

As Comparative Example 2, a polyethylene terephthalate film was used instead of the laminated sheet 1 without using an aluminum foil.
A polyethylene sheet (μ) was extruded and laminated to obtain a laminated sheet (A ′). A laminated packaging material (3) having no conductive layer on the sheet (A ') in the same manner as in Example 2 above.
Was prepared, and the oxygen absorber package using the packaging material (2) was double-wrapped to obtain an oxygen absorber package made of a packaging material having a 70 × 70 mm conductive layer.

KOP / PE with these oxygen absorber packages together with 2 sheets of bread
The bag was sealed, stored at 25 ° C. and analyzed for oxygen concentration after 2 days.

Next, these samples were microwave-heated for 5 minutes in a microwave oven (frequency 2450 ± 50MHz, 500W) manufactured by Mitsubishi Electric Corporation,
The change in the external shape of the oxygen absorber package was observed. The results are shown in Table-2.

Example 3 (microwave sterilization of raw udon) Using the laminated packaging material obtained in Example 1, 2 g of an iron-based oxygen scavenger was filled inside to produce an oxygen absorber package with an oxygen absorption capacity of 50 ml. . On the other hand, flour 100 parts, water 29 parts, salt 2
100g of raw udon prepared by further adding water to the mixture of 1 part and adjusting the water content to 31% was prepared, and KON (polyvinylidene chloride) with the oxygen scavenger package having the above-mentioned conductivity and air permeability was prepared. Coated nylon, same below) (thickness 15μ) / PE
It was stored in a bag (dimension 150 × 150 mm) made of (thickness 70 μ) and hermetically sealed. At that time, the amount of air in the bag was 200 ml. Then, using a microwave oven RP-40 (output 500W) manufactured by Mitsubishi Electric Corp., the bag was irradiated with microwaves for 40 seconds, and then stored at 25 ° C for a predetermined number of days, and the storage condition of raw udon was analyzed by a sensory test. Examined. The results are shown in Table-3.

(Comparative Example 3-1) In Example 3, instead of using the laminated packaging material obtained in Example 1 as the oxygen absorber package, the one obtained in Comparative Example 1 with respect to Example 1 was used. The same treatments and tests as in Example 3 were carried out except that they were used. The results are shown in Table 3 together with Example 3 as Comparative Example 3-1.

(Comparative Example 3-2) In Comparative Example 3-1, the same treatment and test as in Comparative Example 3-1 were carried out except that the microwave was not applied. The results are shown in Table 3 together with Example 3 as Comparative Example 3-2.

(Comparative Example 3-3) In Example 3, the same treatments and tests as in Example 3 were carried out except that the oxygen absorber package was not used. The results are shown in Comparative Example 3
-3 is shown in Table 3 together with Example 3.

(Comparative Example 3-4) In Comparative Example 3-3, the same treatment and test as in Comparative Example 3-3 were performed except that the microwave irradiation was not performed. The results are shown in Table 3 together with Example 3 as Comparative Example 3-4.

As can be seen from Table-3, even if the oxygen absorber was used without microwave irradiation, a fermentation odor was emitted on the 5th day, but irradiation with microwave for 40 seconds maintained good quality for 14 days,
It was discovered that there was an effect of microwave irradiation. But,
In the conventional oxygen scavenger package (Comparative Example 3-1), the oxygen scavenger rapidly expanded during microwave irradiation, peeling of the seal portion was observed, and the bag was broken. On the other hand, the oxygen scavenger package of the present invention had no sudden expansion, no abnormality was observed, and micro irradiation could be safely performed.

〔The invention's effect〕

As described above, according to the present invention, the water content is 8%.
The above foods are first subjected to microwave irradiation for sterilization, pest control, enzyme deactivation, etc., and during storage and distribution thereafter, the effect of the oxygen scavenger prevents the food from discoloring and fading, preventing the oxidation of oils and fats, and maintaining the flavor. It is possible to prevent the reproduction of aerobic bacteria.

Further, in the oxygen scavenger package used in the present invention, the packaging material reflects most of the microwave without impairing the oxygen absorption function of the oxygen scavenger. Even if it is irradiated with microwaves in a packaged state, it is possible to prevent the oxygen absorber from being heated by the microwaves, so that the oxygen absorber package bursts and the oxygen absorber in it is discharged. It is possible to prevent such a phenomenon, and accordingly, it is possible to provide an oxygen absorber package that can withstand microwave heating.

Therefore, according to the present invention, after encapsulating the food and the oxygen absorber package, the oxygen absorber is not heated even by microwave irradiation while preventing secondary contamination, and as a result, the oxygen absorber is reduced. The package does not break and the oxygen scavenger in the package is not discharged, which is excellent in safety and hygiene.

[Brief description of drawings]

FIG. 1 is a sectional view showing an aspect of the present invention, FIG. 2 is a sectional view showing a second aspect of the present invention, and FIG. 3 is a sectional view showing a third aspect of the present invention. 10 ... Packaging material, 14 ... Conductive layer 22 ... Oxygen absorber, 24 ... Vent hole 26 ... Small hole

Claims (1)

[Claims] 1. A food having a water content of 8% or more, a packaging material having an electrically conductive layer and an oxygen scavenger package having air permeability, and having an oxygen permeability of 200 ml / m ² · 24 hr · atm or less. A method for preserving foods, characterized by storing in a container made of material, irradiating with microwaves, and then storing.