A wolfberry compound fresh-keeping device and method

Abstract

This invention discloses a composite freshness-locking device and method for wolfberries. The device includes a sequentially connected grading and conveying module, an ultrasonic cleaning module, and a microwave vacuum freeze dryer. The method involves grading fresh wolfberries by particle size, then using ultrasonic cavitation to target and break down the surface waxy film, generating microscopic water separation channels to reduce mass transfer resistance. The grading berries are then fed into corresponding independent freshness-locking compartments. Microwaves are fed into the compartments under vacuum freezing conditions to provide latent heat of sublimation. Simultaneously, an external vibration mechanism drives the material to tumble at high frequency and amplitude. During drying, the microwave input power and excitation frequency are dynamically adjusted based on real-time monitoring of the surface sublimation temperature to prevent thermal runaway. This invention couples surface micro-cracks with a dynamic spatial heat equalization mechanism, significantly shortening the sublimation drying cycle and effectively avoiding fruit expansion and cracking, as well as sugar melting and adhesion, thus comprehensively ensuring the dehydration efficiency and appearance integrity of the freshness-locked wolfberries.

Description

Technical Field

[0001] This invention relates to the field of wolfberry freshness preservation, specifically to a wolfberry composite freshness preservation device and method. Background Technology

[0002] In recent years, with the increasing demand from consumers for high-quality goji berries, goji berry "freshness-locking" technology has gradually replaced traditional processes and become the mainstream in the industry. Existing goji berry freshness-locking processes typically abandon the traditional alkaline water dehydration method, and instead adopt intelligent variable temperature hot air, vacuum freeze-drying, or multi-energy field coupling composite drying technology, in order to remove moisture while preserving the natural form and heat-sensitive nutrients of goji berries.

[0003] However, fresh goji berries are naturally covered with a dense waxy protective film about 2.8 micrometers thick. Under the premise of green freshness preservation through alkali-free washing, this complete waxy film greatly increases the mass transfer resistance of water from the inside of the fruit to the outside.

[0004] In existing composite methods for preserving freshness (such as microwave combined with hot air, vacuum combined with infrared, etc.), the rate of moisture release from the interior is severely limited due to the lack of effective intervention in the physical structure of this waxy film. When external heat or energy field causes the free water inside the fruit pulp to vaporize rapidly, if the water vapor cannot penetrate the dense waxy layer in time, it will not only significantly prolong the drying cycle and increase the overall energy consumption, but also create a high local vapor pressure inside the fruit.

[0005] This internal and external pressure difference can easily cause the fruit to swell and crack locally, or harden and form a crust due to prolonged heating of the skin (i.e., the "dry outside and wet inside" phenomenon), which ultimately seriously affects the appearance integrity, effective ingredient retention rate, and subsequent rehydration performance of the fresh goji berries. Summary of the Invention

[0006] The purpose of this invention is to provide a compound freshness-locking device and method for wolfberries, in order to solve the problems in existing wolfberry freshness-locking processes, such as the large resistance to outward migration of moisture due to the intact and dense waxy film, the long drying cycle, and the local expansion and rupture or "outer dry and inner wet" problems caused by the pressure difference between the inside and outside during compound drying.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution: A compound freshness-locking device and method for wolfberry includes a graded conveying module, an ultrasonic cleaning module, and a microwave vacuum freeze dryer connected in sequence. The grading and conveying module is configured to sieve the incoming fresh goji berries according to their particle size and output them from the corresponding different discharge ports. The grading and conveying module has at least two discharge ports for different particle size levels. The ultrasonic cleaning module includes a treatment tank for containing a liquid conductive medium, multiple permeable material conveyor belts partially immersed in the liquid conductive medium, and ultrasonic transducers installed in an array on the tank wall. The feed ends of the permeable material conveyor belts correspond to the discharge ports of the graded conveying module. The middle section of the permeable material conveyor belts is immersed in the liquid conductive medium. Ultrasonic transducers are arranged on both sides of each permeable material conveyor belt. The ultrasonic transducers are configured to emit ultrasonic waves into the liquid conductive medium to induce cavitation effect. The microwave vacuum freeze dryer includes several independent freshness-locking compartments. Each freshness-locking compartment is designed to hold goji berry materials of different particle sizes after being processed by an ultrasonic cleaning module. Each freshness-locking compartment is connected to an independent microwave feed inlet, and each freshness-locking compartment is equipped with a vibration mechanism. The vibration mechanism is configured to drive the goji berry particles in the corresponding freshness-locking compartment to generate high-frequency micro-amplitude vibration and physical tumbling between the particles.

