JP2017176033A - Method and apparatus for thawing frozen food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for easily thawing, which: enable no breakdown of cell membranes during thawing; prevent water (drip) containing taste component from flowing out; maintain original state as much as possible so that taste of high grade is kept; shorten thawing time; and enable sterilization of pathogen.SOLUTION: A method for thawing frozen fish, shellfish and meat comprises: a step of mounting an object to be thawed (a frozen block of fish or meat) on a metallic thawing plate in an external vibration applying machine including an electromagnetic vibration generating part and the metallic thawing plate; a step of mounting a metallic electrode on the frozen block of fish or meat, in which an electric power supply for electrification and the metallic electrode are included in a Joule heating machine; and a step of providing external vibration with the frozen block of fish or meat together with electrifying the frozen block of fish or meat to subject the frozen block of fish or meat to Joule heating. An apparatus for thawing frozen fish, shellfish and meat comprises: an external vibration applying machine; and a Joule heating machine, in which the external vibration applying machine includes: an electromagnetic vibration generating part; and a metallic thawing plate, and the Joule heating machine includes: an electric power supply for electrification to generate Joule heat; and a metallic electrode to be mounted on a frozen block of fish or meat.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method and apparatus for thawing frozen foods, particularly frozen fresh fish meat and frozen livestock meat.

  In the fishery industry, the wholesale price is low due to the large amount of catch when there is a large amount of good quality fish in an environment where the target fish is well grown and the food is abundant. However, there was a problem that income was not stable because the amount of capture was small. However, in recent years, freezing technology that can maintain the original state without cell destruction such as cell alive system (CAS) freezing and supercooling freezing has been developed (Japanese Patent No. 4041673; Patent Document 1), and it is of good quality during large fishing. By freezing fresh fish and shipping them when it is not fishing, stable supply becomes possible and the income of fishermen is also stabilized.

There are problems with thawing techniques for frozen fresh fish meat and frozen livestock meat.
Meat and fish are aggregates of cells, including protein, water and blood. When a company handling meat and fish freezes, the cells are not destroyed because they are frozen quickly at -60 ° C. When thawing, thawing starts from the surface and proceeds toward the inner surface, but the freezing point of meat and fish cell aggregates (-1 to -2 ° C) and the freezing point of blood and water (0 ° C) Because of the difference in temperature, cell aggregates (particularly proteins) are first melted and contracted during thawing to destroy the cell membrane. Cell membrane disruption occurs at the interface between the frozen and thawed portions. Therefore, there is a problem in that moisture (drip) containing an umami component leaks from the gap between the cell membranes broken at the time of thawing and flows out, and the quality of the taste is significantly lowered.

  Accordingly, various thawing devices that do not generate drip have been proposed. For example, a method of obtaining a product having quality equivalent to that of natural thawing in a short time by applying Joule heating while applying pressure (Patent No. 4323712; Patent Document 2), primary voltage applied as a thawing condition in a closed storage (AC) (Or DC voltage) is controlled so that the rise in food temperature is + 3 ° C or less, and one pole of the secondary voltage side is grounded at one end, and the current is controlled by resistance to perform external heating at 10 to 40 ° C. There has been proposed a method for thawing and / or storing frozen foods by applying a voltage (Japanese Patent Laid-Open No. 2007-75096; Patent Document 3).

  However, there is no known simple method that can be thawed without producing drip for fish meat that is commercialized as fillet. In small-scale restaurants that provide fish meat, unsold goods (loss) after thawing have a significant effect on business income. Accordingly, there is a need for a small and simple apparatus and method that can maintain the original state as much as possible and maintain a high-quality taste and can be thawed in a short time each time an order is placed.

Japanese Patent No. 4041673 Japanese Patent No. 4323712 JP 2007-75096 A

An object of the present invention is to prevent the outflow (drip) of water containing umami components by preventing cell membrane destruction when thawing fish meat, and maintain high quality taste while maintaining the original state as much as possible, izakaya and small dishes An object of the present invention is to provide a small and simple thawing device and thawing method suitable for restaurants, restaurants, and the like, food processing and sales food stores, and general households.
It is another object of the present invention to provide a thawing apparatus and a thawing method for sterilizing pathogenic bacteria that inhabit a thawing target object at the time of thawing and thawing safe and high-quality fish meat in a short time.

