Nanoscale ginseng freeze-dried powder and preparation method thereof

Abstract

The invention relates to the technical field of freeze-dried powder, and particularly discloses nanoscale ginseng freeze-dried powder and a preparation method thereof.Ginseng is pulped and then inoculated with zymophyte for fermentation, after fermentation is completed, sterilized fermentation liquor is sprayed into liquid nitrogen to be rapidly solidified to form freeze-dried particles, then the freeze-dried particles are transferred into a vacuum freeze-drying device for freeze-drying, and finally the freeze-dried powder is obtained. The powder obtained by freeze-drying is further ball-milled by a ball mill to obtain the nano-scale ginseng freeze-dried powder, the bioactive components in the nano-scale ginseng freeze-dried powder are easily absorbed by a human body, and the freeze-dried powder has good stability.

Description

Technical Field

[0001] The present invention relates to the technical field of freeze-dried powder, and specifically to a nano-level ginseng freeze-dried powder and a preparation method thereof. Background Art

[0002] Ginseng belongs to the Araliaceae perennial herb, distributed between 40° and 45° north latitude, and prefers cold, cool, and humid climates. The medicinal history of ginseng is very long. The efficacy and application of ginseng were recorded in "Shennong Ben Cao Jing". Traditional Chinese medicine believes that ginseng has the efficacy of replenishing qi and promoting the production of body fluid, with a powerful medicinal effect, being good at greatly tonifying primordial qi, and being an important medicine for tonifying qi and strengthening the body. Modern medicine has found that in addition to inorganic elements such as calcium, iron, and zinc necessary for the human body and amino acids required by the human body, ginseng also contains various bioactive components such as ginsenosides, ginseng proteins, and ginseng polysaccharides. Among them, ginsenosides can play a positive role in anti-tumor, anti-aging, protecting nerves, hematopoietic recovery, and promoting osteogenesis; ginseng polysaccharides play a positive role in anti-tumor, anti-inflammatory, antioxidant, regulating immune function, and regulating gastrointestinal function; while the research on ginseng protein is less compared to other bioactive components, but existing research has shown that ginseng protein has positive effects in antioxidant, protecting nerves, protecting muscles, and promoting healing.

[0003] With the improvement of people's living standards, as a food homologous to medicine, ginseng is increasingly widely used in various health products, and the products are also sought after by more and more consumers. New ginseng foods are constantly introduced in the market, such as ginseng tea, ginseng wine, ginseng powder, ginseng candy, ginseng oral liquid, etc. It is difficult to control the processing degree of ginseng in these ginseng products, and it is difficult to be absorbed by the human body after taking, with low bioavailability, resulting in the waste of bioactive components in ginseng products. Therefore, developing a ginseng product that is easily absorbed by the human body and can effectively utilize the bioactive components of ginseng is of great significance for promoting the development of the ginseng health food industry. Summary of the Invention

[0004] The purpose of the present invention is to provide a nano-level ginseng freeze-dried powder and a preparation method thereof, which process ginseng into nano-scale particles to solve the problem that ginseng foods are difficult to be absorbed by the human body and have low bioavailability after taking.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] A preparation method of a nano-level ginseng freeze-dried powder, specifically as follows:

[0007] Step 1: Wash and crush ginseng, then add it to deionized water and make a pulp to obtain ginseng pulp;

[0008] Step 2: After the ginseng pulp is sterilized, inoculate it with a mixed fermentation bacterial suspension for fermentation. After fermentation is completed, inactivate it by pulse to obtain fermented ginseng pulp;

[0009] Step 3: Add a freeze-drying protectant to the fermented ginseng pulp, stir evenly to obtain a mixture, and then lyophilize the mixture to obtain freeze-dried ginseng powder;

[0010] Step 4: Use ball milling technology to mill and pulverize the freeze-dried ginseng powder to obtain nano-level freeze-dried ginseng powder.

[0011] As a limitation of the present invention, the mass ratio of the ginseng to deionized water is 1:(3 - 5).

[0012] As a limitation of the present invention, the mixed bacterial suspension is a mixture of Lactobacillus plantarum bacterial suspension and Lactobacillus bulgaricus bacterial suspension. The mass ratio of the Lactobacillus plantarum bacterial suspension to the Lactobacillus bulgaricus bacterial suspension is 1:(1 - 3), and the mass ratio of the ginseng pulp to the mixed bacterial suspension is 1:(4% - 10%).

[0013] As a limitation of the present invention, in Step 2, during fermentation, adjust the pH to 3.0 - 5.0, the fermentation temperature is 50 - 60°C, and the fermentation time is 3 - 5 h.

[0014] As a limitation of the present invention, the freeze-drying protectant is a mixture of glucose and mannitol, and the mass ratio of glucose to mannitol is 1:(1.5 - 2.5); the mass fraction of the freeze-drying protectant in the mixture is 12 - 18%.

[0015] As a limitation of the present invention, in Step 3, before freeze-drying, pre-treat the mixture to pre-solidify the mixture into solidified microparticles. Specifically:

[0016] Adopt ultrasonic spray technology to atomize the mixture into small droplets and then quickly send them into the cold medium liquid nitrogen for solidification. After solidification is completed, transfer them to a refrigerator at -40 - -50°C and anneal for 3 - 5 h to obtain solidified microparticles.

[0017] As a limitation of the present invention, the process parameters during pre-solidification are: the ultrasonic power is 3.0 - 4.0 W, the flow rate of the mixture is 3 - 7 mL / min, and the solidification time is 5 - 10 min.

[0018] As a limitation of the present invention, the process parameters during freeze-drying are: the drying pressure is 1 - 1.5 KPa, and the freeze-drying process is: drying at -30 - -25°C for 24 - 30 h, drying at -20 - -15°C for 1 - 3 h, drying at -10 - -5°C for 1 - 3 h, and drying at 0 - 5°C for 1 - 3 h.

[0019] As a limitation of the present invention, in Step 4, specifically obtaining nano-level freeze-dried ginseng powder by ball milling is as follows:

[0020] Add freeze-dried ginseng powder into a ball mill jar for ball milling and pulverization. Select zirconia balls as the grinding balls. During the pulverization process, use deionized water to cool down the ball mill jar to keep the temperature inside the jar at 25-35 °C. The ball milling time is 3-5 h to obtain nano-level freeze-dried ginseng powder.

[0021] A nano-level freeze-dried ginseng powder is prepared by the preparation method according to any one of the above.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] The present invention uses Lactobacillus plantarum and Lactobacillus bulgaricus to ferment ginseng pulp, decompose ginseng fibers, change the sugar chain structure of ginsenosides, promote the conversion of conventional ginsenosides to rare ginsenosides, facilitate the release of bioactive components such as ginsenosides. At the same time, the fibers in the ginseng pulp become shorter after fermentation treatment, which is beneficial to the formation of nano-level freeze-dried powder.

[0024] The present invention performs pre-curing treatment before freeze-drying. After using ultrasonic waves to atomize the liquid into small droplets, liquid nitrogen is used to quickly shape them into microparticles with uniform morphology and high sphericity, which is beneficial to the diffusion of water from the inside of the particles to the outside during freeze-drying. The formed freeze-dried powder has good dispersibility and stability. After freeze-drying, ball milling treatment is carried out to further improve the particle size of the freeze-dried powder, forming nano-level freeze-dried powder and promoting the dissolution and release of bioactive components such as ginsenosides. Detailed implementation manners

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Ginseng was purchased from Wanliang Ginseng Market in Baishan, Jilin. Lactobacillus plantarum (1×10 7 CFU / mg), Lactobacillus bulgaricus (1×10 7 CFU / mg) and liquid MRS medium (pH: 6.2±0.2) are all from Shandong Jiacheng Biology.

[0027] Preparation of bacterial suspension: Inoculate Lactobacillus plantarum or Lactobacillus bulgaricus in liquid MRS medium and culture at 37 °C for 18 h to obtain the first-generation activated bacteria. Then inoculate the first-generation activated bacteria into liquid MRS medium at an inoculation amount of 3% and culture again. Repeat the above steps 3 times to obtain the third-generation activated bacteria. Dilute the third-generation activated bacteria with deionized water to obtain a Lactobacillus plantarum bacterial suspension or a Lactobacillus bulgaricus bacterial suspension with a concentration of 100 CFU / mL.

