Medlar vacuum drying method capable of preventing nutrition loss

Abstract

The invention relates to the technical field of food processing, and provides a Chinese wolfberry vacuum drying method capable of preventing nutrition loss, which comprises the following steps: S1, pretreatment; s2, initial drying; s3, an equipment using step; s4, a drying process; s5, a post-treatment stage; s6, auxiliary functions; through a humidity sensor, a pressure sensor and an intelligent control system, vacuum degree, temperature and pulsation parameters are monitored in real time and dynamically adjusted to adapt to wolfberry characteristics (moisture diffusion rate and heat resistance) in different drying stages, accurate drying of multi-physics field coupling is achieved, and the problems that traditional equipment is rigid in parameter and poor in adaptability are solved; the material transfer link is reduced through integrated equipment integration, and secondary pollution is avoided; nitrogen-filled packaging is combined with inert gas protection to further inhibit oxidative deterioration, meanwhile, equipment modular design (such as a speed-adjustable stirring device and an automatic feeding and discharging system) simplifies the operation process, the labor cost is reduced, and an efficient and low-consumption solution is provided for industrial production of the dried Chinese wolfberry fruits.

Description

Technical Field

[0001] The present invention relates to the technical field of food processing, and specifically to a vacuum drying method for wolfberries to prevent nutrient loss. Background Art

[0002] As an important economic crop with both medicinal and edible uses, the drying and processing quality of wolfberries directly affects the nutritional value and commercial value of the products. The following technical bottlenecks in current industrial production need to be urgently broken through:

[0003] 1. Inherent defects of traditional drying processes

[0004] Although the natural sun-drying method has a relatively low cost, it is greatly affected by environmental climate, has a long drying cycle, and wolfberries are easily contaminated by dust, microorganisms, etc. during this period. Moreover, the drying conditions cannot be accurately controlled, resulting in a large loss of nutrients such as vitamins, flavonoids, and polysaccharides in wolfberries. At the same time, the color and appearance quality of the fruits are difficult to guarantee, and there may also be mildew losses due to factors such as rainfall. Although hot air drying can shorten the drying time to a certain extent, there are problems such as a relatively high drying temperature and difficulty in uniform control. The high temperature seriously damages heat-sensitive nutrients such as vitamin C inside the wolfberries. At the same time, the excessive temperature may also trigger adverse chemical reactions such as the Maillard reaction, changing the flavor and taste of the wolfberries, making the fruit color darker and duller, and having a relatively high energy consumption, making it difficult to balance drying efficiency and quality;

[0005] 2. Insufficient integration of equipment systems

[0006] In the current vacuum system drying process, a constant vacuum degree and heating temperature are often used, and it is difficult to dynamically adjust according to the actual drying characteristics of wolfberries. In different drying stages of wolfberries, the moisture diffusion rate, heat resistance, etc. are all different. The constant drying conditions are likely to result in a slow drying speed in the early stage and may affect the quality due to overheating in the later stage, and it is impossible to achieve an efficient and high-quality drying effect;

[0007] 3. Lag in research on nutrient retention mechanisms

[0008] The vacuum acquisition and maintenance systems of ordinary vacuum drying equipment are relatively simple, and the stability and accuracy of the vacuum degree are poor. This not only affects the drying efficiency but may also cause uneven evaporation of the surface moisture of wolfberries due to vacuum fluctuations, resulting in local over-drying or under-drying phenomena, thereby affecting the overall quality and the degree of retention of nutrients.

[0009] Therefore, developing an intelligent vacuum drying system based on dynamic parameter regulation and constructing a precise drying model coupled with multiple physical fields have become the key technological breakthrough directions for improving the processing quality of wolfberries. Summary of the Invention

[0010] The invention provides a wolfberry vacuum drying method for preventing nutrient loss. The method adopts a composite vacuum system (Roots+Roots+screw pump group) and dynamic parameter regulation to quickly establish a high vacuum environment and stably maintain it, shorten the drying cycle, reduce energy consumption, and accelerate moisture migration through periodic pressure fluctuations in a vacuum pulsation program. Combined with segmented temperature control, drying efficiency and quality are taken into account, breaking through the bottleneck of slow speed and high energy consumption of traditional constant vacuum drying. Customized equipment design (carbon steel freeze-drying bin, ambient temperature mechanical heating system) ensures that materials are heated evenly to avoid local overheating or uneven drying. Multi-layer insulation materials reduce heat loss. An intelligent temperature control device adjusts the heating power in real time to accurately control the moisture content and drying uniformity of wolfberry dried fruit. The product has bright red color and is free of stratification, mildew or skin cracking, thereby extending the storage period of the product to solve the problems raised in the background technology.