[0008] Furthermore, the processing tank is divided into several parallel and independent liquid ultrasonic channels by longitudinal partitions. The number of liquid ultrasonic channels is the same as the number of discharge ports to respectively receive goji berry material flows of different particle sizes. Ultrasonic transducers are installed on both inner walls of each liquid ultrasonic channel, and the operating frequency of the ultrasonic transducers in different liquid ultrasonic channels is differentiated according to the goji berry particle size they receive.

[0009] Furthermore, the treatment tank is equipped with a constant temperature control component to keep the temperature of the liquid conductive medium constant within a preset low-temperature non-thermal damage threshold.

[0010] Furthermore, the vibration mechanism includes a vibration generator installed on the outer wall of the microwave vacuum freeze dryer chamber, and a rigid coupling rod penetrating the outer wall of the chamber. The inner end of the coupling rod is physically engaged with the carrying tray in the freshness-locking compartment, and the outer end of the coupling rod is connected to the power output end of the vibration generator to transmit the excitation force.

[0011] Furthermore, a metal bellows sealing assembly is fitted at the penetration point of the coupling rod through the outer wall of the chamber. One end of the metal bellows sealing assembly is sealed and fixed to the outer wall of the chamber, and the other end is sealed and fixed to the outer peripheral wall of the coupling rod, so as to maintain the vacuum seal state inside the microwave vacuum freeze dryer while allowing the coupling rod to transmit reciprocating vibration displacement along the axial direction.

[0012] Furthermore, each freshness-locking compartment is equipped with an infrared temperature monitoring probe. The infrared temperature monitoring probe is pointed at the material tumbling area in the center of the freshness-locking compartment, which is used to collect the sublimation temperature of the surface of the goji berries under high-frequency vibration in real time without contact.

[0013] A compound method for preserving the freshness of wolfberries, comprising the following steps: S1, the cleaned fresh goji berries are introduced into the grading and conveying module to screen and separate at least two material streams of different particle size levels to form independent conveying batches; S2, the goji berries in the independent batch are sent into the independent liquid ultrasonic channels of the ultrasonic cleaning module. In the liquid transmission medium, the cavitation effect is induced by the ultrasonic waves of different frequencies, which target and destroy the dense wax film on the surface of the goji berries, so as to generate micro water separation channels on the surface of the wax layer by vibration. S3, the goji berries of each grade that have undergone the gap-breaking treatment in S2 are introduced into their respective independent fresh-locking compartments. Microwave feeding is turned on in a vacuum freezing environment. The microwave field provides the latent heat required for the direct sublimation of the ice crystals inside the goji berries. At the same time, the external vibration mechanism is turned on, so that the goji berries in different independent fresh-locking compartments undergo high-frequency micro-amplitude bouncing and physical tumbling in the carrying tray. This eliminates the local hot spots caused by the microwave standing wave field and drives the water inside the goji berries to be discharged through the micro water separation channels. S4. During the sublimation drying process in step S3, the surface sublimation temperature of the material tumbling zone in each freshness-locking compartment is monitored in real time without contact. When the local sublimation temperature in a certain freshness-locking compartment approaches the preset freezing point danger threshold, thermal runaway prevention intervention is triggered: the microwave input power corresponding to that freshness-locking compartment is immediately reduced to reduce the latent heat supply, and the excitation frequency of the corresponding vibration mechanism is simultaneously increased to accelerate the spatial tumbling and homogenization of the material in that layer until the sublimation temperature of the material in that layer drops back to a safe temperature below the lower limit of the freezing point danger threshold, and the original drying parameters are restored.

[0014] Furthermore, in step S2, the configuration logic for the differentiated frequency ultrasound is as follows: For large-particle-size goji berry material flow, low-frequency ultrasound is used to generate large-size cavitation bubbles, and the strong micro-jet generated when the bubbles burst breaks through the thick wax film. For small-particle-size goji berry material flow, high-frequency ultrasound is used to generate high-density small-sized cavitation bubbles, which peel off the surface wax layer without breaking the small-particle pulp by ultrasonic mechanical force.

