Freeze-drying protective agent for stems and leaves of ligusticum wallichii and freeze-drying method

Abstract

The invention discloses a freeze-drying protective agent for stems and leaves of ligusticum wallichii and a freeze-drying method. The freeze-drying protective agent is maltodextrin, or the freeze-drying protective agent is composed of maltodextrin and a low-molecular-weight protective agent in a mass ratio of (1-3): (1-3), and the low-molecular-weight protective agent is mannitol, xylitol, lactose or sorbitol. The invention investigates the influence of the combination of high and low molecular protective agents on the volatile oil and protein content of the Ligusticum wallichii stem and leaf freeze-dried powder, and screens out the freeze-drying protective agent with the best effect. The freeze-drying protective agent screened by the invention can effectively protect volatile oil and protein in the stems and leaves of ligusticum wallichii, further ensures the quality of the stems and leaves of ligusticum wallichii to the greatest extent, and has a relatively good application prospect.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of freeze drying, and in particular to a freeze drying protective agent for stems and leaves of Chuanxiong and a freeze drying method. Background Art

[0002] With the continuous development and progress of pharmaceutical preparation technology and the food industry, vacuum freeze drying technology has become a widely used preparation and food drying technology. This is a drying method that uses vacuum to transfer liquid substances directly from solid to gaseous. Its advantages are that it can improve product quality, extend shelf life, reduce volume and weight, facilitate transportation and storage, and effectively retain active ingredients. During the vacuum freeze drying process, the high variability and instability of the material makes the activity interfered with by adverse factors such as temperature, humidity, oxygen, and light, resulting in problems with its quality and stability. In order to effectively protect and stabilize the product, people often add lyoprotectants during the freeze drying process. Lyoprotectants are chemical or natural substances added during the freeze drying process to increase the stability and protection of the substance during the drying process. They can effectively protect the active ingredients and chemical structure in the product, extend the storage life, and reduce oxidation, decomposition and degradation during the process.

[0003] The stems and leaves of Chuanxiong, which are the stems and leaves of the dicotyledonous Umbelliferae plant Chuanxiong, are also known as Miwu. They have the functions of removing wind and stopping dizziness, nourishing the liver and improving eyesight, removing mucus and stopping saliva. The Famous Doctors' Records states that "Miwu, the seedling of Chuanxiong, is used to treat old wind in the body, long-term wind in the head, and dizziness..." Studies have shown that it contains rich nutrients that are beneficial to the human body, such as vitamins, dietary fiber, iron, and zinc. It has phthalide components that can dilate blood vessels and has high nutritional value. The main Chuanxiong producing areas in Dujiangyan and Pengzhou, Sichuan, all have the habit of eating Miwu. In other parts of Asia, such as Japan and South Korea, it is often used as a food material for salads, frying, and cooking.

[0004] Therefore, in-depth research on the protective agents used in the freeze-drying process of Chuanxiong stems and leaves is necessary to maximize the retention of the original active ingredients and nutrients in Chuanxiong stems and leaves, which is of great significance for the subsequent further development and utilization of Chuanxiong stems and leaves. Summary of the invention

[0005] To this end, the embodiment of the present invention provides a freeze-drying protective agent and freeze-drying method for stems and leaves of Chuanxiong. The present invention screens out freeze-drying protective agents that can effectively protect the effective components of stems and leaves of Chuanxiong by adding freeze-drying protective agents of different types and different contents respectively, taking the volatile oil and protein content of freeze-dried powder of stems and leaves of Chuanxiong as indicators. The research results can provide more effective protective agent selection and combination suggestions for the preparation of stems and leaves of Chuanxiong, and provide technical support for the development and utilization of stems and leaves of Chuanxiong.

[0006] In order to achieve the above purpose, the embodiment of the present invention provides the following technical solutions:

[0007] According to a first aspect of an embodiment of the present invention, the present invention provides a freeze-drying protective agent for Chuanxiong stems and leaves, wherein the freeze-drying protective agent is maltodextrin, or is composed of maltodextrin and a low-molecular protective agent in a mass ratio of 1-3:1-3, wherein the low-molecular protective agent is mannitol, xylitol, lactose or sorbitol.

[0008] Furthermore, the freeze-drying protective agent consists of maltodextrin and xylitol in a mass ratio of 1:1.

