JPH08591B2 - Food container suitable for microwave heating - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

TECHNICAL FIELD The present invention relates to a food container suitable for microwave heating, which has a function of controlling humidity in the container and a function of preventing spillage of boiling liquid when heating processed foods in a microwave.

[Prior art]

Recently, processed foods have been developed that are supposed to be heated in a microwave oven. Microwave oven heating is a method of heating a substance by applying microwaves for inductively heating water molecules to the substance containing water. Recently, foods in disposable containers which are supposed to be heated in a microwave oven have been developed. When heated in a microwave oven, foods containing a large amount of water are generally sealed with wraps to prevent spillage and foods with a low water content are sealed and heated.

[Problems to be Solved by the Invention]

Microwave oven heating has the advantages that it can be heated in a short time and is safe because it does not use fire, but it has the following problems. When microwave-heated foods containing a large amount of water, such as noodles such as ramen and udon, boiled vegetables and fish, various soups, etc., the broth may spill out when heated without sealing the container. Many. In particular, when heating is performed in a short time by increasing the strength of the microwave, it often blows. When the container is sealed and heated, boiling causes the internal pressure of the container to rise and steam or content liquid spouts when opening the lid, or when sealed with wraps, the wrap comes off or breaks and the content liquid spouts. In many cases. When microwave-heated food with relatively low water content, such as hamburgers, the surface of the food dries when microwave-heated without covering the container, and conversely the container is covered or packed. When the food is heated in the microwave as it is, the flavor of the heated food is deteriorated because the surface of the food becomes excessively moist. Microwave heating has the disadvantages mentioned above. However, so far, food products premised on microwave heating are marketed only when the above-mentioned drawbacks are not a significant problem, or even when they are already recognized as the drawbacks of microwave foods. There is. However, if the above drawbacks can be solved, the types of microwave oven foods can be greatly expanded. Further, the flavor of current microwave oven foods can be significantly improved.

[Means for Solving the Problems]

As a result of extensive studies on the drawbacks of microwave heating, the present inventor has found that the above-mentioned drawbacks can be greatly improved in a container using a nonwoven fabric having waterproofness and breathability. That is, the present invention, the average fineness of the fibers constituting the nonwoven fabric is
0.1 denier or less, air permeability of 1 cc / cm ² / sec. Or more,
A food container suitable for heating in a microwave oven, which is made of a nonwoven fabric having a water resistance of 10 cm or more. The food container of the present invention is a container or packaging bag at least a part of which is covered with a non-woven fabric having air permeability and waterproofness. When a container having such a structure is used, it is possible to prevent spilling of simmered liquid when heating a food having a high water content in a microwave oven. In particular, even when the strength of the microwave is increased (heating for a short time), spillage can be prevented. Furthermore, even in the case of a food in which the flavor of the food is deteriorated due to the surface of the food getting wet, it is possible to reduce excessive moisture on the food surface generated by microwave heating and at the same time prevent the food from drying. I can. The higher the air permeability and the water resistance of the nonwoven fabric used in the present invention, the more preferable. The air permeability is at least 1 cc / cm ² / sec. And the water resistance is at least 10 cm. More preferably, the air permeability is 10 cc / cm ² / sec. Or more and the water resistance is 20 cm or more.
If the air permeability is less than 1 cc / cm ² / sec., Water vapor in the container cannot be quickly diffused, and if the water resistance is less than 10 cm, spillage cannot be prevented. A sheet material having such characteristics cannot be satisfied with a porous film, and needs to be a non-woven fabric. Although there is a general problem that the water resistance of a non-woven fabric is lowered if the air permeability is increased, it is possible to increase both the air permeability and the water resistance by reducing the average fineness of the fibers constituting the non-woven fabric. The breathability referred to in the present invention is JIS L.
It is the value measured by -1096A method, and the water resistance is JIS L-10.
It is the value measured by the 92A method. The non-woven fabric used in the present invention may be a needle-punched non-woven fabric or a hydroentangled non-woven fabric that has been subjected to waterproofing or water repellent treatment, as long as it has the above-mentioned characteristics, but is safe for use in foods. From this point of view, a non-woven fabric by the melt blow method, which can satisfy the above-mentioned characteristics without using a treating agent such as a water repellent agent and is advantageous for industrial production, is preferably used. Non-woven fabric made by melt blow method is polyolefin resin,
It can be obtained by melting polyester resin or polyamide resin, extruding it from a die, blowing it into thin fibers with high-temperature and high-pressure gas, and collecting it on wire mesh etc., and the fibers are thin and the entanglement of the fibers is three-dimensional. It has a feature that it is configured. In the present invention, a polyolefin resin having high hydrophobicity as a resin, a non-woven fabric having a high water resistance without adding a water repellent, etc. can be easily obtained, and a fiber having an average fineness of 0.1 denier or less can be easily obtained. A non-woven 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 non-woven fabric is preferably 0.1 denier or less, more preferably 0.07 denier or less, and the smaller the average fineness, the better the air permeability and water resistance. It is preferable not to mix fibers having a denier of 1 or more. The basis weight of the non-woven fabric used in the present invention is not particularly limited, but in order to satisfy the above characteristics, it is preferable to use one having a weight of 7 g / m ² or more, preferably 10 g / m ² or more and 200 g / m ² or less.
When the basis weight is small, the air permeability is high but the water resistance is low, and when the weight is large, the water resistance is high but the air permeability is low. The nonwoven fabric used in the present invention can be used by embossing or by laminating it with another nonwoven fabric within a range satisfying air permeability and water resistance. In particular, when laminated with a spunbonded nonwoven fabric, the strength is increased and the handleability is improved. In the present invention, it is not necessary to cover all of the food containers with a nonwoven fabric. It suffices that the steam generated from the food can be quickly released to the outside of the container or bag by heating in the microwave oven. A non-woven fabric is used as a lid or a part of a lid formed of styrofoam, thermoplastic resin, or the like, or a polyethylene bag or the like is welded to form a packaging bag, thereby forming a food container. The lid of the container may be heat-sealed or may be mechanically fitted. The food container of the present invention is heated so that the nonwoven fabric surface is above the container when the food is put inside and heated in a microwave oven. When using for food with a large amount of juice, be sure to use the non-woven fabric surface above the liquid surface of the container (if there is no air in the container and there is no liquid surface, the liquid surface created by evaporation of water in the container). To do. In the present invention, at least 5 of the upper area
%, Preferably 10% or more of non-woven fabric. It is particularly preferably in the range of 20% or more. The upper area here is 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 frozen or stored in a state of containing food, but to prevent the food from drying and deteriorating during storage, and for further blocking the permeation of water vapor and oxygen. It is preferable to provide a lid or store in a packaging bag. When heating food in a microwave oven, the barrier lid or the packaging bag can be removed, and the food can be heated in a microwave oven as it is in a container or bag.

