JPH03200575A - Container for food suitable for heating in electronic oven - Google Patents

Abstract

PURPOSE:To enable heating without causing boiling over of soup, excessive humidification or excessive drying of surface by using non-woven fabric, as material for a container, having air permeability and water resistance higher than specific values. CONSTITUTION:Higher air permeability and water resistance of non-woven fabric is desirable, that is, air permeability of 1cc/cm<2>/sec or more and water resistance of 10cm or more is desired. When air permeability is less than 1cc/ cm<2>/sec, water vapor in a container cannot be rapidly diffused and when water resistance is less than 10cm, boiling over cannot be prevented. Since non-woven fabric has such characteristics, waterproofing or water repellency treatment may be applied to needle punch non-woven fabric or stream intertwinds non- woven fabric. If water vapor generated from food by the heat of an electronic oven can be rapidly discharged from a container or bag, it is not required to fully cover the container for food with non-woven fabric.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a food container suitable for heating in a microwave oven, which has a function of adjusting humidity within the container and a function of preventing boiling liquid from boiling over when heating processed foods or the like in a microwave oven.

[Conventional technology]

Recently, processed foods that are intended to be heated in a microwave oven have been developed. Microwave heating is a method of heating a substance containing water by applying microwaves that dielectrically heat water molecules to the substance. Recently, food products packaged in disposable containers that are intended to be heated in a microwave oven have also been developed. When heating in a microwave oven, the container is generally sealed with plastic wrap to prevent foods that contain a large amount of moisture from boiling over, and foods that have little moisture to prevent them from drying out.

[Problem to be solved by the invention]

Microwave heating has advantages such as being able to heat in a short time and being safe because it does not use fire, but it also has the following problems. ■When heating foods that contain a large amount of water in the microwave, such as noodles such as ramen and udon, boiled vegetables and fish, and various soups, the liquid may boil over if the container is heated without sealing the container. There are many. Particularly when heating is performed in a short time by increasing the intensity of the microwave, boiling over often occurs. If a container is sealed and heated, the internal pressure of the container will increase as it boils due to heating, and steam and liquid contents will spout out when the lid is opened.If the container is sealed with plastic wrap, the wrap will come off or break and the liquid contents will spout out. There are many cases. ■When heating foods with relatively low moisture content, such as hamburgers, in the microwave without covering the container, the surface of the food will dry out, and conversely, if you do not cover the container with a lid or pack it, Heat it in the microwave as it is packed.
;If the surface of the food becomes excessively moist,
The flavor of heated foods decreases. Electron heating has the drawbacks mentioned above. However, to date, foods that can be heated in a microwave oven have only been marketed in cases where the above disadvantages are not a noticeable problem, or even if they are a problem, they are already recognized as a disadvantage of microwave foods. There is. However, if the above drawbacks can be solved, the variety of microwave foods can be greatly expanded. Furthermore, the flavor of current microwave foods can be significantly improved.

[Means to solve the problem]

The inventors of the present invention have conducted intensive studies on the drawbacks of microwave heating, and have found that the above-mentioned drawbacks can be significantly improved by using a container made of a waterproof and breathable nonwoven fabric. That is, the present invention has an air permeability of l cc/cm"/s
ec, or more, and the food container is made of a nonwoven fabric and has a water resistance of 1Oc- or more and is suitable for heating in a microwave oven. The food container of the present invention is a container or packaging bag that is at least partially covered with a nonwoven fabric that is breathable and waterproof. When a container with such a structure is used, it is possible to prevent the boiling liquid from boiling over when heating a food with a high water content in a microwave oven. Particularly when the intensity of the microwave is increased (heating for a short time), boiling over can be prevented. Furthermore, even in the case of foods where the flavor of the food deteriorates due to moisture on the surface of the food, it is possible to reduce the excessive moisture on the surface of the food that occurs when heated in a microwave oven, and at the same time prevent the food from drying out. I can do it. The higher the air permeability and water resistance of the nonwoven fabric used in the present invention, the better, and the air permeability is at least lcc/ca+"
/sec, and the water resistance is at least IOam. More preferably, the breathability is 1Occ/c+s”/
sec. The water resistance is 20 cm or more. Breathability is l cc
/cm”/sec, if it is smaller, the water vapor inside the container will not be able to dissipate quickly, and the water resistance will be lower than loc
If it is smaller, boiling over cannot be prevented. A sheet material having such characteristics cannot be satisfied with a porous film, but must be a nonwoven fabric. There is also a general problem in nonwoven fabrics that increasing air permeability lowers water resistance, but by reducing the average fineness of the fibers that make up nonwoven fabrics, both air permeability and water resistance can be increased. In addition, the air permeability referred to in the present invention is JI
The value is measured by the SL-1096A method, and the water resistance is the value measured by the JISL-1092A method. The nonwoven fabric used in the present invention may be a needle bunch nonwoven fabric or a hydroentangled nonwoven fabric treated with waterproofing or water repellent treatment, as long as it has the above-mentioned characteristics.
From the viewpoint of safety for use in food products, it is preferable to use a nonwoven fabric produced by the melt-blowing method, which can satisfy the above characteristics without using a treatment agent such as a water repellent and is also advantageous for industrial production. Nonwoven fabrics produced by melt-blowing can be obtained by melting polyolefin resin, polyester resin, polyamide resin, etc., extruding it through a die, blowing it into fine fibers with high-temperature, high-pressure gas, and collecting it on a wire mesh, etc., so that the fibers become fine. It also has the characteristic that the fibers are intertwined in a three-dimensional structure. In the present invention, a nonwoven fabric with high hydrophobicity as a resin and high water resistance can be easily obtained without adding a water repellent or the like, and fibers with an average fineness of 0.1 denier or less can be easily obtained. A nonwoven fabric using a polyolefin resin is preferable, and a nonwoven fabric using a polypropylene resin having a glass transition temperature of 100° C. or higher is more preferable. The average fineness of the fibers constituting the nonwoven fabric is preferably 0.1 denier or less, more preferably 0.0
The average fineness is preferably 7 denier or less, and the smaller the average fineness, the higher the air permeability and water resistance. It is preferable that fibers of 1 denier or more are not mixed. The basis weight of the nonwoven fabric used in the present invention is not particularly limited, but in order to satisfy the above characteristics, it should be 7'g/a'' or more,
It is preferable to use log/m'' or more and 200 g/m'' or less. When the basis weight is decreased, air permeability increases, but water resistance decreases, and when basis weight is increased, water resistance increases but air permeability decreases. The nonwoven fabric used in the present invention can be embossed or laminated with other nonwoven fabrics within a range that satisfies air permeability and water resistance. In particular, lamination with spunbond nonwoven fabric increases strength and improves handling properties. In the present invention, it is not necessary to cover all of the food containers with nonwoven fabric. It is sufficient if the water vapor generated from the food when heated in a microwave oven can be quickly released to the outside of the container or bag. Food containers are made by methods such as using nonwoven fabric as a lid or part of a lid of a container molded from expanded polystyrene or thermoplastic resin, or welding it with polyethylene film or the like to make a packaging bag. The lid of the container may be heat-sealed or mechanically fitted. When food is placed inside the food container of the present invention and heated using an electronic oven, the food container is heated with the nonwoven fabric surface facing upward of the container. When using it for foods with a lot of liquid, make sure that the surface of the nonwoven fabric is above the liquid level in the container (if there is no air in the container and there is no liquid level, the liquid level created by evaporation of water within the container). do. In the present invention, it is preferable to use nonwoven fabric for at least 5%, preferably 10% or more of the upper area. Particularly preferably, the range is 20% or more. The upper area here refers to the area of the upper surface observed when the container or bag is viewed from above. The container or bag of the present invention can be used to freeze or store food while it is in the container or bag. It is preferable to provide a lid or store it in a packaging bag. When heating food in a microwave oven, the barrier lid or packaging bag can be removed and the food can be heated in the microwave as it is in the container or bag.

[Effect]

When food is placed in the food container of the present invention and heated in a microwave oven, even if the water in the food boils, the breathability of the nonwoven fabric prevents water vapor from escaping to the outside and increasing the internal pressure of the container. The waterproof nature of the non-woven fabric prevents the contents from spilling over.

【Example】

Reference Example (Preparation of nonwoven fabric having waterproofness and breathability) A nonwoven fabric having an average fineness of 0.05 d was prepared from molten polypropylene by a melt blowing method. The basis weight is 9g/l, 12g/w+”,
Three types of nonwoven fabrics with a weight of 20 g/g*" were prepared. All of them were embossed. Furthermore, for reinforcement, a polypropylene spunbond nonwoven fabric with a basis weight of 20 g/m" was attached to one side and embossed. Table 1 shows the water resistance and breathability of these nonwoven fabrics. (Left below) Table l Weight: g/1 Air permeability: cc/ctm”/sec, (JIS L
-1096A method) water resistance, cII (JIS L-1
092A method) Examples 1 to 3 The lid of a commercially available instant noodle cup (Cup Noodles manufactured by Nissin Food Products Co., Ltd.) was removed, and a predetermined amount of water was poured inside. Next, three types of nonwoven fabrics produced in reference examples were attached as a lid by heat welding. This was placed in a microwave oven and heated at high heat. No matter which type of nonwoven fabric was used, the broth did not boil over during heating, and cup noodles that were ready to eat could be made. Comparative Example 1.2 In the above example, the container was not covered with a lid, and a membrane having waterproofness and air permeability with an air permeability of 0.0013 cc/cm''/sec (Duraguard film manufactured by Polyplastics Co., Ltd.) was used. A container made of polypropylene (polypropylene family) was placed in a lid and heated strongly in the microwave as in the example.If the container was left uncovered, the broth would boil over as soon as it boiled, and if it was covered with Juraguard film, it would boil over. As a result, the inside of the container became pressurized, and the Duraguard film ruptured and the broth gushed out.Example 4, Comparative Example 3.4 A hamburger was placed in a deep polypropylene plate and the nonwoven fabric of Reference Example No. 2 was pasted. A lid was placed on the lid.A polyethylene film was then pasted to form a double lid.For comparison, two lids were prepared with a polyethylene film pasted without a non-woven fabric, and both were frozen overnight.The example was made with a non-woven fabric. The polyethylene film was removed from one of the two comparative examples, leaving the lid on, and the other was thawed and heated in the microwave with the lid intact.The hamburger in the container of the example was thawed and heated in the microwave. The bread was able to warm up just when it was ready to eat without becoming damp.If the bread was heated with the lid covered with polyethylene film, the surface of the bread would be damp and the taste would be bad.On the other hand, if the lid was removed When heated, the surface of the bread was dry and crumbly.

【Effect of the invention】

When food is heated in a microwave oven in the food container of the present invention, whether the food has a high moisture content or a low moisture content, there is no problem of boiling liquid boiling over or the surface becoming too wet or too dry. It can be heated. By using the food container of the present invention as a container for retort food, etc., the range of foods that can be heated in a microwave oven is expanded, and the eating habits can be enriched.

Claims (1)

[Claims] (1) Air permeability is 1cc/cm^2/sec. A food container suitable for heating in a microwave oven, which is made of a nonwoven fabric and has a water resistance of 10 cm or more.