DE2611389A1 - METHOD OF STERILIZING FOOD - Google Patents

Description

BESELERSTRASSE 4 fc. UII

DR. J.-D. FRHR. by UEXKÜLL

DR.ULRICH GRAF STOLBERQ DIPL.-ING. JÜRGEN SUCHANTKE

Pacific Industrial Co., Ltd. (Prio: 7 priorities

10O; Kyutoku-Cho, Ohgaki City, ^{see Appendices} ^ ^{e "12954)} Gifu Prefecture, Japan

Hamburg, March 17, 1976

Method of sterilizing food

The invention relates to a method for sterilization of food by placing the food to be sterilized in a flexible container, sealing of the container, placing the container in a sterilizer and sterilizing using pressure and Heat.

It is already known to sterilize or sterilize food by boiling it down, i.e. by applying pressure and heat. to make durable. Sterilizing food in cans or bottles affects the shape of the can or Bottle contents practically not. However, cans or bottles are often unsuitable packaging because they are enclosed Food can take on the smell of the can or bottle. To eliminate these disadvantages will be more recently containers made of plastic or aluminum foil for sterilization using pressure and heat

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used, which allow long storage times. The known Preserving or packaging processes using pressure and heat are for containers made of plastic or made of Similar materials are unsuitable because between the container and the sterilizer due to the high temperature expanding food there is no pressure equilibrium. Thus, a container filled with food has cavities between the packaged goods and its wall, this is compressed or stretched during sterilization, whereby the deformations of the container remain on the finished product, result in an unattractive appearance and in the worst case, can even cause the container to tear open. To prevent such tearing of plastic containers these are before printing and Heat sterilize almost completely evacuated. A disadvantage of this known method is that the Evacuation must be done before pressure and heat sterilization. This makes the production much more expensive. Even harder weighs that the food to be packaged often lose their shape when evacuated. Food are now mainly packed in bags. After evacuation, there is a negative pressure in the bag, which the Walls of the bag are pressed tightly against the packaged goods. If the packaging is heated under pressure in this state, then the pressure acts directly on the packaged food, which then loses its shape. Thus can be in bags only package liquid food, for example soups or liquid food with solid additives,

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whose smell and taste are not changed by deformation of the solids.

In contrast, it is the object of the invention to provide a method for sterilizing food using To create pressure and heat with which a wide variety of foods can be long without changing their shape Have storage packed.

To solve this problem, a method of the type mentioned, which is characterized in that the The container is partially filled with a gas before closing and the pressures in the sterilizer and in the container are measured be, and that the pressure difference between the sterilizer pressure and container pressure during preheating, des Heat sterilization and cooling of the food is kept constant within predetermined limits.

The containers are preferably _{filled with a CO 2} -containing gas, the water contained in the food _{absorbing CO 2} and preventing the container from expanding due to its contraction due to residual deformation, which essentially reduces the pressure difference between the container pressure and the sterilizer pressure remains constant.

In particular, the pressure difference between the sterilizer pressure and container pressure kept constant by measuring the container pressure. 809 8 40/0808

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According to a further development of the invention, a uniform heat distribution is achieved in the sterilizer by spraying hot water jets achieved through perforated plates.

Further advantageous refinements of the invention emerge from the description of the figures and the subclaims.

The invention is explained in more detail below with reference to the figures; show it

Figure 1 is a perspective view of a pressure and heat sterilizer for carrying out the invention Procedure;

FIG. 2 shows a pipeline plan between the sterilizer and a tank;

FIG. 3 shows a circuit diagram for measuring pressure in the container and in the sterilizer;

FIG. 4 shows a plan view of another embodiment of a pipeline guide to a sterilizer without hot water tank;

FIG. 5 shows a view of a perforated plate for the sterilizer;

FIG. 6 partial sections through pressure gauges for measuring ^and the container pressure of the packaged food;

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FIG. 8 sections through cup-shaped or plate-shaped containers for packaging food;

FIG. 12 shows a pressure / time diagram of the method according to the invention;

FIG. 13 shows a pressure / time diagram to compare the method according to the invention and the known method ; and

FIG. 14 is a pressure or temperature / time diagram of the
method according to the invention.

FIG. 1 shows a sterilizer 20 known per se for carrying out the method according to the invention. The sterilizer 20 includes a flat trolley 22 for receiving trays 21 stacked on top of one another. The trolley 22 is on Rails 23 movable. After pulling out the trolley, the floors 21 with the food containers placed on them inserted and pushed the cart into the sterilizer. One end of the sterilizer 20 can be closed with a lid, through recesses that can be moved by a pinion 25 and engage behind extensions 27 on the cover 24 26 is lockable.

On the sterilizer 20 is a hot water tank 30 for the Provision is made for the supply of hot water to the sterilizer.

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FIG. 2 shows a pressure steam line 31 and a water line 32 connected to the hot water tank 30. A pressure steam line 33, a pressurized water pipe 34, a water drain pipe 35, a pressure reducing line 36 and a pressure line 37 are connected to the sterilizer 20. aside from that A ring line 38 and a return line 39 are provided between the sterilizer 20 and the hot water tank. The sterilizer 20 also includes pressure sensors, differential pressure indicators, solenoid valves and similar devices. FIG. 3 shows differential pressure indicators in the form of pressure sensors 40, 41 for determining the sterilizer pressure and pressure sensors 42, 43 for direct or indirect measurement of the container pressure, as well as a pressure reducing solenoid valve 46 and a Solenoid valve 47 controllable by the differential pressure indicator.

After the food containers have been placed in the sterilizer, a ring line valve is opened after the sterilizer has been closed 48 opened in the ring line 38 and hot water from the water tank 30, which is kept at a constant temperature fed into the sterilizer 20 under pressure. If the pressure in the sterilizer 20 exceeds a predetermined pressure, the is above the pressure in the food container 50, then a pressure difference at the pressure sensors 40, 42 is determined. This pressure difference controls the differential pressure indicator 44 and is converted by this into electrical signals, for controlling a pressure reducing solenoid valve 46 in

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the pressure reducing line 36 to the sterilizer 20 are used and ventilate the sterilizer 20, so that the sterilizer pressure and the food container pressure can be set within fixed limits. Then the packaged food by opening a steam valve exposed to pressure and heat in the pressure steam line 33.

The vapor pressure is preferably 3 to 3.5 kg / cm and

the steam temperature 120 to 130 ° C. Will the pressure in the sterilizer 20 higher than the pressure in the food container 50, the pressure conditions are then readjusted the manner previously described. After a few minutes of pressure and heat sterilization, the hot pressurized water becomes by opening a solenoid valve 52 in the return line 39 returned to the hot water tank 30 from the sterilizer 20 under pressure. For cooling the hot water to around 100 ° C for example, cooling water is supplied on the way to the water tank 30.

If the pressure in the sterilizer 20 drops below the food container pressure as a result of the hot pressurized water flowing out from, then the pressure sensors 41 and 43 indicate a pressure difference that controls the differential pressure indicator 45 and can be converted by this into electrical or compressed air signals. From these signals the solenoid valve 47 is controlled in the pressure line 37 to the sterilizer 20 and compressed air is fed into the sterilizer 20, so that the sterilizer pressure and the container pressure are controlled within specified limits.

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Then, the sterilizer 20 containing no hot pressurized water is supplied with cooling water through the opening of a pressurized water supply valve 53 supplied in the pressurized water supply line 34. The cooling water lowers the temperature in the sterilizer 20 and thereby reduces the sterilizer pressure below the container pressure 50, the pressures in the sterilizer and are adjustable in the container in the manner described above within predetermined limits.

Finally, by opening a drain valve 54 in the Drain line 35 removed water from the sterilizer 20 and completed a pressure and heat sterilization process.

FIG. 4 shows a ring line 60 connected to both sides 20a and 20b of the sterilizer 20. Through a ring line 60 hot pressurized water is passed into the sterilizer 20 and returned through the other ring line 60, and the process is repeated in the sterilizer 20 to distribute heat evenly.

Hot water stored in the sterilizer 20 is fed by a pump 63 in the direction of an arrow 66 through a hole with holes provided plate 61, a ring line 60 and a switching valve 62 with time control conveyed and under pressure through a flow adjusting valve 64, a switching valve 65 with timing control, the ring line 60 and the one provided with holes Plate 61 returned to the sterilizer 20.

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After a certain delivery time in the direction of arrow 66 the water is conveyed by switching the switching valves 62 and 65 in the direction of an arrow 67, so that hot water not only flows in one direction into the sterilizer 20, but is distributed in this.

The perforated plates 61 are formed to hold the hot water flowing into the sterilizer 20 ζε ^^ θμεη; they are arranged opposite one another so that they cover the mouths of the ring lines in the sterilizer between the carriage 22 and the inner wall of the sterilizer, The plate 61 provided with holes has openings 68, the diameter, number and spacing of which are uniform Allow flow, that is to say uniform heat distribution, for each point in the sterilizer 20. With increasing flow velocity of the hot water flowing through the plate 61, this is swirled more strongly and the heat transfer to the packaged food more favored, so that the heat quickly and evenly on the Acts on food. However, excessively high flow rates can break or deform the packaged items Cause food. The maximum permissible flow rate is therefore preferably chosen so that there is no breaking or shaking of the food. The best way to control the flow rate in the sterilizer by adjusting the flow control valve 64 depending on the weight, shape or the like Adjust the properties of the packaged food. At

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the opening in the perforated plate can also be slots.

The method for measuring the pressure in the food container 50 is described in connection with FIG. A Food container 50 is accordingly placed in a solid housing 70 which has excellent heat-conducting properties and has sufficient dimensional stability.

A pressure sensor 73 is connected to the housing 70 by means of fasteners 74 and has one on the pressure-sensitive film 71 lying on the upper surface 50a of the container 50. The housing 70 also has a thin tube 73 for pressure transmission from the pressure sensor 73 and a signal generator 76 for converting the measured Pressure into an output signal.

In the pressure and heat sterilization according to the invention, the steps of increasing temperature, heat sterilization and Includes cooling, the container pressure changes depending on the change in vapor pressure of the food, wherein see the pressure change of air and other gases according to the Boyle-Mariotte's Act occurs and is caused by the expansion and contraction of the heated food. The change in pressure is applied to the pressure sensitive on the top surface 50a of the food container 50 Transfer slide 71. If the food is brought directly into the solid housing 70, then the pressure

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sensitive film are also in direct contact with the food and cause the pressure measurement and transmission through the thin tube 75 to the signal generator 76. The signal generator 76 converts the pressure change in the container in an electric or a pneumatic signal for automatically controlling the sterilizer to _f for which the signal is transmitted to the mentioned valves. In this way, the pressure in the food container can be measured exactly during pressure and heat sterilization by placing the food-filled container 50 or the food directly in the solid, highly thermally conductive housing and the food container or the food in the housing hermetically to eliminate environmental influences be completed.

To determine changes in pressure, a sample or dummy can be used instead of the food or the food container are inserted into the fixed housing 70.

FIG. 7 shows one in a solid housing made of aluminum, brass or some other suitable material inner film 77 arranged with very good thermal conductivity properties and one under the inner film 77 Sample 78. The rest of the arrangement corresponds to the arrangement shown in FIG. As a sample, for example Water used. A water sample has similar pressure and temperature properties as the food to be packaged.

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The inner film only needs to be heat-resistant and have an adiabatic effect. By coating their inside with a heat-resistant synthetic resin, for example FRP, polypropylene, polyester, Polycarbonate or a similar material, or with a heat-resistant and adiabatic material, for example Asbestos or calcium silicate achieve the properties mentioned.

A container for packaging the food according to the invention is described below. Leave the containers can essentially be classified into two groups: one group essentially comprises bags, while the other Group contains cup or plate shapes. All such containers are made of heat-resistant, harmless Plastic, for example made of polypropylene, polyester, vinylidene chloride, nylon, or a mixture of these Plastics, for example as a laminate with an aluminum foil. Depending on the type of storage and the duration of storage either a bag, a cup or a plate-shaped container is selected. In addition, the cup or plate-shaped containers have a wide variety of shapes depending on the intended use.

Figures 8 to 11 show various examples of cup-shaped containers. A vertical section through such a container can take the most varied of shapes

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according to the type and condition of the goods to be picked up, and the plan can also be any, for example rectangular or circular.

A separate, plate-shaped container 80 according to Figure 8 is preferably used to hold food that to be sterilized separately under pressure, for example a combination of sausages and one Slice of bread or rice with a ragout. The one-piece, plate-shaped container 81 shown in FIG. 9 is used for example to hold rice while two different soups in a separate, cup-shaped container 82 according to FIG. 10 can be packaged. The cup-shaped container 83 shown in Figure 11 is for example can be filled with a liquid food. The containers shown in Figures 8-11 are sealed at a flange 86 by means of a sealing film 84, with a space 85 in the upper region of the container remains. The packages produced in this way are placed on floors 21 which are stacked on top of one another in the flat trolleys 22 of the sterilizer 20 can be hung. They are then pressure and heat sterilized.

The method according to the invention differs from the known packaging method essentially in that that a space is left in the container after the introduction of the food, which space is filled with a gas.

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According to the invention, both bag-shaped and beaker-shaped or plate-shaped containers are filled with gas.