[0009] According to a second aspect of an embodiment of the present invention, the present invention provides a freeze-drying method for stems and leaves of Ligusticum chuanxiong, the method comprising the following steps:

[0010] (1) adding distilled water to fresh stems and leaves of Chuanxiong to pulp using a juicer to obtain a first pulp;

[0011] (2) adding the freeze-drying protective agent for stems and leaves of Chuanxiong as claimed in claim 1 to the first slurry, and continuing to slurry to obtain a second slurry;

[0012] (3) Pour the second slurry into a material tray, place it on a pre-freezing rack, put it into a cold trap, and pre-cool it. After it is completely frozen, take the pre-freezing rack out of the cold trap, transfer the material tray to a freeze-drying rack, place it above the cold trap, and perform vacuum freeze drying.

[0013] Furthermore, in step (1), the weight volume ratio of the fresh chuanxiong stems and leaves to distilled water is 240 g:300-400 ml;

[0014] The beating conditions are: rotation speed 50-100r / min, 3-5min.

[0015] Furthermore, in step (2), when the freeze-drying protective agent for the stems and leaves of Chuanxiong is maltodextrin, the amount of the freeze-drying protective agent for the stems and leaves of Chuanxiong is 7% of the mass of the fresh stems and leaves of Chuanxiong;

[0016] When the freeze-drying protective agent for the stems and leaves of Chuanxiong consists of maltodextrin and xylitol in a mass ratio of 1:1, the added amount of the freeze-drying protective agent for the stems and leaves of Chuanxiong is 14% of the mass of the fresh stems and leaves of Chuanxiong.

[0017] Furthermore, in step (2), the conditions for continuing beating are: rotation speed 50-100 r / min, 1-3 min.

[0018] Furthermore, in step (3), the precooling conditions are: freezing at -60°C for 4-5h;

[0019] The vacuum freeze-drying conditions are: vacuum degree ≤ 10 Pa, time 20-30 hours.

[0020] The embodiments of the present invention have the following advantages:

[0021] The invention prepares fresh chuanxiong stems and leaves into a homogenate, respectively adds maltodextrin with a content of 2%, 5%, 7%, 12% and 15% as a high molecular weight protective agent, and freeze-dries to obtain chuanxiong stem and leaf freeze-dried powder; the volatile oil and protein content in the chuanxiong stem and leaf freeze-dried powder are respectively determined by a steam distillation method and a Coomassie brilliant blue method, and finally scores are performed on the addition of different protective agents according to a weight ratio of volatile oil to protein (6:4). Mannitol, xylitol, lactose and sorbitol are then used as low molecular weight protective agents, and are combined with maltodextrin in different proportions to investigate the influence of the combination of high and low molecular weight protective agents on the volatile oil and protein content of the chuanxiong stem and leaf freeze-dried powder, and the freeze-dried protective agent with the best effect is screened out.

[0022] The freeze-drying protective agent screened out by the present invention can effectively protect the volatile oil and protein in the stems and leaves of Chuanxiong, thereby maximally ensuring the quality of the stems and leaves of Chuanxiong, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0024] Figure 1 The protein standard curve provided by the present invention;

[0025] Figure 2 Comparison of volatile oil content in freeze-dried powder of stems and leaves of Chuanxiong when maltodextrin with different contents provided by the present invention is used as a protective agent;

[0026] Figure 3 Comparison of protein content of maltodextrin with different contents as protective agent provided by the present invention;

[0027] Figure 4 Comparison of volatile oil content of the low molecular weight protective agent provided by the present invention and 7% maltodextrin in a 1:1 ratio;

[0028] Figure 5 Comparison of protein content of the low molecular weight protective agent provided by the present invention and 7% maltodextrin in a 1:1 ratio;

[0029] Figure 6 Comparison of volatile oil content of xylitol provided by the present invention and 7% maltodextrin in different proportions;

[0030] Figure 7 The present invention provides a comparison of the protein content of xylitol and 7% maltodextrin in different proportions. DETAILED DESCRIPTION

[0031] The following is a description of the implementation of the present invention by specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] 1 Materials and Instruments

[0034] 1.1 Materials and reagents

[0035] Table 1 Main materials and reagents

[0036]

[0037] 1.2 Instruments and Equipment

[0038] Table 2 Main experimental instruments and equipment

[0039]

