Multi-stage synergistic energy-saving synergistic type waxberry freeze-drying processing method

Abstract

The invention relates to a multi-stage synergistic energy-saving synergistic type waxberry freeze-drying processing method, and belongs to the technical field of agricultural product processing. The multi-stage synergistic energy-saving synergistic waxberry freeze-drying processing method provided by the invention comprises the following steps: selecting fresh waxberries which are uniform in size, color and luster, consistent in maturity and free of mechanical damage on the surface, firstly, performing ultrasonic synergistic subacid electrolyzed water cleaning, secondly, performing freeze-thaw cycle combined intensive pulse light pretreatment, and finally, performing freeze-drying. And carrying out variable-temperature vacuum freeze drying again, and finally, carrying out intensive pulse light treatment on the dried product to obtain the waxberry product. Multi-stage physical fields such as ultrasonic cavitation, freeze-thaw phase change, light energy sterilization and variable-temperature mass transfer are coordinated for the first time, the problems that a traditional waxberry drying processing technology is low in efficiency, poor in quality and high in safety risk are solved, a reusable technical normal form is provided for green manufacturing of agricultural products, and the industrial competitiveness and the sustainable development capacity are remarkably improved.

Description

Technical Field

[0001] This invention relates to a multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries, belonging to the field of agricultural product processing technology. Background Technology

[0002] Waxberries (Myrica rubra Seib & Zucc.), a specialty fruit of southeastern my country, are sweet and sour, and rich in bioactive components such as total phenols, anthocyanins, and ascorbic acid, making them popular with consumers. However, the fresh waxberry harvest season is short and concentrated, with a post-harvest storage period of only 3-5 days, making them susceptible to external damage, with spoilage rates reaching 20-30%. Freeze-drying technology can effectively inhibit the spoilage of fresh waxberries, eliminating their seasonality, allowing for immediate use, and preserving excellent product quality.

[0003] However, traditional freeze-drying processes for bayberries generally suffer from prominent problems such as high water consumption, high energy consumption, low efficiency, and low quality. These problems mainly occur in the washing, drying, and sterilization of dried bayberries: (1) In the washing process, due to the "protrusion-like" structure on the surface of bayberries, external impurities are easily left behind. The traditional water rinsing method has a high water consumption per unit and the microbial content exceeds the standard. Although ozone or sodium hypochlorite treatment can reduce the number of microorganisms, due to their strong oxidizing properties, it is easy to cause changes in the color of the peel and the sterilization effect is difficult to last. (2) In the freeze-drying process, low-temperature (-18℃) freeze-drying takes about 225 hours and consumes nearly 3600 kWh / t of energy. Although room temperature (25℃) freeze-drying can be shortened to about 70 hours, due to uneven water migration, the product volume shrinkage rate exceeds 40%, and the color difference is serious, making it difficult to balance production efficiency and quality. (3) In the sterilization process of dried products, because freeze-drying maintains microbial activity well, it often leads to excessive microbial content in the final freeze-dried product, resulting in food safety issues.

[0004] In summary, the current freeze-drying process for bayberries operates independently at each stage, lacking a coordinated, green, efficient, and high-quality processing system. There is an urgent need for a systematic solution that can achieve energy conservation and efficiency improvement, thereby contributing to the high-quality development of the bayberry freeze-drying processing industry. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a multi-stage synergistic energy-saving and efficiency-enhancing method for freeze-drying bayberries, specifically including the following steps:

[0006] (1) Whole fruit sorting: Select fresh bayberries that are uniform in size and color, consistent in maturity, and free from mechanical damage on the surface;

[0007] (2) Ultrasonic synergistic cleaning with slightly acidic electrolyzed water: The bayberries selected in step (1) are mixed with slightly acidic electrolyzed water. After mixing, the mixture is first subjected to ultrasonic treatment, and then stirred to obtain cleaned bayberries.

