JPS59103822A - Method of heating and sterilizing tray package - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat sterilization of a tray packaged product (hereinafter referred to as a tray packaged product) used.

The tray packaging product is widely used as a so-called shrink packaging product or a trench packaging product as a simple packaging for food products. However, these tray-packaged products are air-containing packages, the trays and films have poor gas barrier properties, and the storage stability of packaged foods is limited due to the tendency of foods to reduce salt content, acid saccharification, and restrictions on the use of food preservatives. Improvement is required.

Conventionally, various methods such as heat sterilization, gas replacement, vacuum packaging, sterilization packaging, and use of oxygen absorbers have been used to improve the shelf life of packaged foods. Among these sterilization methods,
The tray packaged product targeted by the present invention is a pneumatic packaged product as mentioned above, and since trays and films have the disadvantage of poor gas barrier properties, heat sterilization is the preferred method. .

However, when heat sterilization is used for air-containing tray-packaged products, heating causes an increase in the internal pressure inside the packaged product, causing deformation of the tray or expansion and deformation of the film. Due to a sudden drop in internal pressure due to a drop in internal pressure, the product may become packaged in a so-called close-contact/vacuum packaging, where the film adheres closely to the shape of the food, or the film may expand due to film sagging. may remain in the form of wrinkles, and the appearance of the tray-packed product after heat sterilization deteriorates significantly, making it worthless as a product.

The present inventor conducted research on a heat sterilization method for tray-packaged products that prevents deterioration of the packaged product's appearance and maintains the sterilization effect, and arrived at the present invention.

That is, in the heat sterilization of tray packaging products using trays and plastic films, the present invention provides at least one small deaeration hole in the film on the two sides of the tray, performs heat sterilization, and then sterilizes the deaeration hole. This is a heat sterilization method for tray-packaged products, which is characterized by sealing the tray-packed products with an adhesive label.

The tray packaging product of the present invention is a shrink-packed product using a tray made of polystyrene, polypropylene, polyvinyl chloride, paper, etc., and a film made of polyolefin, polyvinyl chloride, etc., such as a shrink film or a film called a stretch film. It is a simple packaging product whose typical example is a wrapped product or a stretch wrapped product. Since the tray and film used are heated, they are preferably made of materials with high heat resistance.

The deaeration holes prevent the internal pressure from increasing in the four parts of the packaged product during heat sterilization, and their size and number vary depending on the size of the tray, the amount of food, the required heating temperature, the size of the adhesive label, etc. Although it is different, it is preferable to make it as small as possible and to have as few pieces as possible, and the usual size is 05 to 3 in diameter and at least 1 piece, but the position of the deaeration hole should be provided in the film on the top surface of the tray. is necessary. When a deaeration hole is provided in the film on the side of the tray, as described in Comparative Example 2 below,
After heat sterilization, the film adhered to the food along the shape of the food inside, resulting in a significant deterioration in the appearance of the packaged product. A method for providing deaeration holes is to use a pin-shaped object or a heated pin-like object to form a deaeration hole in a predetermined position of the film corresponding to the top surface of the tray. Alternatively, after the tray packaging product is created, deaeration holes may be provided at predetermined positions in the film on the top surface of the tray. Practically speaking, the latter method is preferable, and the deaeration hole can be provided at a predetermined position by using a phototube or the like.

Since heat sterilization involves the provision of deaeration holes, moist heat heat sterilization using hot water or steam is not preferred because hot water or steam flows into the package through the deaeration holes, and dry heat heat sterilization is preferred. Typical dry heating methods include a method using hot air and a method using microwave irradiation. In particular, the heating method using microwave irradiation is a method widely used in microwave ovens, but it is possible to heat the food from inside.
This method is the most suitable as the method for heat sterilization of tray-packaged products of the present invention, as it has features such as uniform heating in a short time and easy heating control and automation. The heating temperature is selected depending on the type of food and the required heating temperature, but generally the temperature of the food is 70 to 100°C.
It is often used within the range of

Adhesive labels are labels with adhesive applied to the back side of product name labels, quality content labels, price labels, product display labels, etc. that are commonly used for tray-packaged products. It is attached to the position of the deaeration hole of the film and used to seal the deaeration hole, prevent contamination of bacteria due to outside air flowing in from the deaeration hole during storage, and maintain the sterilization effect. Materials for the label include paper, plastic film/sheet, metal foil, etc., and labels made of plastic film/sheet and metal foil are preferred in terms of sealability. Methods for attaching adhesive labels to the degassing holes of the film include a method of visually attaching using a hand labeler, or a method of attaching while automatically positioning using an automatic labeler using a phototube, etc. is used. Note that it is preferable to seal the deaeration hole with an adhesive label when the product temperature is about 50° C. or lower.

A model diagram of a tray packaged product produced by the method of the present invention is shown in FIG. FIG. 1A is a top view, and the opening is a sectional view. In the figure, 1 is a tray, 2 is a food product, 3 is a film, 4 is a seal portion of the film, 5 is a degassing hole, and 6 is an adhesive label.

Examples and comparative examples of the present invention will be described below.

Examples 1 to 3 120 pieces of chopped kamaboko were placed as a food in polypropylene and polystyrene trays (all sizes are RL 95 mm, length 185 mm, and height 20 mm).
Shrink-wrapped products using cross-linked polyethylene shrink film, stretch-wrapped products using polyvinyl chloride stretch film and polyethylene stretch film were created using commonly used packaging methods. Next, one deaeration hole with a diameter of 1 mm was provided in the center of the film on the upper surface of the tray packaged product. After heat sterilization, when the temperature of the product reached approximately 50°C, the deaeration hole was sealed with an adhesive label. The food was heated in a household microwave oven (Sharp Corporation, R-520T), and the temperature of the food after heating and changes in the appearance of the packaged product were evaluated. 1st
As shown in the table, all had good appearance. In addition, 2
Compared to cross-linked polyethylene shrink film packaging, which has increased heat resistance through cross-linking, stretch-wrapped seeds have
It was observed that the film softened due to heating. In Table 1, the tray dimensions are measured and determined after heating and cooling to room temperature.

Ratio Example 1 A shrink packaged product consisting of a polypropylene tray and a crosslinked polyethylene shrink film was prepared in the same manner as in Example 1 except that no deaeration holes were provided, and heated in an electric microwave for 1 minute and 2 minutes. went. The film expanded during heating, and the degree of expansion was approximately 3 Q mm in height from the top of the tray to the film in the case of 1 minute heating and approximately 50 mm in the case of 2 minutes heating. Also, the dimensions of the tray after heating (
Width x length x height) is 85 x 182 x when heated for 1 minute.
25 mm, 83 x 180 x 30 M when heated for 2 minutes, the tray deforms significantly, and furthermore, the film adheres to the food along the shape of the food when it is cooled after heating.
The appearance of the packaged product had deteriorated significantly and the packaged product had no commercial value.

Comparative Example 2 In Comparative Example 1, three deaeration holes with a diameter of 1 mm were placed at equal intervals on one side of the film on the side surface in the length direction of the tray.
(The film was heated for 2 minutes in a microwave oven. During heating, the film made noise and expanded about 30,111 m. After heating, the tray dimensions (width x length x height) were 87 x 183.
x 25 mm. Furthermore, as in Comparative Example 1, the film adhered to the food due to cooling after heating, resulting in no commercial value. In this comparative example, the expansion of the film was large despite the provision of deaeration holes, and the reason why the film came into close contact with the food was because moisture released from the food due to heating adhered between the periphery of the tray and the film. However, it is presumed that this is because the peripheral edge of the tray and the film are in close contact with each other, and the deaeration holes provided in the film on the side surface of the tray are unable to quickly supply fresh air or allow fresh air to flow in as the internal pressure decreases due to cooling after heating.

As described above, the method of the present invention can prevent mold 5 in tray-packed products.
It is possible to use the microwave heat sterilization method, which can easily perform heat sterilization at temperatures below 100°C, which kills most of the general spoilage bacteria such as yeast and bacteria, and pathogens, and by providing deaeration holes, the tray and film can be deformed. This is a very practical and effective method, as it prevents this and maintains the sterilizing effect by sealing the degassing holes with various types of commonly used adhesive labels for display.

[Brief explanation of the drawing]

Figure 1 is a model of a tray package obtained by the method of the present invention; (a) is a top view and (b) is a cross-sectional view. 1゛Tray 2゛Food 3: Film 5, deaeration hole
6: Adhesive label applicant Asahi Kasei Industries Co., Ltd. agent Yutaka 1) Yoshio Figure 1 (b)

Claims (1)

[Claims] When heat sterilizing trays and tray-packaged products using plastic film, provide at least one small deaeration hole in the film on the top of the tray, perform heat sterilization, and then seal the deaeration hole with an adhesive label. A method for heat sterilization of tray-packaged products, characterized by: