Preparation method and application of wild jujube core-shell dry distillation oil
The three-stage gradient heating and dry distillation method and segmented condensation purification were used to prepare the jujube core-shell distillation oil, which solved the problem of low added value of the jujube core-shell utilization, and achieved effective inhibition of E. coli and Staphylococcus aureus, making it suitable for industrial production.
Patent Information
- Application Number
- CN202510582558.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-07
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, the utilization of jujube core shells mainly stays at the basic application level such as physical crushing and preparation of activated carbon or chemical extraction of furfural, and has high energy consumption, low added value and failure to develop its biologically active value.
The dry distillation method of the three-stage gradient heating program was used to extract the dry distillation oil of the jujube core shell, and the condensate was collected in segments through the first and second stage condensers, and centrifuged and rotary evaporated to prepare the dry distillation oil of the jujube core shell rich in biologically active ingredients.
The prepared jujube core-shell distilled oil has a significant inhibitory effect on pathogenic bacteria such as E. coli and Staphylococcus aureus, filling the gap in the high-value utilization of core-shell waste, reducing production costs, and being suitable for large-scale industrial production.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of natural product extraction, and particularly relates to a preparation method of sour jujube kernel shell dry distillation oil and application thereof. Background Art
[0002] The sour jujube (Ziziphus jujuba var. spinosa) is a unique medicinal plant resource in my country. Its seeds, the sour jujube kernel, are listed in the Chinese Pharmacopoeia as a tranquilizing herb, with an annual demand exceeding 10,000 tons. However, the sour jujube kernel only accounts for 10% to 20% of the total mass of the sour jujube kernel. The remaining 80% to 90% of the sour jujube kernel shell lacks clear medicinal value and is often discarded as waste during processing. With the surge in demand for sour jujube kernels, the amount of kernel shell waste has also continued to rise. How to efficiently utilize this resource has become a pressing challenge for the industry.
[0003] Existing research shows that the jujube kernel shell mainly contains lignin, cellulose and minerals. The current utilization of the jujube kernel shell mainly remains at the basic application level such as physical crushing to prepare activated carbon or chemical extraction of furfural. These traditional processing methods have problems such as high energy consumption and low added value, and fail to effectively develop its potential biological activity value. Summary of the Invention
[0004] In response to the problems in the prior art, the present invention provides a preparation method and application of jujube kernel shell dry distillation oil. The distillation oil has significant antibacterial effect and has potential application value in the fields of medicine, daily chemicals, etc. It can be used to prepare antibacterial agents, antioxidants, and skin care product additives, providing a new direction for the high-value utilization of jujube kernel shells.
[0005] The method for preparing the dry distillation oil of jujube kernel shells of the present invention comprises the following steps:
[0006] (1) Raw material pretreatment: take the shell of sour jujube, wash, dry, crush or grind;
[0007] (2) Temperature-controlled pyrolysis and dry distillation: Place the pretreated jujube shells in a dry distillation device, isolate them from air, heat them to 200-250°C for dehydration for 30-50 minutes, then heat them to 300-350°C for 1.5-2.5 hours, and finally heat them to 400-450°C for constant temperature cracking for 1-1.5 hours;
[0008] The present invention adopts a three-stage gradient heating program: the first stage (200-250°C): removal of bound water and low-molecular volatiles; the second stage (300-350°C): cracking of hemicellulose and lignin side chains to release phenolic compounds; the third stage (400-450°C): deep cracking of cellulose to generate aldehydes and ketones.
[0009] (3) Fraction collection: The condensate is collected in sections through the primary condenser and the secondary condenser;
[0010] (4) Product purification: Combine the two-stage condensate, centrifuge, take the upper oil phase, remove water and purify it by rotary evaporation, and collect the brown oil in the rotary evaporation bottle, which is the dry distillation oil of jujube kernel shell.
[0011] Specifically, in step (1), the product is generally dried to a moisture content of ≤5%, and crushed or pulverized to 10-80 mesh.
[0012] In step (3) of the present invention, the temperature of the primary condenser is controlled at 0-80°C, and the temperature of the secondary condenser is controlled at 10-30°C. The primary condenser collects high-boiling-point components (such as tar acid), while the secondary condenser focuses on capturing antimicrobial active ingredients with boiling points less than 150°C (such as phenol and guaiacol), with a total collection efficiency exceeding 85%. The light components collected by the primary condenser account for 10%-20% of the total distillate, while the active components collected by the secondary condenser account for 65%-80%.
[0013] In step (4), the centrifugal speed is 5000-8000 r / min, the centrifugal time is 20-30 minutes, the rotary evaporation water purification temperature is set to 70-100° C., and the rotary evaporation time is 30-90 minutes.
[0014] The inventors found that the distilled oil obtained by the above method has a significant inhibitory effect on common pathogens such as Escherichia coli and Staphylococcus aureus. The minimum inhibitory concentration (MIC) for Staphylococcus aureus and Escherichia coli is 3%, and the minimum bactericidal concentration for Staphylococcus aureus and Escherichia coli is 12%. It can be used to prepare antibacterial products, such as antibacterial sprays, antibacterial washes, or antibacterial coatings for medical dressings.
[0015] Compared with the prior art, the present invention has the following beneficial effects:
[0016] (1) The dry distillation extraction method used in the present invention is carried out under high temperature conditions isolated from air, avoiding the problem of solvent residue in traditional extraction methods and conforming to the concept of green environmental protection. At the same time, the method is simple to operate, has relatively low equipment requirements, does not require complex instruments and equipment, reduces production costs, and is suitable for large-scale industrial production.
[0017] (2) The extract of the jujube kernel distillate oil prepared by the method of the present invention is rich in a variety of bioactive ingredients. In terms of antibacterial properties, it has a significant inhibitory effect on common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus, expanding its application in the fields of antibacterial and other fields, filling the gap in the technology of high-value utilization of kernel and shell waste, and providing a new direction for the high-value utilization of jujube kernel and shell. It is of great strategic significance to realize the full component utilization of jujube resources and enhance the added value of the industry. DETAILED DESCRIPTION
[0018] Example 1
[0019] A method for preparing sour jujube kernel shell dry distillation oil, characterized by comprising the following steps:
[0020] (1) Raw material pretreatment: Take 1 kg of sour jujube kernel shell, wash it, dry it to a moisture content of ≤5%, and crush it into 10-80 mesh;
[0021] (2) Temperature-controlled pyrolysis and dry distillation: The pretreated jujube shells were placed in a dry distillation device, isolated from air, heated to 200°C for dehydration for 50 minutes, then heated to 300°C for 2.5 hours, and finally heated to 400°C for constant temperature cracking for 1.5 hours;
[0022] (3) Fraction collection: The condensate is collected in sections through the primary condenser and the secondary condenser (primary condenser 70°C / secondary condenser 15°C);
[0023] (4) Product Purification: Combine the two condensates and centrifuge at 5000 rpm for 30 minutes. The upper oil phase is collected and purified by rotary evaporation to remove water. The brown oil in the rotary evaporation flask is collected, which is 138 g of jujube kernel shell dry distillation oil. The rotary evaporation temperature for water removal and purification is set at 90°C and the rotary evaporation time is 30 minutes.
[0024] Example 2
[0025] A method for preparing sour jujube kernel shell dry distillation oil, characterized by comprising the following steps:
[0026] (1) Raw material pretreatment: Take 1 kg of sour jujube kernel shell, wash it, dry it to a moisture content of ≤5%, and crush it into 10-80 mesh;
[0027] (2) Temperature-controlled pyrolysis and dry distillation: The pretreated sour jujube shells were placed in a dry distillation device, isolated from air, heated to 250°C for dehydration for 30 minutes, then heated to 350°C for 1.5 hours, and finally heated to 450°C for constant temperature cracking for 1 hour;
[0028] (3) Fraction collection: The condensate is collected in sections through the primary condenser and the secondary condenser (primary condenser 70°C / secondary condenser 15°C);
[0029] (4) Product Purification: Combine the two condensates and centrifuge at 6000 rpm for 25 minutes. The upper oil phase is collected and purified by rotary evaporation to remove water. The brown oil in the rotary evaporation flask is collected as 119 g of dry distilled oil from the jujube kernel shell. The rotary evaporation temperature for water removal and purification is set at 70°C and the rotary evaporation time is 90 minutes.
[0030] Example 3
[0031] A method for preparing sour jujube kernel shell dry distillation oil, characterized by comprising the following steps:
[0032] (1) Raw material pretreatment: Take 1 kg of sour jujube kernel shell, wash it, dry it to a moisture content of ≤5%, and crush it into 10-80 mesh;
[0033] (2) Temperature-controlled pyrolysis and dry distillation: The pretreated sour jujube shells were placed in a dry distillation device, isolated from air, heated to 220°C for dehydration for 40 minutes, then heated to 330°C for 2 hours, and finally heated to 420°C for constant temperature cracking for 1.2 hours;
[0034] (3) Fraction collection: The condensate is collected in sections through the primary condenser and the secondary condenser (primary condenser 70°C / secondary condenser 15°C);
[0035] (4) Product Purification: Combine the two condensates and centrifuge at 8000 rpm for 20 minutes. The upper oil phase is collected and purified by rotary evaporation to remove water. The brown oil in the rotary evaporation flask is collected, which is 129 g of jujube kernel shell dry distillation oil. The rotary evaporation temperature for water removal and purification is set at 90°C and the rotary evaporation time is 50 minutes.
[0036] Example 4
[0037] A method for preparing sour jujube kernel shell dry distillation oil, characterized by comprising the following steps:
[0038] (1) Raw material pretreatment: Take 1 kg of sour jujube kernel shell, wash it, dry it to a moisture content of ≤5%, and crush it into 10-80 mesh;
[0039] (2) Temperature-controlled pyrolysis and dry distillation: The pretreated sour jujube shells were placed in a dry distillation device, isolated from air, and heated to 350°C for constant temperature cracking for 3 hours;
[0040] (3) Fraction collection: collecting condensate through a condenser;
[0041] (4) Product Purification: The condensate was centrifuged at 5000 rpm for 30 minutes. The upper oil phase was collected and purified by rotary evaporation to remove water. The brown oil in the rotary evaporation flask was collected to obtain 112 g of dry distilled oil from the jujube kernel shell. The rotary evaporation temperature for water removal and purification was set at 90°C for 30 minutes.
[0042] Example 5
[0043] A method for preparing sour jujube kernel shell dry distillation oil, characterized by comprising the following steps:
[0044] (1) Raw material pretreatment: Take 1 kg of sour jujube kernel shell, wash it, dry it to a moisture content of ≤5%, and crush it into 10-80 mesh;
[0045] (2) Temperature-controlled pyrolysis and dry distillation: The pretreated sour jujube shells were placed in a dry distillation device, isolated from air, and heated to 450°C for constant temperature cracking for 2 hours;
[0046] (3) Fraction collection: collecting condensate through a condenser;
[0047] (4) Product Purification: The condensate was centrifuged at 5000 rpm for 30 minutes. The upper oil phase was collected and purified by rotary evaporation to remove water. The brown oil in the rotary evaporation flask was collected to obtain 107 g of dry distilled oil from the jujube kernel shell. The rotary evaporation temperature for water removal and purification was set at 90°C for 30 minutes.
[0048] Experimental example
[0049] 1. Determination of antibacterial effect of dried distilled oil from jujube kernel shell
[0050] The antibacterial activity of dried jujube kernel oil was determined using the Oxford cup method. 100 μL of each suspension of Escherichia coli and Staphylococcus aureus was spread evenly on a solid culture medium. Two Oxford cups were placed equidistantly on the culture medium and 100 μL each of 0.9% sterile sodium chloride solution and 12% dried jujube kernel oil was injected. This was repeated three times. The mixture was incubated in a 37°C incubator for 20 hours, and the diameter of the inhibition zone was measured. Antibacterial activity was assessed according to the "Standards for Antimicrobial Susceptibility Testing" (USA, Committee for Clinical Laboratory Standards). Inhibition zone diameters greater than 20 mm are considered extremely sensitive, 15-20 mm are considered highly sensitive, 10-15 mm are considered moderately sensitive, and less than 10 mm are considered hyposensitive.
[0051] Table 1 Measurement results of the antibacterial zone diameter of the dried distilled oil of jujube kernel shell
[0052]
[0053] As shown in Table 1, the jujube dry distillation oil obtained by the present invention has good antibacterial effects on Escherichia coli and Staphylococcus aureus, and the antibacterial effect on Escherichia coli is better than that on Staphylococcus aureus. At the same time, the yield and antibacterial effect of the dry distillation oil obtained by gradient temperature increase are significantly stronger than those of the dry distillation method without gradient temperature increase.