[0008] (3) Freeze-thaw cycle combined with pulsed intense light pretreatment: The bayberries cleaned in step (2) are subjected to freeze-thaw pretreatment, and then subjected to the first pulsed intense light pretreatment to obtain pretreated bayberries; the freeze-thaw pretreatment step is to freeze and then thaw.

[0009] (4) Variable temperature vacuum freeze drying: The bayberries pretreated in step (3) are frozen again, and then transferred to a vacuum freeze dryer. The vacuum degree, cold trap temperature and variable temperature main drying program are set to carry out freeze drying treatment until the drying endpoint is reached, that is, the dry basis moisture content is ≤5% and the drying is stopped to obtain freeze-dried bayberries.

[0010] (5) Pulse intense light treatment of dried products: The freeze-dried bayberries obtained in step (4) are subjected to a second pulse intense light treatment to finally obtain freeze-dried bayberry products.

[0011] Furthermore, in step (2), the effective chlorine concentration of the slightly acidic electrolyzed water is 20-50 mg / L, and the temperature is 25℃; the ratio of bayberry to slightly acidic electrolyzed water is 1:5 (g / mL).

[0012] Furthermore, the conditions for ultrasonic treatment in step (2) are: ultrasonic power density of 50W / L, frequency of 40kHz, and time of 10-50s; stirring speed of 120rpm and time of 430-470s.

[0013] Furthermore, the freeze-thaw pretreatment in step (3) is performed 1-3 times; the freezing conditions in the freeze-thaw pretreatment are -20℃ for 2 hours, and the thawing conditions are 25℃ for 2 hours.

[0014] Furthermore, the parameters for the first pulsed high-intensity light preprocessing in step (3) are: intensity 600-1000 mJ / cm². 2 The processing distance is 4-8cm (distance from the light source to the material), and the flashing is performed 5-15 times.

[0015] Furthermore, in step (4), the conditions for refreezing are: freezing at -20℃ for 4 hours; the vacuum degree is 0.518 mbar and the cold trap temperature is -65℃; the variable temperature main drying program is: heating from -20℃ to 25℃ at a rate of 0.5-2℃ / 2.6h, and maintaining at 25℃ until the drying endpoint is reached.

[0016] Furthermore, in step (4), the volatile water collected by the cold trap during the freeze-drying process is used for the backwashing step.

[0017] Furthermore, the parameters for the second pulsed high-intensity light treatment in step (5) are: intensity 600-1000 mJ / cm². 2The processing distance is 4-8cm (distance from the light source to the material), and the flashing frequency is 15-25 times.

[0018] The beneficial effects of this invention are:

[0019] (1) The present invention proposes a “cleaning-drying” water circulation technology: applying ultrasonic waves to the cleaning process after the harvest of bayberries to enhance cleaning efficiency; the material evaporation water generated during drying is collected by a cold trap and reused in the cleaning process to greatly save water resources.

[0020] (2) This invention proposes a three-point integrated energy-saving and consumption-reducing technology: the cavitation effect of ultrasound can improve the cell permeability of bayberry; the freeze-thaw cycle pretreatment destroys the cell structure of bayberry, reduces the water diffusion barrier and reduces the initial water load; the variable temperature drying mode improves the freeze-drying heat transfer efficiency; the three together shorten the freeze-drying processing time and effectively reduce energy consumption.

[0021] (3) The present invention proposes a whole-process sterilization and control technology: in the cleaning stage, ultrasonic combined with slightly acidic electrolyzed water is used to complete the first sterilization; in the pretreatment stage, freeze-thaw cycle combined with pulsed light pretreatment is used to complete the second sterilization; in the sterilization stage, pulsed light treatment is used to complete the third sterilization.

