JPH024459B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for cooling canned goods after sterilization in a retort sterilizer. Conventionally, retorts have been used to heat sterilize and then cool the contents of filled and sealed cans. That is, canned goods are stacked and sealed in a retort and heated with steam for a certain period of time. After the heat sterilization is completed, cooling water is introduced into the retort, and the canned goods are cooled by being immersed in the cooling water. Once cooling is complete, the cooling water is discharged, completing the sterilization and cooling process. During this submerged cooling, to prevent the temperature of the cooling water in the retort from becoming different between the upper and lower parts,
The cooling water circulation pump was operated, and as soon as cooling was completed, the circulation pump was stopped and the cooling water was drained. According to this cooling method, the cooling water does not circulate during the draining process, and the cooling effect continues even during the draining process, so the temperature of the upper part of the cooling water rises compared to the lower part, and the cooling water increases as the water drains. Since cans exposed above water lose their cooling effect, the higher the layer of cans in the stack, the higher the temperature after cooling compared to the lower layer. The temperature difference between the canned food in the upper and lower rows is only a few degrees at most, and has not been a problem in the past.
However, as the automation of the inspection process progresses in recent years, such as the introduction of line inspection machines to inspect the quality of seaming, it has become clear that this temperature difference has an effect on the detected value, leading to variations in the temperature of canned goods. There is a strong desire for a cooling method that reduces The present invention uses a retort sterilizer that is almost the same as the conventional one, but by operating a circulation pump not only during the cooling process but also during the draining process, the difference in water temperature between the upper and lower parts of the cooling water is minimized. By cooling the cans stacked on top of each other, it is possible to prevent variations in the temperature of the cans after cooling. A detailed description will be given below with reference to the drawings. The figure is a schematic diagram of a retort sterilizer. Inside the retort body 1, canned goods 4 are stored and sealed by being placed on partition plates 3 provided in multiple stages in a basket 2. Reference numeral 5 denotes a steam valve, and when this valve is opened, steam is ejected from the lower steam pipe 6 into the retort main body 1, and sterilization is carried out by steam heating at a predetermined temperature for a predetermined time. For example, for some beverage cans, the sterilization temperature is 120°C and the sterilization time is 25 minutes. When the steam heating sterilization is completed, the steam valve 5 is closed, the water supply valve 7 is opened, and water supply from the upper water supply pipe 8 is started. The canned goods stacked in the basket 2 are cooled, and the heated cooling water is drained through a drain valve 10. The cooling water temperature measured between water levels L and h is
When cooling has progressed to 75° C., the drain valve 10 is closed, water is supplied to the water level H, and the canned food is completely immersed in the cooling water. Next, the circulation pump 9 is operated, and cooling is performed while averaging the temperature difference between the upper and lower portions of the cooling water. When cooling is completed, conventionally, the circulation pump 9 is stopped, the drain valve 10 is opened to drain the inside of the retort, and the cooled cans are taken out and sent to the next process. In the above cooling method, after the circulation pump 9 is stopped, the canned goods in the cooling water continue to be cooled until the drainage is completed (about 3 minutes), and the temperature of the cooling water increases as it moves toward the top of the retort. It gets expensive. Also, the cooling time for canned goods in the lower part of the basket is longer than that in the upper part. For this reason, the temperature of the canned goods taken out after the cooling process is higher in the upper tier of the basket than in the lower tier, and the variation in temperature poses a problem as described above. An example of temperature variations at this time is shown in Table 1. Data represent average values for 1500 250g coffee cans.

[Table] In the present invention, even if the drain valve 10 is opened after cooling is completed and drainage in the retort is started, the circulation pump 9
During the draining process, cooling water is injected onto the canned food from the upper cooling water circulation pump 11 by the circulation pump without stopping the operation. This makes it possible to minimize the temperature difference between the upper and lower parts of the cooling water in the drain water, and also to substantially reduce the difference in cooling time between the upper and lower canned cans. Table 2 shows the data obtained by measuring the temperature variation of canned foods using this method in the same manner as in Table 1 above.

[Table] The temperature difference between the upper and lower rows of canned goods has been reduced from 5 to 6 degrees Celsius to around 2 degrees Celsius, and the effect is clear.

[Brief explanation of drawings]

The figure is a schematic diagram of a retort sterilizer. 1: Retort body, 2: Basket, 3: Partition plate, 4: Canned food, 5: Steam valve, 6: Steam pipe,
7: Water supply valve, 8: Water supply pipe, 9: Circulation pipe,
10: Drain valve, 11: Circulation pipe.

Claims (1)

[Claims] 1. During the cooling and draining process of canned goods in a retort sterilizer that sterilizes canned goods in a retort by steam heating and then cools them by injecting water, a circulation pump is operated even during the draining process to circulate the cooling water remaining in the retort. A method for cooling canned goods in a retort sterilizer, characterized by: