JPH0446108B2 - - Google Patents

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for producing sterilized food, and more specifically, a sterilization method for sufficiently sterilizing food without deteriorating its texture, flavor, nutritional value, etc. Concerning the manufacturing method of food products.

(Prior Art) It is widely known that spoilage during food storage is caused by microorganisms. Therefore, various technologies have been developed to process foods to a microbially safe state and increase their shelf life. A typical example is one in which food is subjected to heat sterilization treatment, as seen in the case of canning, retorting, etc.

By the way, in the conventional heat sterilization treatment as described above, foods are heated together with an aqueous liquid, that is, in the presence of more or less water. This is because many microorganisms are most easily killed when heated in moist heat conditions.

However, when heating food with moist heat, a sufficient sterilizing effect can be obtained, but water-soluble flavor components and nutritional components contained in the food are heated in a water-based liquid that is part of the heat medium, that is, the heating means. There was a tendency for the flavor and nutritional components of the food mentioned above to be easily impaired. Furthermore, for example, if the heating time is too long, there is a tendency for the food to absorb too much water, resulting in a watery texture.

Therefore, heating with water-based liquids had to be done extremely carefully. Moreover, the above-mentioned phenomena are particularly noticeable in the case of starch-based foods such as cereals and pasta.

On the other hand, when foods are fried, that is, when they are heated in the presence of only oil, the loss of various components in the foods can be prevented. However, since it is heated in a dry state, it has the disadvantage that microorganisms cannot be sufficiently killed. Therefore, for example, when heated food is mixed with other water-based foods such as stock or sauce to produce a product, microorganisms remaining in the food are likely to multiply in the water-based food, which can be critical in terms of shelf life. A problem arose. Also, with this method,
The loss of water contained in the food increased, making it impossible to obtain a soft texture of the food.

Therefore, the applicant of the present invention proposed a method of deep-frying the food without damaging the moisture in the food, by first mixing the food into oil, raising the temperature of the oil to a predetermined temperature, and at the same time developing a method for frying the food without damaging the moisture in the food. A processing method in which food is heated while forcibly suppressing the boiling of water in the food under a pressure higher than the saturated vapor pressure (patent application 1983).
-107342) was presented.

According to this processing method, the water in the food does not boil, so the food becomes moist and heated due to its own water. Therefore, the food was cooked to have a very soft texture, and at the same time water-soluble flavor components and nutritional components in the food were difficult to dissolve into oil, and the food itself could be sterilized.

However, although this method has a higher bactericidal effect than conventional fried tofu etc., it does not sufficiently kill microorganisms in the food to the point where it can be stored for a long period of time.
This is because, according to this treatment method, only the outer surface of the food is heated in the presence of only oil (heated in a dry state), and therefore, sterilization in this area may not be carried out sufficiently.

(Problems to be Solved by the Invention) The present invention achieves sufficient and efficient sterilization without impairing the soft texture, flavor, and nutritional value of foods, which could not be achieved with conventional heat sterilization treatments. Our goal is to provide manufacturing methods for various foods.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present inventors conducted various studies on methods for producing sterilized foods.

As a result, the present inventors have developed a method for heat treatment of foods using the aforementioned oil as a heat medium (Japanese Patent Application No. 107342/1982).
By intentionally adding water to oil, which serves as a heat transfer medium, the sterilizing effect on food can be dramatically increased. The present invention was achieved based on the discovery that, in addition to the bactericidal effect, the texture, flavor, and nutritional value of foods are also well maintained.

The present invention has been made based on the above findings. That is, in the present invention, food is mixed into emulsified oil containing 0.02 to 14.0% by weight of water based on the weight of oil and water, the temperature of the oil is raised to a predetermined temperature, and the temperature of the water at that temperature is increased. This invention relates to a method for producing sterilized foods, which is characterized by heating under pressure exceeding saturated vapor pressure.

The present invention will be explained in detail below.

First, the foods to be subjected to the sterilized food manufacturing method of the present invention include, for example, meat, vegetables, fruits, and starch foods such as pasta, potatoes, and grains, and are usually solid or solid. It is.

These various foods may be raw or partially cooked. In the case of starch-based foods, it is desirable to adjust the moisture content to 42.0 to 125.0% by weight based on the dry weight of the starch food (before heat treatment, which will be detailed later). When adjusted in this way, the moisture in the food and the moisture in the heat medium can achieve a better sterilization effect, and can also better prevent the food from becoming soggy due to heating. It can be effective. In addition, the dry weight of starch food here is, for example, 105~
The weight of starch food heated and dried at 110℃.

The present invention consists of using a food product as described above using oil containing a specific proportion of water as a heating medium, ie, as part of a heating multistage. Here, any edible oil can be used as the heat medium. A known conventional method is used to impregnate water in the oil. For example, both may be mixed by stirring or emulsified. In the emulsification mixing, it is possible to heat the mixture to an appropriate temperature, or to use an emulsifier such as sucrose fatty acid ester or glycerin fatty acid ester. When oil and water are emulsified and mixed as described above, the water becomes fine particles and is uniformly dispersed in the oil. Therefore, during heating, there are more opportunities for microorganisms to come into contact with water particles, and they are easily killed, achieving a high sterilizing effect.

The gist of the present invention is to specify the water content in the heat medium as described above. That is, in the present invention, the water content in the oil is 0.02 to 14.0% by weight based on the total weight of oil and water. Only when the present invention is carried out with the water content within the above range, the food will be sufficiently sterilized by the action of the water contained within itself and the water in the oil, and the texture will be improved during heat treatment. , does not impair flavor, nutritional value, etc. In other words, when the water content is less than 0.02%, microorganisms in the oil are not sufficiently killed and the food sterilizing effect is insufficient. On the other hand, if it exceeds 14.0%, the food will be sterilized well, but the action of water will be rather strong, and the texture, flavor, and nutritional value of the food will be easily impaired.
In addition, the most preferable water content in oil is within the above range, particularly from 0.40 to 9.80, in order to shorten the sterilization time and at the same time maintain the texture, flavor, and nutritional value of the food.

In the present invention, heating is performed as follows.

That is, in the present invention, when raising the temperature of oil, a pressure exceeding the saturated vapor pressure of water at that temperature is applied, and the food is heated while forcibly suppressing the boiling of the water in the food. In the above, if the applied pressure is lower than the saturated vapor pressure of water at that temperature, the water in the food will boil during heating, so the food with the soft texture desired by the present invention (for example, (boiled in water) cannot be obtained.

Hereinafter, the method for producing sterilized foods of the present invention will be explained in more detail using the heating device shown in the drawings.

FIG. 1 shows one embodiment of a patch-type heating device used when heating food according to the present invention. The heating device 1 is pressure-resistant and heat-resistant, and is divided into a main body 1' and a lid portion 1'', both of which are connected in a hermetically sealed manner by mounting bolts 2. A retainer 3 for accommodating food is provided so as to be movable up and down between an oil layer 4 in the heating device 1 and the space above it. A series of heating/temperature control mechanisms such as an oil circulation pipe 5, an oil circulation pump 6, a heater 7, a heater power source 8, a temperature controller 9, a thermometer 10, etc. are provided for controlling the temperature to a constant temperature. Additionally, a pressurized air pipe 12 equipped with an air regulator 11 and a pressurized air pipe 12' equipped with a pressure control valve 13 are used to increase the pressure inside the heating device 1 and control it to a constant pressure.
is provided.

When heating food using this device, the mounting bolts 12 are first removed and the lid 1' of the heating device 1 is opened. You can put in enough for dipping. The food is stored in a retainer 3 within the heating device 1. At this time, the food stored in the retainer 3 is
In order to heat effectively, it is preferable to cut it into pieces of appropriate size. Further, when storing food, the retainer 3 is usually in a state of being pulled up above the oil layer 4 within the heating device 1.

When food is stored in the retainer 3, the heating device 1
The lid 1'' is closed, the mounting bolts 2 are tightened, and the inside of the heating device 1 is hermetically sealed.

In this state, a pressure exceeding the saturated vapor pressure of water at the oil temperature required to sterilize food is applied within the heating device 1. (For example, when processing food at 120°C, it is necessary to apply a pressure of 1.1 kg/cm ² or more, and when processing food at 140°C, it is necessary to apply a pressure of 3.7 kg/cm ² or more inside the heating device 1.) As a specific pressurization method, pressurized air is first fed into the heating device 1 from the pressurized air piping 12 that is directed to the compressor 14 and the like. On this occasion,
The air regulator 11 provided in the pressurized air pipe 12 acts to continuously feed pressurized air into the heating device 1 at a constant pressure. Further, when the pressure inside the heating device 1 exceeds a predetermined pressure, the pressure control valve 13 provided in the pressurized air pipe 12' acts, and a part of the pressurized air is transferred to the pressurized air pipe 12'.
2' to the outside of the heating device 1. In this way, a predetermined pressure is maintained within the heating device 1.

Note that the means for increasing and controlling the pressure within the heating device 1 may be any known means as long as it can maintain a predetermined pressure within the heating device 1.

In the present invention, the conditions for heating food are as follows:
Naturally, it varies depending on the type of food. But usually
It is preferable to treat the oil at an oil temperature of 100 to 180°C for about 1 to 60 minutes in order to effectively sterilize the food.

In the present invention, a specific method for increasing the temperature of the oil in the heating device 1 is to operate the heater 7 and operate the oil circulation pump to circulate the oil in the oil circulation pipe 5. Do this depending on the situation. Further, the oil temperature in the heating device 1 is sensed by a thermometer 10 provided in the heating device 1 so as to be in contact with the oil layer 4, and a temperature controller 9 interlocked with this is activated, and the heater power source 8 It can be kept constant by turning ON/OFF.

In addition to the above-mentioned means for increasing or controlling the temperature of the oil in the heating device 1, various known means can be used as long as a predetermined oil temperature can be achieved.
It will be adopted as is. For example, the heating device 1 may be heated from outside with a direct flame, or the heating device 1 may be connected to various heat exchangers and oil may be circulated between them, or a jacket may be provided outside the heating pot and an appropriate heat exchanger may be installed in this area. Introducing a heat medium, etc. (Second)
The oil temperature can also be raised by

In the present invention, a predetermined pressure and oil temperature can be achieved in the heating device 1 as described above;
The process sequence of achieving a predetermined pressure and achieving a predetermined oil temperature may be performed at the same time or at different times. However, when food is housed in the retainer 3 and pre-immersed in the oil layer 4, and the pressure and oil temperature in the heating device 1 are increased to a predetermined level, loss of moisture in the food is prevented. Because it is possible to
It is preferable to increase the oil temperature while appropriately achieving a pressure exceeding the saturated vapor pressure, or to increase the oil temperature after pressurization.

When a predetermined pressure and oil temperature are achieved in the heating device 1, the retainer 3 containing the food is lowered into the oil layer 4, and the food is processed within the oil layer 4 at a predetermined temperature and time.

The processed food is heated in the heating device 1 once the retainer 3 is pulled up from the oil layer 4 to the upper space.
For example, the product is cooled down to a temperature of 99°C or lower. Here, if cooling is not achieved to 99°C or lower, when the pressure inside the heating device 1 is reduced as described below, the water in the food will boil rapidly and the desired soft texture will not be achieved. Food may not be available.

When the food is cooled to a constant temperature in the heating device 1, the pressure control valve 13 is loosened and pressurized air is discharged from the pressurized air pipe 12', and the heating device 1
The internal pressure is reduced to, for example, normal pressure.

Finally, the mounting bolts 2 are removed, the lid 1'' of the heating device 1 is opened, and the heat-treated food is taken out from the retainer 3.

In the present invention, when food is continuously processed using the heating device 1, the oil heated in the previous batch is not cooled down to room temperature, and the food processed in the previous batch is heated. After taking out the food from the heating device 1, put the food to be newly processed into the retainer 3,
With the heating device 1 sealed and the retainer 3 raised above the oil layer 4, the pressure inside the heating device 1 is increased, and when a predetermined pressure is achieved, the retainer 3 is lowered into the oil layer 4. Process it. Such a treatment method can shorten the heat treatment time.

Further, the retainer 3 may be provided with, for example, a mesh lid for the purpose of preventing food from floating in the oil. Further, in the heating device 1, suitable means for stirring or circulating the oil may be provided for the purpose of increasing thermal efficiency during heating or uniformly heating the food. Furthermore, as in the heating pot shown in FIG. 2, the food can be directly heated between the pots without the retainer.

Foods heated as described above are not watery and have the same soft texture as when heated in an aqueous system, and water-soluble components such as vitamin C and minerals are hardly lost, and the flavor and It has excellent nutritional value and is also well sterilized.

By the way, a sterilized food can also be produced by adding a food that has been separately sterilized to the food that has been processed as described above.

The above method will be explained based on the case where the heating pot shown in FIG. 2 is used. The heating pot 15 is pressure-resistant and heat-resistant, and is divided into a main body 15' and a lid part 15'', both of which are connected in a hermetically sealed manner by mounting bolts 2. Jacket 1 to raise the temperature and control it at a constant temperature
6. A series of heating and temperature control mechanisms such as the control valve 17, transmitter 18, and regulator 19 are provided. The means for controlling the pressure inside the pot are the same as those of the heating device 1 shown in FIG. The heating pot 15 is also provided with an inlet pipe 20 for introducing separately sterilized food into the pot, and an oil drain port 21 for draining oil from the pot.

According to the heating pot 15 described above, food is heated by appropriately achieving a pressure equal to or higher than the saturated vapor pressure in the pot and increasing the oil temperature in the same manner as in the case of FIG. 1. However, to control the oil temperature in the pot, the oil temperature is cooled by the transmitter 18, and a detection signal is transmitted from there to the regulator 19.
In addition to identifying the deviation of the oil temperature from the set temperature,
This is done by sending an operation signal based on this to the control valve 17 to adjust its opening degree.

Once heating is complete, the food is cooled and the pressure inside the pot is released. In this state, the oil is drained from the oil drain port 21, leaving only the food in the pot. Next, food that has been separately sterilized, for example, in various heat exchangers connected to the feed pipe 20, is aseptically transferred from the feed pipe 20 into the pot by operating an on-off valve. A sterilized food can be obtained by introducing and mixing with food that has been previously sterilized in a pot. The food that is separately sterilized and introduced into the pot may be, for example, a liquid, paste, or water-based food.

As mentioned above, conventional products made by mixing oil-based sterilized foods with water-based liquids have had problems in terms of shelf life. However, according to the present invention, solid or solid foods can be sufficiently sterilized without deterioration of texture, flavor, nutritional value, etc.; By this method, it is possible to obtain a high-quality solid-containing liquid food that has no microbial problems, has a high shelf life, and has a high preservability. Specifically, soups and stews containing solid foods such as corn, meat pieces, potatoes, and carrots are provided, and these are completely new foods in that they have both preservability and quality.

The present invention has been described above based on an embodiment in which food is heated using a batch type heating device. However, it should be understood that the means, devices, etc. used for heating food in the present invention are not limited to those described above. That is, any device that can achieve the desired pressure and oil temperature and process the food may be used. Further, the material may be any material as long as it can maintain the desired pressure and oil temperature.

Next, the present invention will be specifically explained using examples.

Example 1 (Sterilization of rice) Emulsified oil obtained by emulsifying 95 parts of rapeseed oil and 5 parts of water using a homogenizer was used as a heat medium.

The heating pot shown in FIG. 2 was used as an apparatus for the heat treatment. First, open the lid part 15'',
After putting rice and the above-mentioned emulsified oil into the heating pot 15 and closing the lid 15'' to seal the inside of the pot, the temperature inside the pot is adjusted to a level higher than the saturated vapor pressure as appropriate in exactly the same manner as explained in FIG. 1 above. The oil temperature was gradually increased while achieving the pressure of 130°C.
The pressure inside the heating pot ¹⁵ and the amount of steam inside the jacket 16 were controlled so that this temperature was continuously achieved.
℃ temperature) for 5 minutes. At this time, the rice and emulsified oil in the pot were mixed by the stirring blade 22.

After the heating was completed, water was introduced into the jacket 16 and the rice was cooled down to a temperature of 99° C. or lower. Subsequently, the pressure inside the heating pot 15 was lowered to normal pressure.

After the above operation, the lid 15'' of the heating pot 15 is opened, the emulsified oil is separated, and the collected rice is sufficiently sterilized to a commercially sterile state, and at the same time retains its original texture, flavor, and nutritional value. It was something that had value.