[0011] The technical solution of the present invention is as follows:

[0012] A method for vacuum drying wolfberries to prevent nutrient loss comprises the following steps:

[0013] S1. Pretreatment: Select high-quality wolfberry fruits that are well-matured, free of pests and mildew, rinse gently with clean water to remove dust, impurities and residual pesticides on the surface, then drain the water and evenly spread them on a well-ventilated tray to prepare for drying;

[0014] S2, initial stage of drying: placing the tray containing fresh wolfberry fruits into the freeze-drying chamber of the special vacuum drying equipment of the present invention, closing the chamber door, and starting the equipment;

[0015] S3. Equipment use steps: first turn on the vacuum pump group to quickly form a certain vacuum degree in the freeze-drying chamber (the initial vacuum degree can be controlled between 80-300Pa, and the specific value can be flexibly adjusted according to the actual equipment performance and the initial moisture content of wolfberry);

[0016] Then start the ambient temperature mechanical heating system to slowly heat the freeze-drying chamber, control the heating temperature within an appropriate range (30°C-50°C), and start the vacuum pulsation program at the same time;

[0017] S4, Drying process: Continuously monitor the key parameters of wolfberry such as moisture content and temperature, and dynamically adjust the heating temperature, vacuum degree and vacuum pulsation parameters according to real-time data feedback to ensure that wolfberry can be in the best drying environment at each drying stage until the moisture content of wolfberry reaches the safe storage requirement (controlled at about 10%-15%), and the drying operation is completed;

[0018] S5. Post - processing stage: After drying is completed, first stop the heating and vacuum pulsation programs, slowly fill the freeze - drying chamber with inert gas to restore normal air pressure in the chamber, then open the chamber door, take out the dried goji berries, and perform packaging and storage. During the packaging process, methods such as nitrogen - filled packaging are used to further extend the shelf life.

[0019] S6. Auxiliary functions: Other auxiliary functions are made according to the standards of freeze - drying equipment. For example, an automated material transfer device is equipped to facilitate the feeding and discharging operations of fresh goji berries.

[0020] As a technical solution of the present invention, the freeze - drying chamber in S2 is made of carbon steel. Carbon steel has good strength and corrosion resistance, can withstand a certain pressure difference, ensure the structural integrity and sealing of the chamber in a vacuum environment, and provide a stable space environment for goji berry drying. The internal shape of the chamber is designed as a regular square or circle, which is conducive to the uniform heating of materials and gas circulation. At the same time, it is equipped with multiple layers of heat - insulating materials to reduce heat loss and improve energy utilization efficiency.

[0021] As a technical solution of the present invention, the special vacuum drying equipment in S2 adopts a vacuum pulsation drying program. That is, during the drying process, through an accurate control system, the vacuum degree in the freeze - drying chamber is periodically changed to fluctuate within a certain range (on the basis of the basic vacuum degree, the vacuum degree is briefly increased every once in a while and then restored to the basic vacuum degree. Specific pulsation frequency, amplitude and other parameters can be optimized and adjusted according to factors such as the variety, quantity, and initial moisture content of goji berries). This vacuum pulsation operation can effectively promote the diffusion and evaporation of moisture inside goji berries, achieve high - efficiency drying at a lower temperature, and minimize the damage to heat - sensitive nutrients to the greatest extent.

[0022] As a technical solution of the present invention, the vacuum system in the special vacuum drying equipment in S2 adopts a combined vacuum pump group of Roots + Roots + screw. This configuration can quickly and efficiently obtain a high vacuum degree and can stably maintain the required vacuum environment during the drying process, meeting the precise control requirements of the vacuum pulsation drying process for the vacuum degree.

[0023] Through reasonable pipeline layout and valve control, the coordinated operation of different vacuum pumps is realized to ensure the reliability and stability of the vacuum system. At the same time, a vacuum sensor is equipped to monitor the vacuum degree in the chamber in real time and feed the data back to the control system for timely adjustment of vacuum - related parameters.

[0024] As a technical solution of the present invention, in step S2, the special vacuum drying equipment of the present invention is provided with an observation window for facilitating the observation of the drying condition of goji berries in the chamber at any time, and is equipped with a variety of monitoring components such as humidity sensors and pressure sensors to real-time master environmental parameters such as humidity and pressure in the chamber, providing data support for the precise control of the drying process. At the same time, it also has good electrical safety protection functions and fault alarm functions to ensure the safety and stability of the equipment operation.

[0025] As a technical solution of the present invention, in step S3, the ambient temperature mechanical heating system is an ambient temperature mechanical heating method, which realizes the uniform heating of the air inside the chamber through the heating elements surrounding the freeze-drying chamber, avoiding local overheating or uneven temperature, ensuring that the goji berries are evenly heated during the drying process, and being beneficial to maintaining the stability of their quality and nutritional components.

[0026] The heating system is equipped with an intelligent temperature control device, which can automatically adjust the heating power according to the set temperature parameters and the real-time monitored temperature in the chamber to precisely control the heating temperature.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. Through the innovative vacuum pulsation drying process (periodically changing the vacuum degree), the present invention accelerates the diffusion and evaporation of moisture under low-temperature conditions, avoiding the damage of heat-sensitive components by high temperature, and effectively solving the core problem of serious nutrient loss caused by traditional processes.

[0029] 2. By adopting a compound vacuum system (Roots + Roots + screw pump group) and dynamic parameter regulation, the present invention quickly establishes a high-vacuum environment and stably maintains it, shortens the drying cycle, reduces energy consumption. The vacuum pulsation program accelerates moisture migration through periodic pressure fluctuations, and cooperates with segmented temperature control to take into account both drying efficiency and quality, breaking through the bottleneck of slow drying speed and high energy consumption of traditional constant vacuum drying; and through customized equipment design (carbon steel freeze-drying chamber, ambient temperature mechanical heating system), it ensures that the material is evenly heated, avoids local overheating or uneven drying, and the multi-layer heat insulation material reduces heat loss. The intelligent temperature control device adjusts the heating power in real time to precisely control the moisture content and drying uniformity of goji berry dried fruits. The product has a bright red color, no stratification, mildew or skin cracking phenomenon, thereby extending the storage period of the product.

[0030] 3. Through a humidity sensor, a pressure sensor and an intelligent control system, the present invention monitors in real time and dynamically adjusts the vacuum degree, temperature and pulsation parameters (such as frequency, amplitude), adapts to the characteristics of wolfberries in different drying stages (moisture diffusion rate, heat resistance), realizes precise drying with multi-physical field coupling, and solves the problems of rigid parameters and poor adaptability of traditional equipment; the integrated equipment integration (low-temperature crushing, vacuum pulsation drying, nitrogen filling packaging) reduces the material transfer link and avoids secondary pollution; the nitrogen filling packaging combined with inert gas protection further inhibits oxidation and deterioration. At the same time, the modular design of the equipment (such as adjustable-speed stirring device, automatic feeding and discharging system) simplifies the operation process, reduces labor costs, and provides an efficient and low-consumption solution for the industrial production of dried wolfberries. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a flowchart of the method of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following further describes in detail the embodiments of the present invention in conjunction with the drawings. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0033] Example 1

[0034] 1. Pretreatment: Select high-quality fresh wolfberries with good maturity, no pests and diseases, and no mildew (such as a moisture content of 75%), rinse them with clean water, drain them, and evenly spread them on a breathable tray (single-layer thickness ≤ 5 mm);

[0035] 2. Initial drying stage: Place the tray into a carbon steel freeze-drying chamber body, set the initial vacuum degree to 80 Pa, and start the equipment;

[0036] 3. Equipment operation: Turn on the Roots + Roots + screw vacuum pump group, and stabilize the vacuum degree to 80 Pa within 10 minutes;

[0037] Start the ambient temperature mechanical heating system and heat it to 30°C - 40°C;

[0038] 4. Vacuum pulsation program: Increase the vacuum degree to 150 Pa every 10 minutes, and maintain it for 3 minutes before returning to 80 Pa;

[0039] 5. Drying process: Monitor in real time through a humidity sensor and dynamically adjust the parameters until the moisture content is dried to 12%;

[0040] 6. Post-treatment: Restore the air pressure with nitrogen, take out the dried wolfberries, and use nitrogen filling packaging (nitrogen purity ≥ 99.9%).

[0041] Example 2

[0042] 1. Pretreatment: Select high-quality fresh goji berries with good maturity, no pests, diseases or mildew (such as a moisture content of 75%), rinse them with clean water, drain, and evenly spread them on a breathable tray (single-layer thickness ≤ 5 mm);

[0043] 2. Initial drying: Place the tray into a carbon steel freeze-drying chamber, set the initial vacuum degree to 100 Pa, heat the chamber to 35 °C, and start the equipment;

[0044] 3. Equipment operation: Turn on the Roots + Roots + screw vacuum pump group, and stabilize the vacuum degree to 100 Pa within 15 minutes;

[0045] Start the ambient temperature mechanical heating system and heat it to 40 °C - 50 °C;

[0046] 4. Vacuum pulsation program: Increase the vacuum degree to 150 Pa every 10 minutes, and after 3 minutes, restore it to 100 Pa;

[0047] 5. Drying process: Monitor in real time through a humidity sensor, dynamically adjust the parameters, and dry until the moisture content reaches 10%;

[0048] 6. Post-treatment: Restore the air pressure by filling with nitrogen, take out the dried goji berries, and use nitrogen-filled packaging (nitrogen purity ≥ 99.9%).

[0049] Example 3

[0050] 1. Pretreatment: Select high-quality fresh goji berries with good maturity, no pests, diseases or mildew (such as a moisture content of 75%), rinse them with clean water, drain, and evenly spread them on a breathable tray (single-layer thickness ≤ 5 mm);

[0051] 2. Initial drying: Place the tray into a carbon steel freeze-drying chamber, set the initial vacuum degree to 120 Pa, heat the chamber to 35 °C, and start the equipment;

[0052] 3. Equipment operation: Turn on the Roots + Roots + screw vacuum pump group, and stabilize the vacuum degree to 120 Pa within 15 minutes;

[0053] Start the ambient temperature mechanical heating system and heat it to 40 °C - 50 °C;

[0054] 4. Vacuum pulsation program: Increase the vacuum degree to 150 Pa every 10 minutes, and after 3 minutes, restore it to 120 Pa;

[0055] 5. Drying process: Monitor in real time through a humidity sensor, dynamically adjust the parameters, and dry until the moisture content reaches 10%;

[0056] 6. Post-treatment: Restore the air pressure by filling with nitrogen, take out the dried goji berries, and use nitrogen-filled packaging (nitrogen purity ≥ 99.9%).

[0057] Comparative Example 1

[0058] 1. Pretreatment: same as Example 1;

[0059] 2. Drying: Continuously dry for 12 hours with a hot air dryer (70°C);

[0060] 3. Post-treatment: Seal and package with a common PE bag.

[0061] Comparative Example 2

[0062] 1. Pretreatment: same as Example 1;

[0063] 2. Equipment: Single-screw vacuum pump (fixed vacuum degree of 100 Pa), heating temperature of 45°C;

[0064] 3. Drying process: Without vacuum pulsation regulation, dry until the moisture content reaches 15%.

[0065] Wolfberry quality inspection process

[0066] Detection steps for the retention rate of ORAC value:

[0067] 1. Sample preparation

[0068] Raw material and finished product extraction:

[0069] Take fresh wolfberries and dried wolfberry fruits, and grind them into powder.

[0070] Extract active ingredients (such as polysaccharides, flavonoids, etc.) with methanol, ethanol or water, take the supernatant after centrifugation, and filter for standby.

[0071] 2. Reagent preparation

[0072] Free radical source: AAPH solution (final concentration of about 20 mM).

[0073] Fluorescent probe: Sodium fluorescein solution (final concentration of about 70 nM).

[0074] Standard: Trolox (a water-soluble vitamin E analogue), used to make a standard curve.

[0075] 3. Reaction system establishment

[0076] Microplate method (taking a 96-well plate as an example):

[0077] Blank well: Fluorescein + AAPH + buffer (without sample).

[0078] Sample well: Fluorescein + AAPH + sample extract.

[0079] Standard well: Fluorescein + AAPH + Trolox gradient concentration solution.

[0080] 4. Real-time monitoring

[0081] Using a fluorescence spectrophotometer or a microplate reader, record the fluorescence intensity every 1 - 2 minutes at an excitation wavelength of 485 nm and an emission wavelength of 520 nm for 1 - 2 hours.

[0082] Detection steps for vitamin C retention rate:

[0083] 1. Sample preparation

[0084] Treatment of fresh wolfberries: Take fresh wolfberry fruits (such as 100 g), remove impurities, and quickly chop or homogenize them;

[0085] Add an extraction solution containing 1% metaphosphoric acid (stabilizer) (such as 2% oxalic acid solution) to prevent the oxidation of vitamin C;

[0086] Centrifuge (8000 rpm, 10 minutes), take the supernatant, and filter (0.45 μm filter membrane) for standby.

[0087] Treatment of dried wolfberries: Take dried wolfberry fruits (such as 10 g) and grind them into powder;

[0088] Extract vitamin C according to the above method to prepare the test solution.

[0089] 2. Reagents and instruments

[0090] Reagents: Ascorbic acid standard (purity ≥ 99%), metaphosphoric acid (analytical grade), oxalic acid solution (2%), mobile phase (methanol: 0.1% phosphoric acid aqueous solution = 5:95, pH 2.5);

[0091] Instruments: High - performance liquid chromatograph (equipped with an ultraviolet detector);

[0092] Chromatographic column: C18 reversed - phase column (250 mm × 4.6 mm, 5 μm);

[0093] Centrifuge, ultrasonic extractor.

[0094] 3. Standard curve drawing

[0095] Prepare ascorbic acid standard solution (0.1 - 100 μg / mL);

[0096] Inject for analysis, record the peak area, and draw the concentration - peak area standard curve (linear range R > 0.999).

[0097] 4. HPLC detection conditions

[0098] Flow rate: 1.0 mL / min;

[0099] Detection wavelength: 245 nm;

[0100] Column temperature: 30 °C;

[0101] Sample injection volume: 20 μL.

[0102] 5. Sample detection

[0103] Inject the extracts of fresh wolfberries and dried wolfberries for analysis respectively, record the peak areas of ascorbic acid, and calculate the concentration through the standard curve.

[0104] Detection steps for polysaccharide retention rate:

[0105] 1. Sample preparation

[0106] Extraction of polysaccharides from fresh wolfberries:

[0107] Take fresh wolfberry fruits (such as 50 g), chop them and add 10 times the volume of distilled water, extract in a boiling water bath for 2 hours;

[0108] Centrifuge (4000 rpm, 15 minutes), and take the supernatant;

[0109] Add 4 times the volume of absolute ethanol to precipitate the polysaccharides, let it stand overnight, centrifuge and collect the precipitate, and freeze-dry to obtain the crude polysaccharide.

[0110] Extraction of polysaccharides from dried wolfberries:

[0111] Take dried wolfberry fruits (such as 10 g), pulverize them and extract polysaccharides by the above method.

[0112] 2. Reagents and instruments

[0113] Reagents: Glucose standard (purity ≥ 99%), concentrated sulfuric acid (analytical grade), phenol (5% aqueous solution), absolute ethanol, distilled water.

[0114] Instruments: UV-visible spectrophotometer, centrifuge, constant temperature water bath, analytical balance.

[0115] 3. Standard curve plotting

[0116] Prepare a glucose standard solution (0.1 - 1.0 mg / mL);

[0117] Take 1 mL of the standard solution, add 1 mL of 5% phenol solution, quickly add 5 mL of concentrated sulfuric acid, shake well and let it stand for 30 minutes;

[0118] Measure the absorbance at 490 nm and plot the concentration-absorbance standard curve (linear range R > 0.999).

[0119] 4. Sample determination

[0120] Dissolve the crude polysaccharides of fresh wolfberries and dried wolfberries in distilled water and dilute to an appropriate concentration;

[0121] Take 1 mL of the sample solution, develop the color and measure the absorbance according to the standard curve procedure;

[0122] Calculate the polysaccharide content (calculated as glucose) according to the standard curve.

[0123] The product quality only needs to be observed by the staff.

[0124]

[0125]

[0126] In the above Examples 1-3, through the innovative vacuum pulsation drying process, the moisture diffusion and evaporation are accelerated under low-temperature conditions, avoiding the destruction of heat-sensitive nutrients in goji berries by high temperature, significantly improving the nutrient retention rate, and adopting a compound vacuum system and dynamic parameter regulation technology to quickly establish and stably maintain a high-vacuum environment, shortening the drying cycle, reducing energy consumption, and simultaneously achieving a double improvement in drying efficiency and quality. At the same time, the customized equipment design ensures uniform heating of goji berries during the drying process, avoiding problems such as local overheating or uneven drying. After drying, the goji berry dried fruits have bright colors, a high nutrient retention rate, and relatively high retention degrees of ORAC value, vitamin C retention rate, and polysaccharide retention rate. The product has a bright red color (L* value ≥ 45), no stratification or mildew, and the drying cycle is shortened to 8 hours. In Comparative Examples 1-2, uneven drying caused by high-temperature drying and constant vacuum degree and heating temperature affects the product quality. Compared with the method of the present invention, the nutrient retention rate is lower, the drying cycle is longer, and the energy consumption is relatively higher.

[0127] The embodiments of the present invention are given for the purposes of illustration and description. Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A vacuum drying method for wolfberries to prevent nutrient loss, characterized in that, It includes the following steps: S1. Pretreatment: Select high-quality wolfberry fresh fruits with good maturity, no pests, diseases or mildew. Gently rinse them with clean water to remove the dust, impurities and residual pesticides on the surface, then drain the water, and evenly spread them on a well-ventilated tray to prepare for the drying operation. S2. Initial drying stage: Place the tray with wolfberry fresh fruits into the freeze-drying chamber of the special vacuum drying equipment of the present invention, close the chamber door, and start the equipment. S3. Equipment operation steps: First, turn on the vacuum pump group to quickly form a certain vacuum degree basis in the freeze-drying chamber. Then start the ambient temperature mechanical heating system to slowly heat the freeze-drying chamber, control the heating temperature within an appropriate range, and at the same time start the vacuum pulsation program. S4. Drying process: Continuously monitor the key parameters of the moisture content and temperature of the wolfberries. According to the real-time data feedback, dynamically adjust the heating temperature, vacuum degree and parameters of the vacuum pulsation to ensure that the wolfberries can be in the best drying environment at each drying stage until the moisture content of the wolfberries reaches the safe storage requirement, and complete the drying operation. S5. Post-treatment stage: After drying, first stop the heating and vacuum pulsation programs, slowly fill the freeze-drying chamber with inert gas to restore the normal air pressure in the chamber, then open the chamber door, take out the dried wolfberry fruits, and perform packaging and storage. During the packaging process, the nitrogen filling packaging method is used to further extend the shelf life. S6. Auxiliary functions: Make other auxiliary functions according to the freeze-drying equipment standards, such as being equipped with an automated material transfer device to facilitate the feeding and discharging operations of wolfberry fresh fruits.

2. The vacuum drying method of goji berries for preventing nutrient loss according to claim 1, characterized in that: The freeze-drying chamber in S2 is made of carbon steel.

3. The vacuum drying method of wolfberries for preventing nutrient loss according to claim 1, characterized in that: The special vacuum drying equipment in S2 adopts a vacuum pulsation drying program, that is, during the drying process, through an accurate control system, the vacuum degree in the freeze-drying chamber is periodically changed to make it fluctuate within a certain range.

4. The vacuum drying method of goji berries for preventing nutrient loss according to claim 1, wherein: The vacuum system in the special vacuum drying equipment in S2 adopts a combined vacuum pump group of Roots + Roots + screw. Through reasonable pipeline layout and valve control, the coordinated work between different vacuum pumps is realized to ensure the reliability and stability of the vacuum system. At the same time, a vacuum sensor is equipped to monitor the vacuum degree in the chamber in real time and feed the data back to the control system for timely adjustment of the vacuum-related parameters.

5. The method for vacuum drying wolfberries to prevent nutrient loss as described in claim 1, characterized in that: The special vacuum drying equipment of the present invention in S2 should be provided with an observation window, and various monitoring elements such as a humidity sensor and a pressure sensor are installed. At the same time, it also has good electrical safety protection functions and fault alarm functions.

6. The method for vacuum drying Chinese wolfberries to prevent nutrient loss according to claim 1, characterized in that: The ambient temperature mechanical heating system in S3 is of the ambient temperature mechanical heating method. Through the heating elements surrounding the freeze-drying chamber, the uniform heating of the air inside the chamber is realized, avoiding the situation of local overheating or uneven temperature. The heating system is equipped with an intelligent temperature control device, which can automatically adjust the heating power according to the set temperature parameters and the temperature in the chamber monitored in real time, and accurately control the heating temperature.

Images