JPH01302159A - Inspection on high-temperature sterilizing finished positive pressured can - Google Patents

Abstract

PURPOSE:To discriminate a can already sterilized physically, by utilizing characteristic in high temperature sterilization of a positive pressured can for a low acid food. CONSTITUTION:Deformation during the sterilization of an aluminum lid is determined according to a magnitude of a pressure in the can. The pressure in the can during the sterilization is determined by (a) a pressure in the can before sterilization, (b) filling value of contents and (c) sterilization temperature. The higher these values, the higher the pressure in the can during the sterilization. Therefore, a relationship between the degree of deformation of an aluminum lid and the items from (a)-(c) is made clear by measuring the degree of deformation for a can which is already clarified by measurement about the values of the items (a)-(c) beforehand. When a correlationship is clear between above four values, the remaining sterilization temperature can be found by measuring three of the values, namely, the pressure in the can, filling value and the degree of deformation of the aluminum lid. This enables inspection to determine whether the can is already sterilized at a proper temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for testing whether positive pressure canned goods, particularly low acidic beverages, have been sterilized at a predetermined temperature.

Conventional technology Canned coffee and other low-acid beverages are heated at 120'C for 4 minutes or equivalent, as if sterilization is insufficient, the contents will rot and become very harmful to the human body. Heat sterilization in the above manner is required.

Conventionally, canned goods of this type are filled and sealed while the contents are heated, or hot-packed to create a negative pressure inside the can after cooling, which makes it easier to inspect defective canned goods. I'm looking forward to it. In other words, if the inside of a can is maintained at a negative pressure state, if sterilization is insufficient and the contents rot, the gas emitted by the putrefying bacteria will create positive pressure inside the can and cause it to bulge. It is easy to inspect cans with poor sterilization.

On the other hand, in order to save resources and reduce costs, can bodies made of thin-walled materials such as aluminum cans have recently been increasingly used in place of conventional metal cans. This type of can body has low strength against dents (springing) in the can body, so can strength is obtained by creating positive pressure inside the can by some method, such as adding liquid nitrogen into the can. Therefore, when this type of can is applied to cans of low-acid foods as described above, it is necessary to add liquid nitrogen to create positive pressure inside the can immediately before filling and sealing the can, and to perform retort sterilization. These positive pressure cans are constantly inflated, so even if the contents rot and produce gas, it is difficult to determine whether the gas was originally sealed inside the can or whether it is caused by putrefying bacteria. It is difficult to distinguish between defective canned goods, and it is difficult to inspect defective canned goods using a percussion device like conventional negative pressure canned goods. For this reason, conventionally, low-acid foods have been exclusively canned under negative pressure, and positive-pressure canning has not been used from the perspective of quality assurance because it is difficult to inspect defective canned foods. could not be used.

Problems to be Solved by the Invention The present invention has been devised in view of the above-mentioned circumstances, and aims to provide an inspection method that can easily inspect whether or not even positive pressure canned food has been sterilized. The objective is to ensure sufficient quality assurance even when low-acid beverages are canned under positive pressure.

Means for Solving the Problems In order to achieve the above object, the inventor of the present invention, as a result of various studies, discovered the characteristics of high-temperature sterilization of low-acid, positive-pressure canned food, and utilized this to produce sterilized canned food. The present invention was achieved by learning a method of physically determining the difference.

That is, the high-temperature sterilized inspection method for positive-pressure canned goods of the present invention expresses the interrelationships among canned internal pressure, can lid displacement amount, sterilization temperature, and filling amount in high-temperature sterilized positive-pressure canned goods of the same can type as the canned cans to be inspected. By obtaining sterilization temperature test data in advance, measuring the weight, internal pressure, and displacement of the can lid of the canned food to be tested, and calculating the sterilization temperature of the canned food to be tested based on the sterilization temperature test data from the measured values. , which employs a technical means characterized by inspecting the high temperature sterilization of positive pressure canned goods, thereby achieving the above object.

Function Generally, when canned goods are heat sterilized, the internal pressure of the can increases due to the expansion of gas in the head space due to heating during sterilization and the increase in the specific volume of the contents. As a result, the volume of the container attempts to increase, placing a load on the can material.

The aluminum lid, which is the most easily deformable, deforms. Experiments have confirmed that the deformation of the aluminum lid does not completely return to its original state even after sterilization, and the degree of deformation according to the internal pressure is maintained compared to before sterilization. However, the condition is that the pressure within the can is too high to cause buckling, and such cans are usually rejected by a deformation measuring device. The deformation of the aluminum lid during sterilization is determined by the amount of pressure inside the can, and the pressure inside the can during sterilization is determined by: (a) pressure inside the can before sterilization, (b) amount of contents filled, and (c) sterilization. It is determined by the temperature, and the higher both of these are, the greater the pressure inside the can during sterilization. Therefore.

If the degree of deformation of the aluminum lid is measured in advance for canned goods for which the values of (a) to (c) above are clearly measured, the relationship between the degree of deformation of the lid and the above (a) to (c) will be clear. become.

Once the correlation between these four quantities has been clarified, the remaining quantity, the sterilization temperature, can be determined by measuring three of them: the pressure inside the can, the filling volume, and the degree of deformation of the aluminum lid. can be determined. Thereby, it is possible to check whether the canned food has been sterilized at an appropriate sterilization temperature. Therefore, according to the present invention, it is possible to inspect whether each individual can has been sterilized at an appropriate temperature, and it can also be applied to sample inspection for each lot.

Example Embodiments of the present invention will be described below based on the drawings.