  As a result of intensive studies, the present inventors have confirmed the temperature difference between the cell body (particularly the protein-containing portion) and the freezing point of blood and water, and the boundary surface between the frozen portion and the thawed portion of the fish meat As a means to prevent the outflow (drip) of water containing umami components due to cell disruption, the boundary between the frozen part and the thawed part by thawing by joule heating while applying external vibration to the frozen material It is confirmed that the difference in contraction on the surface is relaxed and cell membrane destruction can be prevented, the thawing time is shortened by heating due to Joule heating and molecular vibration, and the pathogen is sterilized by energization. completed.

That is, the present invention relates to the following thawing methods [1] to [6] and thawing devices [7] to [10].
[1] An energizing power source for placing a frozen fish meat mass to be thawed on the metal thawing plate of an external vibration imparting machine composed of an electromagnetic vibration generating unit and a metal thawing plate, and generating Joule heat The metal electrode of the joule heater composed of a metal electrode is placed on the top of the frozen fish meat mass, and is vibrated from the outside of the frozen fish meat mass, while simultaneously energizing the frozen fish meat mass to perform joule heating. A method for thawing frozen fish and shellfish.
[2] The method for thawing frozen fish and shellfish according to item 1 above, wherein the vibration applied by the external vibration applying machine is a slight vibration of 10 Hz to 10 kHz and an amplitude of 1 mm or less.
[3] The method for thawing frozen fish and shellfish meat according to item 1 or 2, wherein an AC voltage having a frequency synchronized with vibration applied by an external vibration applying machine is applied and Joule heating is performed.
[4] The thawing method according to any one of the items 1 to 3, wherein the frozen fish meat is frozen meat stock or frozen fresh fish shellfish.
[5] The thawing method according to item 4, wherein the meat is selected from beef, pork, lamb, chicken and whale meat.
[6] The thawing method according to 4 above, wherein the fresh fish is selected from tuna, skipjack, horse mackerel, mackerel, squid, and scallops.
[7] A power supply for energization having an external vibration applying machine and a Joule heater, the external vibration applying machine comprising an electromagnetic vibration generator and a metal thawing plate, and the Joule heater generating Joule heat. And an apparatus for thawing frozen fish shellfish, characterized by comprising a metal electrode placed on top of the frozen fish meat mass.
[8] The thawing device as described in [7] above, wherein the metal thawing plate is provided with conductive silicon rubber laid or pasted.
[9] The thawing device according to item 7 above, wherein conductive silicon rubber is attached or pasted to a metal electrode.
[10] The thawing device according to any one of 7 to 9 above, wherein the thawing plate and the electrode are electric conductors.

It is a schematic diagram of the apparatus (apparatus of this invention) used for the thawing method of the to-be-thawed food by this invention. It is the microscope picture (A) of the fish part of the bonito thawed using the apparatus of the present invention, and the microscope picture (B) of the fish part of the bonito thawed by the usual method (both magnifications are 2000 times). It is a photograph which shows the drip amount (A) of the bonito thawed using the apparatus of this invention, and the drip amount (B) of the bonito normally thawed. A physiological saline sample containing 5% Escherichia coli culture in physiological saline was conducted for 15 minutes at 7.5 V energized under the conditions of “no vibration” and “vibration”, and a part of the sample was cultured on a tryptosoy agar flat medium. It is a photograph which shows the result of Experiment 1 and 2. Experiment 3 in which a physiological saline sample containing 5% Escherichia coli culture solution in physiological saline was conducted for 15 minutes under the conditions of “no vibration” and “vibration” at 15 V energization, and a part of the sample was cultured on a tryptic soy agar flat medium 4 is a photograph showing the results of 4 and 4; It is a photograph which shows the result of the experiment 5 which carried out 15 minutes on conditions with "vibration" by 7V electricity supply about Escherichia coli culture solution (stock solution), and culture | cultivated a part of sample on the tryptic soy agar flat medium.

The decompression method and decompression apparatus of the present invention will be described below with reference to the accompanying drawings.
The thawing method of the present invention is carried out by an apparatus whose outline is shown in FIG.
In FIG. 1, reference numeral 1 denotes an external vibration imparting machine having an electromagnetic vibration generator (2) including a vibrator driving power source (11), an electromagnetic vibrator (112), and an insulating vibration transmission member (13). Electromagnetic vibrator (12) on the frozen fish meat mass (6) to be thawed placed on the metal thawing plate (4) which also serves as one electrode (lower metal electrode plate) of the Joule heater (3) Transmit vibration due to. The electromagnetic vibration generating unit (2) applies vibration adjusted by changing the frequency and vibration intensity to the object to be thawed.

  The metal thawing plate (4) is made of a metal material having high thermal conductivity such as stainless steel or aluminum, and at least the portion in contact with the food material (the object to be thawed) has an adverse effect on the food material from the metal electrode when energized. Conductive silicon rubber (5a) is laid or pasted to prevent elution of the affected metal ions.

