Method for manufacturing retort pouch food product

Abstract

The purpose of the present invention is to provide a technique for, by using a method of high-temperature heat sterilization under atmospheric pressure, easily manufacturing a retort pouch food product continuously manufactured by a filling and packaging machine. A retort pouch food product is continuously manufactured by means of: a cell body formation step for forming a cell body by individually accommodating, in a pair of metal cells, a retort pouch food continuously manufactured by a filling and packaging machine; a heat sterilization step for immersing the cell body in a heating bath filled with a heating medium having a boiling point exceeding 100°C and, under atmospheric pressure, heating the contents of the retort pouch food accommodated in the cell body; and a cooling step for immersing the cell body heated and sterilized in the heat sterilization step in a cooling bath of 50°C or less, and thereby cooling the contents of the retort pouch food.

Description

Manufacturing method for retort pouch food products

[0001] The present invention relates to a method for easily producing a retort pouch food product by using a filling and packaging machine that mainly uses a multilayer film (laminated plastic film) for packaging and heat-seals it to form a pouch while filling the contents to be packaged, and then sterilizing the pouch at high temperature under atmospheric pressure.

[0002] Retort pouch food products can be stored for long periods at room temperature because the inside of the pouch can be kept sterile. They are convenient for packaging cooked foods such as curry and stew for individual meals, and are also widely used as emergency food in the event of a disaster.

[0003] Retort pouch food products are generally defined in the "Retort Pouch Food Quality Labeling Standards (Notice of the Consumer Affairs Agency)" as "a container (limited to airtight and light-blocking containers) made of plastic film, metal foil, or multiple layers of these molded into a bag or other shape, filled with prepared food, sealed by thermal fusion, and sterilized by pressurized heating."

[0004] For this reason, retort pouch food products are produced by filling and packaging food in a pouch (container) made of a packaging multilayer film, etc. For example, as disclosed in Patent Document 1, the retort pouch food is placed in a retort oven, and high-temperature steam (or hot water) is forced into the retort pouch food while pressurizing the pouch so as not to rupture it, and the pouch food is maintained at a high temperature (105 to 115°C is called semi-retort sterilization, 120°C is called retort sterilization, and 130°C or higher is called high-retort sterilization) for a few seconds to about 30 minutes, thereby performing pressurized, heat-sterilization.

[0005] JP 2016-096786 A

[0006] As described above, the heat sterilization of retort pouch foods is carried out under pressure, which requires expensive and large-scale equipment. Furthermore, during cooling after heat sterilization, the retort pouch foods must be gradually cooled while reducing the pressure inside the retort oven to prevent them from breaking, which is time-consuming and cost-intensive.

[0007] In particular, in recent years, advances in filling and packaging machines and multilayer films for packaging have made it possible to continuously produce retort pouch foods at high speed. However, as described above, the efficiency of the heat sterilization treatment is low, which has resulted in the need for multiple retort ovens and has been an obstacle to improving productivity through automation.

[0008] Therefore, an object of the present invention is to provide a technique for easily producing retort pouch food products continuously produced by a filling and packaging machine by a method of high-temperature heat sterilization under atmospheric pressure.

[0009] The method for producing retort pouch food products according to the present invention, which was developed to achieve the above-mentioned object, involves using a filling and packaging machine to heat-seal a strip-shaped multilayer packaging film to form a pouch, filling and packaging contents into the pouch to produce a retort pouch food, and then heat-sterilizing the pouch to produce the retort pouch food product. The method is characterized in that the retort pouch food products are continuously produced through the following steps: a cell body formation step in which the retort pouch food products continuously produced by the filling and packaging machine are each individually placed into a pair of metal cells to form a cell body; a heat sterilization step in which the cell bodies are immersed in a heating bath filled with a heating medium having a boiling point of over 100°C to heat the contents of the retort pouch food contained in the cell bodies under atmospheric pressure; and a cooling step in which the cell bodies heat-sterilized in the heat sterilization step are immersed in a cooling bath at 50°C or less to cool the contents of the retort pouch food.

[0010] In the method for producing a retort pouch food product according to the present invention, it is preferable that: (1) a recess is provided on at least one of the opposing surfaces of the pair of cells, and the retort pouch food is placed in the recess; (2) the outer peripheral edge of the retort pouch food, including at least the heat-sealed portion, is sandwiched between the outer peripheral portions of the pair of cells and sealed between the pair of cells; (3) the outer peripheral edge of the retort pouch food, including at least the inner edge of the heat-sealed portion, is sandwiched between the pair of cells with a predetermined gap; (4) a stacking step is provided between the cell body forming step and the heat sterilization step, in which a plurality of the cell bodies are stacked to form units, and the cell bodies are moved unit by unit; and (5) the heating medium is one or more oils selected from glycerin, propylene glycol, and 1,3-butylene glycol, saline, or a mixed liquid of the oil and water.

[0011] According to the method for producing retort pouch food products of the present invention, a retort pouch food is sandwiched between a pair of cells to form a cell body, and the cell body is continuously heated under atmospheric pressure using a heating medium, thereby enabling retort pouch food products to be continuously produced by a filling and packaging machine by high-temperature heat sterilization under atmospheric pressure. This method is therefore simpler than conventional pressurized heat sterilization methods using a retort oven, and shortens the sterilization treatment time (the time from heating to cooling). Furthermore, it is possible to significantly improve the productivity of retort pouch food products and reduce the size of the equipment involved in the heat sterilization of retort pouch foods.

[0012] According to the method for producing a retort pouch food product of the present invention, when a retort pouch food is heated at a high temperature, the contents boil, the internal pressure rises, and the food expands, but because the retort pouch food is constrained between a pair of thin cells, no pressure is applied to the heat-sealed portion, preventing the seal from receding or the bag from breaking due to a decrease in heat-seal strength. Furthermore, according to the present invention, when at least the inner edge of the heat-sealed portion located on the outer periphery of the heat-sealed portion is sandwiched between a pair of cells, the pressure from the contents does not directly affect the heat-sealed portion (inner edge), and bag breakage at the heat-sealed portion can be effectively prevented.

[0013] 2(a)-2(b) are views showing an embodiment of a cell body forming step in a method for producing a retort pouch food product according to the present invention.

[0024] FIG. 2(a) is a plan view,

[0025] FIG. 2(b) is a front view,

[0026] FIG. 2(c) is a cross-sectional view taken along line A-A in FIG. 2(a), and

[0027] FIG. 2(d) is a plan view showing the cell body of FIG. 2(a) with the upper cell removed.

[0028] FIG. 2(a) is a view showing another embodiment of the cross-sectional view taken along line A-A in FIG. 2(a).

[0029] FIG. 2(a) is a front view,

[0030] FIG. 2(b) is a right side view showing a state in which a plurality of cell bodies are assembled into one unit.

[0031] FIG. 2(b) is a view showing the state in which the unit of FIG. 4 is suspended and moved to the heat sterilization step and the cooling step.

[0014] An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing one embodiment of a cell body forming step in a method for producing a retort pouch food product according to the present invention. FIG. 2 is a diagram showing one embodiment of a cell body, where (a) is a plan view, (b) is a front view, (c) is a cross-sectional view taken along line A-A in (a), and (d) is a plan view showing the cell body of (a) with the upper cell removed. FIG. 3 is a diagram showing another embodiment of the cross-sectional view taken along line A-A in FIG. 2(a). FIG. 4 is a diagram showing a state in which multiple cell bodies are assembled into a single unit, where (a) is a front view and (b) is a right side view. FIG. 5 is a diagram showing the state in which the unit of FIG. 4 is suspended and moved to the heat sterilization step and the cooling step.

[0015] The method for producing a retort pouch food product of the present invention mainly comprises a cell body forming step, a heat sterilization step, and a cooling step, and each step is described below. In this specification, a pouch refers to a bag made by a filling and packaging machine, a retort pouch food refers to the pouch that has been filled and packaged with contents, and a retort pouch food product refers to the retort pouch food that has been subjected to heat sterilization and cooling treatments.

[0016] (Cell Body Forming Process) The cell body 1 is composed of a retort pouch food 11 and a pair of thin, plate-shaped cells 12a, 12b (lower cell 12a, upper cell 12b), and is formed by transporting the retort pouch food 11 continuously produced by a filling and packaging machine 2 in sequence by a conveyor 21, placing it on the lower cell 12a, and then covering it with the upper cell 12b from above and pressing the upper cell 12b from above, as shown in Fig. 1. The shape, thickness, etc. of the cells 12a, 12b can be changed as appropriate.

[0017] The retort pouch food 11 is formed by a filling and packaging machine 2, such as a known vertical or horizontal filling and packaging machine. The filling and packaging machine 2, for example, folds a strip of multilayer film continuously unwound from a raw film at the center in the width direction, vertically seals the folded-back portions and overlapping side edges of the multilayer film continuously in the conveying direction to form a cylindrical shape, and then, while filling the cylindrical multilayer film with contents, horizontally seals the film in a direction perpendicular to the conveying direction, thereby continuously producing retort pouch food 11 having heat-sealed portions (vertical seal portion 11a, horizontal seal portion 11b) on all four sides of the outer periphery. The multilayer film is preferably made of a plastic film such as PET / aluminum foil / nylon / polypropylene, and has gas barrier properties and light-blocking properties and can withstand temperatures above 100°C.

[0018] The pair of cells 12a, 12b are mainly made of a metal such as aluminum or titanium, and aluminum is one of the most preferable materials because it is lightweight and has excellent thermal conductivity.

[0019] As shown in Figures 2(c) and 2(d), at least one of the pair of cells 12a, 12b has a recess 13 formed in the center of the surface facing each other. The recess 13 is for accommodating a retort pouch food 11 (a portion for accommodating contents) provided between the pair of cells 12a, 12b, and is formed appropriately to match the size of the retort pouch food 11. In this embodiment, recesses 13 of the same shape (depth) are provided in each of the pair of cells 12a, 12b (lower cell 12a, upper cell 12b), but this can be modified appropriately, for example, by providing a recess 13 only in the lower cell 12a and accommodating the retort pouch food 11 in the recess 13.

[0020] At least the inner edge of the heat-sealed portion (vertical seal portion 11a, horizontal seal portion 11b) provided on the outer periphery of the retort pouch food 11 is sandwiched between a pair of cells 12a, 12b as shown in Figure 2(c). As a result, the retort pouch food 11 is sealed between the pair of cells 12a, 12b. When the retort pouch food 11 is sealed (with no gap) between the pair of cells 12a, 12b, heat is transferred evenly from the heating medium to the center and edges of the retort pouch food 11 during the heat sterilization process, and the heating time can be shortened.

[0021] At least the inner edge portion of the heat-sealed portion (vertical seal portion 11a, horizontal seal portion 11b) provided on the outer periphery of the retort pouch food 11 may be sandwiched between a pair of cells 12a, 12b with a predetermined gap d as shown in Figure 3. In this case, it is preferable that the gap d is 5.0 mm or less. By setting the gap d to 5.0 mm or less, the thickness of the heat-sealed portion at the inner edge is reduced, making it difficult for the internal pressure of the contents to be applied to the inner edge portion, and effectively preventing the retort pouch food 11 from breaking.

[0022] The cell body 1 may be integrated by fixing the lower cell 12a and the upper cell 12b with screws or the like, and transported one by one to the heat sterilization process and cooling process described below. However, it is preferable to stack multiple cell bodies 1 to form a cell unit 14 and transport each cell unit 14, as this improves productivity.

[0023] The cell unit 14 has, for example, a pair of L-shaped (inverted L-shaped) support members 32 in each storage space 31 of a cell unit device 3 as shown in FIG. 4 , and the cell bodies 1 are placed one by one on the support members 32 to be stored and held (stacking process). In FIG. 4 , the cell unit 14 is composed of ten cell bodies 1, but the number of stacked cell bodies 1 is not particularly limited. It is preferable that the storage space 31 of the cell unit device 3 has a gap at the top when the cell bodies 1 are stored. By providing such a gap, the thermal expansion volume of the retort pouch food 11 can be absorbed when the cell unit 14 is suspended and immersed in a heating bath 4 for heating, as described below. Furthermore, the cell bodies 1 expand due to the thermal expansion of the retort pouch food 11, and are firmly confined within the storage space 31.

[0024] The cell unit device 3 has a protrusion 34 on the upper wall surface 33, and can be held in a suspended state by hooking a hook onto the protrusion 34, and by moving the hook using, for example, a chain belt and a motor as shown in Figure 5, the cell body 1 can be transported as a unit of cell unit 14. Note that the cell unit 14 and cell unit device 3 can be any type as long as they can stack multiple cell bodies 1 and transport them as a unit, and are not limited to those shown in the figures.

[0025] (Heat Sterilization Step) The heat sterilization step uses a heating bath 4. As described above, the cell unit 14 is hung by a hook attached to the protrusion 34 provided on the cell unit device 3, moved to the heating bath 4, and immersed in the heating medium 41 filled in the heating bath 4. The cell unit 14 is heated by the heating medium 41 while being immersed in the heating bath 4 and moved sequentially. Note that while only one heating bath 4 is provided in FIG. 5, a plurality of heating baths with different temperatures may be connected in series. For example, it is preferable to appropriately configure the first heating bath 4 to a 130°C range to heat the retort pouch food 11 from room temperature, and the second heating bath 4 to a 125°C range to maintain the heated temperature of the retort pouch food 11, thereby enabling efficient heat sterilization.

[0026] The heating medium 41 is preferably salt water or an oil with a high boiling point above 100°C, such as glycerin, propylene glycol, or 1,3-butylene glycol. Alternatively, a mixture of the oil and water may be used, with the amount of water being 20 mass% or less, preferably 15 mass% or less. The use of such a heating medium 41 is highly safe and can be easily removed in the cooling step described below. The heating temperature and heating time in the heating bath 4 are determined according to the specifications and contents of the retort pouch food product. In the case of retort sterilization, the contents are heated so that the central temperature is maintained at 120°C for at least 4 minutes.

[0027] When the retort pouch food 11 in the cell unit 14 is heated to a high temperature by the heating medium 41 and simultaneously sterilized, the filled contents boil, causing the internal pressure to rise and expand. However, because the retort pouch food 11 is restrained from above and below by the pair of cells 12a, 12b, no pressure is applied to the heat-sealed portion, effectively preventing bag rupture. In particular, because the inner peripheral edge of the heat-sealed portion is sandwiched between the pair of cells 12a, 12b, the pressure of the contents does not directly affect the heat-sealed portion (inner edge), effectively preventing bag rupture at the heat-sealed portion. Note that all of these operations are carried out under atmospheric pressure.

[0028] Furthermore, since the retort pouch food 11 is constrained by the pair of cells 12a, 12b, it adheres strongly to the wall surfaces of the cells 12a, 12b (the surfaces that come into contact with the retort pouch food 11) and becomes three-dimensional when heated at high temperatures. Therefore, if the wall surfaces of the cells 12a, 12b are engraved with a company name, product name, or the like, this has the advantage of being transferred to the retort pouch food 11 and becoming part of the design.

[0029] After the heat sterilization process, the cell unit device 3 is lifted and transported to the cooling process, but prior to this, it is preferable to remove the heating medium 41 adhering to the cell unit device 3 (cell unit 14) by blowing air on it, for example.