230.0g of water in a 250g steel DI can, 234
．． By filling the can with 5g, 239.0g, or 244.0g and immediately tightening the aluminum lid with a liquid port after adding liquid nitrogen, you can produce positive pressure canned food with an internal pressure within the range of 0 to 2.5 kg/at. I made a prototype. The weight of this test can, the pressure inside the can before sterilization, and the height of the center of the aluminum lid from the bottom of the can (called center hide) were measured, and the pressure inside the can was Okg/cd.
Using the center hide of the can as a reference, the displacement amount of the center hide, which indicates the degree of deformation of the lid, was determined.

Thereafter, these cans were heat sterilized at temperatures of 105°C, 115°C, and 125°C for 20 minutes each. After cooling, the in-can pressure and center hide displacement were measured again at room temperature.

As a result, it was found that the pressure inside the can and the amount of displacement of the center hide for each filling amount differed between before and after sterilization as shown in Table 1.

Based on the data in Table 1, a graph showing the relationship between center hide displacement amount and can internal pressure at each sterilization temperature was obtained for each filling amount shown in FIG. In addition, Figure 1 shows the filling amount of 230.0g and 239.0g among the data in Table 1.
This example shows the case of

Based on this graph, the relationship between the displacement of the center hide and the sterilization temperature was determined using the can internal pressure as a parameter, and the graph shown in FIG. 2 was obtained. A similar graph is obtained for each filling amount and used as sterilization temperature test data.

Based on the sterilization temperature test data shown in Figure 2 in the margin below, a sterilization test for positive pressure canned food was conducted as follows.

The same can type as above, that is, a 250 g steel DI can, was filled with 239.0 g of water with liquid nitrogen to obtain a positive pressure can, which was heat sterilized, and the subsequent pressure inside the can and center hide displacement were determined. . As a result, the pressure inside the can was 1.0 kg/
ad, and the center hide displacement amount was 1.25 mm. From these measured values, the sterilization temperature is determined using the graph in Figure 2 (b), and as shown in the figure, it is 115°C.
It was found that it was sterilized. When the actual sterilization temperature of the canned food was confirmed using the recorder built into the heat sterilizer, it was found that heat sterilization was indeed carried out at a temperature of 115°C, and the test value of the sterilization temperature according to the present invention and the actual sterilization temperature were confirmed. It was confirmed that the sterilization temperature matched. Similarly, tests were conducted on other types of cans, and the sterilization temperature test value obtained as described above and the actual sterilization temperature matched, and the method of the present invention makes it possible to determine the sterilization temperature of positive pressure canned food and ensure reliable It has been confirmed that sterilized tests can be performed.

To apply the above positive pressure canned sterilized inspection method to an automatic inspection line, a canned weight measuring device, an internal pressure measuring device, and a center hide measuring device are placed along the canned transportation path, and the canned food is moved by a conveyor. As the weight of canned food, internal pressure,
The center hide is measured and the measured data is input into a microcomputer. The canned weight is converted into the amount of contents filled by a microcomputer. Sterilization temperature test data corresponding to the type of canned food to be tested is input in advance to the microcomputer, and based on the test data, the sterilization temperature is calculated from each of the measured values. The sterilization temperature is compared with a preset sterilization temperature, and if it is lower than the sterilization temperature, a reject signal is issued and the canned food is discharged out of the line as an insufficiently sterilized can. Note that the order of each of the above measurements is not limited to the above case, and the order may be arbitrary.

In addition, despite sterilization being carried out at appropriate temperatures,
In the unlikely event that bacterial expansion occurs due to the contamination of extreme heat-resistant bacteria, the value of the can internal pressure will deviate greatly from the correlation between the can internal pressure, sterilization temperature, center hide, and filling amount that has been input in advance. Therefore, such canned goods are also rejected as abnormal canned goods.

Effects By employing the above-mentioned technical means, the present invention makes it possible to reliably inspect the sterilization temperature of positive pressure canned goods, making it possible to inspect sterilized positive pressure canned goods, which has been difficult in the past. was completed. This enables positive pressure canning of low-acid beverages, which previously required strict quality assurance and could not be canned under positive pressure, and streamlined the canning manufacturing process by avoiding the need for hot packs. , it is possible to apply not only conventional metal cans but also cans made of flexible materials to the can material for low-acid beverages, thereby achieving remarkable effects such as making it possible to diversify the types of cans.

[Brief explanation of the drawing]

The drawings show graphs for explaining the present invention in detail, and FIGS. 1(a) and 1(b) show graphs when the filling amount is 230°0g, 239.
A graph showing the relationship between the center hide displacement amount and the can internal pressure at each sterilization temperature of a 0g positive pressure canner, Figure 2 (a) (
b) is a graph showing the relationship between the center hide displacement amount and sterilization temperature for each can pressure, which were determined from the graph in FIG. 1. Patent applicant Toyo Seikan Co., Ltd. Applicant's agent Patent attorney Fumio Sato (2 others) Pressure inside the can (kg/L-11) (a) Pressure inside the can (kg/L-11) (b) No. 1 Zusatsu 1 (C) (a) Stage weight temperature ('C) (b) 2nd 1

Claims (1)

[Claims] 1) Obtain in advance sterilization temperature test data that represents the interrelationship between can internal pressure, can lid displacement, sterilization temperature, and filling volume in high-temperature sterilized positive pressure canned cans of the same can type as the canned cans to be inspected, and calculate the weight of the canned cans to be inspected, It is characterized by inspecting whether the positive pressure canned food has been sterilized at high temperature by measuring the internal pressure and the amount of displacement of the can lid, and determining the sterilization temperature of the canned food to be inspected from the measured values based on the sterilization temperature test data. A high-temperature sterilized inspection method for positive pressure canned food.