[0015] Furthermore, in step S4, the freezing point danger threshold is set between -5℃ and -2℃. The specific way to reduce the microwave input power is to reduce the microwave output duty cycle, forcing the wolfberry ice crystals that are approaching the freezing point danger threshold to use their latent heat of sublimation for physical cooling during the pulse interval.

[0016] Furthermore, in step S3, the microwave input parameters in each independent freshness-locking compartment are initially matched differently based on the particle size of the goji berries it carries: For the freshness-locking compartments that hold large-particle-size goji berries, a higher initial microwave output power or a longer pulse microwave duty cycle is configured to match the large moisture content and latent heat of sublimation of large-particle-size materials. For the freshness-locking compartments that hold small-particle-size goji berries, a lower initial microwave output power or a shorter pulse microwave duty cycle is configured to limit the sublimation heat equivalent of a single input.

[0017] The beneficial effects of this invention are: This invention induces cavitation in a liquid medium through an ultrasonic cleaning module at the front end, targeting and breaking down the dense waxy film on the surface of goji berries and creating microscopic water separation channels through vibration. This significantly reduces the mass transfer resistance of internal moisture migration from the outside, from a physical structure perspective. Combined with a graded conveying module, materials of different particle sizes are introduced into independent fresh-locking compartments. During the microwave vacuum freeze-drying stage, a vibration mechanism drives the particles to physically tumble, eliminating local hot spots caused by the microwave standing wave field. Temperature monitoring is combined to dynamically intervene in microwave power and excitation frequency. This scheme couples the microscopic surface cavitation with a dynamic spatial heat equalization mechanism. It not only significantly improves the dissipation rate of sublimated water and greatly shortens the overall drying cycle due to the unobstructed water separation channels, but also effectively avoids fruit swelling and cracking or sugar melting and adhesion caused by local energy accumulation, ensuring the dehydration efficiency and appearance integrity of the entire batch of fresh-locking goji berries. Attached Figure Description

[0018] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0019] Figure 1 This is a schematic diagram showing the connection relationship between the graded conveying module and the ultrasonic cleaning module in an embodiment of the present invention; Figure 2 This is a schematic cross-sectional view of the ultrasonic cleaning module according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the planar structure of a microwave vacuum freeze dryer according to an embodiment of the present invention; The labels in the diagram represent the following: 1-Grading conveying module; 1a-Discharge port; 2-Ultrasonic cleaning module; 2a-Processing tank; 2a1-Longitudinal partition; 2a2-Liquid conductive medium; 2b-Water-permeable material conveyor belt; 2c-Ultrasonic transducer; 3-Microwave vacuum freeze dryer; 3a-Freshness-locking compartment; 3a1-Carrying tray; 3a2-Microwave feed inlet; 3a3-Vibration generator; 3a4-Coupled rod; 3a5-Metal bellows sealing assembly. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] This embodiment provides a compound freshness-locking device and method for wolfberries, aiming to solve the problems in existing wolfberry freshness-locking processes, such as the large resistance to outward migration of moisture due to the intact and dense waxy film, the long drying cycle, and the local expansion and rupture or "outer dry and inner wet" problems caused by the internal and external pressure difference during compound drying.

[0022] Specifically, refer to Figures 1 to 3 As shown, this wolfberry compound freshness-locking device includes a graded conveying module 1, an ultrasonic cleaning module 2, and a microwave vacuum freeze dryer 3, which are connected in sequence.

[0023] The grading and conveying module 1 is configured to screen the incoming fresh goji berries according to their particle size and output them from the corresponding different discharge ports 1a. The grading and conveying module 1 has at least two discharge ports 1a for different particle size levels.

[0024] The ultrasonic cleaning module 2 includes a treatment tank 2a for containing a liquid conductive medium 2a2, multiple permeable material conveyor belts 2b partially immersed in the liquid conductive medium 2a2, and ultrasonic transducers 2c installed in an array on the tank wall of the treatment tank 2a. The feed end of each permeable material conveyor belt 2b corresponds to the discharge port 1a of the graded conveying module 1. The middle section of the permeable material conveyor belt 2b is immersed in the liquid conductive medium 2a2. Ultrasonic transducers 2c are arranged on both sides of each permeable material conveyor belt 2b. The ultrasonic transducers 2c are configured to emit ultrasonic waves into the liquid conductive medium 2a2 to induce cavitation effect.

