JPH08133345A - Germfree cooked rice package and its manufacture - Google Patents

Abstract

PURPOSE: To preserve cooked rice at a normal temperature by a method wherein in a container formed of a laminate sheet for which a polyolefine layer is provided on respective surfaces of a resin layer with an oxygen-absorbing function and oxygen barrier layer, a specified quantity of germfree cooked rice is put in a nitrogen gas replacing zone, and the container is sealed with an oxygen barrier lid material. CONSTITUTION: An oxygen-absorbing resin layer 2 wherein a master batch of low density polyethylene and a 30% iron based free-oxygen scavenger is blended in a polypropylene resin, gas barrier layer 4 of an ethylene-vinyl acetate copolymer saponified substance, polypropylene innermost layer 1 for which a coloring agent and moisture absorbent are added, outermost layer 6 and adhesive layer 3 are simultaneously extruded by four units of extruders. After the joining of the molten resins, the joined molten resin is extruded into a sheet-form and cooled to manufacture a multi-layer sheet. Then, a tray container of which corners are rounded is formed of the multi-layer sheet by the plug- assist vacuum forming method. A nitrogen gas replacement is performed for just cooked rice in a germfree atmosphere, and then, the container is sealed and stored at a normal temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a package of aseptic cooked rice using a container formed of a sheet composed of a laminate having an oxygen absorbing function and a method for producing the same, which is for preventing the oxidation of cooked rice and propagating aerobic microorganisms. Can be prevented.

[0002]

2. Description of the Related Art Retort cooked rice has been the mainstream of commercially processed cooked rice. However, it has a bad taste because it is sterilized by heating after it is packaged in a gourmet-oriented manner. Because it was molded, it looked bad. Therefore, recently, the rice has been commercialized by processing the cooked rice under normal cooking conditions and filling it in an aseptic molding container in an aseptic environment.

Since this method is not completely sterile, it is necessary to prevent the growth of aerobic bacteria by absorbing oxygen. As a method, it is not possible to completely remove oxygen in the container by nitrogen replacement. It is done in combination with. However, in this case, a step of filling the oxygen absorbent is required. In addition, pH adjustment is also used in combination to enhance the bacteriostatic effect. On the other hand, in the current barrier container, aluminum is the most effective for infiltration from the outside, but internal oxygen needs to be removed. In addition, the actual tray is a plastic molded product, and even a material with the highest oxygen barrier will be slightly permeable.

[0004]

Therefore, according to the present invention, as a method for storing cooked rice at room temperature, the cooked rice is filled in a container with a deoxidizing function and packaged in a nitrogen gas replacement zone environment. It is an object of the present invention to provide a package capable of being stored at room temperature and a method for producing the same.

[0005]

The present invention has been conceived to solve the above-mentioned problems, and has a resin layer having an oxygen absorbing function and an oxygen barrier layer, and the resin layer having the oxygen absorbing function and an oxygen barrier. To a container formed of a sheet composed of a laminate provided with a polyolefin layer on each surface of the layer, a certain amount of sterile rice is filled in a nitrogen gas replacement zone,
A sterilized cooked rice package formed by sealing with an oxygen barrier lid, which has a resin layer having an oxygen absorbing function and an oxygen barrier layer, and each surface of the resin layer having the oxygen absorbing function and the oxygen barrier layer. A container formed by vacuum- or pressure-forming a sheet made of a laminate provided with a polyolefin layer on a container is filled with a certain amount of aseptic cooked rice in a nitrogen gas replacement zone, and then sealed with an oxygen barrier lid material. It is a method for producing a packaged rice cooked product.

[0006]

In the package and the method for producing a package of the present invention, by using a container having an oxygen absorbing function and a nitrogen-displacement package together, it is possible to completely remove oxygen insufficiently by only nitrogen-displacement and prevent oxidation and The bacteriostatic effect is effectively exhibited.

<Example 1> The following resins were simultaneously extruded by four extruders by a coextrusion multilayer sheet manufacturing apparatus, and after the molten resins were joined, they were extruded into a sheet by a T die and cooled,
A multilayer sheet of 4 types and 6 layers having a total thickness of 500 μ was manufactured. The oxygen-absorbing resin layer is made of polypropylene resin, low-density polyethylene, and a master batch of 30% iron-based oxygen scavenger (made of iron powder with a bulk specific gravity of 2.0 or more and a surface area of 0.5 or more and salt) 1: It was compounded in a ratio of 2. The gas barrier layer is a saponified ethylene vinyl acetate copolymer (ethylene content 33%, saponification degree 99%). The innermost layer is made by adding TiO ₂ as a coloring agent and a hygroscopic agent to polypropylene. The outermost layer is made of polypropylene to which TiO ₂ is added as a colorant. The thickness of each layer of the multi-layered sheet thus obtained was manufactured to be uniform as follows. Inner layer opalescent polypropylene (1) 80 μ / oxygen absorption layer 130 μ (2) / adhesive layer (3) 15 μ / EVOH (ethylene-vinyl alcohol copolymer) layer (4) 40 μ / adhesive layer (5) 15 μ / outer layer opalescent polypropylene ( 6) 25
It was 0 μ. This is illustrated in FIG.