[0040]

[0041] 2 Experimental methods

[0042] 2.1 Freeze drying of stems and leaves of Chuanxiong

[0043] 2400g of fresh Chuanxiong stems and leaves were added to 3500ml of distilled water by a juicer, and beaten at 100r / min for 3min. Different contents and types of protective agents were added, and the beating was continued for 2min. The resulting homogenate was evenly poured into the material tray, placed on the pre-freezing rack, and placed in a cold trap. First, it was pre-frozen at -60℃ for 5h. After complete freezing, the pre-freezing rack was taken out from the cold trap, and the material tray was transferred to the freeze-drying rack, placed above the cold trap, and vacuum freeze-dried for 28h under the condition of vacuum degree ≤10Pa. After freeze-drying, the freeze-dried block was powdered for 1min with a high-speed multifunctional pulverizer to obtain the freeze-dried powder of Chuanxiong stems and leaves, which was weighed and set aside.

[0044] 2.2 Determination of volatile oil content

[0045] 2.2.1 Volatile oil determination method

[0046] Accurately weigh 500 g of lyophilized powder of stems and leaves of Chuanxiong was added to a round-bottom flask, and distilled water was added at a liquid-to-solid ratio of 16 mL / g, stirred and mixed, and ultrasonicated for 17 min. The flask was then placed in an electric heating mantle and connected to a volatile oil extractor, and heated under reflux for 4 h. The obtained volatile oil was collected, extracted with petroleum ether, and the water was removed with methanol. The volatile oil was added to a heart-shaped bottle, and the petroleum ether and methanol were evaporated under reduced pressure to obtain volatile oil. The calculation of the volatile oil content is shown in formula (1).

[0047] Volatile oil content (%) = (M 挥发油 / M 川芎茎叶冻干粉 )×100% (1)

[0048] 2.2.2 Scoring criteria for volatile oil content

[0049] The volatile oil content of freeze-dried powder of stems and leaves of Ligusticum chuanxiong added with different contents and types of protective agents was determined according to method 2.2.1, and scored according to the volatile oil scoring criteria in Table 3 below.

[0050] Table 3 Volatile oil scoring details

[0051]

[0052]

[0053] 2.3 Protein content determination (Coomassie Brilliant Blue method)

[0054] 2.3.1 Solution preparation

[0055] (1) Preparation of standard protein solution

[0056] Accurately weigh 10.0 mg of bovine serum albumin (BSA), dissolve it in ultrapure water and make up to 100 mL to obtain a BSA standard solution with a concentration of 0.1 mg / mL, which is ready for use.

[0057] (2) Preparation of Coomassie Brilliant Blue G-250 Solution

[0058] Take 100 mg of Coomassie Brilliant Blue G250, add 50 mL of 95% ethanol and stir to dissolve, add 100 mL of 85% phosphoric acid, make up to 1000 mL with distilled water, filter twice and set aside.

[0059] 2.3.2 Methodological investigation

[0060] (1) Drawing of standard curve

[0061] Take 6 clean test tubes, add 0, 0.003125, 0.00625, 0.03, 0.5, 0.08, 0.1mL of BSA standard solution respectively, and add distilled water to 1mL to prepare BSA solutions of different concentrations. Add 5mL of Coomassie Brilliant Blue staining solution to the test tube and stain for 5 minutes. Use the test tube without BSA standard solution as the blank control, and measure the absorbance of the solution in the remaining 5 test tubes at 595nm. Using the protein concentration of the standard solution (mg / mL) as the horizontal coordinate x and the absorbance value as the vertical coordinate y, the regression equation is y=6.3607x+0.4356, R=0.9995, and the standard curve is drawn as shown in the figure. Figure 1 shown.

[0062] (2) Precision test

[0063] 0.5 mL of 0.1 mg / mL BSA standard solution was accurately pipetted for precision test. The absorbance was measured for 6 consecutive times, and RSD was 1.93%, indicating good precision. The results are shown in Table 4.

[0064] Table 4 Precision test results

[0065]

[0066] (3) Stability test

[0067] Take 0.5g of lyophilized powder of stems and leaves of Ligusticum chuanxiong prepared without freeze-drying protective agent, prepare sample solution according to the conditions of 2.3.3, take 0.5mL, measure absorbance every 10min, and observe its stability. The results show that the stability is good within 60min, RSD = 1.79%, the results are shown in Table 5 below.

[0068] Table 5 Stability test results

[0069]

[0070] (4) Reproducibility test

[0071] Five portions of the same sample solution without protective agent were precisely pipetted, each with 0.5 mL, and the absorbance of the sample was measured according to the conditions in 2.3.3 to test the reproducibility of the method. RSD = 1.33% was obtained, indicating good reproducibility. The results are shown in Table 6 below.

[0072] Table 6 Reproducibility test results

[0073]

[0074] (5) Spike recovery test

[0075] Accurately pipette 5 portions of the same test solution (referring to the sample solution) without adding protective agent, 0.5 mL per portion, add 0.1 mL, 0.2 mL, 0.3 mL, 0.4 mL, and 0.5 mL of protein reference solution respectively, measure the absorbance according to the conditions of 2.3.3, calculate the recovery rate, RSD = 1.81%, indicating a good recovery rate. The results are shown in Table 7 below.

[0076] Table 7 Spike recovery test results

[0077]

[0078] 2.3.3 Determination of total protein content

[0079] Accurately weigh 0.5g of lyophilized powder of stems and leaves of Chuanxiong, extract with water at constant temperature and ultrasonic for 50min, filter after fully dissolving, repeat twice, add distilled water to 50mL. Take 0.5mL and measure the absorbance of the solution according to the operation in 2.3.2. Calculate the percentage of protein based on the prepared standard curve.

[0080] 2.3.4 Protein content scoring rules

[0081] The protein content of freeze-dried powder of stems and leaves of Rhizoma Chuanxiong with different contents and types of protective agents was measured and scored according to the protein scoring criteria in Table 8 below.

[0082] Table 8 Protein scoring details

[0083]

[0084] 2.4 Screening of the optimal protective agent

[0085] 2.4.1 Score weights of volatile oil and protein in freeze-dried powder of Ligusticum chuanxiong stems and leaves

[0086] Studies have shown that the main active ingredient in the stems and leaves of Chuanxiong is volatile oil, and the phthalide compounds contained in volatile oil are the main material basis for its medicinal value. Based on this, according to the importance of volatile oil and protein to the stems and leaves of Chuanxiong, the final score was given with a weight of 60% for volatile oil and 40% for protein, and the optimal protective agent ratio was obtained.

[0087] 2.4.2 Optimal protective agent ratio screening process

[0088] According to the above experimental conditions, the volatile oil and protein content of the freeze-dried powder of Chuanxiong stems and leaves were first determined when different amounts of maltodextrin were used as a protective agent. The amount of maltodextrin was set to 2%, 5%, 7%, 12%, and 15% (based on the mass of fresh Chuanxiong stems and leaves). According to the weighted scores of volatile oil and protein, the optimal amount of maltodextrin was screened out. Then, the optimal content of maltodextrin was used in combination with mannitol, lactose, sorbitol, and xylitol at a ratio of 1:1 (mass ratio) as a protective agent, and the best combination of high and low molecular protective agents was screened out according to the weighted scores of volatile oil and protein. Finally, high and low molecular protective agents were combined in different proportions to obtain the weighted scores of volatile oil and protein, and the optimal protective agent ratio was screened out.

[0089] 3 Experimental results

[0090] 3.1 Screening of polymer protective agents

[0091] 3.1.1 Volatile oil content of freeze-dried powder of Ligusticum chuanxiong stems and leaves

[0092] Using maltodextrin as a polymer protective agent, the volatile oil content of freeze-dried powder of Chuanxiong stems and leaves after adding different amounts of maltodextrin was compared by steam distillation. The results were calculated according to formula (1) and are shown in Tables 9 and Figure 2 When the amount of maltodextrin added increased from 2% to 7%, the volatile oil content of the freeze-dried powder of Chuanxiong stems and leaves showed a gradual increase. When the amount of maltodextrin added was 7%, the volatile oil content was the highest, reaching 0.20%, which was 3.55 times that of the group without protective agent. The volatile oil content was ranked from high to low as follows: 7%>15%>12%>5%>2%. As the amount of maltodextrin added continued to increase, the volatile oil content decreased instead.

