JP5808186B2 - Freezing equipment and freezing method for frozen food production - Google Patents

Description

  The present invention relates to a freezing facility and method for producing frozen foods such as meat / fish meat, marine products, and agricultural products.

A freezing facility for producing frozen foods has a closed space to be cooled, stores food to be frozen in the closed space, and cools the food in a sealed state to freeze the food.
In patent document 1, it cools by making a liquid refrigerant collide with food. Patent Document 2 discloses a nitrogen production apparatus.

Japanese Patent Laid-Open No. 2003-322452 Japanese Patent Laid-Open No. 2005-200245

Frozen meat, fish meat (marine products), and agricultural products are intermediate products when viewed as processed foods, which are used to produce various products. It is important to maintain their freshness, and the freezing process is also is important. The inventor of the present application considered that the factor that deteriorates food is oxygen, and considered that the presence of oxygen was eliminated as much as possible to freeze.
The problem to be solved is to improve the freezing process of frozen foods, thereby adding the added value of suppressing the decrease in freshness to frozen foods and increasing the consumption effect.

A first aspect of the present invention includes a contact freezer chamber that is a closed space to be cooled to produce frozen foods,
A vacuum pump for extracting air from the contact freezer chamber;
A food freezing facility comprising a nitrogen gas injection device for injecting nitrogen gas into the contact freezer chamber,
The food is stored in a flat tank in the contact freezer chamber, and after the mechanical pressure is applied to the food by the flat tank, the pressure in the contact freezer chamber is reduced by the vacuum pump, and then the nitrogen gas injection device is used to Nitrogen gas is injected into the contact freezer chamber to fill the chamber to atmospheric pressure, and when the food is coated with nitrogen gas, the temperature in the contact freezer chamber is set to minus 40 degrees Celsius to cool and freeze the food. It is characterized by doing.
The second aspect of the present invention provides a contact freezer chamber that is a closed space to be cooled, a vacuum pump for extracting air from the contact freezer chamber, and a nitrogen gas injection into the contact freezer chamber A method for freezing food in the production of frozen food using a freezing facility comprising a nitrogen gas injection device,
A storage step for storing food to be frozen in a flat tank in the contact freezer chamber and closing the contact freezer chamber;
In the contact freezer chamber closed in the storage step, in a state where mechanical pressure is applied to the food by the flat tank, the pressure reducing step of reducing the pressure in the contact freezer chamber by the vacuum pump;
A nitrogen gas injection step of injecting nitrogen gas into the contact freezer chamber decompressed in the pressure reduction step by the nitrogen gas injection device to fill the chamber to atmospheric pressure, and coating the food with nitrogen gas;
After the nitrogen gas is injected in the nitrogen gas injection step, the temperature of the contact freezer chamber is set to minus 40 degrees Celsius to cool and freeze the food.

  In the freezing equipment and freezing method of the present invention, by injecting nitrogen gas after evacuating the air in the closed space for freezing food, and performing freezing in a state where the gas in the closed space is almost nitrogen gas, Compared to the case of freezing in normal air without nitrogen gas replacement, the effect of suppressing the freshness of frozen food can be obtained. This is due to the following two reasons.

  First, because the gas contained in the frozen food becomes nitrogen instead of oxygen, oxidation during freezing storage after freezing is suppressed. Frozen foods usually contain air with large and small gaps, but by replacing the air in the closed space with nitrogen gas before freezing, the gas present in the gaps in the food is also almost replaced with nitrogen. And frozen in that state. Conventionally, for example, when packaging frozen food frozen in air, there is a conventional technique for replacing the air in the packaging bag with nitrogen gas, but the method of the present invention is essentially the conventional technique. Is different.

  Secondly, by substituting nitrogen gas for the air in the closed space, the freezing time is shortened compared with the case of freezing in air. In the example, the freezing time was shortened by 25% compared to the comparative example. Therefore, since food can be frozen in a shorter time, freezing in a state with higher freshness is realized.

  As described above, the present invention in which the surroundings of the target food are replaced with nitrogen gas before freezing and frozen while being covered with nitrogen gas is a technique with a very high freshness maintaining effect. As a result, added value is added to the frozen food and the consumption effect is increased.

FIG. 1 is a block diagram showing a configuration of a freezing facility according to the present invention. FIG. 2 is a diagram showing an example in which the present invention is applied to a contact freezer. FIG. 3 is a graph showing temperature changes in an example in which the present invention was applied to freeze food in nitrogen gas. FIG. 4 is a graph showing a temperature change in a comparative example in which food is frozen in the air as usual.

