JPS6350249B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for filling canned goods, and in particular, a method for filling canned goods that can freely obtain a desired degree of vacuum while suppressing the amount of residual oxygen in the head space of a can to a desired value or less. Regarding. [Prior art] Conventionally, in order to prevent the contents of cans from oxidizing, the amount of residual oxygen in the head space of a can is kept below a predetermined amount by applying a hot filling method or steam flow method to the head space to a high degree of vacuum. This method is generally adopted. In recent years, in order to prevent oxidation or to prevent can deformation when using thin-walled cans, nitrogen gas has been blown into the headspace instead of the hot filling method or steam flow method to reduce the amount of residual oxygen in the headspace. Nitrogen flow methods have also been used. [Problems to be solved by the invention] Although the nitrogen gas flow method is effective as a method for reducing the amount of residual oxygen in the head space,
Since the air in the head space is replaced with nitrogen gas, only a relatively low degree of vacuum can be obtained. Canning manufacturing equipment is generally designed to operate on the assumption that there is a certain degree of vacuum in the can head space, so if the head space has a low vacuum, for example during retort sterilization, Inconveniences such as buckling (bulging deformation of the can) due to thermal expansion of the gas, or inability to detect pressure increase due to abnormal expansion when identifying cans with abnormal expansion due to deterioration of the contents. occurs. On the other hand, although a sufficiently high degree of vacuum can be obtained using the hot filling method or the steam flow method, there is a limit to the reduction in the amount of residual oxygen, and it is difficult to suppress the amount of oxygen below a desired value. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and provide a method for filling canned goods that can obtain a desired degree of vacuum while suppressing the amount of residual oxygen in the head space to a desired value or less. . [Means for Solving the Problems] As a result of repeated research and experiments in order to solve the above problems, the present inventors created a nitrogen gas-water vapor mixed gas by pre-mixing nitrogen gas and water vapor at an appropriate ratio. It was discovered that when this mixed gas is blown into the head space of a can when filling and sealing the can, the degree of vacuum in the head space and the amount of residual oxygen can both be within the desired ranges, and the present invention has been achieved. That is, the method of the present invention for achieving the above object is to prepare a mixed gas by pre-mixing nitrogen gas and water vapor at a predetermined ratio, and to blow this mixed gas into the head space of the can after filling the can with the contents. It is designed to be tightly wound. The feature of the present invention is that the method of blowing nitrogen gas and water vapor into the head space of a can is not to blow nitrogen gas and water vapor separately over time or on a line, but to mix the nitrogen gas and water vapor in advance in a mixing device. This method uses a method in which a mixed gas is prepared by mixing at a predetermined ratio, and the prepared mixed gas is blown into the head space using an undercover gassing method. Over time or separately on each line, for example, first blowing steam and then blowing nitrogen gas,
