Ultrasonic-ultraviolet combined sterilization equipment and method for pasteurizing mango juice

Abstract

The invention belongs to the technical field of food processing, and particularly relates to ultrasonic-ultraviolet combined sterilization equipment and method for mango juice pasteurization, and the equipment system comprises an integrated sterilization tank, an ultrasonic component and an ultraviolet sterilization component. Pasteurization of the sterilization tank is achieved through jacket heating, the ultrasonic component drives the tool head through the transducer to generate a cavitation effect, and the ultraviolet component conveys materials to the quartz tube through the feeding pump for ultraviolet irradiation. The equipment supports three independent modes of Pasteur, ultrasonic and ultraviolet and four combined modes thereof. The method comprises the steps of mango juice preparation, primary sterilization and optional secondary sterilization. Through the synergistic effect of sound, light and heat, the sterilizing effect is guaranteed, meanwhile, the nutritional ingredients and sensory quality of the juice are well reserved, and the method is suitable for industrial continuous production.

Description

Technical Field

[0001] This invention belongs to the field of food processing technology, and in particular relates to an ultrasonic-ultraviolet combined sterilization device and method for pasteurizing mango juice. Background Technology

[0002] Mango juice is rich in heat-sensitive nutrients such as vitamin C, carotenoids, and polyphenols, making it a popular choice among consumers. However, mango juice is highly susceptible to browning and nutrient loss during processing, especially vitamin C, which is easily oxidized and decomposed at high temperatures, leading to discoloration, loss of flavor, and a decline in nutritional value.

[0003] Currently, the mango juice processing industry commonly uses ultra-high temperature (UHT) sterilization or pasteurization. While UHT sterilization is highly efficient, it typically requires processing at temperatures above 135°C for several seconds, which easily destroys the original flavor compounds of the mango (such as esters and aldehydes), resulting in a "cooked" taste in the juice, and the vitamin C retention rate is usually less than 60%. Although pasteurization uses lower temperatures (60-90°C), the longer processing time also leads to nutrient loss and deterioration in taste. In addition, traditional chemical sterilization methods (such as adding chlorine dioxide or hydrogen peroxide) can inhibit microorganisms to some extent, but they easily introduce chemical residues, posing food safety risks and potentially producing off-flavors.

[0004] In recent years, non-thermal sterilization technology has been gradually applied to juice processing. However, ultra-high pressure technology requires huge investment in equipment and usually operates intermittently, resulting in low production efficiency; pulsed electric field technology has problems such as uneven electric field intensity distribution and limited penetration depth, and its sterilization effect is unstable for mango juice with high turbidity.

[0005] Ultraviolet (UV) sterilization, as a physical disinfection technology, has the advantages of being residue-free and easy to operate. However, in mango juice applications, UV light has weak penetrating power and is not effective at killing microorganisms deep within the juice or attached to suspended particles; using UV light alone is insufficient to achieve commercial sterility standards. Ultrasonic sterilization technology utilizes cavitation to destroy the cell structure of microorganisms, but its sterilization efficiency is limited when used alone, and prolonged high-intensity ultrasonic treatment may cause localized overheating or off-flavors in the juice.

[0006] While there are reports of combined ultrasonic and ultraviolet sterilization in existing technologies, these are mostly focused on water treatment. Their device structures and process parameters are not suitable for liquid foods like mango juice, which are rich in suspended particles and have high viscosity. Given the unique heat sensitivity and tendency to browning of mango juice, there is an urgent need for ultrasonic-ultraviolet combined sterilization equipment and methods for mango juice pasteurization. Summary of the Invention

[0007] The purpose of this invention is to provide an ultrasonic-ultraviolet combined sterilization device and method for pasteurizing mango juice, in order to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention provides the following solution: An ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice includes: A frame and a sterilization tank connected to the frame, wherein the sterilization tank has a heat exchange device for pasteurizing the material inside the sterilization tank; The sterilization tank is equipped with an ultrasonic component, which is used to sterilize the material inside the sterilization tank using ultrasonic sterilization. The first discharge port of the sterilization tank is connected to the inlet of the ultraviolet sterilization component, which is used to sterilize the material flowing through it with ultraviolet light. The feeding port of the sterilization tank is connected to the feeding pump via a pipe; The feed pump is used to pump mango juice into the sterilization tank; It also includes three independent sterilization modes: pasteurization, ultrasonic sterilization, and ultraviolet sterilization. It also includes four combined sterilization modes, namely pasteurization ultrasonic sterilization mode, pasteurization ultraviolet sterilization mode, ultrasonic ultraviolet sterilization mode and pasteurization ultrasonic ultraviolet sterilization mode.

[0009] Optionally, the ultrasonic component includes a tool head, an amplitude transformer, and a transducer. The transducer is fixed to the top of the sterilization tank, the top end of the amplitude transformer is fixed to the output end of the transducer, and the amplitude transformer is located inside the sterilization tank. The tool head is fixed to the bottom end of the amplitude transformer.

[0010] Optionally, the heating device includes a first outer shell fitted over the outside of the sterilization tank, and the outside of the first outer shell is covered with a heat insulation layer; A gap is provided between the first outer shell and the outer wall of the sterilization tank, and a cavity for storing heat-conducting liquid is formed between the inner wall of the first outer shell and the outer wall of the sterilization tank; The cavity is connected to a heat transfer fluid inlet and a heat transfer fluid outlet; The cavity is equipped with at least one heating rod; A temperature probe is connected inside the discharge end of the sterilization tank.

[0011] Optionally, the ultraviolet sterilization component includes a second outer shell, which is fixed to the frame. The ultraviolet disinfection unit is fixed inside the second outer casing; The second housing contains a feed pump and a quartz tube. One end of the quartz tube is connected to the discharge end of the feed pump, and the other end of the feed pump is connected to the first discharge port. The light emitted by the ultraviolet disinfection unit shines on the quartz tube; The other end of the quartz tube passes through the side wall of the second outer shell and connects to the second discharge port.

[0012] Optionally, a control panel and an observation window are fixed on the second housing.

[0013] The method of using the ultrasonic-ultraviolet combined sterilization equipment for pasteurization of mango juice includes the following steps: Prepare mango juice; The mango juice is injected into the sterilization tank via the feed pump; The pasteurized ultrasonic ultraviolet sterilization mode is activated to sterilize the mango juice once. The mango juice, which has undergone one sterilization, is injected back into the sterilization tank through the feeding pump, and a second sterilization is performed by selecting the pasteurization mode, the ultrasonic sterilization mode, the ultraviolet sterilization mode, the pasteurization-ultrasonic sterilization mode, the pasteurization-ultraviolet sterilization mode, the ultrasonic-ultraviolet sterilization mode, or the pasteurization-ultrasonic-ultraviolet sterilization mode.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: This invention integrates pasteurization, ultrasonic sterilization, and ultraviolet sterilization to construct a synergistic sterilization system, effectively solving the problems of nutrient loss and flavor deterioration caused by high-temperature processing in mango juice. The equipment adopts a modular design, organically combining sterilization tanks, ultrasonic components, and ultraviolet sterilization components. Through flexible configuration of multiple sterilization modes, it adapts to different raw material characteristics and production needs. Ultrasonic sterilization utilizes cavitation to disrupt the microbial cell structure, pasteurization provides gentle heat treatment conditions, and ultraviolet sterilization compensates for the shortcomings of the former two through radiation. The synergistic effect of the three significantly improves sterilization efficiency while avoiding the introduction of chemical reagents, ensuring product safety. The equipment is simple and efficient to operate, capable of continuous operation, and not only inhibits browning reactions in the juice but also better preserves heat-sensitive components such as vitamin C and polyphenols, maintaining the natural color and taste of the mango. It provides reliable technical support for the production of high-quality mango juice and has broad application prospects. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 The variation in sterilization rate of mango juice under different pasteurization conditions in this invention; Figure 3 The variation in sterilization rate of mango juice under different ultrasonic sterilization conditions in this invention; Figure 4 The variation of sterilization rate of mango juice under different ultraviolet sterilization conditions in this invention; The components are as follows: 1. Transducer; 2. Amplifier rod; 3. Insulation layer; 4. First outer shell; 5. Support frame; 6. Tool head; 7. Heat transfer fluid outlet; 8. Frame; 9. First heating rod; 10. First discharge port; 11. Temperature probe; 12. Second heating rod; 13. Feed port; 14. Heat transfer fluid inlet; 15. Feed pump; 16. Quartz tube; 17. Observation window; 18. Second outer shell; 19. Electrodeless lamp; 20. Electromagnetic resonant cavity; 21. Magnetron; 22. Drive power supply; 23. Microwave transmitting antenna; 24. Control panel; 25. Second discharge port. Detailed Implementation

[0016] 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.

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] Reference Figures 1 to 4 This invention discloses an ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice, comprising: The frame 8 and the sterilization tank connected to the frame 8, the heat exchange of the sterilization tank is equipped with a heating device, the heating device is used to pasteurize the material in the sterilization tank; The sterilization tank is equipped with an ultrasonic component, which is used to sterilize the materials inside the sterilization tank using ultrasonic technology. The first discharge port 10 of the sterilization tank is connected to the feed end of the ultraviolet sterilization component, which is used to sterilize the material flowing through it with ultraviolet light. The feeding port 13 of the sterilization tank is connected to the feeding pump via a pipe; The feed pump is used to pump mango juice into the sterilization tank; It also includes three independent sterilization modes: pasteurization, ultrasonic sterilization, and ultraviolet sterilization. It also includes four combined sterilization modes, namely pasteurization ultrasonic sterilization mode, pasteurization ultraviolet sterilization mode, ultrasonic ultraviolet sterilization mode and pasteurization ultrasonic ultraviolet sterilization mode.

[0019] Mango juice is pumped into the sterilization tank via a feed pump. Supported by the frame 8, the sterilization tank uses a heating device to pasteurize the material, while simultaneously using an ultrasonic component to perform ultrasonic sterilization. After sterilization, the material enters the ultraviolet sterilization component through the first discharge port 10 for ultraviolet sterilization. This equipment achieves efficient, low-temperature, and residue-free sterilization of mango juice by flexibly switching between three independent sterilization modes—pasteurization, ultrasonic sterilization, and ultraviolet sterilization—and four combined sterilization modes, effectively preserving the juice's nutrients and flavor.

[0020] As an optional implementation, the ultrasonic component is provided with one or more.

[0021] This equipment significantly enhances the uniformity of the acoustic field within the sterilization tank by incorporating one or more ultrasonic components. As the mango juice flows within the tank, the cavitation effect generated by multiple ultrasonic components covers a larger processing area, effectively solving the dead zone problem that may exist in single-point ultrasonic treatment. This multi-component layout not only improves sterilization efficiency but also ensures more uniform heating of the mango juice during pasteurization, thus better preserving its nutrients and flavor.

[0022] As an optional implementation, the ultrasonic component includes a tool head 6, an amplitude transformer 2, and a transducer 1. The transducer 1 is fixed to the top of the sterilization tank, the top end of the amplitude transformer 2 is fixed to the output end of the transducer 1, and the amplitude transformer 2 is located inside the sterilization tank. The tool head 6 is fixed to the bottom end of the amplitude transformer 2.

[0023] Transducer 1 converts electrical energy into mechanical vibration, and amplitude transformer 2 amplifies the amplitude and transmits it to tool head 6. Tool head 6 generates cavitation effect in sterilization tank to achieve efficient sterilization.

[0024] As an optional implementation, the distance between the tool head 6 and the material liquid surface is 20~30cm.

[0025] The tool head 6 is kept 20-30cm away from the liquid surface. This distance effectively avoids the impact of liquid fluctuations on the tool head 6, ensuring the stable operation of the ultrasonic component within the sterilization tank. Simultaneously, this distance range ensures sufficient propagation space for the ultrasonic waves in the liquid, generating a robust cavitation effect, thereby achieving highly efficient sterilization of the mango juice.

[0026] As an optional implementation, the heating device includes a first outer shell 4 fitted over the outside of the sterilization tank, and the outside of the first outer shell 4 is covered with a heat insulation layer 3; A gap is provided between the first outer shell 4 and the outer wall of the sterilization tank, and a cavity for storing heat-conducting liquid is formed between the inner wall of the first outer shell 4 and the outer wall of the sterilization tank. The cavity is connected to a heat transfer fluid inlet 14 and a heat transfer fluid outlet 7; The cavity contains at least one heating rod; A temperature probe 11 is connected inside the discharge end of the sterilization tank.

[0027] The device stores a heat-conducting liquid in a cavity formed by the first outer shell 4 and the outer wall of the sterilization tank. A heating rod heats the heat-conducting liquid, and an insulation layer 3 reduces heat loss, ensuring that the mango juice inside the sterilization tank is heated evenly. A temperature probe 11 monitors the temperature at the discharge end in real time, ensuring that the pasteurization temperature is precisely controlled within the set range, effectively killing microorganisms while preserving the flavor of the juice.

[0028] As an alternative implementation, the first outer shell 4 is fixed to the frame 8 by a support frame 5.

[0029] As an optional implementation, the ultraviolet sterilization component includes a second outer shell 18, which is fixed to the frame 8; The ultraviolet disinfection unit is fixed inside the second outer casing 18; The second housing 18 has a feed pump 15 and a quartz tube 16 fixed inside. One end of the quartz tube 16 is connected to the discharge end of the feed pump 15, and the other end of the feed pump 15 is connected to the first discharge port 10. The light emitted from the ultraviolet disinfection unit shines on the quartz tube 16; The other end of the quartz tube 16 passes through the side wall of the second outer shell 18 and connects with the second discharge port 25.

[0030] After flowing out of the first outlet 10, the mango juice is pumped into the quartz tube 16 by the feed pump 15. Within the sealed space of the second outer casing 18, light emitted from the ultraviolet disinfection unit penetrates the wall of the quartz tube 16, irradiating and sterilizing the mango juice flowing inside. The sterilized mango juice flows out from the other end of the quartz tube 16 and is discharged through the second outlet 25, completing the ultraviolet sterilization process.

[0031] As an optional implementation, the ultraviolet disinfection unit includes an electrodeless lamp 19, an electromagnetic resonant cavity 20, a magnetron 21, a driving power supply 22, and a microwave transmitting antenna 23.

[0032] The driving power supply 22 is directly connected to the magnetron 21 via a wire to provide it with working power. The output end of the magnetron 21 is tightly coupled to the microwave transmitting antenna 23 through a waveguide or coaxial interface, so that the microwave transmitting antenna 23 can radiate the generated microwave energy into the electromagnetic resonant cavity 20. The electromagnetic resonant cavity 20 is a sealed metal cavity, and its inner wall is fixed to the electrodeless lamp tube 19 by a mechanical bracket to ensure that the microwave field energy can efficiently excite the lamp tube to emit light. All these components—including the driving power supply 22, the magnetron 21, the microwave transmitting antenna 23, the electromagnetic resonant cavity 20, and the electrodeless lamp tube 19—are fixed to the internal frame of the second outer shell 18 by bolts or welding to form a complete modular structure. The quartz tube 16 runs horizontally through the second outer shell 18 and is parallel to the electrodeless lamp tube 19 with a distance of 10~30mm, so that ultraviolet light can be perpendicularly irradiated to the wall of the quartz tube.

[0033] The working process is as follows: the driving power supply 22 supplies power to the magnetron 21, which generates microwaves that are radiated into the electromagnetic resonant cavity 20 through the microwave transmitting antenna 23. The electromagnetic resonant cavity 20 focuses and amplifies the microwave energy, exciting the electrodeless lamp 19 inside the cavity to generate high-intensity ultraviolet light. The components of this ultraviolet disinfection unit are electrically connected to form a complete photoexcitation system: driving power supply 22 → magnetron 21 → microwave transmitting antenna 23 → electromagnetic resonant cavity 20 → electrodeless lamp 19. During operation, when mango juice flows through the quartz tube 16, the ultraviolet light emitted by the electrodeless lamp 19, with a wavelength of 200-380nm, penetrates the quartz tube wall and irradiates the material. The technical principle is that microwave excitation causes the inert gas inside the electrodeless lamp 19 to generate plasma discharge, radiating ultraviolet light with strong bactericidal effect. Compared with traditional electrode ultraviolet lamps, this excitation method has the advantages of fast start-up, long life, and stable intensity.

[0034] As an optional implementation, a control panel 24 and an observation window 17 are fixed on the second housing 18.

[0035] Specifically, this device includes a sterilization tank, an ultrasonic component, and an ultraviolet sterilization component. The sterilization tank includes an insulation layer 3, an outer shell 4, a support frame 5, a heat transfer fluid outlet 7, a feeding port 13, a heat transfer fluid inlet 14, a first heating rod 9, a second heating rod 12, a discharge port 10, and a temperature probe 11.

[0036] The ultrasonic components include a transducer 1, an amplitude transformer 2, and a tool head 6.

[0037] The ultraviolet sterilization components include a feed pump 15, a quartz tube 16, an observation window 17, a housing 18, an electrodeless lamp 19, an electromagnetic resonant cavity 20, a magnetron 21, a drive power supply 22, a microwave transmitting antenna 23, a control panel 24, and a discharge port 25.

[0038] The sterilization tank is equipped with a feeding pump, and the feeding port 13 is sealed and connected to the feeding pump through a pipeline.

[0039] The sterilization tank is equipped with one or more ultrasonic components.

[0040] The ultrasonic component has an ultrasonic power of 1500~3000W and an ultrasonic frequency of 20~50kHz, and is more preferably 2500W and 40kHz.

[0041] The insulation layer 3 is filled with polyurethane or rock wool as a heat insulation material, and the thickness of the insulation layer 3 is 10~30mm.

[0042] The temperature probe 11 is placed on the stainless steel inner wall of the sterilization tank and near the liquid discharge port.

[0043] The first heating rod 9 or the second heating rod 12 is fixed in one or more stainless steel jackets of the sterilization tank to heat the heat transfer liquid in the jacket and to adjust the temperature of the liquid in the sterilization tank to between 40 and 80°C through a temperature system; the heat transfer liquid is pure water or mineral-based heat transfer liquid.

[0044] The ultraviolet sterilization component includes one or more ultraviolet generating components, which include an electrodeless lamp 19, an electromagnetic resonant cavity 20, a magnetron 21, a driving power supply 22, and a microwave transmitting antenna 23. The electrodeless lamp 19 is installed parallel to the quartz tube 16 with a spacing of 10~30mm. When there are multiple ultraviolet generating components, they are installed in parallel along the direction of the quartz tube 16.

[0045] Among them, the ultraviolet irradiance of electrodeless lamp 19 is 100~150mW / cm². 2 The ultraviolet light wavelength is 200~380nm, and more preferably 280nm.

[0046] The quartz tube 16 has an outer diameter of 20~45mm and a wall thickness of 1.5~4.0mm, and is more preferably an outer diameter of 25mm and a wall thickness of 2.2mm. The quartz tube 16 is connected to the discharge port 10 of the sterilization tank through a feed pump 15 and a stainless steel pipeline. The pumping speed of the feed pump 15 is 0.5~5L / min, and the ultraviolet irradiation time of the liquid is adjusted by controlling the pumping speed.

[0047] The discharge port 25 is connected to the feeding port 13 to achieve repeated sterilization of the liquid. After the initial sterilization, the liquid re-enters the sterilization tank through the discharge port 25 and the feeding port 13. After accepting or not accepting pasteurization and ultrasonic sterilization, it enters the ultraviolet sterilization component for repeated ultraviolet irradiation or to end sterilization, and then flows out from the discharge port 25.

[0048] Among them, the feed pump 15 can adjust the flow rate of the liquid within the range of 0.5~5L / min.

[0049] Among them, observation window 17 is used to observe the material conveying and equipment operation.

[0050] The control panel 24 is equipped with a PLC touch screen and is connected to the feed pump 15, drive power supply 22, sterilization tank temperature control system and ultrasonic generator, which are used to control the pump feed rate, pasteurization temperature, ultrasonic power and sterilization time of each stage.

[0051] A method for using an ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice is also provided. The method for using the aforementioned ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice is characterized by comprising the following steps: Prepare mango juice; The mango juice is injected into the sterilization tank via the feed pump; The pasteurized ultrasonic ultraviolet sterilization mode is activated to sterilize the mango juice once. The mango juice, which has undergone one sterilization, is injected back into the sterilization tank through the feeding pump, and a second sterilization is performed by selecting the pasteurization mode, the ultrasonic sterilization mode, the ultraviolet sterilization mode, the pasteurization-ultrasonic sterilization mode, the pasteurization-ultraviolet sterilization mode, the ultrasonic-ultraviolet sterilization mode, or the pasteurization-ultrasonic-ultraviolet sterilization mode.

[0052] First, mango juice is prepared and injected into the sterilization tank through the feed inlet 13 by the feed pump. The pasteurization ultrasonic ultraviolet sterilization mode is then activated: the heating equipment heats the heat transfer liquid to achieve pasteurization, while the ultrasonic component generates a cavitation effect. After the material flows out from the first outlet 10, it is pumped into the ultraviolet sterilization component by the feed pump 15. After being irradiated by the ultraviolet light tube 19 through the quartz tube 16, it is discharged from the second outlet 25. After the first sterilization, the mango juice can be injected back into the sterilization tank, and other modes can be flexibly selected for secondary processing.

[0053] Specifically, it includes the following steps: Prepare mango juice, which can be freshly squeezed or concentrated.

[0054] The freshly squeezed juice is made from mangoes through a process of peeling and pitting, pulping with a colloid mill, hydrolyzing with pectinase, filtering with a 100-mesh screen, and homogenizing under high pressure at 80MPa.

[0055] The concentrated juice is made by evaporating or freezing fresh juice to remove some of the water.

[0056] Among them, the tool head 6 of the ultrasonic component is located 20-30cm below the liquid surface of the material in the sterilization tank. The vibration during operation can promote the mixing of the liquid and ensure that the liquid is heated evenly during pasteurization, thereby improving the sterilization quality.

[0057] The sterilization quality evaluation indicators include sterilization rate, browning rate, total phenol content, and vitamin C content. The sterilization rate is tested according to the method of national standard GB4789.2-2016 "Food Microbiology Examination - Determination of Total Colony Count", and the vitamin C content is tested according to the method of national standard GB5009.86-2016 "Determination of Ascorbic Acid in Food". The browning rate and total phenol content are determined by the following methods.

[0058] Browning rate: Take 1 mL of mango juice before and after sterilization, dilute it with deionized water 5 to 10 times, centrifuge it at 4℃ and 4000 r / min for 10 min, take the supernatant, measure the absorbance at a wavelength of 420 nm, and calculate the browning rate according to the following formula.

[0059] Browning rate (%) = (A1 - A0) / A0 × 100% In the formula, A0 is the absorbance value of the juice before sterilization at a wavelength of 420nm, and A1 is the absorbance value of the juice after sterilization at a wavelength of 420nm.

[0060] Total phenol content: The Folin-Ciocalteu method was used. 1 mL of mango juice was mixed with 1 mL of Folin-Ciocalteu reagent and incubated at room temperature for 10 min. Then, 3 mL of 7.5% Na₂CO₃ solution and 5 mL of distilled water were added, and the mixture was reacted in a 40℃ water bath for 20 min. After the reaction, the absorbance of the sample solution at 765 nm was measured. Each sample was measured three times. A standard curve was obtained by plotting gallic acid concentration (mg / L) on the x-axis and absorbance on the y-axis: y = 0.0070x + 0.0184 (R² = 0.9974). The total phenol content of the sample was calculated by substituting the absorbance values ​​into the curve.

[0061] In this process, after the mango juice is added to the sterilization tank, pasteurization and ultrasonic sterilization are simultaneously activated (power 2000~3000W, frequency 40kHz) to raise the temperature of the mango juice to 55~65℃ and maintain it for 4~8 minutes. Then, the ultraviolet sterilization component is pumped in for ultraviolet sterilization, and the pumping rate is controlled at 0.5~1.5L / min. The sterilization rate of the collected mango juice is 100%.

[0062] The radiation dose of the feed liquid can be adjusted by changing the pumping rate of the feed pump 15, the number of ultraviolet sterilization cycles, or the number of electrodeless lamps 19.

[0063] After the mango juice has undergone one sterilization, it is pumped back into the sterilization tank for secondary or multiple sterilizations. The sterilization methods can be selected as single sterilization, pasteurization / ultrasound combined, pasteurization / ultraviolet combined, ultrasound / ultraviolet combined, and pasteurization / ultrasound / ultraviolet combined sterilization. The sterilization plan is tailored to the characteristics of the raw materials and the sterilization requirements.

[0064] High-quality mango juice is prepared by using the equipment and method of this invention. The mango juice is sterilized and then cooled and aseptically filled to obtain sterilized juice.

[0065] Mango juice can be one of the following: freshly squeezed mango juice, concentrated mango juice, fermented mango juice, or mango compound juice.

[0066] To illustrate with a specific embodiment, the above-mentioned sterilization equipment is used for pasteurization of mango juice. The sterilization method includes the following steps: Preparation of mango juice: Fresh, ripe mangoes are selected, washed, peeled, and pitted. They are then pulped in a colloid mill at 6000-10000 rpm. During the pulping process, 2-3 times the weight of the pulp in distilled water is added. 0.1-0.3 g / L of pectinase is added to the mango pulp. After enzymatic hydrolysis at 25℃ for 2-4 hours, the mixture is filtered through 100-mesh gauze. The filtrate is homogenized under high pressure at 80 MPa for 5-8 minutes. Freshly squeezed mango juice with a solid content of 12.0-16.5% is collected. The total bacterial count (n0), vitamin C content, and total phenol content are measured to be 1.14×10⁵ CFU / mL, 10.54 mg / L, and 117.28 mg / L, respectively.

[0067] Preheating of the sterilization tank: Using purified water as the heat transfer fluid, inject it into the jacket of the sterilization tank through the heat transfer fluid inlet 14. Set the pasteurization temperature to 62℃ and turn on the heating mode for 3 minutes of preheating.

[0068] Ultrasonic pasteurization: Freshly squeezed mango juice is poured into the sterilization tank through the feeding port 13, the cover is closed, the ultrasonic power is set to 2100W and the ultrasonic mode is turned on, so that the liquid is ultrasonically pasteurized at 62℃ for 5 minutes.

[0069] UV sterilization: Turn on the drive power supply 22 to activate the UV sterilization mode. Set the pumping rate of the feed pump 15 to 1.2 L / min. Open the discharge port 10 and collect the sterilized liquid from the discharge port 25. The sterilization rate, browning rate, vitamin C content, and total phenol content of the sterilized juice were measured to be 98.53%, 6.20%, 9.17 mg / L, and 106.64 mg / L, respectively.

[0070] The impact of different pasteurization conditions on the sterilization rate was evaluated, as follows: The sterilization temperatures were 50, 60, 70, and 80℃, and the pasteurization times were 2, 4, 6, 8, and 10 minutes, respectively. The ultrasonic treatment time remained at 5 minutes. During sterilization, heating and ultrasonic treatment were simultaneously activated. After one sterilization method was completed, the activation was turned off, and only the other sterilization method was performed. The total number of colonies in the sterilized liquid was measured, and the sterilization rate was calculated. The results are shown in Table 1.

[0071] Table 1. Sterilization rate (%) of mango juice under different pasteurization conditions As shown in Table 1, increasing the sterilization temperature or extending the sterilization time can improve the sterilization rate of mango juice. Heating at 60℃ for 10 minutes, 70℃ for more than 8 minutes, or 80℃ for more than 6 minutes can achieve a sterilization rate of 100%. According to the national standard GB7101-2022 "National Food Safety Standard for Beverages", the acceptable level limit (m value) for total bacterial count in fruit juice beverages is 100 CFU / mL. The total bacterial count of the raw material before sterilization was 1.14×10⁵ CFU / mL. After treatment at 70℃ for 6 minutes, the total bacterial count dropped to 23 CFU / mL, and the sterilization rate was 99.98%. This sterilization condition cannot completely kill microorganisms, but it still meets the national standard requirements.

[0072] The impact of different ultrasonic sterilization conditions on the sterilization rate was evaluated, as follows: Ultrasonic power was set at 1500, 2000, 2500, and 3000 W, with sterilization times of 2, 4, 6, 8, and 10 min. Pasteurization treatment time remained at 5 min. During sterilization, heating and ultrasonic treatment were simultaneously activated initially, and then deactivated after one sterilization method was completed. Only the other sterilization method was then applied. The total bacterial count in the sterilized solution was measured, and the sterilization rate was calculated. The results are shown in Table 2.

[0073] Table 2. Sterilization rate (%) of mango juice under different ultrasonic sterilization conditions As shown in Table 2, increasing the ultrasonic power or extending the ultrasonic time can improve the sterilization rate of mango juice. Ultrasonic treatment at 2000W for 10 minutes or at 2500-3000W for more than 6 minutes can achieve a sterilization rate of 100%. After treatment with ultrasonic treatment at 1500W for 10 minutes and ultrasonic treatment at 2000W for 8 minutes, the sterilization rates were 99.94% and 99.92%, respectively, and the total number of colonies was less than 100 CFU / mL, which meets the microbial limits in the national standard GB7101-2022 "National Food Safety Standard for Beverages".

[0074] The impact of different UV sterilization conditions on the sterilization rate was evaluated, as follows: Pumping rates of 0.5, 1.5, 2.5, 3.5, and 4.5 L / min were used, with 1, 2, 3, and 4 UV sterilization cycles respectively. For experiments requiring more than one UV sterilization cycle, the outlet 25 and feed inlet 13 were connected by a flexible hose. After one UV sterilization cycle, the liquid was returned to the sterilization tank for the next sterilization cycle. The total bacterial count of the sterilized liquid was measured, and the sterilization rate was calculated. The results are shown in Table 3.

[0075] Table 3. Sterilization rate (%) of mango juice under different UV sterilization conditions As shown in Table 3, reducing the pump rate or increasing the number of sterilization cycles can improve the sterilization rate of mango juice. A sterilization rate of 100% can be achieved by repeating UV sterilization more than twice at a pump rate of 0.5 L / min, more than three times at a pump rate of 1.5 L / min, or four times at a pump rate of 2.5 L / min.

[0076] To verify the sterilization effect of this device and method, comparative examples 1-7 were set up, and comparative examples 1-7 were compared with unsterilized mango juice and mango juice processed by the device and method of this invention. Comparative Example 1 is a pasteurization treatment only. The ultrasonic treatment is not turned on during the sterilization process. After pasteurization, the liquid is directly discharged from the discharge port 10.

[0077] Comparative Example 2 only underwent ultrasonic sterilization, the difference being that heating was not turned on during the sterilization process, and the liquid was directly discharged from the outlet 10 after ultrasonic sterilization.

[0078] Comparative Example 3 only underwent ultraviolet sterilization treatment. The difference was that heating and ultrasound were not turned on during the sterilization process. After the liquid was put into the sterilization tank, step (4) was performed directly.

[0079] Comparative Example 4 only underwent pasteurization-ultrasonic sterilization, the difference being that ultraviolet sterilization was not performed during the sterilization process, and the liquid was directly released from the outlet 10 after the ultrasonic pasteurization operation was completed.

[0080] Comparative Example 5 was treated with pasteurization and ultraviolet sterilization only, the difference being that the ultrasound was not turned on during the sterilization process.

[0081] Comparative Example 6 only underwent ultrasonic-UV sterilization, the difference being that the heating was not turned on.

[0082] Comparative Example 7 uses conventional high-temperature sterilization equipment to treat mango juice with high-temperature steam sterilization. The specific method is as follows: (1) Preparation of mango juice: Same as in Example 2.

[0083] (2) Filling: Mango juice is sealed and dispensed into PP plastic bottles, placed in a steam sterilizer, and the lid is closed and locked; a certain amount of distilled water is injected into the sterilizer before filling.

[0084] (3) High-temperature steam sterilization: The sterilization temperature is set to 121℃ and the sterilization time is 15min.

[0085] (4) Discharge: After sterilization, wait for the temperature inside the pot to drop below 90℃, then open the pot lid and remove the juice.

[0086] The test results for each indicator are shown in Table 4.

[0087] Table 4. Test results of mango juice before and after sterilization Note: " / " indicates that the indicator was not detected.

[0088] (5) As can be seen from Table 4, the sterilization rate and browning rate of Comparative Example 4, which was not treated with ultraviolet light, were lower than those of Example 2, while the content of vitamin C and total phenols were slightly higher. This is because high-dose ultraviolet irradiation can destroy the DNA or RNA molecular structure in microbial cells, thereby reducing the number of microorganisms in the liquid to a certain extent. However, ultraviolet light has no obvious effect on the color protection and antioxidant properties of fruit juice. Therefore, Comparative Example 4 omitted the ultraviolet treatment step, shortened the time of contact between the liquid and air, and reduced oxidative browning and loss of active ingredients to a certain extent.

[0089] (6) Comparative Example 5, which was not subjected to ultrasonic treatment, showed significantly lower sterilization rates, vitamin C levels, and total phenol levels compared to Example 2. Simultaneously, its browning rate increased, indicating that ultrasonic treatment has a positive effect on killing microorganisms, inhibiting browning, and retaining heat-sensitive components. This is because the high-frequency vibrations and cavitation effects generated by ultrasound can disrupt the microbial cell structure, deactivate oxidase activity, and remove dissolved oxygen from the feed solution, thereby improving sterilization efficiency and reducing enzymatic browning and oxidative loss of active ingredients.

[0090] (7) Comparative Example 6, which was not subjected to heat treatment, had significantly reduced sterilization rate and browning rate, and increased vitamin C and total phenol content. This indicates that non-heat treatment can effectively avoid browning of the liquid and destruction of heat-sensitive components, but it is difficult to achieve efficient sterilization.

[0091] (8) Comparative Examples 1 to 3 were all treated with a single sterilization method, and the sterilization rate was significantly lower than that of other comparative examples and Example 2. This is because the three sterilization conditions are relatively mild, and a single treatment method is difficult to kill microorganisms efficiently. However, the combination of different treatment methods can achieve synergistic effect of sterilization.

[0092] (9) Comparative Example 7 is a traditional high-temperature sterilization method, which is widely used because of its high sterilization efficiency and simple operation. However, compared with Example 2, the browning rate of the treated liquid increased by about 2.5 times, the vitamin C content decreased by about 30.5%, the total phenol content decreased by about 42.0%, and the appearance and nutritional quality of the product decreased significantly.

[0093] (10) In summary, the ultrasonic-ultraviolet combined sterilization method and equipment for pasteurizing mango juice of the present invention can achieve efficient sterilization while effectively reducing the adverse effects of sterilization on heat-sensitive active ingredients and color in the raw materials.

[0094] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0095] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice, characterized in that, include: The frame (8) and the sterilization tank connected to the frame (8) are equipped with a heating device for heat exchange, which is used to pasteurize the material in the sterilization tank. The sterilization tank is equipped with an ultrasonic component, which is used to sterilize the material inside the sterilization tank using ultrasonic sterilization. The first discharge port (10) of the sterilization tank is connected to the feed end of the ultraviolet sterilization component, which is used to sterilize the material flowing through it with ultraviolet light. The feeding port (13) of the sterilization tank is connected to the feeding pump through a pipe; The feed pump is used to pump mango juice into the sterilization tank; It also includes three independent sterilization modes: pasteurization, ultrasonic sterilization, and ultraviolet sterilization. It also includes four combined sterilization modes, namely pasteurization ultrasonic sterilization mode, pasteurization ultraviolet sterilization mode, ultrasonic ultraviolet sterilization mode and pasteurization ultrasonic ultraviolet sterilization mode.

2. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 1, characterized in that, The ultrasonic component has one or more.

3. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 1, characterized in that, The ultrasonic component includes a tool head (6), an amplitude transformer (2), and a transducer (1). The transducer (1) is fixed to the top of the sterilization tank. The top end of the amplitude transformer (2) is fixed to the output end of the transducer (1), and the amplitude transformer (2) is located inside the sterilization tank. The tool head (6) is fixed to the bottom end of the amplitude transformer (2).

4. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 3, characterized in that, The distance between the tool head (6) and the material liquid surface is 20~30cm.

5. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 1, characterized in that, The heating device includes a first outer shell (4) fitted on the outside of the sterilization tank, and the outside of the first outer shell (4) is covered with a heat insulation layer (3); A gap is provided between the first outer shell (4) and the outer wall of the sterilization tank, and a cavity for storing heat-conducting liquid is formed between the inner wall of the first outer shell (4) and the outer wall of the sterilization tank; The cavity is connected to a heat transfer fluid inlet (14) and a heat transfer fluid outlet (7). The cavity is equipped with at least one heating rod; A temperature probe (11) is connected inside the discharge end of the sterilization tank.

6. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 5, characterized in that, The first outer shell (4) is fixed to the frame (8) by a support frame (5).

7. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 1, characterized in that, The ultraviolet sterilization component includes a second outer shell (18), which is fixed to the frame (8); The ultraviolet disinfection unit is fixed inside the second outer casing (18); The second housing (18) contains a feed pump (15) and a quartz tube (16). One end of the quartz tube (16) is connected to the discharge end of the feed pump (15), and the other end of the feed pump (15) is connected to the first discharge port (10). The light emitted by the ultraviolet disinfection unit shines on the quartz tube (16); The other end of the quartz tube (16) passes through the side wall of the second outer shell (18) and is connected to the second discharge port (25).

8. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 7, characterized in that, The ultraviolet disinfection unit includes an electrodeless lamp (19), an electromagnetic resonant cavity (20), a magnetron (21), a driving power supply (22), and a microwave transmitting antenna (23).

9. The ultrasonic-ultraviolet combined sterilization equipment for pasteurizing mango juice according to claim 7, characterized in that, The control panel (24) and the observation window (17) are fixed on the second outer shell (18).

10. A method of using an ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice, comprising using the ultrasonic-ultraviolet combined sterilization device for pasteurizing mango juice as described in any one of claims 1-9, characterized in that, Includes the following steps: Prepare mango juice; The mango juice is injected into the sterilization tank via the feed pump; The pasteurized ultrasonic ultraviolet sterilization mode is activated to sterilize the mango juice once. The mango juice, which has undergone one sterilization, is injected back into the sterilization tank through the feeding pump, and a second sterilization is performed by selecting the pasteurization mode, the ultrasonic sterilization mode, the ultraviolet sterilization mode, the pasteurization-ultrasonic sterilization mode, the pasteurization-ultraviolet sterilization mode, the ultrasonic-ultraviolet sterilization mode, or the pasteurization-ultrasonic-ultraviolet sterilization mode.

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