  The freezing equipment according to the present invention enhances the quality of a product by freezing in a nitrogen atmosphere in a freezing process in producing frozen food. Freezing in an atmosphere where oxygen that causes oxidation is removed as much as possible. FIG. 1 is a block diagram showing a configuration of a freezing facility according to the present invention. The freezing equipment 10 may be a freezing equipment capable of producing frozen food. The freezing equipment 10 has a closed space 20 to be cooled. A food to be a product is placed in the freezing space 10 and is cooled and frozen in a sealed state to produce a frozen food.

  An example of the freezing facility 10 is a contact freezer 50. FIG. 2 is a diagram showing an example in which the present invention is applied to a contact freezer. The contact freezer 50 is a refrigeration facility used for freezing a large amount of meat, fish, seafood, and agricultural products with the same thickness, and usually has a width of 2 meters and a height of about 1.5 meters. It is box-shaped. A door is attached to the side surface, and a plurality of horizontal shelf-like metal plates called flat tanks 52 are provided inside, and the interval can be adjusted.

  When the food is frozen, the weighed food is placed with the interval between the flat tanks 52 widened. After the food is spread all over, the upper flat tank 52 is lowered by the hydraulic pump 53 at a predetermined interval so as to come into contact with the food. After completing this work for all the flat tanks 52, the doors are closed and the temperature is lowered and frozen while applying a predetermined mechanical pressure to the entire flat tank. In order to realize this, a hydraulic cylinder 51, a surge drum 54, and an operation panel 55 are provided.

  The freezing facility 10 of the present invention includes a vacuum pump 30 that draws air from the closed space 20 to be cooled in the freezing facility, and a nitrogen gas injection device 40 that injects nitrogen gas into the closed space 20 that has been decompressed by the operation of the vacuum pump 30. And have. The nitrogen gas injection device 40 is configured to take compressed air into one end of a pressure vessel provided with a nitrogen separation membrane made of a polyimide hollow fiber membrane, discharge oxygen from a side port, and take out nitrogen gas from multiple ends of the pressure vessel, for example It is. This utilizes the fact that the permeation speed of the membrane differs depending on the type of gas. As the nitrogen gas injection device 40, a nitrogen production device that obtains nitrogen from the atmosphere disclosed in Patent Document 2 or a commercially available device uses a deaeration device provided by Katayama Chemical Co., Ltd. in Higashiyodogawa-ku, Osaka-shi. be able to.

  Here, a freezing facility in which a vacuum pump for depressurizing the closed space and a nitrogen gas injection device for injecting nitrogen gas into the closed space are connected to a closed space (contact freezer room) to be cooled in the contact freezer. This will be described as an example. Food (for example, surimi products) is spread in the contact freezer chamber, and the contact freezer chamber is evacuated (depressurized) using a vacuum pump in a state where mechanical pressure is applied to the flat tank. At this time, excess water in the contact freezer chamber is removed and the oxygen concentration is lowered. Next, nitrogen gas is injected into the contact freezer chamber and filled.

  Nitrogen gas injection returns the pressure in the contact freezer chamber to atmospheric pressure, but the original air is almost replaced with nitrogen gas. In this state, foods before freezing (meat, fish, marine products, agricultural products) are coated with nitrogen gas, and even in gaps inside the food (especially gaps where gas can be exchanged with the outside) Almost replaced with nitrogen gas. The reason for “substantially” here is that the oxygen concentration is significantly lower than the original air, but is not completely zero. Freezing is started in this state, and the freezing is completed by cooling to a predetermined temperature. In the frozen product thus obtained, deterioration is suppressed as compared with the frozen product obtained by the conventional method.

  The extent to which the pressure is reduced by the vacuum pump is such that it is necessary for removing excess water and does not deprive the water necessary for freezing. Continued operation of the vacuum pump is not desirable because it deprives moisture necessary for freezing. In addition, it is not preferable to perform freezing while keeping the air pressure in the closed space (contact freezer room) low because it may cause an excessive load on various devices and cause deterioration and consumption. Further, as is well known, heat is transferred by conduction, convection, and radiation. However, if the gas is cooled in a closed space with a low gas pressure, it is considered that the heat transfer effect by convection is reduced. Therefore, nitrogen gas is injected to return to atmospheric pressure and then cooled. As a result, freezing in a state where the concentration of oxygen that may deteriorate food (frozen product) is lowered is realized.

  In the present invention, the temperature in the freezing step is desirably set to about 10 degrees lower than the conventional temperature, and a temperature of minus 40 degrees Celsius is used.

  More preferably, the temperature in the frozen storage process is set to be 10 degrees lower than before, and is set to minus 35 degrees Celsius.

  In addition, it turned out that the freezing time is shortened in the freezing process under the nitrogen atmosphere to which the present invention is applied, compared with the freezing process under the conventional air atmosphere. This effect will be described with reference to FIGS.

FIG. 3 is an example of the present invention, and is a graph showing the results of measuring the temporal change in the temperature of the closed space in the freezing process. “Liquid temperature” and “suction temperature” in the graph are the temperatures of the refrigerant gas in the liquid state and in the gas state, respectively, in the cooling circulation system. These temperature changes substantially correspond to the temperature changes in the contact freezer chamber. The “surimi surface temperature” is a measurement of the temperature of the surimi surface.
The vacuum pump is turned on 5 minutes after entering the surimi, and the vacuum pump is stopped by continuing the evacuation for 5 minutes. The pressure at the time of depressurization in the contact freezer chamber was −0.02 MPa (gauge pressure). Subsequently, the nitrogen gas injection apparatus was operated for 5 minutes to fill the closed space with nitrogen gas (containing 99% or more of nitrogen). The pressure in the contact freezer chamber after filling with nitrogen gas was atmospheric pressure. Up to this point, 15 minutes have passed since surimi storage. Thereafter, the surimi was allowed to stand until the surimi surface temperature reached minus 40 degrees Celsius. It took about 90 minutes for the surimi surface temperature to reach minus 40 degrees Celsius. Here, the freezing process was completed and surimi was delivered.

  FIG. 4 is a graph showing the results of a comparative example in which the freezing step was performed under the same cooling conditions as in the example of FIG. In the comparative example, nitrogen gas replacement was not performed, and freezing was performed in a normal air atmosphere. As a result of the comparative example, it took about 120 minutes for the surimi surface temperature to reach minus 40 degrees Celsius.

  Comparing the example of FIG. 3 and the comparative example of FIG. 4, the freezing time in the example is 25% shorter than that of the comparative example.

  It can be applied to freezing equipment that freezes foods that are more strongly desired to maintain freshness, for example, blood of cultured sea bream, frozen surimi salmon, sashimi, boiled crabs, raw shrimp, squid rings, shumai, croquettes, hamburgers, gyoza and the like. Besides contact freezer, it can be applied to freezing equipment such as tunnel freezer, pusher type continuous freezing device, spiral type continuous freezing device, air blast type quick freezing unit.

10 Freezing equipment 20 Closed space 30 to be cooled Vacuum pump 40 Nitrogen gas injection device 50 Contact freezer 51 Hydraulic cylinder 52 Flat tank 53 Oil pump unit 54 Surge drum 55 Operation panel

Claims (6)

A contact freezer room, which is a closed space to be cooled to produce frozen food ,
A vacuum pump for extracting air from the contact freezer chamber ;
A food freezing facility comprising a nitrogen gas injection device for injecting nitrogen gas into the contact freezer chamber ,
After storing food to be frozen in the flat tank in the contact freezer chamber, the pressure in the contact freezer chamber is reduced by the vacuum pump in a state where mechanical pressure is applied to the food by the flat tank, and then the nitrogen gas is injected. The apparatus is filled with nitrogen gas into the contact freezer chamber to fill the chamber to atmospheric pressure, and when the food is coated with nitrogen gas, the temperature in the contact freezer chamber is set to minus 40 degrees Celsius and the food is A food freezing facility characterized by cooling and freezing . A food freezing facility according to claim 1,
The nitrogen gas injection device includes:
A freezing facility for food , which takes in nitrogen gas in the atmosphere and injects it into the enclosed space. A food freezing facility according to claim 1 or 2 ,
The food freezing facility is characterized in that the pressure reduction by the vacuum pump is necessary to remove excess water from the food and does not deprive the water necessary for freezing. Use a contact freezer compartment is a closed space to be cooled, a vacuum pump for evacuating air from the contact freezer compartment, a freezing equipment and a nitrogen gas injection device for injecting nitrogen gas into the contact freezer compartment A method of freezing food in the production of frozen food ,
A storage step for storing food to be frozen in a flat tank in the contact freezer chamber and closing the contact freezer chamber ;
In the contact freezer chamber closed in the storage step, in a state where mechanical pressure is applied to the food by the flat tank , the pressure reducing step of reducing the pressure in the contact freezer chamber by the vacuum pump;
A nitrogen gas injection step of injecting nitrogen gas into the contact freezer chamber decompressed in the pressure reduction step by the nitrogen gas injection device to fill the chamber to atmospheric pressure, and coating the food with nitrogen gas ;
And a cooling step of cooling and freezing the food by setting the temperature in the contact freezer chamber to minus 40 degrees Celsius after the nitrogen gas is injected in the nitrogen gas injection step. . A method for freezing food according to claim 4 ,
The method for freezing food, wherein the nitrogen gas in the nitrogen gas injection step is taken from the atmosphere. A method for freezing food according to claim 4 or 5,
The method for freezing food, wherein the decompression in the decompression step is a degree necessary for removing excess water from the food and does not deprive the water necessary for freezing.

Images