[0022] In summary, this invention innovatively combines ultrasonic synergistic slightly acidic electrolytic water cleaning, freeze-thaw cycle combined with pulsed intense light pretreatment, variable-temperature vacuum freeze-drying, and pulsed intense light treatment of dried products. This achieves water savings of 87.70%, time reduction of 78.70%, and energy savings of 75.00%, while simultaneously reducing the total bacterial count of bayberry products by 66.67%, mold and yeast count by 75.00%, ΔE value by 77.60%, and anthocyanin retention rate by 42.88%, demonstrating substantial technical effectiveness. Furthermore, the various technical elements are synergistic and irreplaceable, not simply a procedural additive process; otherwise, performance indicators would be significantly degraded, failing to achieve the desired technical effects. Detailed Implementation

[0023] The present invention will now be described in detail, but it is not limited to these embodiments. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These modifications and improvements all fall within the scope of protection of the present invention.

[0024] Example 1:

[0025] A multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries includes the following steps:

[0026] (1) Whole fruit sorting: Select fresh bayberries that are uniform in size and color, consistent in maturity, and free from mechanical damage on the surface.

[0027] (2) Ultrasonic synergistic cleaning with slightly acidic electrolyzed water: Selected bayberries were mixed with slightly acidic electrolyzed water (25℃, available chlorine 40mg / L) at a material-to-liquid ratio of 1:5 (kg / L); treated for 30s under ultrasonic power density of 50W / L and frequency of 40kHz; then stirred at 120rpm for 450s (the total time for ultrasonic and stirring was 480s) to obtain cleaned bayberries.

[0028] (3) Freeze-thaw cycle combined with pulsed intense light pretreatment: The bayberries cleaned in step (2) were subjected to three freeze-thaw pretreatment cycles (each cycle included: freezing at -20℃ for 2 hours, followed by thawing at 25℃ for 2 hours). After the freeze-thaw pretreatment, they were subjected to a first pulsed intense light pretreatment with an intensity of 1000 mJ / cm². 2 The distance between the light source and the material was 6cm, and the material was flashed 15 times to obtain the pretreated bayberries.

[0029] (4) Variable-temperature vacuum freeze-drying: After freezing the pretreated bayberries in step (3) at -20℃ for 4 hours, they were transferred to a vacuum freeze dryer (vacuum degree 0.518 mbar, cold trap temperature -65℃). The variable-temperature main drying program was used to raise the temperature from -20℃ to 25℃ at a rate of 1℃ / 2.6h, and then maintained at 25℃ until the drying endpoint was reached (dry basis moisture content ≤5%), resulting in freeze-dried bayberries. During the drying process, the volatile water collected by the cold trap was used for the backwashing process.

[0030] (5) Pulse intense light treatment of dried products:

[0031] The freeze-dried bayberries from step (4) were then subjected to a second pulsed intense light at an intensity of 1000 mJ / cm². 2 Under conditions where the distance between the light source and the material is 8cm, the material is flashed 15 times to finally obtain the freeze-dried bayberry product.

[0032] The water consumption, drying time, and freeze-drying energy consumption during the processing of bayberries were measured, along with the total bacterial count, mold and yeast count, ΔE value, and anthocyanin retention rate of the bayberry products. Specific testing methods are as follows:

[0033] (2) Water consumption

[0034] Water consumption refers to the amount of water required throughout the entire freeze-dried bayberry product preparation process, with the key stages being bayberry washing and drying. Specifically, bayberry washing must meet the following standards: under 360° white light visual inspection, the fruit surface should be free of visible dust, sand, and fruit fly larvae, and should not feel slippery when lightly rubbed with fingers. If these standards are not met, the fruit must be washed again, and subsequent water consumption calculations include the total water used for all repeated washing processes.

[0035] During the drying process, the collected volatile water is deducted from the water consumption during the cleaning process.

[0036]

[0037] Where W2 is the water consumption (L) used in the bayberry washing process, W3 is the amount of volatile water recovered in the bayberry drying process (L), and m is the weight of the bayberries (kg).