[Action]

When putting the food in the food container of the present invention and heating in a microwave oven, water vapor does not increase the internal pressure of the container due to the breathability of the nonwoven fabric even if the water in the food is boiled, and also, Because of the waterproof property of the non-woven fabric, the content liquid does not spill out.

【Example】

Reference Example (Preparation of Nonwoven Fabric Having Waterproofness and Breathability) A nonwoven fabric having an average fineness of 0.05d was prepared from molten polypropylene by a melt blow method. Unit weight is 9g / m ² , 12g / m ² , 20
Three types of nonwoven fabric of g / m ² were produced. All of them were embossed. Further, a spunbond nonwoven fabric made of polypropylene having a basis weight of 20 g / m ² was attached to one side for reinforcement, and embossing was performed. Table 1 shows the water resistance and air permeability of these nonwoven fabrics. Examples 1 to 3 The lid of a commercially available instant noodle with cup (cup noodle made by Nisshin Foods Co., Ltd.) was removed, and a predetermined amount of water was put inside.
Next, the three types of non-woven fabrics produced in the reference example were used as lids and attached by hot bathing. This was placed in a microwave oven and heated by intense heating. No matter which nonwoven fabric was used, the broth did not spill during heating, and cup noodles ready for eating could be made. Comparative Examples 1 and 2 In the above examples, the container is not covered, and a membrane having a waterproofness and a breathability of 0.0013 cc / cm ² / sec. (Jiura Guard Film manufactured by Polyplastics Co., Ltd.,
A container with a lid made of polypropylene) was placed in a microwave oven and heated strongly as in the example. Boiled juice spilled out at the same time as boiling, while those without a lid boiled, and the inside of the container was pressurized by boiling due to boiling, and the julagard film burst and boiled. Example 4, Comparative Examples 3 and 4 A hamburger was placed in a polypropylene basin and the non-woven fabric of No. 2 of Reference Example was attached thereto and the lid was covered. Further, a polyethylene film was attached to form a double lid. For comparison, two non-woven fabrics were attached to the polyethylene film and the lid was also prepared, and both were frozen overnight. In the example, only the polyethylene film was removed, leaving the nonwoven fabric lid, one of the two comparative examples was removed of the polyethylene film, and the other was left as it was for thawing and heat treatment in a microwave oven. The hamburger in the container of the example was able to be warmed just before eating without the surface of the bread becoming moist. If the bread is heat-treated with the lid on, the surface of the bread will be damp and will have a bad taste.On the other hand, if the lid is removed and heated, the surface of the bread will be dry and sticky. there were.

【The invention's effect】

Microwave heating the food in the food container of the present invention, spilled syrup even if the food is high in moisture or low in food, without causing the problem that the surface is too wet or too dry. It can be heated. By using the food container of the present invention for a container such as a retort food, 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. A food suitable for heating in a microwave oven, which is made of a non-woven fabric having an average fineness of 0.1 denier or less, an air permeability of 1 cc / cm ² / sec. Or more and a water resistance of 10 cm or more. container.