[0028] Example 1: A preparation method of nanoscale ginseng freeze-dried powder, specifically as follows:

[0029] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, add them to a high-speed pulping machine for pulping to obtain ginseng pulp;

[0030] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the pulse number to 50 times, use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, ferment at 40 °C for 3 days. During the fermentation process, stir the ginseng pulp once a day for 15 min each time. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the pulse number to 30 times to obtain fermented ginseng pulp;

[0031] Step 3: Open the pressure tank, add 36 g of glucose and 64 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixed solution. Adopt ultrasonic spray technology to atomize the mixed solution into small droplets and quickly send them into liquid nitrogen, a cold medium, for solidification. The solidification conditions are: ultrasonic power is 3.0 W, the flow rate of the mixed solution is 5 mL / min, and the solidification time is 10 min. After solidification, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified particles. Transfer the solidified particles to a vacuum freeze-dryer and vacuum-dry under a drying pressure of 1 KPa. The freeze-drying conditions are: dry at -25 °C for 30 h, dry at -15 °C for 1 h, dry at -5 °C for 1 h, dry at 5 °C for 1 h, and finally warm up to room temperature and open the dryer to obtain ginseng freeze-dried powder;

[0032] Step 4: Put the ginseng freeze-dried powder into a high-energy nano ball mill. Circulating water is passed through the jacket of the ball mill. Add zirconia balls with a diameter of 10 mm according to a ball-to-material mass ratio of 3:1. Control the temperature in the tank at 25 °C during the crushing process and the ball milling time is 5 h to obtain nanoscale ginseng freeze-dried powder.

[0033] Example 2: A preparation method of nanoscale ginseng freeze-dried powder, specifically as follows:

[0034] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, add them to a high-speed pulping machine for pulping to obtain ginseng pulp;

[0035] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the number of pulses to 50 times. Use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, and ferment at 40 °C for 3 days. During the fermentation process, stir the ginseng pulp once a day for 15 min each time. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the number of pulses to 30 times to obtain fermented ginseng pulp;

[0036] Step 3: Open the pressure tank, add 36 g of glucose and 64 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixture. Using ultrasonic spray technology, atomize the mixture into small droplets and quickly send them into liquid nitrogen, a cold medium, for solidification. The solidification conditions are: ultrasonic power of 3.0 W, mixture flow rate of 5 mL / min, solidification time of 10 min. After solidification, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified particles. Transfer the solidified particles to a vacuum freeze dryer and vacuum dry at a drying pressure of 1 KPa. The freeze-drying conditions are: drying at -25 °C for 30 h, -15 °C for 1 h, -5 °C for 1 h, 5 °C for 1 h, and finally raise the temperature to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0037] Step 4: Put the freeze-dried ginseng powder into a high-energy nanomill. Circulating water is passed through the jacket of the ball mill. Add zirconia balls with a diameter of 10 mm according to a ball-to-material mass ratio of 3:1. Control the temperature in the tank at 25 °C during the pulverization process and the ball milling time is 5 h to obtain nanoscale freeze-dried ginseng powder.

[0038] Example 3: A method for preparing nanoscale freeze-dried ginseng powder, specifically as follows:

[0039] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water and add them to a high-speed pulper to make pulp to obtain ginseng pulp;

[0040] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the number of pulses to 50 times. Use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, and ferment at 40 °C for 3 days. During the fermentation process, stir the ginseng pulp once a day for 15 min each time. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the number of pulses to 30 times to obtain fermented ginseng pulp;

[0041] Step 3: Open the pressure tank, add 36 g of glucose and 64 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixed solution. Using ultrasonic spray technology, atomize the mixed solution into small droplets and then quickly send them into the cold medium liquid nitrogen for solidification. The solidification conditions are: ultrasonic power is 3.0 W, the flow rate of the mixed solution is 5 mL / min, the solidification time is 10 min. After solidification is completed, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified microparticles. Transfer the solidified microparticles to a vacuum freeze dryer and vacuum dry under a drying pressure of 1 KPa. The freeze-drying conditions are: drying at -25 °C for 30 h, -15 °C for 1 h, -5 °C for 1 h, 5 °C for 1 h, and finally raise the temperature to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0042] Step 4: Put the freeze-dried ginseng powder into a high-energy nanosphere mill. Pass circulating water through the jacket of the ball mill. Add zirconia balls with a diameter of 10 mm according to a ball-to-material mass ratio of 3:1. Control the temperature in the tank at 25 °C during the pulverization process and the ball milling time is 5 h to obtain nanoscale freeze-dried ginseng powder.

[0043] Example 4: A preparation method of nanoscale freeze-dried ginseng powder, specifically as follows:

[0044] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water and add them to a high-speed pulper for pulping to obtain ginseng pulp;

[0045] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the pulse number to 50 times. Use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization is completed, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, and ferment at 40 °C for 3 days. Stir the ginseng pulp once a day during the fermentation process, each time for 15 min. After fermentation is completed, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the pulse number to 30 times to obtain fermented ginseng pulp;

[0046] Step 3: Open the pressure tank, add 40 g of glucose and 80 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixed solution. Using ultrasonic spray technology, atomize the mixed solution into small droplets and then quickly send them into the cold medium liquid nitrogen for solidification. The solidification conditions are as follows: the ultrasonic power is 3.0 W, the flow rate of the mixed solution is 5 mL / min, the solidification time is 10 min. After solidification is completed, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified particles. Transfer the solidified particles to a vacuum freeze dryer and vacuum dry under a drying pressure of 1 KPa. The freeze-drying conditions are: drying at -25 °C for 30 h, -15 °C for 1 h, -5 °C for 1 h, 5 °C for 1 h, and finally raise the temperature to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0047] Step 4: Put the freeze-dried ginseng powder into a high-energy nano ball mill. Circulating water is passed through the jacket of the ball mill. Zirconia balls with a diameter of 10 mm are added according to the mass ratio of balls to materials of 3:1. During the pulverization process, control the temperature in the tank at 25 °C and the ball milling time is 5 h to obtain nano-scale freeze-dried ginseng powder.

[0048] Based on Example 1 below, control experiments are carried out, specifically Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4, as described below:

[0049] Comparative Example 1: This comparative example relates to a method for preparing nano-scale freeze-dried ginseng powder. The difference from Example 1 is that fermented bacteria are not used to treat the ginseng pulp. Specifically:

[0050] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, and add them to a high-speed pulper for pulping to obtain ginseng pulp;

[0051] Step 2: Transfer the obtained ginseng pulp to a pressure tank, add 36 g of glucose and 64 g of mannitol, stir evenly to obtain a mixed solution. Using ultrasonic spray technology, atomize the mixed solution into small droplets and then quickly send them into the cold medium liquid nitrogen for solidification. The solidification conditions are as follows: the ultrasonic power is 3.0 W, the flow rate of the mixed solution is 5 mL / min, the solidification time is 10 min. After solidification is completed, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified particles. Transfer the solidified particles to a vacuum freeze dryer and vacuum dry under a drying pressure of 1 KPa. The freeze-drying conditions are: drying at -25 °C for 30 h, -15 °C for 1 h, -5 °C for 1 h, 5 °C for 1 h, and finally raise the temperature to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0052] Step 3: Put the freeze-dried ginseng powder into a high-energy nano ball mill. Circulating water is passed through the jacket of the ball mill. Zirconia balls with a diameter of 10 mm are added according to a ball-to-material mass ratio of 3:1. During the pulverization process, the temperature inside the tank is controlled at 25°C, and the ball milling time is 5 h to obtain nano-level freeze-dried ginseng powder.

[0053] Comparative Example 2: This comparative example relates to a method for preparing nano-level freeze-dried ginseng powder, which is different from Example 1 in that no freeze-drying protectant is added. Specifically:

[0054] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, and add them to a high-speed pulper to make pulp to obtain ginseng pulp;

[0055] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the pulse number to 50 times, use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, and ferment at 40°C for 3 days. Stir the ginseng pulp once a day during the fermentation process, each time for 15 min. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the pulse number to 30 times to obtain fermented ginseng pulp;

[0056] Step 3: Adopt ultrasonic spray technology to atomize the fermented ginseng pulp into small droplets and quickly send them into the cold medium liquid nitrogen for solidification. The solidification conditions are: ultrasonic power is 3.0 W, the flow rate of the mixed liquid is 5 mL / min, and the solidification time is 10 min. After solidification, transfer it to a refrigerator at -40°C and anneal for 3 h to obtain solidified particles. Transfer the solidified particles to a vacuum freeze dryer and vacuum dry at a drying pressure of 1 KPa. The freeze-drying conditions are: dry at -25°C for 30 h, -15°C for 1 h, -5°C for 1 h, �°C for 1 h, and finally warm up to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0057] Step 4: Put the freeze-dried ginseng powder into a high-energy nano ball mill. Circulating water is passed through the jacket of the ball mill. Zirconia balls with a diameter of 10 mm are added according to a ball-to-material mass ratio of 3:1. During the pulverization process, the temperature inside the tank is controlled at 25°C, and the ball milling time is 5 h to obtain nano-level freeze-dried ginseng powder.

[0058] Comparative Example 3: This comparative example relates to a method for preparing nano-level freeze-dried ginseng powder, which is different from Example 1 in that no pre-solidification treatment is carried out during freeze-drying. Specifically:

[0059] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, add them to a high-speed pulping machine to make pulp, and obtain ginseng pulp;

[0060] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the pulse number to 50 times, use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, ferment at 40 °C for 3 days, stir the ginseng pulp once a day during the fermentation process, each time for 15 min. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the pulse number to 30 times, and obtain fermented ginseng pulp;

[0061] Step 3: Open the pressure tank, add 36 g of glucose and 64 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixture. Transfer the mixture to a vacuum freeze dryer and vacuum dry it under a drying pressure of 1 KPa. The freeze-drying conditions are: drying at -25 °C for 30 h, -15 °C for 1 h, -5 °C for 1 h, 5 °C for 1 h, and finally heat up to room temperature and open the dryer to obtain freeze-dried ginseng powder;

[0062] Step 4: Put the freeze-dried ginseng powder into a high-energy nanomill, pass circulating water through the jacket of the ball mill, add zirconia balls with a diameter of 10 mm according to the mass ratio of ball to material of 3:1, control the temperature in the tank at 25 °C during the crushing process, and the ball milling time is 5 h to obtain nanoscale freeze-dried ginseng powder.

[0063] Comparative Example 4: This comparative example relates to a method for preparing freeze-dried ginseng powder, which is different from Example 1 in that no ball milling treatment is carried out after freeze-drying. Specifically:

[0064] Step 1: Wash the purchased ginseng with deionized water, crush it into small pieces, screen out the impurities in the ginseng, weigh 100 g of the crushed ginseng and 500 g of deionized water, add them to a high-speed pulping machine to make pulp, and obtain ginseng pulp;

[0065] Step 2: Transfer the obtained ginseng pulp to a pressure tank, set the pulse intensity to 400 J and the pulse number to 50 times, use a pulsed electric field sterilization device to sterilize the ginseng pulp. After sterilization, add 18 g of Lactobacillus plantarum suspension and 18 g of Lactobacillus bulgaricus suspension, stir evenly and seal the pressure tank, ferment at 40 °C for 3 days, stir the ginseng pulp once a day during the fermentation process, each time for 15 min. After fermentation, use the pulsed electric field sterilization device to sterilize again, set the pulse intensity to 400 J and the pulse number to 30 times, and obtain fermented ginseng pulp;

[0066] Step 3: Open the pressure tank, add 36 g of glucose and 64 g of mannitol to the fermented ginseng pulp, stir evenly to obtain a mixed solution. Using ultrasonic spray technology, atomize the mixed solution into small droplets and then quickly send them into the cold medium liquid nitrogen for solidification. The solidification conditions are as follows: the ultrasonic power is 3.0 W, the flow rate of the mixed solution is 5 mL / min, the solidification time is 10 min. After solidification is completed, transfer it to a refrigerator at -40 °C and anneal for 3 h to obtain solidified microparticles. Transfer the solidified microparticles to a vacuum freeze dryer and conduct vacuum drying under a drying pressure of 1 KPa. The freeze-drying conditions are as follows: dry at -25 °C for 30 h, dry at -15 °C for 1 h, dry at -5 °C for 1 h, dry at 5 °C for 1 h, and finally raise the temperature to room temperature, open the dryer, and crush the caked freeze-dried powder to obtain ginseng freeze-dried powder.

[0067] Detection experiment:

[0068] Prepare ginseng freeze-dried powder samples required for testing according to the preparation methods in each example and comparative example respectively and conduct the following tests.

[0069] Microscopic morphology and particle size test: Add 0.5 g of ginseng freeze-dried powder sample to 10 mL of deionized water, stir evenly, suck it with a dropper and drop it on the placement table, observe the microscopic morphology of each sample with an electron microscope, and measure the particle size of the freeze-dried powder with a laser particle size analyzer.

[0070] Saponin content test: Use ultraviolet spectrophotometry to measure the total saponin content in the sample. Add ginsenoside (purity: 99%, Suzhou Yuanrui) to methanol, stir evenly to obtain a standard solution with a concentration of 1.17 mg / mL. Dissolve 1 g of vanillin in a small amount of perchloric acid and make the volume up to 100 mL to obtain vanillin perchloric acid test solution. Use a dropper to suck 0.2 mL, 0.4 mL, 0.8 mL, 1.0 mL, and 1.2 mL of the standard solution respectively and drop them into test tubes. After volatilizing the solvent, add 0.5 mL of vanillin perchloric acid test solution, mix evenly, heat in a water bath at 60 °C for 15 min, immediately cool with ice water for 2 min, add 5 mL of sulfuric acid solution with a mass fraction of 77%, mix evenly to obtain mixed solutions with different saponin contents. Use 0.5 mL of vanillin perchloric acid test solution as the blank sample, measure the absorbance of each mixed solution at a wavelength of 540 nm, and draw a standard curve (absorbance as the ordinate and concentration as the abscissa) to obtain the regression equation y = 4.1006x + 0.027 (R 2 = 0.9991); Take 1 g of each ginseng freeze-dried powder sample respectively, add it to an ethanol solution with a mass fraction of 70%, ultrasonic at 70 °C for 45 min, filter, and for the filtrate, use the same method, add vanillin perchloric acid test solution and sulfuric acid solution, and then measure the absorbance at a wavelength of 540 nm. Substitute the obtained absorbances into the regression equation to obtain the saponin content in each ginseng freeze-dried powder sample.

[0071] Lyophilized powder stability test: After placing the ginseng lyophilized powder sample at room temperature for 7 days, observe the microscopic morphology of the sample again and measure the particle size of the sample to judge the stability of the sample.

[0072] Particle size (nm) Saponin content (mg / g) Particle size after 7 days (nm) Example 1 217.52 nm 6.553 mg / g 276.24 nm Example 2 218.46 nm 6.556 mg / g 275.36 nm Example 3 218.05 nm 6.559 mg / g 277.42 nm Example 4 219.23 nm 6.564 mg / g 278.18 nm Comparative Example 1 267.41 nm 4.977 mg / g 359.15 nm Comparative Example 2 243.16 nm 6.234 mg / g 446.72 nm Comparative Example 3 292.68 nm 5.828 mg / g 405.17 nm Comparative Example 4 8096.37 nm 5.442 mg / g 12950.42 nm

[0073] Conclusion: Compared with Example 1, in Comparative Example 1, the ginseng pulp was not treated with fermentation bacteria, and the particle size and saponin content of the lyophilized powder were higher than those in Example 1; in Comparative Example 2, no lyoprotectant was added, the lyophilized powder was prone to moisture absorption, and the particle size of the lyophilized powder increased rapidly after 7 days, and the stability of the lyophilized powder was inferior to that in Example 1; in Comparative Example 3, the pre-curing technology was not adopted. From the microscopic morphology, the microscopic morphology of the lyophilized powder in Example 1 was better than that in Comparative Example 3. Under the electron microscope, it was observed that the lyophilized powder in Example 1 was spherical particles, and the lyophilized powder in Comparative Example 3 was needle-shaped, columnar, and flat flake-shaped. The sphericity of the lyophilized powder in Example 1 was better, and the particle size and stability were superior to those in Comparative Example 3; Comparative Example 4 was treated by ball milling, only the caked powder after freeze-drying was crushed, and its particle size was much larger than that in Example 1, and the saponin content and stability were lower than those in Example 1. It can be seen from the test data that the particle size of the nano-scale ginseng lyophilized powder prepared by the preparation method in the example is about 200 nm, the morphology of the lyophilized powder is good, the sphericity of the powder is relatively high, and it has good stability, and the saponin content is also very high and is easily absorbed by the human body.

[0074] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes falling within the meaning and scope of the equivalent elements of the claims within the present invention.

Claims

1. A preparation method of nano-level freeze-dried ginseng powder, characterized in that: Specifically as follows: Step 1: Wash and crush ginseng, add it to deionized water, and make a pulp to obtain ginseng pulp. Step 2: After sterilizing the ginseng pulp, inoculate it with a mixed fermentation bacterial suspension for fermentation. After fermentation is completed, inactivate it by pulse to obtain fermented ginseng pulp. Step 3: Add a freeze-drying protectant to the fermented ginseng pulp, stir evenly to obtain a mixture, and then freeze-dry the mixture to obtain freeze-dried ginseng powder. Step 4: Use ball milling technology to mill and crush the freeze-dried ginseng powder to obtain nano-level freeze-dried ginseng powder.

2. The preparation method of a nano-level freeze-dried ginseng powder according to claim 1, characterized in that: The mass ratio of ginseng to deionized water is 1:(3 - 5).

3. The preparation method of a nanoscale ginseng freeze-dried powder according to claim 1, characterized in that: In Step 2, during fermentation, the fermentation temperature is 35 - 45°C, and the fermentation time is 3 - 5 days.

4. The preparation method of a nanoscale ginseng freeze-dried powder according to claim 1, characterized in that: The mixed bacterial suspension is a mixture of Lactobacillus plantarum bacterial suspension and Lactobacillus bulgaricus bacterial suspension. The mass ratio of Lactobacillus plantarum bacterial suspension to Lactobacillus bulgaricus bacterial suspension is 1:(1 - 3), and the mass ratio of ginseng pulp to the mixed bacterial suspension is 1:(4% - 10%).

5. The preparation method of a nano-level freeze-dried ginseng powder according to claim 1, characterized in that: The freeze-drying protectant is a mixture of glucose and mannitol. The mass ratio of glucose to mannitol is 1:(1.5 - 2.5), and the mass fraction of the freeze-drying protectant in the mixture is 12 - 18%.

6. The preparation method of a nanoscale ginseng freeze-dried powder according to claim 1, characterized in that: In Step 3, before freeze-drying, pre-treat the mixture to pre-solidify it into solid particles. Specifically: Use ultrasonic spray technology to atomize the mixture into small droplets, and then quickly send them into the cold medium liquid nitrogen for solidification. After solidification is completed, transfer them to a refrigerator at -40 to -50°C and anneal for 3 - 5 h to obtain solid particles.

7. The preparation method of a nano-level freeze-dried ginseng powder according to claim 6, characterized in that: The process parameters during pre-solidification are: ultrasonic power is 3.0 - 4.0 W, the flow rate of the mixture is 3 - 7 mL / min, and the solidification time is 5 - 10 min.

8. The preparation method of a nanoscale ginseng freeze-dried powder according to claim 1, characterized in that: The process parameters during freeze-drying are: drying pressure is 1 - 1.5 KPa, and the freeze-drying process is: drying at -30 to -25°C for 24 - 30 h, drying at -20 to -15°C for 1 - 3 h, drying at -10 to -5°C for 1 - 3 h, and drying at 0 to 5°C for 1 - 3 h.

9. The preparation method of a nanoscale ginseng freeze-dried powder according to claim 1, characterized in that: In Step 4, specifically, the ball milling to obtain nano-level freeze-dried ginseng powder is as follows: Add the freeze-dried ginseng powder to a ball milling tank for ball milling and crushing. Select zirconia balls as the grinding balls. During the crushing process, use deionized water to cool the ball milling tank to keep the temperature in the tank at 25 - 35°C. The ball milling time is 3 - 5 h to obtain nano-level freeze-dried ginseng powder.

10. A nanoscale freeze-dried ginseng powder, characterized in that: Prepared according to the preparation method of any one of claims 1 - 9.