[0025] The microwave vacuum freeze dryer 3 includes several independent fresh-locking compartments 3a. Each fresh-locking compartment 3a corresponds to carrying goji berry materials of different particle sizes after being processed by the ultrasonic cleaning module 2. Each fresh-locking compartment 3a is connected to an independent microwave feed inlet 3a2, and each fresh-locking compartment 3a is equipped with a vibration mechanism. The vibration mechanism is configured to drive the goji berry particles in the corresponding fresh-locking compartment 3a to generate high-frequency micro-amplitude vibration and physical tumbling between particles.

[0026] In actual production, if fresh goji berries of all sizes are mixed together for ultrasonic treatment, using a single frequency of ultrasound cannot accommodate the differences in peel thickness. Too low a frequency will cause the small-diameter pulp to be crushed, while too high a frequency will not be able to effectively penetrate the thick waxy layer on the surface of the large-diameter berries.

[0027] To solve this problem, the processing tank 2a is divided into several parallel and independent liquid ultrasonic channels by longitudinal partitions 2a1. The number of liquid ultrasonic channels is the same as the number of discharge ports 1a, so as to respectively receive goji berry material flows of different particle sizes. Ultrasonic transducers 2c are installed on both sides of the inner wall of each liquid ultrasonic channel, and the working frequency of the ultrasonic transducers 2c in different liquid ultrasonic channels is differentiated according to the goji berry particle size they receive.

[0028] The specific differentiated configuration logic is as follows: For large-particle-size goji berry material flow, a lower frequency ultrasonic wave is used to generate large-size cavitation bubbles, and the strong micro-jet generated when the bubbles break down is used to penetrate the thicker wax film. For small-particle-size goji berry material flow, high-frequency ultrasound is used to generate high-density small-sized cavitation bubbles, which peel off the surface wax layer without breaking the small-particle pulp by ultrasonic mechanical force.

[0029] During the cavitation process, the collapse of microbubbles inevitably generates a severe localized thermal effect (i.e., a byproduct of cavitation). If the heat is allowed to accumulate, the resulting increase in medium temperature will cause thermal damage to the heat-sensitive fresh goji berries, violating the physical premise that the material must remain in its original frozen state during the subsequent freeze-drying process.

[0030] To suppress the temperature rise caused by the byproducts of cavitation, a constant temperature control component is installed in the treatment tank 2a to keep the temperature of the liquid conductive medium 2a2 constant within a preset low temperature non-thermal damage threshold, ensuring that the goji berries are only subjected to mechanical force to break the pores without thermal denaturation.

[0031] Furthermore, it should be noted that, to ensure that the fresh goji berries partially submerged in the liquid conductive medium 2a2 can overcome the buoyancy and resistance of the water and move stably forward with the belt, baffles are fixed at equal intervals along the conveying direction on the outer surface of the permeable material conveyor belt 2b. During operation, the baffles forcefully push the goji berry particles below the water surface forward synchronously. This belt-type baffle conveyor structure is a conventional and mature technology in this field, and its specific dimensions and distribution spacing can be conventionally selected and adjusted by those skilled in the art according to the actual material flow rate, and will not be elaborated further here.

[0032] In the extreme environment of the microwave vacuum freeze dryer 3, if conventional electromechanical equipment is placed directly inside the chamber, the high vacuum environment will cause the heat generated by the motor to burn out because it cannot be dissipated through air convection. Furthermore, the exposed metal coils are prone to tip discharge and antenna effect under strong microwave fields, resulting in severe arcing.

[0033] To mitigate the risk of physical failure of the aforementioned electromechanical hardware in a vacuum microwave field, the vibration mechanism adopts an externally powered structure. The vibration mechanism includes a vibration generator 3a3 mounted on the outer wall of the microwave vacuum freeze dryer 3, and a rigid coupling rod 3a4 penetrating the outer wall of the chamber. The inner end of the coupling rod 3a4 is physically engaged with the carrying tray 3a1 inside the freshness-locking compartment 3a, and the outer end of the coupling rod 3a4 is connected to the power output end of the vibration generator 3a3 to transmit the excitation force.

[0034] When using a rigid rod to transmit reciprocating vibration displacement, conventional rotary dynamic seals (such as magnetohydrodynamic seals or rubber O-rings) cannot withstand high-frequency axial pulling friction, which can lead to a rapid collapse of the vacuum barrier. To solve the high-vacuum sealing problem during the transmission of axial reciprocating motion, a metal bellows sealing assembly 3a5 is fitted at the penetration point of the coupling rod 3a4 through the outer wall of the chamber. One end of the metal bellows sealing assembly 3a5 is sealed and fixed to the outer wall of the chamber, and the other end is sealed and fixed to the outer peripheral wall of the coupling rod 3a4, so as to maintain the vacuum sealing state inside the microwave vacuum freeze dryer 3 while allowing the coupling rod 3a4 to transmit reciprocating vibration displacement axially.

[0035] During microwave heating, due to differences in the distribution of ice crystals inside the goji berries and changes in material morphology, localized heat absorption can easily exceed sublimation heat dissipation, inducing localized thermal runaway caused by ice crystal melting. Simply relying on preset macroscopic parameters is insufficient to intervene in sudden thermal imbalances within the chamber.

[0036] Therefore, each freshness-locking compartment 3a is equipped with an infrared temperature monitoring probe. The infrared temperature monitoring probe is pointed to the material tumbling area in the center of the freshness-locking compartment 3a, which is used to collect the sublimation temperature of the surface of the goji berries under high-frequency vibration in real time without contact.

[0037] Based on the above-described apparatus, this embodiment also provides a method for locking in the freshness of wolfberries, which includes the following steps: S1, the washed fresh goji berries are introduced into the grading and conveying module 1 to screen and separate at least two material streams of different particle size levels to form independent conveying batches. S2, the independently transported batches of goji berries are sent into the independent liquid ultrasonic channels of the ultrasonic cleaning module 2. In the liquid conduction medium 2a2, the cavitation effect is induced by ultrasonic waves of different frequencies to target and destroy the dense wax film on the surface of the goji berries, so as to generate micro water separation channels on the surface of the wax layer by vibration. In step S3, the goji berries of different grades that have undergone the gap-breaking treatment in step S2 are introduced into their respective independent fresh-locking compartments 3a. In practice, the carrying trays 3a1 can be manually fed into the corresponding fresh-locking compartments 3a. After entering the fresh-locking compartments 3a, if the same initial microwave energy is applied to all goji berries of different particle sizes, the smaller-sized goji berries, due to their larger specific surface area and shorter water evaporation path, will face an excessively rapid dehydration rate, easily leading to a sharp decrease in internal residual ice and the inability to dissipate heat in time.

[0038] To prevent premature local thermal runaway caused by excessively rapid dehydration and a sharp decrease in internal residual ice in small-particle materials, the microwave input parameters in each independent freshness-locking compartment 3a are initially matched differently based on the particle size of the goji berries they contain: For the freshness-locking compartment 3a, which carries large-particle-size goji berries, a higher initial microwave output power or a longer pulse microwave duty cycle is configured to match the large moisture content and latent heat of sublimation of large-particle-size materials. For the freshness-locking compartment 3a, which carries small-particle-size goji berries, a lower initial microwave output power or a shorter pulse microwave duty cycle is configured to limit the sublimation heat equivalent of a single input.

[0039] After completing parameter matching, microwave feeding is turned on in a vacuum freezing environment. The microwave field provides the latent heat required for the direct sublimation of ice crystals inside the goji berries. Simultaneously, the external vibration mechanism is turned on, so that the goji berries in different independent fresh-locking compartments 3a undergo high-frequency micro-amplitude bouncing and physical tumbling in the carrying tray 3a1. This eliminates the local hot spots caused by the microwave standing wave field and drives the water inside the goji berries to be discharged through the micro water separation channel. S4. During the sublimation drying process in step S3, the surface sublimation temperature of the material tumbling zone in each freshness-locking compartment 3a is monitored in real time using a non-contact method. When the local sublimation temperature in a certain freshness-locking compartment 3a is detected to be close to the preset freezing point danger threshold (set between -5℃ and -2℃), thermal runaway prevention intervention is triggered.