[0093] Table 9 Comparison of volatile oil content of different contents of maltodextrin as protective agent

[0094]

[0095] 3.1.2 Protein content of freeze-dried powder of Chuanxiong stems and leaves

[0096] Using maltodextrin as a polymer protective agent, the protein content was determined according to the conditions of 2.3.3. The results are shown in Table 10 and Figure 3 As shown. When 2% maltodextrin was added, the protein content of the freeze-dried powder of Chuanxiong stems and leaves was the highest, reaching 4.89%. The protein content was ranked from high to low as follows: 2%>15%>7%>5%>12%. As the amount of maltodextrin added increased, the protein content decreased, and the addition of a polymer protective agent did not show a protective effect on the protein of Chuanxiong stems and leaves.

[0097] Table 10 Comparison of protein content of maltodextrin with different contents as protective agent

[0098]

[0099] 3.1.3 Scoring of polymer protective agents with different contents

[0100] According to the obtained volatile oil and protein content, the protective effect of different amounts of maltodextrin as a protective agent on the stems and leaves of Chuanxiong was scored according to the scoring criteria of 2.2.2 volatile oil content and 2.3.4 protein content. The results are shown in Table 11. The highest score was 6.8 when 7% maltodextrin was added as a freeze-drying protective agent. Therefore, 7% maltodextrin was selected as a polymer protective agent in subsequent experiments.

[0101] Table 11 Scores of different contents of maltodextrin as protective agent

[0102]

[0103] 3.2 Screening of low molecular weight protective agents

[0104] 3.2.1 Volatile oil content of freeze-dried powder of Ligusticum chuanxiong stems and leaves

[0105] 7% maltodextrin was used as a high molecular weight protective agent in combination with sorbitol, xylitol, lactose, and mannitol low molecular weight protective agents in a 1:1 (mass ratio). The volatile oil content was calculated according to formula (1). The results are shown in Tables 12 and Figure 4 The results showed that the volatile oil content was ranked from high to low as follows: xylitol > lactose > sorbitol > mannitol. When xylitol was added as a low molecular weight protective agent, the volatile oil content was the highest, reaching 0.15%, which was 7.5 times that of mannitol. However, compared with adding only 7% maltodextrin, the volatile oil content was slightly lower.

[0106] Table 12 Comparison of volatile oil content in combination of low molecular weight protective agent and 7% maltodextrin 1:1

[0107]

[0108] 3.2.2 Protein content of maltodextrin combined with low molecular weight protective agent

[0109] The 7% maltodextrin with the highest score in the above experimental conclusion was used as a high molecular weight protective agent in combination with low molecular weight protective agents such as sorbitol, xylitol, lactose, and mannitol in a 1:1 (mass ratio). The results are shown in Tables 13 and Figure 5 The results showed that the combination of high-molecular-weight and low-molecular-weight protective agents had a better protective effect on the protein in the freeze-dried powder of Chuanxiong stems and leaves. The protein content was ranked from high to low as follows: sorbitol > lactose > xylitol > mannitol. Among them, the combination of sorbitol and 7% + maltodextrin 1:1 as freeze-dried protective agents had the best protein protection effect, reaching 11.21%.

[0110] Table 13 Comparison of protein content in combination of low molecular weight protective agent and 7% maltodextrin 1:1

[0111]

[0112]

[0113] 3.2.3 Scoring of combined use of high and low molecular weight protective agents

[0114] According to the obtained volatile oil and protein content, the protective effect of 7% maltodextrin and different low molecular weight protective agents used as freeze-drying protective agents on the stems and leaves of Chuanxiong was scored according to the 2.2.2 volatile oil content scoring criteria and 2.3.4 protein content scoring criteria. The results are shown in Table 14. Xylitol and 7% maltodextrin in a 1:1 (mass ratio) freeze-drying protective agent had the best protective effect on the effective components of the stems and leaves of Chuanxiong in this group, with a score of 7.

[0115] Table 14 Low molecular weight protective agent and 7% maltodextrin 1:1 combination and 7% maltodextrin score

[0116]

[0117] 3.3 Screening of the ratio of high and low molecular weight protective agents

[0118] 3.3.1 Volatile oil content of xylitol combined with 7% maltodextrin in different proportions

[0119] Xylitol and 7% maltodextrin were selected and used in four different ratios of 1:3, 1:2, 3:1, and 2:1 (mass ratio). The volatile oil content was calculated according to formula (1). The volatile oil content was ranked from high to low as follows: 1:3 = 1:2 = 2:1 > 3:1. The results are shown in Tables 15 and Figure 6 The results showed that the volatile oil content of these four groups was lower than that of the volatile oil in the stems and leaves of Chuanxiong Rhizoma Cistanches, which was 0.06% at most, when xylitol and 7% maltodextrin were used as freeze-drying protective agents in a ratio of 1:1 (mass ratio).

[0120] Table 15 Comparison of volatile oil content in different proportions of xylitol and 7% maltodextrin

[0121]

[0122] 3.3.2 Protein content of xylitol combined with 7% maltodextrin in different proportions

[0123] The results are shown in Table 16 and Figure 7 As shown, the protein content is ranked from high to low as 2:1>3:1>1:2>1:3. When xylitol and 7% maltodextrin are used in a 2:1 (mass ratio) ratio, the content of Chuanxiong stems and leaves reaches 6.52%, the highest among the four ratios, but still lower than the result of 1:1 (mass ratio) combination.

[0124] Table 16 Comparison of protein content in different proportions of xylitol and 7% maltodextrin

[0125]

[0126] 3.3.3 Scoring of xylitol and 7% maltodextrin in different proportions

[0127] According to the obtained volatile oil and protein content, the protective effect of 7% maltodextrin and xylitol in different proportions as freeze-drying protective agents on Chuanxiong stems and leaves was scored according to the 2.2.2 volatile oil content scoring criteria and 2.3.4 protein content scoring criteria. The results are shown in Table 17. The 1:1 combination of xylitol and 7% maltodextrin scored the highest in this group, with a score of 7.

[0128] Table 17 Scoring of xylitol and 7% maltodextrin in different proportions

[0129]

[0130] 4 Discussion

[0131] Volatile oil is the main active ingredient in the stems and leaves of Chuanxiong, and the phthalide compounds contained in it are the main material basis for its medicinal value. Protein and polysaccharide content are the main indicators for the subsequent experiments to make Chuanxiong stem and leaf products, but because maltodextrin as a polymer protective agent in the auxiliary material has a high influence on the polysaccharide content of Chuanxiong stem and leaves, the experiment chose to determine the volatile oil and protein content of Chuanxiong stem and leaf powder as indicators to screen freeze-drying protective agents.

[0132] When screening polymer protective agents, it was found that adding 2% and 5% maltodextrin as a protective agent had a poor protective effect on the effective ingredients of Chuanxiong stems and leaves. It is speculated that this may be because the amount of maltodextrin added is too low, and it may not form a sufficient protective layer, and it cannot effectively alleviate the physical and chemical stimulation during the freeze-drying process. It may also be because maltodextrin is not completely volatilized after freeze-drying, which will affect the volatile oil and protein content, and thus fail to achieve the protective effect of the effective ingredients. After adding 12% and 15% maltodextrin as a freeze-drying protective agent, the protection of the volatile oil in the freeze-dried powder of Chuanxiong stems and leaves did not increase but decreased compared to 7%. It is speculated that the addition of too much maltodextrin affects certain reactions or other factors in the freeze-drying process, resulting in the loss or reduction of the quality of the volatile oil. In addition, adding too much maltodextrin may affect the taste of the food and cause negative reviews. Therefore, when using maltodextrin as a protective agent, care should be taken to control the amount of maltodextrin added, and personalized adjustments and optimizations should be made based on factors such as different materials and processing conditions to achieve the best protective effect and maintain the best taste.

[0133] When high-molecular-weight and low-molecular-weight protective agents were used together, the protective effect on the volatile oil in the stems and leaves of Chuanxiong was not as good as that when only high-molecular-weight protective agents were added. This may be due to the different physical and chemical properties of high-molecular-weight and low-molecular-weight protective agents during the freeze-drying process, which led to uneven drying of the samples. After adding mannitol as a low-molecular-weight protective agent, the volatile oil content in the stems and leaves of Chuanxiong was the lowest, which may be due to the reaction between maltodextrin and mannitol to form an ester bond, thereby affecting the volatile oil content.

[0134] After adding low molecular weight protective agents, the proteins in the stems and leaves of Chuanxiong were effectively protected. The protective effect of sorbitol on proteins was particularly prominent. It is speculated that this may be because the protective effect of sorbitol is relatively stable and is less affected by environmental conditions such as pH and temperature. It may also be because this ratio has a strong ability to interact with proteins, and can effectively form hydrogen bonds and van der Waals forces with proteins, resulting in a better protective effect.

[0135] 5 Conclusion

[0136] The present invention uses the volatile oil and protein content of the freeze-dried powder of Chuanxiong stems and leaves as indicators to screen the freeze-dried protective agent. The results show that adding maltodextrin or combining maltodextrin with different low-molecular protective agents as freeze-dried protective agents has a certain degree of protective effect on the effective components of Chuanxiong stems and leaves. Using 7% maltodextrin alone has the best protective effect on volatile oil, reaching 0.20%, which is 3.5 times the volatile oil in the Chuanxiong stems and leaves without freeze-dried protective agents, and the weighted score is 6.8; the best effect after 7% maltodextrin is combined with a low-molecular protective agent is the combination of xylitol and 7% maltodextrin in a ratio of 1:1, and the volatile oil content of Chuanxiong stems and leaves reaches 0.15%, and the protein content reaches 8.94, which are 2.5 and 1.9 times of the group without adding protective agents, respectively, and the weighted score is 7.

[0137] According to the weighted scoring results, the optimal formula for freeze-drying of Chuanxiong stems and leaves was finally obtained, which was to add 7% maltodextrin and xylitol in a ratio of 1:1 (mass ratio) as a freeze-drying protectant. Under this condition, it has a good effect in protecting the effective ingredients of Chuanxiong stems and leaves, and can be used as a protectant for Chuanxiong stem and leaf freeze-dried powder.

[0138] Although the present invention has been described in detail above by general description and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, these modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A freeze-drying protective agent for stems and leaves of Chuanxiong, characterized in that: The freeze-drying protective agent is maltodextrin, or is composed of maltodextrin and a low-molecular protective agent in a mass ratio of 1-3:1-3, wherein the low-molecular protective agent is mannitol, xylitol, lactose or sorbitol.

2. The freeze-drying protective agent for the stems and leaves of Chuanxiong according to claim 1, characterized in that: The freeze-drying protective agent consists of maltodextrin and xylitol in a mass ratio of 1:

1.

3. A freeze-drying method for stems and leaves of Chuanxiong, characterized in that: The method comprises the following steps: (1) adding distilled water to fresh stems and leaves of Chuanxiong to pulp using a juicer to obtain a first pulp; (2) adding the freeze-drying protective agent for stems and leaves of Chuanxiong as claimed in claim 1 to the first slurry, and continuing to slurry to obtain a second slurry; (3) Pour the second slurry into a material tray, place it on a pre-freezing rack, put it into a cold trap, and pre-cool it. After it is completely frozen, take the pre-freezing rack out of the cold trap, transfer the material tray to a freeze-drying rack, place it above the cold trap, and perform vacuum freeze drying.

4. The freeze-drying method for the stems and leaves of Ligusticum chuanxiong according to claim 3, characterized in that: In step (1), The weight volume ratio of the fresh chuanxiong stems and leaves to distilled water is 240g:300-400ml; The beating conditions are: rotation speed 50-100r / min, 3-5min.

5. The freeze-drying method for stems and leaves of Ligusticum chuanxiong according to claim 3, characterized in that: In step (2), When the freeze-drying protective agent for the stems and leaves of Chuanxiong is maltodextrin, the added amount of the freeze-drying protective agent for the stems and leaves of Chuanxiong is 7% of the mass of the fresh stems and leaves of Chuanxiong; When the freeze-drying protective agent for the stems and leaves of Chuanxiong consists of maltodextrin and xylitol in a mass ratio of 1:1, the added amount of the freeze-drying protective agent for the stems and leaves of Chuanxiong is 14% of the mass of the fresh stems and leaves of Chuanxiong.

6. The freeze-drying method for stems and leaves of Ligusticum chuanxiong according to claim 3, characterized in that: In step (2), The conditions for continuing beating are: rotation speed 50-100r / min, 1-3min.

7. The freeze-drying method for stems and leaves of Ligusticum chuanxiong according to claim 3, characterized in that: In step (3), The precooling conditions are: -60°C freezing for 4-5h; The vacuum freeze-drying conditions are: vacuum degree ≤ 10 Pa, time 20-30 hours.

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