Example 2 (Manufacture of sterile porridge) In Example 1, when the rice was cooled after the heat treatment, the pressure inside the heating pot 15 was reduced to 0.5 Kg/cm ² .
Only the emulsified oil was extracted from the extraction port 21 to the outside of the pot.
Next, while keeping the rice in the pot in a sterile state, separately sterilized Japanese-style soup stock and ingredients are aseptically introduced into the pot from the feed pipe 20 and mixed with the rice in the pot. did. The rice porridge obtained by mixing as described above was sent to an aseptic filling machine, which filled and sealed paper containers.

The containerized rice porridge obtained in this way does not cause any microbial problems even after being stored at room temperature for 30 days, and the rice contained in it retains its original texture, flavor, and nutritional value. It was a product of high commercial value.

Example 3 (sterilization of macaroni) Emulsified oil obtained by emulsifying 95 parts of salad oil and 5 parts of water using a homogenizer was used as a heat medium.

First, I put the macaroni in boiling water to rehydrate it. In this case, the water content of the macaroni after re-boiling is 100% by weight based on the dry weight of the macaroni.
I re-boiled it so that it was. Thereafter, the macaroni was sterilized under pressure and heat for 30 minutes at 121° C. (in this case, the pressure inside the heating pot 15 was 1.1 Kg/cm ² ) in the same manner as in Example 1.

After the treatment, the macaroni separated from the emulsified oil and collected was sufficiently sterilized to commercially sterile conditions, and at the same time had the texture, flavor, and nutritional value inherent in macaroni.

In this case, in the same manner as in Example 2, only the emulsified oil is extracted from the heating pot 15, and while the macaroni in the pot is maintained in a sterile state, white sauce that has been separately sterilized is placed in the pot. introduced aseptically and mixed with macaroni to obtain macaroni gratin;
This was aseptically filled into a paper container.

The packaged macaroni gratin obtained in this way does not cause any microbial problems even after being stored at room temperature for 30 days, and the macaroni contained therein has its original texture, flavor, and nutritional value. It had a very high commercial value.

(Effects of the Invention) According to the present invention, food is sterilized very well and in a short time, has a soft texture similar to that when heated in an aqueous system, and has vitamin C, minerals, etc. contained in the food. The water-soluble active ingredients are almost intact and retain their original flavor and nutritional value.

Furthermore, according to the present invention, even when heat-treated food is mixed with an aqueous liquid material that has been separately sterilized, the storage stability is extremely good, and the solid food contained therein remains as fresh as originally. Retains texture. In other words, a liquid food containing high quality solid food is provided.

[Brief explanation of the drawing]

FIGS. 1 and 2 show one embodiment of a heating device used for sterilizing food according to the present invention. 1 (1', 1'')... Heating device, 2... Mounting bolt, 3... Retainer, 4... Oil layer, 5... Oil circulation piping, 6... Oil circulation pump, 7... Heater, 8... Power source for heater, 9... Temperature controller, 10... Thermometer, 11... Air regulator, 12, 12'... Piping for pressurized air, 13...
...Pressure control valve, 14...Compressor, 15
(15', 15'')... Heating pot, 16... Jacket, 17... Steam control valve, 18... Transmitter, 19... Regulator, 20... Feed pipe, 21...
...Oil drain port, 22...Agitation blade.

Claims (1)

[Claims] 1. 0.02 to 14.0 of food based on the total weight of oil and water
Mixing in emulsified oil containing % by weight of water, raising the temperature of the oil containing water to the sterilization temperature of the food, and heating it by applying a pressure that exceeds the saturated vapor pressure of water at that temperature. A method for producing sterilized food, characterized by: 2 The food is a starch-based food,
A method for producing a sterilized food according to claim 1. 3. The method for producing a sterilized food according to claim 2, wherein the food contains 42.0 to 125.0% by weight of water based on its dry weight. 4 Foods: 0.02 to 14.0 based on the total weight of oil and water
It is mixed into an emulsified oil containing % by weight of water, and the temperature of the oil containing water is raised to the sterilization temperature of the food, and after heating by applying a pressure that exceeds the saturated vapor pressure of water at that temperature, A method for producing sterilized food, which comprises separating food and oil and adding sterilized food to the separated food. 5 The food is characterized by being a starch-based food,
A method for producing a sterilized food according to claim 4. 6. The method for producing a sterilized food according to claim 5, wherein the food contains 42.0 to 125.0% by weight of water based on its dry weight. 7. The method for producing a sterilized food according to claim 4, 5 or 6, wherein the sterilized food is an aqueous liquid.