Water vapor is removed when nitrogen gas is blown. Conversely, if water vapor is blown in after nitrogen gas is blown in, it will have the same effect as a steam flow, and the nitrogen gas in the head space will be removed and the canned product will be in a high vacuum, but the amount of residual oxygen will not necessarily decrease. It is not possible to keep the value below the desired value. By blowing a mixed gas prepared in advance into the head space at once as in the present invention, nitrogen gas and water vapor can always be supplied at a stable mixing ratio. In addition, the method of the present invention involves pre-mixing nitrogen gas and water vapor at a predetermined ratio to create a mixed gas, heating this mixed gas in the atmosphere, filling the contents into a can, and then pouring the heated mixed gas into the can. It is designed to be blown into the head space and tightened. When the mixed gas is blown into the headspace, a portion of the mixed gas is atomized due to the influence of the ambient temperature, and this atomized portion has no effect of displacing the air in the headspace, so the remaining oxygen is reduced accordingly. However, by heating the mixed gas in the atmosphere and then blowing it into the headspace, this atomization of water vapor can be prevented and the amount of residual oxygen in the mixed gas can be reduced. The effect can be further enhanced. To heat a mixed gas, for example, the mixed gas can be passed through a pipe and the pipe heated to 100°C or higher. [Example] Example 1 Using the apparatus shown in Fig. 1, the steam flow method,
The degree of vacuum in the head space and the amount of residual oxygen were measured using the nitrogen gas flow method and the nitrogen gas-water vapor mixed gas flow method according to the present invention. In FIG. 1, A is a nitrogen gas-steam mixing device, and nitrogen gas supplies are connected to a nitrogen gas supply source (not shown) and a water vapor supply source (not shown) on both sides of the hollow casing 1, respectively. A valve 2 and a steam supply valve 3 are provided, and baffle plates 4 and 5 for stirring are provided inside the casing 1. 6 is a drain pipe for discharging water vapor that has turned into water. A pseudo undercover gassing device B for experimental use is connected to the nitrogen gas-steam mixing device A via a communication pipe 6. This device B also consists of a hollow case 8,
A recess 10 having a semicircular cross section is formed on one side of the recess 10 into which the can 9 is fitted after being filled with the contents of the can and before being sealed, and a gas outlet 11 is opened in the upper part of the recess 10. ing. 12 is a drain pipe for discharging water vapor that has become water. To perform various gas flows using the above device, open the nitrogen gas supply valve 2 and the steam supply valve 3 to supply either one or both of nitrogen gas N ₂ and steam S into the enclosure 1 of the device A. do. After filling the contents, the can 9 before being sealed is inserted into the recess 10 of the device B and left standing. The gas supplied into the enclosure 1 (after being stirred and mixed in the case of mixed gas) is transferred to the device B via the communication pipe 7.
The gas enters the casing 8 and is blown into the head space of the can 9 through the gas outlet 11. In this experiment, the above device was used, and the filling temperature was 60℃,
A 200 g Toyo Seamnet can filled with water at 80°C and 90°C was used. A semitro seamer was used as the seamer. In the experiment using the above device, the flow rate of nitrogen gas was set to three types: 0 l/min, 10 l/min, and 25 l/min, and the flow rate of water vapor was set to 0.01 Kg/cm ² and 0.02 Kg. / ^cm2 When the above 3
The flow rate of water vapor was measured with respect to the flow rate of nitrogen gas on the street, and was determined as the water vapor flow rate. The measurement results are shown in Table 1 below.