  The Joule heater (3) includes a power source (AC voltage generator) (7), a counter electrode (8a, 8b), and a lower metal electrode plate (metal thawing plate) (4) corresponding to the counter electrode and a metal And an electrode plate (9). The metal electrode plate (9) is attached to an arm (upper electrode fixing arm) (14) for fixing the upper part of the object to be thawed (6) via a deformed contact spring (15), and is to be thawed. While supporting the object (6) from above, the object to be thawed (6) is heated by energization with an alternating voltage. Conductive silicon rubber (5b) is also laid or pasted on the surface of the metal electrode plate (9) in the same manner as the metal thaw plate.

A fine vibration of 10 Hz (600 times per minute) to 10 kHz (600,000 times per minute) is applied to the object to be thawed (frozen fish meat mass) via an thawing plate by an external vibration applying machine.
The vibration frequency, strength, and joule heating power are adjusted as appropriate according to the state of the frozen fish meat mass. That is, at the initial stage of thawing, the material is frozen (−20 ° C. or lower) and is hard and has poor contact with the electrode. Therefore, a small amount of power is supplied at a high frequency (maximum 10 KHz) until the surface becomes familiar with the electrode. Next, in order to speed up the thawing time, a large amount of power is applied to the extent that the material does not burn. The vibration frequency at this time is preferably 50 to 100 Hz, and the strength is preferably 0.5 to 1 mm. At this stage, the material is uneven in temperature, so the power is finally reduced to wait for the natural diffusion of heat. Although these adjustments are not disclosed in detail in this specification, they can be controlled by looking at the rate of change in the resistance value of the object to be thawed (10 in FIG. 1 is a control panel for control). .

  The primary side of the Joule heating power source (8) is connected to the metal thawing plate (3) and the secondary side is connected to the metal electrode part (4), and energized with the thawing object (6) interposed therebetween. The energizing power source (8) is a power source (for example, a sine wave inverter) that can change not only the frequency but also the voltage, power, and waveform (any of sine wave, short wave, and sawtooth wave). The power, which can be changed depending on the type, volume, and mass of the object to be thawed, is used, and the frequency, voltage, and waveform are appropriately selected and adjusted depending on the resistance value of the fish type and solid of the object to be thawed and the freezing temperature at the time of initial operation. By energization adjusted according to the object to be thawed, it is thawed by Joule heat generated by the resistance of the fish species and solid of the object to be thawed between the electrodes.

In the present invention, when the object to be thawed is frozen, it has low conductivity and is an insulator in terms of direct current. Therefore, it is energized in anticipation of a dielectric (impedance) by applying an alternating electric field.
Here, Joule heat is heat generated according to the resistance value of an object when an electric current is passed, and Joule heat quantity (Q) is expressed by the following equation (1).
In the formula, V represents voltage, R represents electric resistance (Ω), and t represents time (seconds).
The frequency to be added at this time is preferably tuned to the frequency of the external vibration adding machine. This is because the cell expansion and contraction vibration generated by energization and the external vibration adding external vibration adding machine are synchronized with each other to prevent friction between cells and to prevent the cell membrane from being destroyed.
Since the object to be thawed is frozen and fixed at the initial operation, the resistance value is high, and the energization efficiency is low, the frequency of the Joule heater may be increased to about 10 KHz.

The Joule heat required to thaw the object to be frozen (that is, the amount of electricity applied by the Joule heater) can be predicted from the specific heat of the object to be frozen (the amount of heat necessary to raise the unit mass of the substance to the unit temperature). .
A frozen tuna mass at −40 ° C. will be specifically described as an example.
The amount of heat when 200 g of water is raised by 40 ° C. is 200 g × 40 ° C. = 8 kcal, and converted to SI units, from 1 kcal = 1.16 Wh to 8 kcal × 1.16 = 9.3 Wh.

Since the specific heat ratio (C ₂ / C ₁ ) between water and frozen tuna is 0.410, the amount of heat when 200 g of frozen tuna is raised by 40 ° C. is 9.3 Wh × 0.410 = 3.81 Wh. Therefore, when a heat amount of 3.81 Wh is added to -40 ° C. salmon tuna, the temperature becomes 0 ° C. To thaw in 10 minutes, 3.81 W × 60 minutes / 10 minutes = 22.9 W may be added for 10 minutes.

  As described above, Joule heat is generated inside the object to be thawed to relax the musculature, and by applying vibration from the outside, it can be thawed without drip in a short time without destroying the cell membrane. The end of can be predicted by the resistance value of the fish species of the thawing object and the internal temperature based on the above formula.

  An object to be thawed is placed on a metal thawing plate to which conductive silicon rubber is applied, and thawed under a temperature condition that is equal to or lower than the body temperature at the time of survival of the thawing target object and the appropriate temperature for habitat. In normal thawing, the freezing temperature difference between the fleshy part and the water, the cell membrane at the interface between the frozen part and the thawed part is destroyed due to the contraction difference, and the moisture (drip) containing the sweetening component flows out. In the device, as a means to prevent cell membrane destruction, the difference in shrinkage at the interface between the frozen part and the thawed part can be mitigated by vibrating the thaw plate from outside the frozen material. Moreover, the fleshy part and the freezing point of water can be quickly passed by Joule heat, and cell membrane destruction can be effectively suppressed to prevent the drip from flowing out, and at the same time, it can be thawed in a short time. At this time, if the frequency is small, the cell membrane is destroyed by the impact and the opposite effect is obtained.

  Induction of molecular vibrations inside the frozen material by energization reduces the difference in shrinkage between thawing and non-thawing, and the cell membrane is destroyed by quickly passing through the flesh and freezing points of moisture by the induced Joule heat. At the same time prevent and reduce the thawing time.

  The object of the thawing method of the present invention is frozen fish meat, and is not limited, but as a specific example, frozen meat storage selected from beef, pork, lamb, chicken, and whale meat, and tuna, Frozen fresh fish such as bonito, horse mackerel, mackerel, squid and scallops. In particular, the method (apparatus) of the present invention is effective for thawing frozen fresh fish such as tuna and bonito, whose quality is significantly deteriorated due to leakage of moisture (drip) containing a sweetening component during thawing.

  Furthermore, when the apparatus of the present invention was used to test the combination of vibration and energization that is the same as the thawing conditions for frozen fish meat with respect to physiological saline containing Escherichia coli, it was confirmed that Escherichia coli was killed (see test examples described later). . Therefore, according to the method for thawing frozen fish shellfish using the thawing device of the present invention, even if microorganisms are present in the frozen fish shellfish, the microorganisms can be sterilized at the time of thawing.

  The present invention will be described with reference to examples, comparative examples, and test examples, but the present invention is not limited to the following examples.

Example The primary side of a variable frequency power supply is connected to a thawing plate with conductive silicone rubber on an external vibration imparting machine, and a bonito fillet with a thermometer inserted in the center of a freezer (minus 20 ° C) with a mass of 500 g. Then, the secondary side of the frequency variable power source was connected to the electrode with conductive silicone rubber attached, and it was installed so as to sandwich the salmon fillet.
Operate the external electromagnetic vibration applicator, apply fine vibration 50 Hz (3000 times per minute, amplitude 1 mm or less), and start energization with the Joule heater. The frequency of the Joule heater was set to 1000 Hz because it was fixed and the resistance value was high and the energization efficiency was low. With this setting, the energization efficiency was improved, and the center temperature tended to rise all at once, coupled with the generation of Joule heat. When the center temperature showed minus 10 ° C. (after about 3 minutes), the frequency was set to 50 Hz in synchronization with the external vibration applying machine. The conversion point of minus 10 ° C. has a significant difference in shrinkage between thawing and non-thawing in a temperature range higher than that. This is based on the experience of repeated experiments. The thawing was completed when the central thermometer showed 0 ° C. Table 1 shows electrical changes (voltage, current, and power) and center temperature data (average value) performed five times. The room temperature was 20 ° C., the thawing time was 18 minutes, and the amount of drip water was 1 ml. FIG. 2 (A) and FIG. 3 (A) show micrographs (2000 magnifications) and drip amounts of the thawed bonito fish meat part and blood part, respectively.

Comparative Example A sample (500 g) equivalent to the bonito fillet sample of the example was placed on a plastic dish and thawed normally (room temperature 20 ° C.) and measured for thawing time and drip water. The amount of drip water was 5.5 ml for 35 minutes. The microphotograph (2000 times) and the amount of drip of the thawed fish meat part and blood part are shown in FIG. 2 (B) and FIG. 3 (B), respectively.

  In FIG. 2 (A), the bonito cells maintain a clear shape, whereas in FIG. 2 (B), it can be observed that the shape of the cells collapses and there are many gaps. As can be seen from a comparison of these micrographs, the thawing method of the present invention did not destroy the cell membrane, and the amount of drip flowing out was small. Also in the taste test by panelists of multiple persons, good answers with sweetness and texture were overwhelmingly obtained by the thawing of the examples.

Test example: Bactericidal test of Escherichia coli The salinity (approximately 0.9%) of teleosts and human body fluids is equivalent. Therefore, the following experiment was performed on physiological saline containing E. coli.
40 ml of a suspension of 5% Escherichia coli culture solution in physiological saline was prepared in a vial and used as a sample solution. The physical factors at the time of thawing were modeled, and in the vial, energization was performed at 7.5 V and 15 V for 15 minutes under a combination of conditions of “no vibration” and “with vibration”. After energization, 100 μl of the sample solution was taken and spread on a tryptic soy agar flat medium. After culturing at 37 ° C. for 24 hours, the number of colonies was observed.
As a control, 100 μl of the sample solution was taken and spread on a tryptic soy agar flat medium and cultured at 37 ° C. for 24 hours before energization.

The test was conducted four times under the following conditions.
Experiment 1: 7.5V, no vibration, sample solution temperature change in 15 minutes is 25-27 ° C;
Experiment 2: 7.5V, with vibration, sample solution temperature change in 15 minutes is 25-27 ° C;
Experiment 3: 15V, no vibration, sample solution temperature change in 15 minutes is 25-38 ° C;
Experiment 4: 15 V, with vibration, change in sample solution temperature in 15 minutes is 25-38 ° C.
In all of Experiments 1 to 4, colony formation was not observed. Furthermore, although culture was performed for up to 48 hours, no colony formation was observed.
FIG. 4 shows a photograph of the tryptic soy agar flat medium of Experiment 1 and Experiment 2, and FIG. 5 shows a photograph of the tryptic soy agar flat medium of Experiment 3 and Experiment 4.

Experiment 5: An experiment was performed using 40 ml of E. coli culture solution (stock solution) under the same conditions as Experiment 2 (7.5 V, with vibration, 15 minutes), but no colony formation was observed. Furthermore, although culture was performed for up to 48 hours, no colony formation was observed. FIG. 6 shows a photograph of the Tryptosoy agar flat medium in Experiment 5.
From the above experiments, it can be expected that even if microorganisms are present in the frozen fish, an effect of sterilizing the microorganisms in the process of thawing by the apparatus of the present invention can be expected.

DESCRIPTION OF SYMBOLS 1 External vibration imparting machine 2 Electromagnetic vibration generating part 3 Joule heater 4 Metal thaw plate (lower metal electrode)
5a, 5b Conductive silicone rubber 6 Thaw object (frozen fish chunk)
7 Power supply (AC voltage generator)
8a, 8b Counter electrode 9 Metal electrode plate 10 Control panel 11 Vibrator drive power supply 12 Electromagnetic vibrator 13 Vibration transmitting component (insulating)
14 Upper electrode fixing arm 15 Spring for irregular shaped contact

Claims (10)

  An energizing power source and a metal electrode for generating a Joule heat by placing a frozen fish meat mass to be thawed on the metal thawing plate of an external vibration imparting machine comprising an electromagnetic vibration generator and a metal thawing plate A frozen fish shell, characterized in that the metal electrode of the Joule heating machine is mounted on the top of the frozen fish meat mass, vibrates from the outside of the frozen fish meat mass, and at the same time energizes the frozen fish meat mass to Joule heat How to thaw meat.   The method for thawing frozen fish and shellfish according to claim 1, wherein the vibration applied by the external vibration applying machine is a slight vibration of 10 Hz to 10 kHz and an amplitude of 1 mm or less.   The method for thawing frozen fish and shellfish according to claim 1 or 2, wherein an AC voltage having a frequency synchronized with vibration applied by an external vibration applying machine is applied to perform Joule heating.   The thawing method according to any one of claims 1 to 3, wherein the frozen fish meat is frozen meat stock or frozen fresh fish shellfish.   The thawing method according to claim 4, wherein the livestock meat is selected from beef, pork, lamb, chicken and whale meat.   The thawing method according to claim 4, wherein the fresh fish is selected from tuna, skipjack, horse mackerel, mackerel, squid, and scallops.   An external vibration imparting machine and a Joule heater, the external vibration imparting machine comprising an electromagnetic vibration generator and a metal thawing plate, and a power supply for energization and frozen fish meat for the Joule heater to generate Joule heat An apparatus for thawing frozen fish and shellfish, characterized by comprising a metal electrode placed on top of the lump.   The thawing device according to claim 7, wherein the metal thawing plate is provided with conductive silicon rubber laid or pasted.   The thawing device according to claim 7, wherein conductive silicon rubber is attached to or pasted on the metal electrode.   The thawing device according to any one of claims 7 to 9, wherein the thawing plate and the electrode are electric conductors.