According to the known methods, free spaces remaining in the container are avoided as far as possible or completely removed suppressed the sterilization, which leads to the aforementioned disadvantages. As mentioned, loose ones lose Food is in its shape, porous food, for example bread or cake, is squeezed together so that they cannot be stored in the known packaging. According to the invention, a clearance is intentionally made left, which, as mentioned, is filled with gas. By measuring the pressure changes in the container and in the sterilizer and by sterilization under pressure differences which can be set within certain limits, the mentioned disadvantages of known methods completely avoided. In a preferred embodiment, the containers are only filled with air filled. The proportion of food in the container is about 50 to 60% by volume, so that the rest of the food after sealing Free space is automatically filled with air.

In another embodiment, a mixture of air and an inert gas, for example CO ₂ or N ₂ , is used as the gas. An inert gas can also be used instead of air, so that practically no air remains in the container.

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Since the pressure difference between the tank pressure and the Sterilizer pressure is regulated according to the invention within predetermined pressure limits, theoretically no breakage occurs of the container. In the case of flexible plastic containers, however, expansion of the container due to heat build-up is due of residual deformation is unavoidable to a certain extent. To avoid these disadvantages, a preferred embodiment of the method according to the invention a gas mixture with at least one easily water-soluble, harmless gas, for example COp, into the container brought in.

The mixing ratio of a gas that is easily soluble in water and a gas that is poorly soluble in water is preferable Despite the dependence on the volume proportion of the food and the free space in the container between 4: 6 volume proportions, with the 5: 5 and 3: 7 ratios of food to space giving excellent results. Will a food package with a gas that is readily soluble in water and a gas that is poorly soluble in water in the Sterilized free space under pressure and heat, then the gas, which is easily soluble in water, becomes in the water of the food absorbed according to Henry's law in relation to the pressure in the sterilizer and the steam pressure in the container. Accordingly, the aforementioned expansion of the container due to heat build-up from residual deformations caused by being in the water is easy Avoid soluble gas that is absorbed by the water contained in the food.

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The method according to the invention can be carried out even better by inserting a cooling step.

In general, when cooling, hot pressurized water is drained from the sterilizer μηα fed to this cooling water. The sudden temperature drop that occurs in the sterilizer leads to condensation of the steam, and to a sudden pressure drop P1 according to point C in FIG 12 under the pressure P2 in the food container. If the pressure in the sterilizer falls below the food container pressure then the container tears open and the packaged goods fall out.

In a preferred embodiment of the method according to the invention, cooling takes place simultaneously with draining Part of the hot pressurized water from the sterilizer is supplied with cooling water to the same extent as the water drained off will. This leaves a certain amount of hot pressurized water in the sterilizer. The sudden one Transitioning this remaining hot 'pressurized water into steam increases the sterilizer pressure, thereby maintaining it a pressure balance between the sterilizer and container is facilitated.

If a sudden pressure drop occurs at C as mentioned above, then a considerable pressure difference is created between the pressures in the sterilizer and in the container, whereby

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the container can break. To prevent this cracking the pressures in the sterilizer and in the container should correspond to the dash-dotted line D in FIG. 12 can be maintained by supplying compressed air. However, since the pressure drop in the sterilizer occurs very suddenly, the compressed air supply is necessarily always too late due to the limited flow rate. Consequently you have to leave a certain amount of hot pressurized water in the sterilizer to absorb the sudden drop in pressure and achieve a pressure adjustment. This remaining hot pressurized water goes in when there is a sudden drop in pressure Steam over and creates a steam pressure. This means that only a small amount of compressed air needs to be supplied to the sterilizer. The sterilizer pressure can thus be easily adjusted during cooling. Even at the beginning of the cooling phase, a remains Pressure equilibrium between the sterilizer and the container according to the dash-dotted line D, and the sterilizer pressure can by continuously supplying cooling water while releasing the remaining hot pressurized water be lowered continuously.

A particularly preferred embodiment of the method according to the invention is described with reference to FIGS. 13 and 14.

In FIG. 13, curve P2 gives the pressure in the food container, curve P1 the pressure according to the invention in the sterilizer and the curve X the pressure according to a known method

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start up in the sterilizer. The known method comprises a sudden increase in pressure in the sterilizer, the Sterilizer pressure kept constant over a certain period of time for sterilization and then after Cooling is suddenly lowered again. The pressure difference between the container pressure and the sterilizer pressure

is at least 3 kg / cm in the known method. To the-

after the packaging container must withstand at least 3 kg / cm, for which a known thin-walled container is not in is able to.

The method according to the invention is therefore distinguished from known methods in that the sterilization takes place at a sterilizer pressure P1, which is an essentially constant pressure difference to the container pressure and that the material brought into the sterilizer

container under a sterilizer pressure that is 0 to 2.0 kg / cm higher is sterilized.