[0040] The specific method for reducing the microwave input power is as follows: further reduce the microwave output duty cycle, allowing the goji berry ice crystals, which are approaching the freezing point danger threshold, to undergo physical cooling using their latent heat of sublimation during the pulse interval. Simultaneously, while adjusting the microwave parameters, the excitation frequency of the corresponding vibration mechanism is increased to accelerate the spatial tumbling and homogenization of the material layer until its sublimation temperature drops below the lower limit of the freezing point danger threshold, at which point the original drying parameters are restored. Finally, through the dynamic decoupling feedback of microwave power and excitation frequency, low-temperature vacuum removal of moisture from the goji berries in each bin is achieved.

[0041] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered as falling within the scope of protection of the embodiments of the present invention.

Claims

1. A device and method for preserving wolfberry, characterized in that, It includes a sequentially connected graded conveying module (1), an ultrasonic cleaning module (2), and a microwave vacuum freeze dryer (3). The graded conveying module (1) is configured to sieve the incoming fresh wolfberries according to their particle size and output them from the corresponding different discharge ports (1a). The graded conveying module (1) has at least two discharge ports (1a) of different particle size levels. The ultrasonic cleaning module (2) includes a treatment tank (2a) for containing a liquid conductive medium (2a2), multiple permeable material conveyor belts (2b) partially immersed in the liquid conductive medium (2a2), and ultrasonic transducers (2c) installed in an array on the tank wall of the treatment tank (2a). The feed end of each permeable material conveyor belt (2b) corresponds to the discharge port (1a) of the graded conveying module (1). The middle section of the permeable material conveyor belt (2b) is immersed in the liquid conductive medium (2a2). Each permeable material conveyor belt (2b) is equipped with an ultrasonic transducer (2c) on both sides. The ultrasonic transducer (2c) is configured to emit ultrasonic waves into the liquid conductive medium (2a2) to induce cavitation effect. The microwave vacuum freeze dryer (3) includes several independent fresh-locking compartments (3a). Each fresh-locking compartment (3a) is respectively equipped with different particle size grades of wolfberry material after being processed by the ultrasonic cleaning module (2). Each fresh-locking compartment (3a) is connected to an independent microwave feed inlet (3a2). Each fresh-locking compartment (3a) is equipped with a vibration mechanism. The vibration mechanism is configured to drive the wolfberry particles in the corresponding fresh-locking compartment (3a) to generate high-frequency micro-amplitude vibration and physical tumbling between particles.

2. The device and method of claim 1, wherein, The processing tank (2a) is divided into several parallel and independent liquid ultrasonic channels by longitudinal partitions (2a1). The number of liquid ultrasonic channels is the same as the number of discharge ports (1a) to respectively receive goji berry material flows of different particle sizes. Each liquid ultrasonic channel is equipped with an ultrasonic transducer (2c) on both sides of its inner wall. The working frequency of the ultrasonic transducer (2c) in different liquid ultrasonic channels is differentiated according to the goji berry particle size it receives.

3. The device and method of claim 1 or 2, wherein, The processing tank (2a) is equipped with a constant temperature control component, which is used to keep the temperature of the liquid conductive medium (2a2) constant within a preset low temperature non-thermal damage threshold.

4. The wolfberry compound freshness-locking device and method according to claim 1, characterized in that, The vibration mechanism includes a vibration generator (3a3) installed on the outer wall of the microwave vacuum freeze dryer (3) chamber, and a rigid coupling rod (3a4) penetrating the outer wall of the chamber. The inner end of the coupling rod (3a4) is physically engaged with the carrying tray (3a1) in the freshness-locking compartment (3a), and the outer end of the coupling rod (3a4) is connected to the power output end of the vibration generator (3a3) to transmit the excitation force.

5. The wolfberry compound freshness-locking device and method according to claim 4, characterized in that, A metal bellows sealing assembly (3a5) is fitted at the through-hole position of the coupling rod (3a4) through the outer wall of the cabin. One end of the metal bellows sealing assembly (3a5) is sealed and fixed to the outer wall of the cabin, and the other end is sealed and fixed to the outer peripheral wall of the coupling rod (3a4) so ​​as to maintain the vacuum sealing state inside the microwave vacuum freeze dryer (3) while allowing the coupling rod (3a4) to transmit reciprocating vibration displacement along the axial direction.

6. The wolfberry compound freshness-locking device and method according to claim 4, characterized in that, Each of the freshness-locking compartments (3a) is equipped with an infrared temperature monitoring probe. The infrared temperature monitoring probe is pointed at the material tumbling area in the center of the freshness-locking compartment (3a) to collect the sublimation temperature of the surface of the wolfberry under high-frequency vibration in real time without contact.

7. A method for compound freshness preservation of wolfberries, implemented based on the aforementioned compound freshness preservation device for wolfberries, characterized in that, The method includes the following steps: S1, the cleaned fresh wolfberries are introduced into the graded conveying module (1) to screen and separate at least two material streams of different particle size levels to form independent conveying batches; S2, the independently transported batches of wolfberries are respectively sent into the independent liquid ultrasonic channels of the ultrasonic cleaning module (2). In the liquid conduction medium (2a2), the cavitation effect is induced by ultrasonic waves of different frequencies to target and destroy the dense wax film on the surface of the wolfberry, so as to generate micro water separation channels on the surface of the wax layer by vibration. S3, the goji berries of each grade that have undergone the gap-breaking treatment in S2 are respectively introduced into the corresponding independent fresh-locking compartments (3a). Microwave feeding is turned on in a vacuum freezing environment. The microwave field provides the latent heat required for the direct sublimation of the ice crystals inside the goji berries. At the same time, the external vibration mechanism is turned on, so that the goji berries in different independent fresh-locking compartments (3a) undergo high-frequency micro-amplitude bouncing and physical tumbling in the carrying tray (3a1) to eliminate the local hot spots caused by the microwave standing wave field and drive the water inside the goji berries to be discharged through the micro water separation channel. S4. During the sublimation drying process in step S3, the surface sublimation temperature of the material tumbling zone in each of the freshness-locking compartments (3a) is monitored in real time without contact. When the local sublimation temperature in a certain layer of the freshness-locking compartment (3a) approaches the preset freezing point danger threshold, thermal runaway prevention intervention is triggered: the microwave input power corresponding to the freshness-locking compartment (3a) of that layer is immediately reduced to reduce the latent heat supply, and the excitation frequency of the corresponding vibration mechanism is simultaneously increased to accelerate the spatial tumbling and uniform heating of the material in that layer until the sublimation temperature of the material in that layer falls back to a safe temperature below the lower limit of the freezing point danger threshold, and the original drying parameters are restored.

8. The method for compound freshness preservation of wolfberry according to claim 7, characterized in that, In step S2, the configuration logic for the differentiated frequency ultrasound is as follows: For large-particle-size goji berry material flow, low-frequency ultrasound is used to generate large-size cavitation bubbles, and the strong micro-jet generated when the bubbles burst breaks through the thick wax film. For small-particle-size goji berry material, high-frequency ultrasound is used to generate high-density, small-sized cavitation bubbles, which peel off the surface wax layer without breaking the small-particle pulp by ultrasonic mechanical force.

9. A method for compound preservation of wolfberry according to claim 7, characterized in that, In step S4, the freezing point danger threshold is set between -5℃ and -2℃. The specific method of reducing the microwave input power is to reduce the microwave output duty cycle, forcing the wolfberry ice crystals approaching the freezing point danger threshold to use their latent heat of sublimation for physical cooling during the pulse interval.

10. A method for compound freshness preservation of wolfberry according to claim 7, characterized in that, In step S3, the microwave input parameters in each of the independent freshness-locking compartments (3a) are initially matched differently based on the particle size of the goji berries they contain: For the freshness-locking compartment (3a) that carries large-particle-size goji berries, a higher initial microwave output power or a longer pulse microwave duty cycle is configured to match the large moisture storage and latent heat of sublimation requirements of large-particle-size materials. For the freshness-locking compartment (3a) that carries small-particle-size goji berries, a lower initial microwave output power or a shorter pulse microwave duty cycle is configured to limit the sublimation heat equivalent of a single input.

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