[0030] (Cooling Step) The cooling step is performed by immersing the heat-sterilized cell units 14 in a cooling medium 51, such as water, filled in a cooling bath 5. The cell units 14 are cooled by the cooling medium 51 while being immersed in the cooling bath 5 and moving sequentially. The temperature of the cooling medium 51 in the cooling bath 5 is set to 50°C or less, preferably 40°C or less. Although only one cooling bath 5 is provided in FIG. 5 , multiple cooling baths 5 with different temperatures may be connected in series. For example, it is preferable to configure the first cooling bath 5 in a 50°C range and the second cooling bath 5 in a 20°C range, as appropriate. The cooling medium 51 filled in the cooling bath 5 may be water or any other medium that can be kept at 50°C or less.

[0031] After cooling, the cell unit device 3 is lifted and the cell unit 14 is removed from the cooling bath 5. At this time, it is preferable to remove the adhering cooling medium 51 by, for example, blowing air onto the cell unit device 3 and the cell unit 14. By removing each cell body 1 of the cooled cell unit 14 from the storage space 31 and further removing the pair of cells 12a, 12b from the cell body 1, the heat-sterilized retort pouch food product can be recovered.

[0032] The method for producing a retort pouch food product according to the present invention, which involves heat sterilization under atmospheric pressure, can be suitably used not only for producing retort pouch food products in which cooked foods such as curry and stew are packaged, but also for producing food products that require heat sterilization (boiling sterilization) at 100°C or less, and for producing various other products other than food products for which heat sterilization is effective.

[0033] REFERENCE SIGNS LIST 1 Cell body 11 Retort pouch food 11a Vertical seal portion 11b Horizontal seal portion 12a Cell (lower cell) 12b Cell (upper cell) 13 Recess 14 Cell unit 2 Filling and packaging machine 21 Conveyor 3 Cell unit device 31 Storage space 32 Support portion 33 Upper wall surface 34 Protrusion 4 Heating bath 41 Heating medium 5 Cooling bath 51 Cooling medium

Claims

1. A method for manufacturing a retort pouch food product, comprising: manufacturing a pouch-shaped food product by heat-sealing a strip-shaped multilayer film for packaging with a filling and packaging machine while filling and packaging the contents into the pouch, and then heat-treating the product to produce a retort pouch food product; a cell body forming step of individually accommodating the retort pouch food products continuously manufactured by the filling and packaging machine in a pair of metal cells to form a cell body; a heat sterilization step of immersing the cell body in a heating bath filled with a heating medium having a boiling point exceeding 100°C to heat the contents in the retort pouch food product accommodated in the cell body under atmospheric pressure; and a cooling step of cooling the contents in the retort pouch food product by immersing the cell body heat-sterilized in the heat sterilization step in a cooling bath at 50°C or lower, and continuously manufacturing the retort pouch food product through these steps.

2. The method for manufacturing a retort pouch food product according to claim 1, wherein at least one of the mutually facing surfaces of the pair of cells is provided with a recess, and the retort pouch food product is accommodated in the recess.

3. The method for manufacturing a retort pouch food product according to claim 1 or 2, wherein an outer peripheral edge portion of the retort pouch food product including at least a heat-sealed portion is sandwiched between outer peripheral portions of the pair of cells and sealed between the pair of cells.

4. The method for manufacturing a retort pouch food product according to claim 1 or 2, wherein an outer peripheral edge portion of the retort pouch food product including at least an inner edge portion of the heat-sealed portion is sandwiched between the pair of cells with a predetermined gap therebetween.

5. The method for manufacturing a retort pouch food product according to claim 1 or 2, further comprising a stacking step of stacking a plurality of the cell bodies to form a unit between the cell body forming step and the heat sterilization step, and moving the cell bodies in unit units.

6. The method for manufacturing a retort pouch food product according to claim 1 or 2, wherein the heating medium is one or more oils selected from glycerin, propylene glycol, and 1,3-butylene glycol, brine, or a mixed liquid of the oil and water.

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