During the cooling after the pressure and heat sterilization, the sterilizer pressure is gradually dependent

reduced by the pressure drop in the container, the

Sterilizer pressure in each case 0 to 2.0 kg / cm higher than that

Tank pressure is. As soon as the sterilizer is back to atmospheric pressure prevails, the packaging is removed.

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A pressure drop in the sterilizer below the container pressure causes the container to expand and break open. Therefore, such a pressure drop in the sterilizer must be avoided under all circumstances. This is according to the invention solved in that the sterilizer pressure to each

Time is kept 0 to 2.0 kg / cm higher than the tank pressure.

The pressure difference of up to 0 to 2.0 kg / cm is selected based on the following considerations: There is a pressure change in the container due to a change in temperature of the container, the temperature being the heating temperature at the beginning of the process suddenly increases and suddenly drops on cooling towards the end of the method according to the invention. The tank pressure changes to the same extent as the temperature rise and fall. To avoid the mentioned pressure change as well to maintain a higher sterilizer pressure than the container pressure is used in the known method of Sterilizer pressure kept much higher at the beginning. On the other hand, a minimal pressure difference is desirable, so that the container does not run the risk of being broken open.

set. If, on the other hand, the pressure difference is -2.0 kg / cm, i.e. the container pressure is higher than the sterilizer pressure, then the container breaks. A reliable value for the pressure difference is therefore during the entire sterilization

2
Process 0 kg / cm. The pressure should preferably be in the sterile

2 sator, however, are always 0.3 to 0.5 kg / cm higher than in the container. The appropriate upper limit for the pressure difference

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reference is 2.0kg / cm. Although a bag with no space

2
can withstand greater than 2.0 kg / cm, a thin-walled container with a clearance can rupture at such pressure during known packaging processes.

Table 1 shows the dependence of the temperature and the pressure during the individual process steps of increasing the temperature, heat sterilization and cooling.

It can be seen that the container is at 2.1 kg / cm pressure

differently deformed and breaks open at 2.5 kg / cm. Consequently

ge 2.0 kg / cm is a practical upper limit for one

thin-walled container with a free space.

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Table 1

CX) 00

co O CD

kr. container
temperature
Pressure"""" ---. Temperature rise 100 ° C 110 ° C 120 ° C Hot-
Sterile
sation
130 ° C Cool 120 ° C 11O ° C 100 ° C Result
nis 1 sterilizer kg / cm
2.0 kg / cm
2.4 kg / cm
3.0 ι / 2
kg / cm
3.3 2
kg / cm
2.4 kg / cm
1.9 2
kg / cm
1.2 Well 2 container 1.5 1.9 2.5 2.8 1.9 1.4 0.7 container
deformed 3 sterilizer 3.6 4.0 4.5 4.8 3.9 3.5 2.7 container
Broken 4th container 1.5 1.9 2.5 2.8 1.9 1.3 0.7 container
Broken sterilizer 4.0 4.4 5.0 5.3 - - - container 1.5 1.9 2.5 - - - - sterilizer 1.3 1.7 2.3 - - - - container 1.5 1.9 - - - - -

to I

CO CO CO

example 1

140 g of cooked rice were poured into a 280 cm container Polypropylene poured. The volume ratio of the food to the free space in the container was 50:50. The sealing surface of the container was dry-laminated using a Welded polypropylene and polyester film.

After inserting the filled food container into The sterilizer and the closing of the sterilizer was hot pressurized water by opening a ring valve in a ring line into the sterilizer. The packaged food was preheated to avoid browning. The hot pressurized water had a temperature of 100 ° C. and a pressure of 1.5 kg / cm. The preheating time was 30 minutes. After preheating, the temperature of the hot pressurized water was increased to 120 ° C for sterilization. It was sterilized for 5 minutes after reaching a temperature of 120 ° C in the center of the food.

After the sterilization, part of the hot pressurized water was released through a reflux line by opening a solenoid valve fed back into a hot water tank and at the same time cooling water by opening a pressurized water supply valve via a pressurized water supply line to the sterilizer led to equalize the amount of hot pressurized water drained. At the same time, compressed air was opened A pneumatic solenoid valve in a pressure line is blown into the sterilizer to avoid a sudden drop in pressure due to the cooling water supplied. The to-

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guided compressed air and the evaporation of the hot pressurized water created an equilibrium between the pressures in the sterilizer and in the container. While maintaining this pressure equilibrium and with a continuous supply of Cooling water to the sterilizer, the remaining hot pressurized water was returned to the hot water tank. After cooling was the cooling water by opening a drain valve in drained a water drainage line from the sterilizer and terminated the pressure and heat sterilization.

The rice sterilized in this way in the plastic container has not lost its original appearance. The plastic container was neither deformed nor broken and retained its shape as before treatment.

In addition, cooked noodles were packed in a polypropylene container, with the volume ratio of food too Clearance was 60:40% and the food container was sterilized in the manner described. It wasn't Deformation, no breakage or shrinkage was observed and an excellent result was obtained.

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Example 2

140 grams of cooked rice was placed in a 280 cm polypropylene container poured, the volume ratio of food to free space being 50:50. The sealing surface of the The container was sealed with a dry laminated film made of polypropylene and polyester, with a part for Formation of an opening was left free. Through this opening a gas mixture of carbonic acid and nitrogen in a ratio of 4: 6 was introduced to reduce that in the free space To replace air. The container was then completely sealed. The packaged rice was among the sterilized under pressure and heat under the following conditions. The container was placed in the sterilizer; the sterilizer was locked. Pressurized steam was released by opening a steam valve in a pressurized steam line gradually at a temperature of 120 C and a steam

2

pressure of 1 kg / cm is supplied at a rate of pressure increase of 1 kg / cm every 3 minutes. While maintaining a balance between the pressures in the container and in the sterilizer was made by closing the steam valve and then Opening a hot water valve in a hot one Pressurized water line hot pressurized water of 120 ° C for sterilization in the sterilizer filled with hot water directed. After the temperature in the central area of the food reached 120 ° C, it was 5 minutes

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sterilized. This was followed by opening an air valve in a compressed air line to maintain a balance between the pressures in the container and in the Sterilizer and by simultaneously opening a drain valve in a water drain pipe in the lower part of the Sterilizer hot pressurized water from the sterilizer into a pressurized water tank connected to this through the outlet line directed. After draining the water, shut off the outlet valve in the water outlet line and by opening a water supply valve in a water supply line and by opening a pressure reducing valve Cooling water in a pressure reducing line to completely fill the sterilizer for cooling the packaged food supplied. After cooling, pressure and heat sterilization was carried out by opening the valve the water outlet line for draining the cooling water completed.

The rice sterilized in this way in the plastic container had not lost its original appearance. The plastic container was neither expanded nor altered.

Examples 3 and 5 were carried out under the same conditions as Example 2, the proportions in each However, food packaging was modified according to Table 2 to achieve the results given therein.

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The table shows the results of the sterilization tests according to the invention obtained with cooked rice, where the volume ratio of rice to free space in the container and the mixing ratio of carbonic acid and nitrogen changed became. Table 4 shows test tests for the appearance of the packaging, pressure and heat sterilization was done in a similar way with a curry sauce.

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Table 2

Food in the container container volume
material
Wall thickness Vapor pressure (kg / m
Temperature (° C)
Pressure rise time
(min / kg / m) Example 2 Example 3 Example 4 20% 4, currysauce / 6 Well D. quite
Well Example 5 Ceiling] material
Wall thickness Maximum pressure in the sterile
sator (kg / m)
Temperature in the middle ( ⁰ C)
the food (C)
Time (min) boiled rice currysauce boiled rice 160 cm ³
mm 1
120
3 Soup Free space in the container Appearance 280 cm ³
PP
0.35 mm 320 cm ³
PP + PVDC
0.35 mm 310 cm ³
P]
0.5 fPP
5 mm 2,
12 (
5 150 cm ³
N + PP
0.4 mm 60984 Gas mixture,
Volume ratio 2 ' 2 PET + PP
0.05 mm PP + PVDC
0.05 mm PET
0.0 40% N + PP
0.05 mm 0/0 Preheating 50% 20% 50% 908 Heat 4/6 3/7 5/5 1
120
3 1
120
2 1
120
1 2.6
120
5 2.6
120
5 2.6
120
5 Well some
stretched quite
Well

Note: PP = polypropylene, PET = polyester, PVDC = polyvinylidene chloride, N = nylon

Food/
"- \ ^ free space Tabel 3 8/2 6/4 4/6 10/0 boiled rice XX XX XX Gasmi
schung
(CO ₂ / N ₂ ) 7/3 9/1
ι XX XX XX 6/4 XX 0 ΔΔ XX 5/5 ΔΑ 0 0 Δ 4/6 0 § 0 Δ 3/7 0 0 Δ χ 0/10 0 X X X 0 X