[0038] (3) Drying time

[0039] The drying time is the time (h) required for the bayberries to dry from the start to the end of the drying process.

[0040] (4) Freeze-drying energy consumption

[0041]

[0042] Where E represents the electricity consumption (kWh) used in the bayberry drying process.

[0043] (5) Total bacterial count and mold and yeast count

[0044] Total bacterial count was determined according to GB 4789.2-2022; mold and yeast count was determined according to GB 4789.15-2016. Results are expressed as log CFU / g.

[0045] (6) Color difference value (ΔE value)

[0046] The color parameters L, a, and b of the bayberry were measured using a colorimeter. Based on the color parameters of fresh bayberries, the color difference value (ΔE value) was calculated as follows:

[0047]

[0048] Wherein, L0, a0, and b0 are the color parameters of fresh bayberries, and L1, a1, and b1 are the color parameters of the final freeze-dried bayberry product.

[0049] (7) Anthocyanin retention rate

[0050] Anthocyanin content was determined using a pH differential method, and the results were expressed as anthocyanin retention rate. 0.5 mL of the supernatant was taken, and 4 mL of 0.1 M HCl-KCl buffer (pH 1.0) was added. After mixing, the solution was analyzed at a wavelength of 510 nm (A). 510 Measure the absorbance. Take another 0.5 mL of the supernatant, add 4 mL of 0.5 M acetate-sodium acetate buffer (pH 4.5), mix well, and measure at 700 nm (A). 700 )Measure absorbance.

[0051]

[0052] Wherein, DF is the dilution factor, H1 is the anthocyanin content of the freeze-dried bayberry product, and H0 is the anthocyanin content of the fresh bayberry.

[0053] Example 2:

[0054] The difference from Example 1 is that step (2) is adjusted as follows:

[0055] (2) Ultrasonic synergistic cleaning with slightly acidic electrolyzed water: Fresh bayberries were mixed with slightly acidic electrolyzed water (25℃, available chlorine 20mg / L) at a material-to-liquid ratio of 1:5 (g / mL); treated for 10s under ultrasonic power density of 50W / L and frequency of 40kHz; then stirred at 120rpm for 470s (the total time for ultrasonication and stirring was 480s).

[0056] The remaining steps are the same as in Example 1.

[0057] The specific testing method is described in Example 1.

[0058] Example 3

[0059] The difference from Example 1 is that step (3) is adjusted as follows:

[0060] (3) Freeze-thaw cycle combined with pulsed intense light pretreatment: The cleaned bayberries underwent 5 freeze-thaw cycles (each cycle included: freezing at -20℃ for 2 hours, followed by thawing at 25℃ for 2 hours). Subsequently, they underwent a first pulsed intense light pretreatment with an intensity of 1000 mJ / cm². 2 The distance between the light source and the material is 6cm, and the light is flashed 15 times.

[0061] The remaining steps are the same as in Example 1.

[0062] The specific testing method is described in Example 1.

[0063] Example 4:

[0064] The difference from Example 1 is that step (3) is adjusted as follows:

[0065] (3) Freeze-thaw cycle combined with pulsed intense light pretreatment: The cleaned bayberries underwent three freeze-thaw cycles (each cycle included: freezing at -20℃ for 2 hours, followed by thawing at 25℃ for 2 hours). Subsequently, they underwent a first pulsed intense light pretreatment with an intensity of 600 mJ / cm². 2 The distance between the light source and the material is 8cm, and the light flashes 5 times.

[0066] The remaining steps are the same as in Example 1.

[0067] The specific testing method is described in Example 1.

[0068] Example 5:

[0069] The difference from Example 1 is that step (4) is adjusted as follows:

[0070] (4) Variable-temperature vacuum freeze-drying: After pretreatment, the bayberries were frozen at -20℃ for 4 hours and then transferred to a vacuum freeze dryer (vacuum degree 0.518 mbar, cold trap -65℃). The variable-temperature main drying program was used to raise the temperature from -20℃ to 25℃ at a rate of 2℃ / 2.6h, and then maintained at 25℃ until the drying endpoint was reached (dry basis moisture content ≤5%), resulting in freeze-dried bayberries. During the drying process, the volatile water collected by the cold trap was used for the backwashing process.

[0071] The remaining steps are the same as in Example 1.

[0072] The specific testing method is described in Example 1.

[0073] Example 6:

[0074] The difference from Example 1 is that step (5) is adjusted as follows:

[0075] (5) Pulsed intense light treatment of dried products: The freeze-dried bayberries were subjected to a second pulsed intense light treatment with an intensity of 600 mJ / cm². 2 Under conditions where the distance between the light source and the material is 8cm, the material is flashed 5 times to obtain freeze-dried bayberry product.

[0076] The remaining steps are the same as in Example 1.

[0077] The specific testing method is described in Example 1.

[0078] Comparative Example 1:

[0079] The difference from Example 1 is that step (2) is adjusted as follows:

[0080] (2) The selected bayberries are rinsed with running tap water (25℃) until they meet the cleaning standards, and the cleaned bayberries are obtained.

[0081] The remaining steps are the same as in Example 1.

[0082] The specific testing method is described in Example 1.

[0083] Comparative Example 2:

[0084] The difference from Example 1 is that step (2) is adjusted as follows:

[0085] (2) The ultrasonic treatment was removed and replaced with: Selected bayberries were mixed with slightly acidic electrolyzed water (25℃, pH 5.5, available chlorine 50mg / L) at a material-to-liquid ratio of 1:5 (g / mL); then stirred at 120rpm for 480s to obtain cleaned bayberries. Because the ultrasonic treatment was removed, the cleaning efficiency was insufficient and the cleaning standard could not be directly met; in order to meet the cleaning standard, it is necessary to clean again (the material-to-liquid ratio for each cleaning is 1:5g / mL) until the cleaning standard is met.

[0086] The remaining steps are the same as in Example 1.

[0087] The specific testing method is described in Example 1.

[0088] Comparative Example 3:

[0089] The difference from Example 1 is that step (2) is adjusted as follows:

[0090] (2) The slightly acidic electrolyzed water was removed and replaced with: Selected bayberries were mixed with tap water (25℃) at a material-to-liquid ratio of 1:5 (g / mL); treated with ultrasound at a power density of 50W / L and a frequency of 40kHz for 30s; then stirred at 120rpm for 450s (the total time for ultrasound and stirring is 480s). Due to the removal of the slightly acidic electrolyzed water, the cleaning efficiency was insufficient, and it was found in the actual implementation process that the cleaning standard could not be directly achieved; in order to achieve the cleaning standard, it is necessary to clean again (the material-to-liquid ratio for each cleaning is 1:5g / mL) until the cleaning standard is achieved.

[0091] The remaining steps are the same as in Example 1.

[0092] The specific testing method is described in Example 1.

[0093] Comparative Example 4:

[0094] The difference from Example 1 is that step (3) is adjusted as follows:

[0095] (3) The first pulsed light pretreatment was removed and replaced with: the cleaned bayberries were subjected to 3 freeze-thaw cycles (each cycle included: freezing at -20℃ for 2 hours and thawing at 25℃ for 2 hours after freezing) to obtain the pretreated bayberries.

[0096] The remaining steps are the same as in Example 1.

[0097] The specific testing method is described in Example 1.

[0098] Comparative Example 5:

[0099] The difference from Example 1 is as follows:

[0100] (3) Delete the freeze-thaw cycle pretreatment and change it to: After cleaning, the bayberries undergo a first pulsed intense light pretreatment with an intensity of 1000 mJ / cm². 2 After irradiating the material at a distance of 6cm from the light source for 15 flashes, pre-treated bayberries were obtained.

[0101] The remaining steps are the same as in Example 1.

[0102] The specific testing method is described in Example 1.

[0103] Comparative Example 6:

[0104] The difference from Example 1 is as follows:

[0105] Delete step (3), that is, delete the freeze-thaw cycle combined with pulsed intense light pretreatment;

[0106] The remaining steps are the same as in Example 1.

[0107] The specific testing method is described in Example 1.

[0108] Comparative Example 7:

[0109] The difference from Example 1 is that step (4) is adjusted as follows:

[0110] (4) The variable temperature main drying mode was removed and changed to: the pretreated bayberries were frozen at -20℃ for 4 hours and then transferred to a vacuum freeze dryer (vacuum degree 0.518 mbar, cold trap -65℃); and dried at -20℃ to the endpoint (dry basis moisture content ≤5%) to obtain freeze-dried bayberries. During the drying process, the volatile water collected by the cold trap was used for the backwashing process.

[0111] The remaining steps are the same as in Example 1.

[0112] The specific testing method is described in Example 1.

[0113] Comparative Example 8:

[0114] The difference from Example 1 is that step (5) is adjusted as follows:

[0115] (5) The pulsed light treatment step for dried products is removed; that is, the freeze-dried bayberries obtained in step (4) of Example 1 are directly used as freeze-dried bayberry products.

[0116] The remaining steps are the same as in Example 1.

[0117] The specific testing method is described in Example 1.

[0118] The water consumption, drying time and energy consumption of Examples 1-6 and Comparative Examples 1-8, as well as the total bacterial count, mold and yeast count, ΔE value and anthocyanin retention rate of their bayberry products are shown in Table 1.

[0119] Table 1 shows the water consumption, drying time, and energy consumption of Examples 1-6 and Comparative Examples 1-8, as well as the total bacterial count, mold and yeast count, ΔE value, and anthocyanin retention rate of their bayberry products.

[0120]

[0121]

[0122] The results above show that if any one of the key units (ultrasound-assisted slightly acidic electrolytic water cleaning, freeze-thaw cycle combined with pulsed intense light pretreatment, variable temperature vacuum freeze drying, and pulsed intense light treatment of dried products) is missing, the performance indicators will deteriorate significantly. This proves that the technical elements of this invention are synergistic and irreplaceable, and are not simply a procedural superposition.

[0123] Specifically: Regarding water consumption, Examples 1-6 reduced water consumption by 85.23%-87.70% compared to Comparative Examples 1-3, indicating that the ultrasonic-enhanced cleaning efficiency and slightly acidic electrolyzed water of Examples 1-6 effectively improved cleaning performance and recovered volatile water, demonstrating significant advantages in water conservation. Regarding drying time and freeze-drying energy consumption, Example 5, by increasing the heating rate, shortened the drying time by 78.70% and reduced energy consumption by 75.00% compared to Comparative Example 7, which dried at a constant temperature of -20℃. Regarding microbial safety, the total bacterial count of the bayberry product in Example 1 decreased by 66.7% and the mold and yeast count decreased by 75.0% compared to Comparative Example 8, which sterilized undried products. Regarding color, the ΔE value of the bayberry product in Example 1 was 77.6% lower than that of Comparative Example 4, which did not undergo pulsed intense light pretreatment, indicating that pulsed intense light pretreatment not only effectively inhibits bacteria but also effectively suppresses color deterioration. Furthermore, the ΔE value of the bayberry product in Example 3, which underwent excessive freeze-thaw cycles, was 6.2 times higher than that in Example 1, indicating that the number of freeze-thaw cycles needs to be reasonably limited. Regarding the anthocyanin retention rate, the anthocyanin retention rate of the bayberry product in Example 1 was 29.8% higher than that in Comparative Example 4; and the anthocyanin retention rate of the bayberry product in Example 3 was 26.1% lower than that in the Example 4, further confirming that excessive freeze-thaw cycles are detrimental to the retention of nutrients.

[0124] In summary, the multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries proposed in this invention (Examples 1-6) achieves substantial technical effects compared to Comparative Examples 1-8. This is achieved by saving up to 87.70% of water, reducing processing time by 78.70%, and saving 75.00% of energy, while simultaneously reducing the total bacterial count of bayberry products by 66.67%, the mold and yeast count by 75.00%, the ΔE value by 77.60%, and increasing anthocyanin retention by 42.88%.

[0125] Therefore, this invention can significantly reduce water and energy consumption during bayberry processing, shorten drying time, and produce bayberry products with low microbial load and high color and anthocyanin retention. This invention establishes a bayberry freeze-drying processing technology system that combines energy saving, quality improvement, efficiency enhancement, and microbial safety control, providing a reusable technological paradigm for green agricultural product manufacturing and significantly enhancing industrial competitiveness and sustainable development capabilities.

[0126] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries, characterized in that, Follow these steps: (1) Whole fruit sorting: Select fresh bayberries that are uniform in size and color, consistent in maturity, and free from mechanical damage on the surface; (2) Ultrasonic synergistic cleaning with slightly acidic electrolyzed water: The bayberries selected in step (1) are mixed with slightly acidic electrolyzed water. After mixing, the mixture is first subjected to ultrasonic treatment, and then stirred to obtain cleaned bayberries. (3) Freeze-thaw cycle combined with pulsed intense light pretreatment: The bayberries cleaned in step (2) are subjected to freeze-thaw pretreatment, and then subjected to the first pulsed intense light pretreatment to obtain the pretreated bayberries. The freeze-thaw pretreatment step involves freezing followed by thawing; (4) Variable temperature vacuum freeze drying: The bayberries pretreated in step (3) are frozen again, and then transferred to a vacuum freeze dryer. The vacuum degree, cold trap temperature and variable temperature main drying program are set to carry out freeze drying treatment until the drying endpoint is reached, that is, the dry basis moisture content is ≤5% and the drying is stopped to obtain freeze-dried bayberries. (5) Pulse intense light treatment of dried products: The freeze-dried bayberries obtained in step (4) are subjected to a second pulse intense light treatment to finally obtain freeze-dried bayberry products.

2. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, The effective chlorine concentration of the slightly acidic electrolyzed water in step (2) is 20-50 mg / L, and the temperature is 25℃; the ratio of bayberry to slightly acidic electrolyzed water is 1:5 (g / mL).

3. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, The conditions for ultrasonic treatment in step (2) are: ultrasonic power density of 50W / L, frequency of 40kHz, and time of 10-50s; stirring speed of 120rpm and time of 430-470s.

4. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, The freeze-thaw pretreatment in step (3) is performed 1-3 times; the freezing conditions in the freeze-thaw pretreatment are -20℃ for 2 hours and the thawing conditions are 25℃ for 2 hours.

5. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, The parameters for the first pulsed high-intensity light preprocessing in step (3) are: intensity 600-1000 mJ / cm. 2 The processing distance is 4-8cm, and the flashes are performed 5-15 times.

6. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberry according to claim 1, characterized in that, In step (4), the vacuum degree is 0.518 mbar and the cold trap temperature is -65℃; the variable temperature main drying program is to raise the temperature from -20℃ to 25℃ at a rate of 0.5-2℃ / 2.6h, and maintain it at 25℃ until the drying endpoint is reached.

7. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, In step (4), the volatile water collected by the cold trap during the freeze-drying process is used for the backwashing step.

8. The multi-stage synergistic energy-saving and efficiency-enhancing freeze-drying method for bayberries according to claim 1, characterized in that, The parameters for the second pulsed high-intensity light treatment mentioned in step (5) are: intensity 600-1000 mJ / cm². 2 The processing distance is 4-8cm, and the flashes are 15-25 times.

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