JPH067787B2 - How to cook and sterilize canned food - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for cooking and sterilizing canned foods and the like by using a hot water type retort cooking and sterilizing machine.

Conventional technology Conventionally, in cooking and sterilizing canned food using a retort cooking and sterilizing machine, after loading the canned food into the retort, hot water is injected to perform temperature raising, heat sterilization, cooling by water supply, and water discharge processes. It is known. Further, it is known to employ a multistage depressurizing means in order to keep the internal pressure of the can or pouch and the internal pressure of the processing tank at the time of cooling.

Problems to be Solved by the Invention In the conventional multi-stage depressurizing means for cooling, which is conventionally used, the properties of canned cans, for example, No. 1 can is weak against internal pressure, and No. 2 can,
In the case of a cozy can or the like, there was a problem that the can itself was deformed without being cooled in accordance with the condition that it was weak against external pressure. In the case of the multi-stage depressurization method, a so-called replacement method is used in which hot water is returned from the upper part to the hot water tank by utilizing the difference in specific gravity between hot water and water at room temperature when transferring from heating by hot water to cooling means by water supply. As a result, there was a difficulty in saving heat energy.

Further, in the case of a recovery system in which hot water is recovered and then cold water is injected, the inside of the can is at a high temperature and the temperature difference between the can and the cold water is remarkable, and this pressure control is said to be extremely difficult.

Unlike the conventional multi-stage depressurization method, the method of the present invention can prevent deformation of the can in a recovery method in which depressurization control is performed at a certain time depending on the type of can and hot water is once recovered and then water is supplied again. It is intended to realize efficient use of heat energy by enabling pressure control and reusing the recovered hot water.

Means for Solving the Problems In order to achieve the above object, the present invention, in a method for cooking and sterilizing canned foods and the like with hot water using a retort cooking sterilizer, hot water is injected into a treatment tank to increase pressure. The pressure inside the processing tank is divided into two stages by temporarily maintaining a constant pressure on the way, and then the pressure is increased to a predetermined pressure again, and the predetermined pressure is maintained for heat treatment. For weak cans, the pressure is once reduced immediately before the start of water supply for cooling, and for cans that are weak to the internal pressure, once the water supply is completed.
After cooling under a constant pressure, each step of further reducing the pressure and discharging the liquid was set as one cycle, and the collected hot water was used again in the next step to provide a cooking and sterilizing method for canned food.

Action The present invention has the action of reducing the rise in the internal pressure of the can during the temperature rise by providing the holding state of a constant pressure once while raising the pressure in the processing tank to the predetermined pressure. Also, immediately after the start of cooling after heat sterilization at a predetermined pressure, the pressure in the processing tank is temporarily reduced for cans that are susceptible to external pressure, preventing condensation during cooling and deformation due to imbalanced internal and external pressures due to vacuuming. I can do it now. Further, for cans that are weak in internal pressure, the deformation of the cans can be prevented by extending the equilibrium state of the internal pressure of the cans during pressurization and heating and the pressure in the processing tank until the completion of water supply. Further, in the present invention, since the supply water to the treatment tank for cooling is of a recovery type in which hot water is once recovered and then cold water is injected, the recovery temperature of the hot water is higher than that of the substitution type, and the heat for the next step is again recovered. Energy saving has come to be realized when using water.

Examples The graphs shown in the drawings show the temperatures and pressures when cooking and sterilizing canned food using a retort cooking and sterilizing machine.

As an example, in order to obtain heat sterilization at a temperature of 120 ° C., until the pressure reaches a predetermined pressure of ² kg / cm ² G, pressurization is temporarily stopped during the temperature rise from the injection of hot water (a) Point 1 kg / cm ^The temperature is raised while maintaining a constant pressure of ² G, and then the pressure is increased to a predetermined pressure. Also, after heat sterilization, hot water is collected, and when cooled with cooling water, the pressure is reduced to cool again while maintaining 1 kg / cm ² G. The pressure is further reduced when the liquid is drained.

When decompressing during cooling, for cans that are weak to external pressure, such as No. 2 can and cohesive can, start depressurizing just before water supply as shown in (b), and to cans that are weak to internal pressure, such as No. 1 can. As shown in (c), decompression is started after the water supply is completed.

As described above, when the temperature is raised or cooled, the pressure rise is stopped to maintain a constant pressure, or the depressurization process is performed.
Like a canned food, it has an air layer inside the can, and the bubbles inside the food emerge into the air layer as the temperature rises, causing the wall of the can to expand, and conversely contracting and vacuuming the air layer during cooling. This prevents deformation of the can due to distortion of the can wall. As mentioned above, the reason for changing the pressure at the start of decompression depending on the can that is weak to the internal pressure and the one that is weak to the external pressure is to reduce the difference between the internal pressure of the can and the internal pressure of the processing tank as much as possible to eliminate the cause of deformation of the can. It is a thing.

Further, in the present invention, a collection method is adopted in which water injection, temperature increase, heating, and cooling with cooling water are one cycle, and the hot water used during heating is recovered as it is and the cooling water is separately injected. Therefore, the injection of hot water in the next cycle realizes the saving of heat energy by using the hot water used in the previous cycle. For example, when reusing hot water, (1) In the case of the circulation substitution type, a two-stage retort having a hot water tank in the upper stage and a treatment tank in the lower stage is used as the retort cooking sterilizer.

It is assumed that the liquid amount is M (), the temperature in the treatment tank is 120 ° C., and the temperature is 90 ° C. when returned to the warm water tank. To use this hot water as the next cycle and process at 120 ° C, Is required. On the other hand, in the case of (2) recovery type, if water of M () is recovered in the warm water tank at 115 ° C, In addition, γ indicates enthalpy.

Comparing S ₁ and S ₂ with each other, S ₂ / S ₁ = 10/35 = 0.28 Therefore, in the case of the recovery type, the vapor amount of about 28% is sufficient as compared with the circulation substitution type.

As described above, the method of the present invention uses a depressurizing means over two stages during heating and cooling as a retort cooking sterilization method for cans, as described above, for those weak against the external pressure and internal pressure of the can, respectively. By changing the depressurization time, it was possible to control the pressure inside the processing tank corresponding to the increase in the internal pressure of the can and the decrease due to the vacuum, and it became possible to eliminate almost any deformation of the can due to the retort. Further, even when hot water used in one cycle of temperature raising, heating, and cooling means is collected and supplied by a collecting method, deformation of the can can be prevented and the collected hot water is When it is used in a cycle, it becomes possible to realize a reduction in heat energy, and the cooking and sterilization of canned food can be effectively performed and an energy-saving method can be performed.

[Brief description of drawings]

The drawing shows a temperature and pressure control graph in one cycle such as temperature rising, heating and cooling.

Claims (1)

[Claims] 1. A method for cooking and sterilizing canned foods and the like with hot water using a retort cooking and sterilizing machine, wherein when hot water is poured into the treatment tank to raise the temperature by pressurization, the pressure inside the treatment tank is kept constant at a certain level. It is divided into two stages by providing a holding state, then pressurized again to a predetermined pressure, and this predetermined pressure is held for heat treatment, and after collecting hot water, at the time immediately before the start of water supply for cooling in a can that is weak to external pressure In addition, if the can is weak to the internal pressure, depressurize once from the end of water supply, cool under constant pressure, then further depressurize and drain each process as one cycle, and use the recovered hot water again in the next process. A method for cooking and sterilizing canned foods, which is characterized in that