Table curry sauce

^ * "*" * · ^^^ Food /
Gasmi- ^ ~ \ ^^ free space
s chung ^ "~" - \ ^
(CO ₂ / N ₂ ) ^ \ ^^ 9/1 8/2 6/4 4/6 10/0 ^ Δ X X X 7/3 ΔΔ X X X 6/4 0 0 Δ X 5/5 0 0 0 Δ 4/6 0 © 0 0 3/7 0 Δ X X 0/10 Δ X X X

© Looks good

0 "pretty good

A "somewhat stretched

ΔΔ "somewhat compressed

X "strongly stretched

XX "strong

Example 6

140 g of soup was placed in a thin-walled container made of polypropylene poured with a volume of 280 cm, the volume ratio of soup to free space in the container Was 50:50. The sealing surface of the container was covered with a dry laminated film made of polypropylene and polyester heat sealed. The obtained food package was placed in a sterilizer, and the sterilizer was sealed. Then hot pressurized water was fed from a tank into the sterilizer, the hot water being a Temperature of 100 ° C and a pressure of 1.7 kg / cm. Such treatment represented the initial phase of the Method according to the invention according to the curves RT and PT in Figure 14. The container pressure was dependent measured from the temperature rise by means of a pressure sensor.

2 This provided a container pressure of 1.5 kg / cm for a

Container temperature of 100 ⁰ C according to number 1 in the table.

line blown in to adjust the pressure to 2.0 kg / cm according to the tank pressure. Then the sterilizer temperature gradually increased and sterilized at 130 ° C for 10 minutes. The tank pressure changed according to the curve P2 in Figure 14 according to the temperature increase in the sterilizer. The change in pressure of the Tank pressure was measured with the pressure sensor and the

2 Sterilizer pressure set so that it is 0.5 kg / cm higher

than the tank pressure was. After hot sterilization

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at 130 ° C, the hot water from the sterilizer was partially drained and cooling water through a water inlet pipe fed. At that point the sterilizer temperature dropped suddenly decreased, and the tank pressure also showed a sudden drop in pressure. This pressure drop was measured by means of of the pressure sensor detected. The cooling was carried out gradually, while the sterilizer pressure was

2 tension over the pressure reducing line by 0.5 kg / cm higher than the tank pressure was maintained. The cooling process comprised the continuous supply of cooling water and the discharge the hot water from the sterilizer through a drain pipe. While maintaining a pressure equilibrium the temperature between the sterilizer and the container was lowered to complete the cooling process. Afterward the food container has been removed from the sterilizer. It showed the same excellent condition as before treatment. Food in a thin-walled container under pressure and heat has thus become successful sterilized.

Example 7

It became the same food container as in Example 6 under pressure and heat and under the same temperature conditions Sterilized as in Example 6, but where a different internal pressure prevailed in the sterilizer. The sterilizer pressure was maintained during the entire test

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seeks essentially 2.0 kg / cm higher than the vessel pressure held. With a container temperature of 100 C at the beginning

the heating was the difference in pressure 2.1 kg / cm, while at a temperature of 11O ⁰ C during the Kühlvor-

ganges was 2.2 kg / cm. During the entire process

During the run there was a pressure difference of 2.0 kg / cm. To after sterilization, the container was taken out and observed. He was partially deformed and had a changed a little. The changes in pressure in the sterilizer for this test are shown by curve P3 in FIGS the number 2 in Table 1 reproduced.

Reference example 1

The same food package as in Example 6 was produced under pressure and heat and under the same temperature conditions as in example 6, but sterilized under internal pressure in the sterilizer. The sterilizer pressure

was kept 2.5 kg / cm higher than the pressure in the food container. 12 minutes after the start of heating At the beginning of the test, a temperature of 130 ° C. had been reached and the container had been broken open.

The curve P4 in FIG. 14 and the number 3 in Table 1 show the pressure profile in the sterilizer.

609840/0 806

2611382

Reference example 2

The same food package as in Example 6 was sterilized under pressure and heat, using the same temperature conditions as in Example 6, however, the internal pressure conditions in the sterilizer were different. The sterilizer

pressure was kept 0.2 kg / cm lower than the container pressure. 6 minutes after the start of heating at the beginning during the test, the temperature in the sterilizer was 120C reached and the container was broken.

The curve P5 in FIG. 14 and the number 4 in Table 1 show this pressure curve.

Test attempt

(1) The following were to be sterilized:

23Og cooked rice in a flexible container of 118 mm in length, 106 mm in width and 39 mm in height, the space being filled with air. Such containers were housed in a sterilizer at a distance from each other.

(2) Shape and volume of the sterilizer:

Cylinder with "JOOO mm inside diameter and 2000 mm length,

(3) Hot liquid medium: hot water

The results obtained in the test are shown in FIG. 609840/0808

Table 5

Variable in the experiment Temperature of the hot
Pressurized water 12O ° C 5 (m / sec) 1
(min)
40 .3
20th 15th 50 1
40 3
20th 30th 50 1
40 3
20th 130 ° C 5 50 1
40 3
20th 15th 50 1
40 3
20th 30th 50 1
40 3
20th Result Flow velocity
of the hot pressurized water
in the sterilizer 0.3 (m / min) 1.5 1.5 1 1 / C 0.5 0.5 2 3.5 0.5 0.5 0.3 2, C 1.5 1.5 1 1 / C 0.5 0.5 2 0.5 0.5 0.5 Applied hot pressure
amount of water lake
50 15th 12th 12th 5 8th 5 5 5 22nd 15th 12th 12th 5 8th 5 5 5 609840 / Operating time for at
switching valve _O 2.0
(° C) - - - - - + + + - - - - - - + + + 9080 Minimum temperature dif
reference of hot pressure
water in the sterilizer 22nd
(min) X X X 0 X X X X X X X 0 X X X Time to soften
the minimal tempera
turdifference - A. A ' Breaking up of life
medium tank X Overall assessment description

Note: + = "also"

- = "no breaking open"

The experiments show that a minimal temperature difference in the shortest possible time in cases A and A ¹ in the lowest. Row of Table 5 can be achieved. The flow rate then corresponds essentially to the optimal theoretical flow rate without the container shaking. The amount of water carried in an annular flow must be so large that an optimal flow velocity can be achieved. A time-controlled switching valve is also switched over at such time intervals that the hot pressurized water is fed into the sterilizer at an optimal flow rate.

In known sterilization processes for food containers standing in still water, the attainable minimum temperature difference is 20 ° C., for which times of 40 minutes are required. In another known method, the food containers to be sterilized are rotated and shaken in standing water, and the minimum temperature difference that can be achieved is 15 ° C., which takes 5 minutes. There is a risk of the containers breaking or deforming. In contrast, the invention proposes an extremely effective method for sterilizing food under the application of pressure and heat, in which a minimum temperature difference of 0.5 ^° C. can be achieved in just 5 minutes.

609840/0806

Claims (7)

2611388 Expectations Method of sterilizing food by placing the food to be sterilized in a flexible container, sealing the container, placing it in a sterilizer, and sterilizing under the application of pressure and heat, characterized in that the container before closing partially filled with a gas and the pressures measured in the sterilizer and in the container, and that the pressure difference between sterilizer pressure and container pressure during preheating, des Heat sterilization and cooling of the food kept constant within specified limits will. 2. The method according to claim 1, characterized in that the pressure difference between the sterilizer pressure and tank pressure is 0 to 2.0 kg / cm. 3. The method according to claim 1 or 2, characterized in that that for container pressure measurement food in a rigid container with excellent Thermal conductivity can be brought that the container by a pressure sensor with a pressure sensitive tightly closed with a thin film, and that the pressure change caused by heating in the container 609840/0 806 change is transmitted to the pressure sensor by means of the pressure-sensitive film. 4. The method according to any one of claims 1 to 3, characterized characterized in that the pressure in the container by measuring and transmitting an equally high pressure as in Container by means of a pressure-sensitive container with a rigid housing and approximately the same thermal conductivity how the container is measured, and that in the pressure-sensitive container a dummy with temperature behavior similar to that of the food to be sterilized is included. 5. The method according to any one of claims 1 to 4, characterized in that after during the cooling process After sterilizing under pressure and heat, some of the hot pressurized water is drained from the sterilizer and this cooling water is supplied in an amount replacing the discharged hot water, and that during introducing compressed air into the sterilizer to maintain a pressure balance between Sterilizer and container continuously cooling water is passed into the sterilizer to remove the rest to release hot pressurized water and thereby gradually reduce the pressure in the sterilizer. 609840/0806 6. The method according to any one of claims 1 to 5, characterized in that the space in the container fül- ■ lende gas contains at least carbonic acid, and that the container by dissolving the carbonic acid in the in Do not expand the water contained in the food because of its heat shrinkage due to residual deformation can. 7. The method according to any one of claims 1 to 6, characterized in that hot pressurized water by with Holes provided, covering openings of a ring line at opposite ends in the sterilizer Plates are sprayed in the sterilizer for even heat distribution. su: ah: bü 609840/0806