[Table] Figure 2 shows the results of measuring the degree of vacuum in the head space of the can into which the nitrogen gas-steam mixture gas of the mixture ratio obtained is blown, and Figure 3 shows the results of measuring the amount of residual oxygen in the head space. Each is shown in the figure.
From Figure 2, in the case of nitrogen gas-steam mixed gas flow, and in the case of nitrogen gas flow alone (steam 0 kg/
It can be seen that the degree of vacuum can be increased by 5 to 10 cmHg compared to cm ² ). Also, from Figure 3, in the case of nitrogen gas-steam mixed gas flow, the amount of residual oxygen increases by about 0.05 to 0.7 ml compared to the case of nitrogen gas flow alone.
It can be seen that this is significantly reduced compared to the case of water vapor flow alone (N ₂ : 0 l/min). (For example, about 1 to 1.3 ml when compared at a filling temperature of 80°C). Now, calculate the nitrogen gas-water vapor mixing ratio from Table 1, set the desired degree of vacuum to 30 cmHg or more, and the desired amount of residual oxygen to less than 0.4 ml, and select a suitable nitrogen gas -
The water vapor mixing ratio is derived from the measurement results shown in Figures 2 and 3 as shown in the following table.

【table】

[Table] From Table 2, as the ratio of water vapor in the nitrogen gas-steam mixture increases, the degree of vacuum can be sufficiently high, but the amount of residual oxygen increases; conversely, as the ratio of nitrogen in the mixed gas increases, the amount of residual oxygen increases. It can be seen that the degree of vacuum decreases, although the amount decreases. Also, from the same table, it can be seen that by using a nitrogen gas-steam mixture gas in an appropriate ratio, a sufficiently high degree of vacuum and a sufficiently small amount of residual oxygen can be achieved at the same time. In the same table, the desired degree of vacuum is
When the desired residual oxygen amount is 30 cmHg or more and less than 0.4 ml, the preferred mixing ratio (volume) of the mixed gas is in the range of 1:2.5 to 1:12.5. From the characteristic curves in Figures 2 and 3, the suitable water vapor:nitrogen mixture ratio is 1:2 under typical canned filling and sealing conditions.
It can be seen that the ratio ranges from 1:50 to 1:50, preferably from 1:3 to 1:15. Example 2 The following table shows the results of an experiment using a 21M seamer with an undercover gashing device, in which 250g of coffee was filled into a 250g Toyo Seam Network can at a filling temperature of 85 to 90°C as an object for various gas flows. show. The amount of oxygen remaining in the head space is the value measured immediately after seaming and before retort heat sterilization. The water vapor:nitrogen mixing ratio of the mixed gas is 1:2.5, the line speed is 150 cpm, the nitrogen gas flow rate is 120 l/min, and the water vapor flow rate is 300 l/min.

[Table] Mixed gas

Example 3 The following table shows the results of an experiment conducted under the same conditions as in Example 2, except that a 200 g Toyo Seam Network can was filled with corn soup at a filling temperature of 60 to 62°C.

[Table] Mixed gas

Example 4 The following table shows the results of an experiment conducted under the same conditions as in Example 2, except that a 200 g Toyo Seam Network can was filled with green tea at a filling temperature of 88 to 91°C.

[Table] Mixed gas
[Effects of the Invention] According to the present invention, by mixing nitrogen gas and water vapor in advance at a predetermined ratio to create a mixed gas, and blowing this mixed gas into the head space of the can, residual oxygen in the head space is removed. While keeping the amount below a predetermined value, it is possible to obtain desired degrees of vacuum at various levels that could not be obtained by conventional nitrogen gas flow methods. Therefore, it is possible to eliminate backling and canister inspection problems that may occur in the nitrogen gas flow method. In addition, compared to the conventional steam flow method, it is possible to reduce the amount of residual oxygen and lower the degree of vacuum, so it is possible to effectively prevent quality deterioration of the contents of canned goods and to make cans thinner. . The method of the present invention can be applied to a wide range of canned goods such as drinks such as youth and processed foods. Furthermore, recently, when filling solid foods such as meat into cans, a method of filling cans called dry pack canning has been developed, in which retort sterilization is performed without sealing in any liquid other than the liquid that oozes from the solid food. It is also effective to apply this method. In addition, if this method is applied to so-called high-vacuum canning, the degree of vacuum can be reduced while keeping the amount of oxygen sealed low, which is advantageous in terms of manufacturing, such as eliminating the need for a high-vacuum seamer, and making the cans thinner. This is effective because it allows you to improve your performance.

[Brief explanation of the drawing]

In the accompanying drawings, FIG. 1 is a perspective view showing an example of an experimental apparatus for carrying out the method of the present invention, and FIG.
The figure is a graph showing the effect of the nitrogen-water vapor mixed gas flow on the degree of vacuum, and FIG. 3 is a graph showing the effect of the same mixed gas flow on the amount of residual oxygen.

Claims (1)

[Claims] 1. A mixed gas is prepared by pre-mixing nitrogen gas and water vapor at a predetermined ratio, and after the contents are filled into a can, this mixed gas is blown into the head space of the can and the can is tightened. How to fill canned goods. 2 Prepare a mixed gas by pre-mixing nitrogen gas and water vapor at a predetermined ratio, heat this mixed gas in the atmosphere, fill the contents into a can, and then blow this heated mixed gas into the head space of the can. A method for filling canned goods characterized by rolling and tightening.