The above-mentioned multilayer sheet was plug-assisted vacuum forming method to form a rectangular parallelepiped tray container (Fig. 3) having rounded corners as shown in Fig. 3 and filled with 200 g of cooked rice immediately after cooking in a sterile atmosphere. After replacing with nitrogen gas, lid material polyethylene terephthalate 12μ / Al 9μ
/ Sealed with polypropylene 50μ. This was stored at room temperature and the change in oxygen concentration with time was measured. As shown in (Table 1), the test result shows that the initial oxygen concentration of about 0.3% reached the detection limit (0.01 ppm or less) in one week,
It was found that this deoxidized state was sufficiently maintained for 6 months.

Example 2 Basically, the same coextrusion multilayer sheet manufacturing apparatus as in Example 1 was used to add 20% by weight of sodium ascorbate to polypropylene resin and low density polyethylene resin for the oxygen absorbing resin layer. A sheet was prepared in the same manner as in Example 1 except for the above. A tray of the same type as in Example 1 was formed from the above sheet by a vacuum forming method. Next, the tray was filled with 200 g of cooked rice, replaced with nitrogen gas, and sealed with the same lid material as in Example 1. This was stored at room temperature in the same manner as in Example 1 and the change in oxygen concentration with time was measured. Although the result was lower than that of the iron-based oxygen absorber, it was confirmed that the effect was almost the same. Further, unlike the iron-based oxygen absorber, since it is white, the amount of titanium added can be reduced. Comparative Example 1 Ordinary opalescent polypropylene (10) 230 μ / adhesive layer 5 μ / EVOH (14) 40 μ / adhesive layer 5 μ / milky white polypropylene (16) 250 μ did. Figure 2
Shown in A tray of the same type as that of the example was prepared by the vacuum forming method. The tray was filled with 200 g of cooked rice, replaced with nitrogen gas, and sealed with the same lid material as in the example. This was stored at room temperature in the same manner as in the example, and the change in oxygen concentration with time was measured. The test results are shown in (Table 1). From these results, it was found that the initial oxygen concentration did not change much in one week as compared with the examples, and one month, two months
It decreased gradually after a month, and was below the detection limit after 6 months. This means that the cooked rice was oxidized. It has also been conventionally practiced to use an oxygen scavenger together for filling.

<Comparative Example 2> Basically the same as Comparative Example 1, except that the oxygen absorber is used for filling.

The results of the above-mentioned Examples and Comparative Examples are shown in Table 1 above, and the relationship between the oxygen absorption capacity and cost for each is shown in Table 2.

[0012]

[Table 1]

[0013]

[Table 2]

In the above embodiment, the case where the tray formed by vacuum forming is used has been described, but the present invention is not limited to this, and it goes without saying that it can be applied to cup-shaped, bag-shaped and bottle-shaped containers.

[0015]

[Effects of the Invention] Oxidation of cooked rice is performed in the same manner as in the case of using an oxygen scavenger by packaging cooked rice in combination with nitrogen substitution using a bag, a molding container or the like made of the oxygen-absorbing multilayer structure of the present invention. Highly preventable. Moreover, since the oxygen absorber is not used, the filling step is not necessary, the conventional filling / packaging device for contents can be used as it is, and the cost does not increase.

[0016]

[Brief description of drawings]

FIG. 1 is an explanatory view showing a sheet structure of an embodiment of a container used in the present invention.

FIG. 2 is an explanatory diagram showing a seat structure used in a comparative example.

FIG. 3 is a perspective view showing an example of a container used for the packaging of the present invention.

[Explanation of symbols]

 1, 10: inner layer opalescent polypropylene 2: oxygen absorption layer 3, 5, 13, 15: adhesive layer 4, 14: EVOH 6, 16: outer layer opalescent polypropylene 7: tray

Claims (5)

[Claims] 1. A sheet comprising a laminate having a resin layer having an oxygen absorbing function and an oxygen barrier layer, and a polyolefin layer provided on each surface of the resin layer having an oxygen absorbing function and the oxygen barrier layer is molded. A sterilized cooked rice package in which a certain amount of sterile cooked rice is filled in a container in a nitrogen gas replacement zone and sealed with an oxygen barrier lid. 2. A resin having a function of absorbing oxygen is formed by kneading a master batch in which 50% or less of ascorbic acid and a chemical agent that changes iron powder into iron oxide as an oxygen absorbing function material are mixed with a polyolefin resin. The sterilized cooked rice package according to claim 1, which is used. 3. The initial nitrogen substitution rate is 5.0%, preferably 0.3%.
The sterilized cooked rice package according to claim 1 or 2, characterized in that: 4. A sheet comprising a laminate having a resin layer having an oxygen absorbing function and an oxygen barrier layer, wherein a polyolefin layer is provided on each surface of the resin layer having an oxygen absorbing function and the oxygen barrier layer, is vacuumed. Alternatively, a method for producing a sterilized cooked rice package, which comprises filling a fixed amount of sterile cooked rice in a nitrogen gas replacement zone into a pressure-molded container and then sealing with an oxygen barrier lid. 5. The initial nitrogen substitution rate is 5.0%, preferably 0.3%.
The method for producing a sterilized cooked rice package according to claim 4, wherein: