阅读说明：本技术 船载高活化水处理海产品冻结与冰晶无损感知方法及装置 (Freezing and ice crystal nondestructive sensing method and device for ship-borne high-activation water treatment marine products ) 是由 丁玉庭 周绪霞 柯志刚 刘书来 吕飞 *** 朱士臣 于 2019-08-28 设计创作，主要内容包括：本发明涉及一种船载高活化水处理的海产品冻结与冰晶无损感知方法及装置。本发明通过对海水进行一定气氛下的等离子体处理及等离子体尾气处理以制备高活化水。制备的高活化水杀菌能力强,且不含有亚硝酸根,经船载制冷系统预冷后用于海产品及时的冷却和减菌处理,有效延长了海产品的保鲜期。对冷却后海产品进行的超高频电磁场辅助冻结及冰晶的脉冲超声监测,显著减小了冰晶尺寸,降低了汁液流失,还有效控制了电磁场热效应,提高了冻品品质。本发明实现了“高活化水的冷却减菌-超高频电磁场辅助冻结-冰晶的超声无损感知”的船载高效协同应用,有效提高了海产品的保鲜期和品质,且该方法对设备要求低,绿色环保,具有极大的应用前景。(The invention relates to a marine product freezing and ice crystal nondestructive sensing method and device for shipborne high-activation water treatment. The invention prepares high-activation water by carrying out plasma treatment and plasma tail gas treatment on seawater under a certain atmosphere. The prepared high-activity water has strong sterilization capability, does not contain nitrite, is used for timely cooling and sterilizing marine products after being precooled by a shipborne refrigeration system, and effectively prolongs the fresh-keeping period of the marine products. The ultra-high frequency electromagnetic field assisted freezing and the pulsed ultrasonic monitoring of the ice crystals are carried out on the cooled marine products, so that the size of the ice crystals is obviously reduced, the juice loss is reduced, the thermal effect of the electromagnetic field is effectively controlled, and the quality of the frozen products is improved. The method realizes the shipborne efficient synergistic application of 'cooling and sterilization of high activated water, auxiliary freezing of an ultrahigh frequency electromagnetic field and ultrasonic nondestructive sensing of ice crystals', effectively improves the preservation period and quality of marine products, has low requirement on equipment, is green and environment-friendly, and has great application prospect.)

1. A method for on-board high activation water-treated seafood freezing and ice crystal nondestructive perception, the method comprising:

(1) carrying out plasma treatment on seawater to obtain plasma high-activation water;

(2) leading tail gas generated by plasma treatment into seawater of a tail gas collecting device to obtain high-activation water;

(3) pre-cooling the high-activation water obtained in the step (1) and the step (2) to-3-0 ℃ by using a heat exchange plate;

(4) cooling the marine products twice by using the precooled high-activation water, and achieving the effect of bacteria reduction; the cooling treatment comprises the following steps: spraying the high-activation water precooled in the step (3) to marine products by using a spraying device, and reducing the surface temperature of the marine products to 0-4 ℃ for 5-10 min each time;

(5) freezing the cooled marine products by a freezing device, and carrying out ultrasonic intelligent monitoring on the freezing process;

(6) starting ultrahigh frequency electromagnetic field treatment on the frozen marine product when the ultrasonic monitoring system shows that the ice crystal starts to form, performing electromagnetic field assisted freezing, and stopping the electromagnetic field treatment when the ultrasonic monitoring system shows that the crystallization is finished; the ultrahigh frequency electromagnetic field is a variable frequency electromagnetic field with the frequency of 0.9GHz-4 GHz;

(7) continuously freezing the frozen marine products under the action of the electromagnetic field-free action by the aid of the ultrahigh frequency electromagnetic field until the freezing storage temperature is minus 30 ℃ to minus 18 ℃;

(8) continuously freezing and storing at-30 to-18 ℃.

2. The method according to claim 1, wherein the plasma in the step (1) is generated by corona discharge formed between an electrode above the liquid surface and the liquid surface, the electrode is connected with a plasma generating power supply, the distance between the electrode and the liquid surface is about 10-20 mm, the output voltage of the power supply is 20-80 kV, and the plasma treatment time is 20-60 min.

3. The method according to claim 1, wherein the ice crystal content formed in step (6) is detected by an ultrasonic monitoring system as follows:

the salt content in the marine product is small, the ice crystal content of the marine product is calculated by utilizing the transmission speed of ultrasonic waves in a low-concentration sodium chloride solution model according to the following calculation process:

① the overall temperature T of the frozen seafood is determined by the following equations (1) and (2):

T₀v is the ultrasonic transfer speed;

② the activity alpha of water in frozen seafood is determined by the following equation (3)_w：

③ the mole percent χ of water in frozen seafood is determined by the following formula (4)_ufw:

Water Activity a obtained by equation (3)_wCan be approximately equal to the mole percent of moisture χ_ufwM is shown in formula (4)_dmMeans the content of dry heavy substances, M_wAnd M_dmMolecular weights of water and dry matter, respectively, at an initial freezing point T₀Unfrozen water content (m) at temperature_ufw) Equal to the total free water content (m)_fw) From this, M can be derived_dm；

④ the ice crystal content (m) of frozen seafood was determined by the following method (5)_ice)：

⑤ the average size of ice crystals formed when the ultra-high frequency electromagnetic field assists freezing at a certain temperature can be obtained from the formula (6) based on the average temperature T obtained from the formulas (1) and (2):

r_finrefers to the final radius of the ice crystals.

4. The method of claim 1, wherein the electromagnetic field assisted freezing of step (6) is: the electromagnetic field adopts intermittent treatment, and the actual working time is 50-60% of the period of the electromagnetic field in one electromagnetic field period; the processing strength is 100-500W/kg marine product.

5. The method according to claim 1, wherein the plasma treatment process gas is oxygen gas, the oxygen gas is introduced into the plasma treatment apparatus at a flow rate of 5L/min to 10L/min 5 minutes before the plasma treatment, and the gas flow rate is controlled by a gas regulating valve.

6. The method of claim 1, wherein the seawater is seawater having a salt concentration of 1.5% to 10%.

7. A marine product freezing and ice crystal nondestructive sensing device for shipborne high-activation water treatment is characterized by comprising a plasma treatment device, a tail gas collecting device, an activation water precooling device, a cooling treatment device and a freezing treatment device;

the plasma processing device consists of a plasma generating power supply, a plasma generating electrode, a plasma generating container and a gas chamber; the plasma generating container is provided with a seawater inlet, an activated water outlet, a gas inlet and a gas outlet, wherein the gas inlet is connected with the gas chamber, and the gas outlet is connected with the tail gas collecting device;

the tail gas collecting device is a closed container and is provided with a seawater inlet, an activated water outlet, a gas inlet and a gas outlet;

the activated water precooling device is a heat exchange plate and is connected with an activated water outlet of the plasma treatment device and an activated water outlet of the tail gas collecting device through a water pump;

the cooling treatment device mainly comprises a marine product conveyor belt and a spraying device positioned above the conveyor belt, and the spraying device is connected with an activated water precooling device through a water pump;

the freezing treatment device mainly comprises an ultrahigh frequency electromagnetic field treatment cavity, a vertical freezing plate arranged in the ultrahigh frequency electromagnetic field treatment cavity, an ultrahigh frequency electromagnetic field generation device and a pulse ultrasonic monitoring device; two vertical surfaces and the bottom surface in the ultrahigh frequency electromagnetic field generating cavity, which are vertical to the freezing plate, are provided with ultrahigh frequency electromagnetic field generating devices; the ultrahigh frequency electromagnetic field generating device adopts a variable frequency electromagnetic field generating system, and the output frequency of the variable frequency electromagnetic field generating system is 0.9GHz-4 GHz.

8. The device according to claim 7, wherein the pulsed ultrasound monitoring device comprises a multi-frequency pulsed ultrasound generating receiver, piezoelectric plates, an oscilloscope and a computer, the output frequency of the multi-frequency pulsed ultrasound generating receiver is 30-100 MHz, the two piezoelectric plates are parallelly arranged at the middle positions of the inner sides of two adjacent vertical freezing plates, one of the piezoelectric plates is connected with the multi-frequency pulsed ultrasound generating receiver to serve as an ultrasound generating electrode, the other piezoelectric plate is connected with the oscilloscope to serve as an ultrasound receiving electrode, the oscilloscope is connected with the pulsed ultrasound generating receiver, and the oscilloscope is connected with the computer to serve as a data collecting system.

9. The apparatus of claim 7, wherein said variable frequency electromagnetic field generating system is comprised of a transformer, a magnetron, a variable frequency plate, a waveguide, and a power conditioner.

10. The apparatus of claim 7, wherein the heat exchange panel forms a circulation loop with a refrigeration system onboard the ship using liquid ammonia, freon, carbon dioxide, or a coolant as a refrigerant.

(I) technical field

The invention relates to the field of frozen foods, in particular to a marine product freezing and ice crystal nondestructive sensing method and device for shipborne high-activation water treatment.

(II) background of the invention

The marine products in China are abundant in resources, and the marine food raw materials are various and widely distributed. The seafood is rich in protein, vitamins, essential amino acids, EPA, DHA and other nutrient substances necessary for human body, has the characteristics of low fat, high protein, balanced nutrition, delicious taste and the like, and is widely favored by consumers. It has become an important source of animal protein intake and is an essential component of reasonable dietary structure. However, the marine products contain various endogenous enzymes and various microorganisms, so that the marine products have the defects of easily rotten raw materials, short storage period, unstable fishing amount and the like, the captured marine products are easily rotten, the fishery resources are greatly wasted, and the development of marine fishery is severely restricted. Therefore, the captured marine products must take effective fresh-keeping measures in time to avoid the occurrence of reduced freshness and even spoilage.

The prior common aquatic product preservation technology comprises various methods such as low-temperature preservation, modified atmosphere preservation, cold sterilization preservation, chemical preservation, biological preservation and the like, wherein the low-temperature preservation is the most widely applied method. Common low-temperature fresh-keeping methods include cold preservation, ice preservation, micro-freezing preservation, freezing preservation and the like. The endogenous enzymes and microorganisms of the marine products can be inhibited to a certain degree by refrigeration, ice preservation, micro-freezing preservation and the like, but the endogenous enzymes and the microorganisms are not completely stopped, so that the marine products can be stored only for a short time. Freezing preservation is an effective and widely used method for storing marine products for a long time, which is to reduce the temperature of the marine products to-18 ℃ or below, freeze more than 90% of water in the marine products into ice crystals, and store the ice crystals at the low temperature of-18 ℃ or below. When the fish body is in a frozen state, the water activity of the fish body is reduced, bacteria cannot utilize surrounding food and cannot discharge metabolites, and the growth and the propagation of the fish body are inhibited. Freezing also effectively inhibits enzymatic activity, slowing non-enzymatic changes.

Although preservation by freezing is effective in preventing spoilage of seafood and preserving freshness and nutritional value of food, conventional freezing methods also have the following disadvantages:

(1) freezing can effectively inhibit the activity of microorganisms, but if the frozen marine products are fluctuated in temperature or thawed, the activity of the microorganisms is recovered, so that the spoilage of the marine products can be caused;

(2) the ice crystals formed by the traditional freezing method have large size and uneven distribution, and damage cell membranes and tissue structures to a certain extent, so that the loss of juice after thawing is increased, and the food quality is reduced.

Therefore, the development of the novel low-temperature preservation method is of great significance to meet the requirements of people on high-quality marine products and the development of marine fishery, and particularly, the novel shipborne low-temperature preservation technology is more important. The Chinese patent CN107334031A adopts the plasma activated ice to keep aquatic products fresh, so that the aquatic products can be refrigerated and kept fresh, microorganisms on the surfaces of the aquatic products can be effectively killed, the spoilage is reduced to a great extent, and the shelf life of the aquatic products under the refrigeration condition is remarkably prolonged. However, the liquid used in the method is fresh water such as tap water, purified water, ultrapure water, deionized distilled water and the like, and is difficult to be used on a large scale on a marine fishing boat. In addition, the method has the defects of weak sterilization capability of activated water or nitrite content according to different plasma working gases. Chinese patent CN103168826A discloses a method for simultaneously performing ultrasonic treatment with different powers on dipped and frozen fillets. The method effectively reduces the freezing time of the fish, ensures that the formed ice crystals are fine and uniformly distributed, reduces the damage of the ice crystals to cells, and reduces the freezing denaturation and the nutrition loss of the fish, but the freezing quantity is small, and the ultrasonic wave needs liquid as a transmission medium, so the method is not suitable for large-scale plate freezing on a ship. Chinese patent CN104544475A discloses a microwave-assisted method for freezing dough sheets. The method reduces ice crystal size of dough skin, juice loss rate, nutrition loss and taste damage. However, the used microwave frequency is 2.45GHz, the microwave action distance is limited, the microwave freezing device is difficult to be applied to shipborne large-scale freezing, the real-time intelligent monitoring of the freezing process cannot be realized, and the negative influence of the microwave thermal effect on the freezing process is difficult to avoid.

Therefore, although the method effectively prolongs the fresh-keeping period of the food, or reduces the size of ice crystals formed by the frozen food and improves the quality of the frozen food, the method is difficult to be applied to the timely and large-scale fresh-keeping preservation of the marine products carried on the ship. Particularly, the method has important significance for developing a novel low-temperature preservation method for marine products on board, aiming at the characteristics that the freezing condition on the ship is limited when fishing in open sea, the captured marine products are difficult to be sent to land in time for freezing treatment, the capturing amount is large in short time and the like.

Disclosure of the invention

In order to overcome the defects and shortcomings of the prior art, the invention provides a method for sensing freezing and ice crystal nondestructive of marine products treated by shipborne high-activation water.

The technical scheme adopted by the invention is as follows:

a method for on-board high activation water-treated seafood freezing and ice crystal nondestructive perception, the method comprising:

(1) carrying out plasma treatment on seawater to obtain plasma high-activation water;

(2) leading tail gas generated by plasma treatment into seawater of a tail gas collecting device to obtain high-activation water;

(3) pre-cooling the high-activation water obtained in the step (1) and the step (2) to-3-0 ℃ by using a heat exchange plate;

(4) cooling the marine products twice by using the precooled high-activation water, and achieving the effect of bacteria reduction; the cooling treatment comprises the following steps: spraying the activated water precooled in the step (3) to marine products by using a spraying device, reducing the surface temperature of the marine products to 0-4 ℃, and cooling for 5-10 min each time;

(5) freezing the cooled marine products by a freezing device, and carrying out ultrasonic intelligent monitoring on the freezing process;

(6) starting ultrahigh frequency electromagnetic field treatment on the frozen marine product when the ultrasonic monitoring system shows that the ice crystal starts to form, performing electromagnetic field assisted freezing, and stopping the electromagnetic field treatment when the ultrasonic monitoring system shows that the crystallization is finished; the ultrahigh frequency electromagnetic field is a variable frequency electromagnetic field with the frequency of 0.9GHz-4 GHz;

(7) continuously freezing the frozen marine products under the action of the electromagnetic field-free action by the aid of the ultrahigh frequency electromagnetic field until the freezing storage temperature is minus 30 ℃ to minus 18 ℃;

(8) continuously freezing and storing at-30 to-18 ℃.

The method prepares the high-activation water by carrying out plasma treatment and plasma tail gas treatment on the seawater under a certain atmosphere, and the prepared high-activation water has strong sterilization capability and does not contain nitrite. The prepared high-activation water is pre-cooled by utilizing a shipborne refrigeration system, and the pre-cooled high-activation water can realize timely shipborne cooling and bacteria reduction treatment on fresh marine products, so that the freshness date of the marine products is effectively prolonged. After cooling, the fish body is immediately frozen. The ice coat formed by freezing the high-activation water attached to the surface of the fish body can also effectively prevent the fish body from being infected by various microorganisms in the later period. The variable frequency electromagnetic field is adopted for cooperative treatment in the freezing process, so that the size of ice crystals generated in the freezing process is effectively reduced, the juice loss of frozen products in the unfreezing process is reduced, the quality of the frozen products is remarkably improved, the action range of the electromagnetic field is remarkably enlarged by the adopted variable frequency system, and the problem of uneven action of the electromagnetic field is solved. The freezing process also starts a pulse ultrasonic monitoring system to carry out online, continuous and nondestructive detection on the content and size of ice crystals formed in the fish body, the acting time of an electromagnetic field can be accurately regulated and controlled on the basis, ultrahigh frequency electromagnetic field cooperative treatment is selectively carried out on crystal nucleus formation and phase change stages in the freezing process, and the negative influence of the thermal effect of the electromagnetic field on the freezing process is effectively controlled. Compared with the traditional shipborne marine product preservation method, the method realizes the shipborne efficient synergistic application of 'cooling and sterilization of high activated water, auxiliary freezing of an ultrahigh frequency electromagnetic field and ultrasonic nondestructive sensing of ice crystals', effectively improves the quality guarantee period and quality of marine products, has low requirement on equipment, is green and environment-friendly, and has great application prospect.

Specifically, in the step (1), the plasma is generated by corona discharge formed between an electrode above the liquid level and the liquid level, the electrode is connected with a plasma generation power supply, the distance between the electrode and the liquid level is about 10-20 mm, the output voltage of the power supply is 20-80 kV, and the plasma treatment time is 20-60 min.

The method for detecting the content of the formed ice crystals by the ultrasonic monitoring system in the step (6) comprises the following steps:

the salt content in the marine product is small, the ice crystal content of the marine product is calculated by utilizing the transmission speed of ultrasonic waves in a low-concentration sodium chloride solution model according to the following calculation process:

① the overall temperature T of the frozen seafood is determined by the following equations (1) and (2):

T₀v is the ultrasonic transfer speed (m/s);

② the activity alpha of water in frozen seafood is determined by the following equation (3)_w：

Freezing point T for atmospheric pressure₀Temperature tolerance of water to ice;

③ the mole percent χ of water in frozen seafood is determined by the following formula (4)_ufw:

Water Activity a obtained by equation (3)_wCan be approximately equal to the mole percent of moisture χ_ufwM is shown in formula (4)_dmMeans the content of dry heavy substances, M_wAnd M_dmMolecular weights of water and dry matter, respectively, at an initial freezing point T₀Unfrozen water content (m) at temperature_ufw) Equal to the total free water content (m)_fw) From this, M can be derived_dm；

④ the ice crystal content (m) of frozen seafood was determined by the following method (5)_ice)：

⑤ the average size of ice crystals formed when the ultra-high frequency electromagnetic field assists freezing at a certain temperature can be obtained from the formula (6) based on the average temperature T obtained from the formulas (1) and (2):

r_finrefers to the final radius of the ice crystals.

The electromagnetic field assisted freezing in the step (6) is as follows: the electromagnetic field adopts intermittent treatment, and the actual working time is 50-60% of the period of the electromagnetic field in one electromagnetic field period; the processing strength is 100-500W/kg marine product.

The plasma treatment working gas is oxygen, the oxygen is introduced into the plasma treatment device at the flow rate of 5L/min-10L/min 5 minutes before the plasma treatment, and the gas flow rate is controlled by a gas regulating valve.

The seawater with the salt concentration of 1.5-10% (w/w) is pumped into the plasma treatment container and the tail gas collection device by a water pump respectively.

The invention also relates to a marine product freezing and ice crystal nondestructive sensing device for shipborne high-activation water treatment, which is characterized by comprising a plasma treatment device, a tail gas collecting device, an activation water precooling device, a cooling treatment device and a freezing treatment device;

the plasma processing device consists of a plasma generating power supply, a plasma generating electrode, a plasma generating container and a gas chamber; the plasma generating container is a closed container and is provided with a seawater inlet, an activated water outlet, a gas inlet and a gas outlet, wherein seawater is filled in the plasma generating container as plasma treatment liquid, the gas inlet is connected with a gas chamber, and the gas outlet is connected with a tail gas collecting device; the plasma generating power supply is a high-voltage power supply, and the output voltage is 20-80 kV; the plasma generating electrode is a metal bar, is arranged above the liquid level and has a distance of 10-20 mm with the liquid level; the electrode is connected with the plasma power supply through a lead; the gas chamber is an oxygen storage bottle, oxygen in the gas chamber is introduced into the plasma generating container to exhaust air in the plasma generating container 5 minutes before plasma treatment, and the flow rate of the oxygen is 5-10L/min;

the tail gas collecting device is a closed container and is provided with a seawater inlet, an activated water outlet, a gas inlet and a gas outlet;

the activated water precooling device is a heat exchange plate and is connected with an activated water outlet of the plasma treatment device and an activated water outlet of the tail gas collecting device through a water pump;

the cooling treatment device mainly comprises a marine product conveyor belt and a spraying device positioned above the conveyor belt, and the spraying device is connected with an activated water precooling device through a water pump;

the freezing treatment device mainly comprises an ultrahigh frequency electromagnetic field treatment cavity, a vertical freezing plate arranged in the ultrahigh frequency electromagnetic field treatment cavity, an ultrahigh frequency electromagnetic field generation device and a pulse ultrasonic monitoring device; two vertical surfaces and the bottom surface in the ultrahigh frequency electromagnetic field generating cavity, which are vertical to the freezing plate, are provided with ultrahigh frequency electromagnetic field generating devices; the ultrahigh frequency electromagnetic field generating device adopts a variable frequency electromagnetic field generating system, and the output frequency of the variable frequency electromagnetic field generating system is 0.9GHz-4 GHz.

The pulse ultrasonic monitoring device comprises a multi-frequency pulse ultrasonic generation receiver, piezoelectric plates, an oscilloscope and a computer, wherein the output frequency of the multi-frequency pulse ultrasonic generation receiver is 30-100 MHz, the two piezoelectric plates are arranged in the middle of the inner sides of two adjacent vertical freezing plates in parallel, one piezoelectric plate is connected with the multi-frequency pulse ultrasonic generation receiver to serve as an ultrasonic generation electrode, the other piezoelectric plate is connected with the oscilloscope to serve as an ultrasonic receiving electrode, the oscilloscope is connected with the pulse ultrasonic generation receiver, and the oscilloscope is connected with the computer to serve as a data collecting system.

The frequency conversion electromagnetic field generating system consists of a transformer, a magnetron, a frequency conversion plate, a waveguide tube and a power regulator.

The heat exchange plate and the shipborne refrigeration system form a circulation loop, and liquid ammonia, Freon, carbon dioxide or secondary refrigerant at the temperature of minus 35 ℃ to minus 25 ℃ or below is used as a refrigerant.

The principle of the invention is as follows: plasma is a fourth state of matter existence, an ionized gas consisting of a large number of electrons and charged ions, which is electrically neutral as a whole. Plasma treatment generates various active substances, such as long-life ozone, hydrogen peroxide, nitrogen oxide, short-life hydroxyl radicals, superoxide anions and other various radicals, ultraviolet rays, charged particles, electrons and other various physical factors. Chlorine ions in the seawater can be oxidized by hydroxyl radicals, ozone and the like generated in the oxygen plasma treatment to generate chlorine-containing active groups with strong sterilization capability, so that the seawater treated by the plasma also has strong sterilization capability and does not contain nitrite. After precooling the seawater activated by the plasma, the seawater can be used for cooling the marine products carried on the ship and can also achieve the aim of bacteria reduction. The ultrahigh frequency electromagnetic field treatment can cause the internal temperature of the frozen food to be in oscillation type reduction in the nucleation and phase transition stages, and the oscillation type change of the temperature can destroy the formed ice crystals, finally reduce the size of the formed ice crystals, reduce the juice loss of the frozen food during the unfreezing and improve the food quality. In addition, the ultrahigh frequency electromagnetic field also has the advantages of strong penetrating power, easy installation and the like, and can realize the application in larger space. Therefore, when the marine products are frozen, the ultrahigh frequency electromagnetic field with certain frequency and strength is applied for processing, so that the ice crystal size of the frozen marine products can be effectively reduced, and the quality of the marine products is improved. Besides the above advantages of the UHF electromagnetic field in the freezing process, the heat effect has certain negative effects on the freezing process, such as prolonging the freezing time. In order to reduce the negative influence of the thermal effect of the electromagnetic field on the freezing process as much as possible, the ultrahigh frequency electromagnetic field auxiliary freezing process needs to be monitored in real time, and the time of the electromagnetic field action needs to be accurately regulated and controlled. Ultrasound is a sound wave with frequency higher than 20000Hz, and has the advantages of good directivity, strong penetration capability, easy acquisition of more concentrated sound energy, and the like. The speed of transmission of ultrasound waves in a substance is highly dependent on the physical state of the substance present. Their propagation velocities in water and ice are significantly different. When ice crystals are not formed, the ultrasound propagation speed is slowed down as the temperature is lowered. After the formation of crystal nucleus, the ultrasonic propagation speed is obviously increased, and along with the increase of ice crystal content, the propagation speed is increased until reaching a plateau stage, at which most of water (more than 90%) in the frozen food is in an ice crystal state. According to the principle, the ice crystal content generated in the freezing process of the marine product can be monitored in real time.

The invention has the following beneficial effects:

1) the invention realizes the shipborne efficient synergistic application of 'cooling and sterilization of high activated water, auxiliary freezing of an ultrahigh frequency electromagnetic field and ultrasonic nondestructive sensing of ice crystals', overcomes the defects of the prior single technology in the preservation and preservation of shipborne marine products, effectively prolongs the quality guarantee period of the marine products and improves the quality of the marine products.

2) The invention adopts seawater as the liquid for plasma activation, realizes the shipborne large-scale preparation of high-activation water, and can be applied to the cooling and bacteria reduction treatment of shipborne marine products in a large scale.

3) The invention adopts corona discharge between the electrode and the liquid level as a plasma generation mode, is more stable compared with other discharge modes, and is easy to install and operate; and the plasma form can generate more chemical active groups, so that the treated liquid has stronger sterilization capability.

4) The method adopts oxygen as the working gas of the plasma, not only realizes the high-efficiency activation of the seawater, but also effectively avoids the defect that nitrite is usually used as a sterilization factor in the prior plasma preparation of the activated liquid, avoids the possible negative effect of the plasma activated liquid on the processed marine products, recycles the tail gas of the plasma, and is high-efficiency and environment-friendly.

5) The invention adopts the mode of ultrahigh frequency electromagnetic field assisted freezing to freeze the marine products, effectively reduces the size of ice crystals formed in the frozen marine products and the loss of juice of the frozen marine products after thawing, and improves the quality of the marine products.

6) The invention adopts a frequency conversion electromagnetic field generating system with the frequency range of 0.9GHz-4GHz, which obviously increases the penetration depth and action uniformity of the electromagnetic field and is suitable for large-volume freezing of marine products; in addition, the heating rate of the 0.9GHz electromagnetic field is slow, which also reduces the negative effect of the thermal effect of the electromagnetic field on the freezing process.

7) The pulse ultrasonic monitoring system adopted by the invention realizes real-time, continuous and nondestructive intelligent monitoring of the content and the size of the ice crystals generated in the freezing process, so that the acting time of an electromagnetic field can be accurately regulated and controlled, and the negative influence of the thermal effect of the electromagnetic field on the freezing process is reduced.

(IV) description of the drawings

FIG. 1 is a schematic diagram of an apparatus for on-board high-activity water-treatment marine product freezing and ice crystal non-destructive sensing method.

Fig. 2 is an expanded view of the uhf electromagnetic field generating cavity.

Fig. 3 is a schematic diagram of the composition of a pulsed ultrasound monitoring system.

(V) detailed description of the preferred embodiments

The invention will be further described with reference to specific examples, but the scope of the invention is not limited thereto:

as shown in fig. 1, the device for ship-borne high-activation water treatment marine product freezing and ice crystal nondestructive sensing of the present embodiment includes a plasma generation power supply 1, an air chamber 2, a plasma generation electrode 7, a plasma generation container 8, a tail gas collection device 18, a heat exchange plate 25, a spraying device 28, a conveyor belt 29, an ultrahigh frequency electromagnetic field generation cavity 30, a pulsed ultrasound monitoring system (31 is a piezoelectric plate of an ultrasound monitoring system), a vertical freezing plate 32, and an ultrahigh frequency electromagnetic field generation system 33;

the plasma generating power supply 1 is a high-voltage power supply, and the output voltage is 20-80 kV;

the gas chamber 2 provides working gas for the plasma, and the gas regulating valve 3 controls the flow rate of the gas entering the plasma generating container;

the plasma generating container 8 is a closed container and is provided with a gas inlet 10, a gas outlet 11, a seawater inlet 6 and an activated water outlet 12 respectively, valves (4, 20) and water pumps (5, 21) are mounted at the seawater inlet and the activated water outlet, a plasma electrode 7 is inserted into the plasma generating container 8 and suspended above the liquid level of the seawater 9, the distance between the top end of the electrode and the liquid level is 10-20 mm, and the other end of the electrode is connected with a plasma generating power supply;

the tail gas collecting device 18 is a closed container and is respectively provided with a gas inlet 16, a gas outlet 17, a seawater inlet 15 and an activated water outlet 24, and valves (13, 22) and water pumps (14, 23) are respectively arranged at the seawater inlet and the activated water outlet;

activated seawater 9 in the plasma generation container 8 and activated seawater 19 in the tail gas collection device 18 are pumped into a heat exchange plate 25 through a water pump, a shipborne refrigeration system is connected with the heat exchange plate 25 to form a circulation loop, refrigerants such as liquid ammonia, Freon, carbon dioxide or refrigerating medium with the temperature of minus 35-minus 25 ℃ and below are pumped into the heat exchange plate 25 through a circulation pump, and high-activation water is pre-cooled to minus 3-0 ℃ through the heat exchange plate;

the spraying device 28 is provided with a water quantity regulator, the water pump 27 is used for pumping the pre-cooled high-activation water into the spraying device and carrying out cooling and bacterium reduction treatment on the marine products twice, the surface temperature of the marine products is reduced to 0-4 ℃, and the cooling time is 5-10 minutes each time;

the freezing plate 32 is connected with a ship-borne refrigerating system to form a circulation loop, and the used refrigerants are liquid ammonia, Freon, carbon dioxide or secondary refrigerants and the like at the temperature of between 35 ℃ below zero and 25 ℃ below zero;

the ultrahigh frequency electromagnetic field generating cavity 30 is a cuboid metal cavity, two vertical surfaces (front and back surfaces) and the bottom surface of the ultrahigh frequency electromagnetic field generating cavity perpendicular to the freezing plate are respectively provided with an ultrahigh frequency electromagnetic field generating system 33, the electromagnetic field generating system consists of a transformer, a magnetron, a waveguide tube, a frequency conversion plate and a power regulator, the output frequency of the electromagnetic field generating system is 0.9GHz-4GHz, and the power during processing is 100-500W/kg of fish materials; and when the pulsed ultrasonic monitoring system shows that ice crystals begin to form in the frozen marine products, starting electromagnetic field treatment. Adopting batch treatment: in an electromagnetic field period, the actual working time is 50% -60% of the period, and when the ultrasonic monitoring system shows that the ice crystal content in the frozen marine products reaches more than 90%, the electromagnetic field treatment is stopped.

As shown in fig. 2, the ultrahigh frequency electromagnetic field generating system is arranged in front of, behind and under the ultrahigh frequency electromagnetic field generating cavity.

As shown in fig. 3, the pulsed ultrasound monitoring system is composed of a pulsed ultrasound generation receiver 35, a piezoelectric plate 31, an oscilloscope 37 and a computer 36, wherein the two piezoelectric plates are installed in parallel at the middle position of the inner sides of two adjacent vertical freezing plates, one of the piezoelectric plates is connected with the pulsed ultrasound generation receiver to serve as an ultrasound generation electrode, the other piezoelectric plate is connected with the oscilloscope to serve as an ultrasound receiving electrode, the oscilloscope is connected with the pulsed ultrasound generation receiver, and the oscilloscope is connected with the computer to serve as a data collection system. The content and the size of the ice crystal can be obtained according to the obtained ultrasonic wave propagation velocity, and the calculation process is as follows: the salt content in the marine product is small, the ice crystal content can be calculated by utilizing the transmission speed of ultrasonic waves in a low-concentration sodium chloride solution model, and the calculation process is as follows:

① the overall temperature T of the frozen seafood is determined by the following equations (1) and (2):

T₀is a freezing point, and v is the ultrasonic transfer speed.

② the activity alpha of water in frozen seafood is determined by the following (3)_w：

Freezing point T for atmospheric pressure₀Temperature tolerance of water to ice;

③ the molar percentage χ of moisture in frozen seafood was determined by the following (3)_ufw:

Water Activity a obtained by equation (3)_wCan be approximately equal to the mole percent of moisture χ_ufwM is shown in formula (4)_dmMeans the content of dry heavy substances, M_wAnd M_dmMolecular weights of water and dry matter, respectively, at an initial freezing point T₀Unfrozen water content (m) at temperature_ufw) Equal to the total free water content (m)_fw) From this, M can be derived_dm；

④ the ice crystal content (m) of frozen seafood was determined by the following method (5)_ice)：

⑤ under the assistance of UHF electromagnetic field to freeze, the UHF electromagnetic field will cause the internal temperature of the frozen food to decrease in an oscillating way in the nucleation and phase transition stages, thus reducing the size of the formed ice crystals, assuming that the generated ice crystals are all spherical and have the same radius, based on the average temperature T obtained by the formulas (1) and (2), the average size of the ice crystals formed under the assistance of the UHF electromagnetic field at a certain temperature can be obtained by the formula (6):

r_finby ice crystalsThe final radius.