[0054] 2. Results of Minimum Inhibitory Concentration Determination of Solanum jujuba Shell Dry Distilled Oil
[0055] The double dilution method was used to dilute the jujube kernel dry distillation oil in Example 1 with 60% alcohol to 12.00%, 6.00%, 3.00%, 1.50%, 0.75%, and 0.375% solutions. The antibacterial effects of the jujube kernel dry distillation oil solutions at different concentrations were measured according to the method. The results are shown in Table 2. The results show that the jujube kernel dry distillation oil has an inhibitory effect on Escherichia coli and Staphylococcus aureus. When the concentration of the jujube kernel dry distillation oil is 3%, the growth of Escherichia coli and Staphylococcus aureus is completely inhibited.
[0056] Table 2 Antibacterial test results of different concentrations of dry distilled oil from jujube seeds and shells (n=3)
[0057]
[0058]
[0059] Note: The presence of colonies is recorded as "(+)" and the absence of colonies is recorded as "(-)".
[0060] The same method was used to determine the minimum inhibitory concentration of the dry distillation oil obtained in Examples 1-3. The jujube kernel dry distillation oil completely inhibited the growth of Escherichia coli and Staphylococcus aureus at concentrations of 3%, 6%, and 3%, respectively. The determination results are shown in Table 3.
[0061] Table 3 Antibacterial test results of different concentrations of the dry distilled oil of jujube kernel shell obtained in Examples 1-3 (n=3)
[0062]
[0063] Note: The presence of colonies is recorded as "(+)" and the absence of colonies is recorded as "(-)".
[0064] 3. Results of determination of minimum bactericidal concentration of dry distilled oil from jujube kernel shell
[0065] Based on the determination of the minimum inhibitory concentration (MIC), 100 μL of culture medium was removed from test tubes containing 12.00%, 6.00%, and 3.00% jujube kernel oil and added to 10 mL of nutrient broth. The mixture was then diluted to eliminate the antibacterial effects of the residual drug. The culture was continued at 37°C for 24 hours, and then the plate was spread to observe for bacterial growth. The minimum drug concentration that resulted in no bacterial growth was defined as the minimum bactericidal concentration (MIC). A negative drug control and a culture medium blank were also established. The results are shown in Table 4. The minimum bactericidal concentration of jujube kernel oil against Escherichia coli and Staphylococcus aureus was 12%.
[0066] Table 4 Bactericidal test results of different concentrations of dry distilled oil of jujube kernel shell (n=3)
[0067]
[0068] Note: The presence of colonies is recorded as "(+)" and the absence of colonies is recorded as "(-)".
[0069] The same method was used to determine the minimum bactericidal concentration of the distillation oil obtained in Examples 1-3. The results showed that when the concentration of the sour jujube kernel distillation oil was 12%, no bacteria grew on the plates, indicating that the minimum bactericidal concentration of the distillation oil obtained in Examples 1-3 was 12%. The determination results are detailed in Table 5.
[0070] Table 5 Bactericidal test results of different concentrations of the dry distilled oil of jujube kernel shell obtained in Examples 1-3
[0071]
[0072] Note: The presence of colonies is marked as "(+)" and the absence of colonies is marked as "(-)".
Claims
1. A method for preparing dry distillation oil of sour jujube kernel shell, characterized in that: The following steps are involved: (1) Temperature-controlled pyrolysis and dry distillation: The pretreated sour jujube shells were placed in a dry distillation device, isolated from air, heated to 200-250°C for dehydration for 30-50 minutes, then heated to 300-350°C for 1.5-2.5 hours, and finally heated to 400-450°C for constant temperature cracking for 1-1.5 hours; (2) Fraction collection: The condensate is collected in sections through the primary condenser and the secondary condenser; (3) Product purification: Combine the two-stage condensate, centrifuge, take the upper oil phase, remove water and purify it by rotary evaporation, and collect the brown oil in the rotary evaporation bottle, which is the dry distillation oil of jujube kernel shell.
2. The method for preparing the dry distillation oil of jujube kernel shell according to claim 1, wherein: The pretreatment includes washing, drying, crushing or pulverizing.
3. The method for preparing the dry distillation oil of jujube kernel shell according to claim 1, wherein: The water content of the pretreated sour jujube kernel shell is less than or equal to 5%, and the mesh size is 10 to 80 meshes.
4. The method for preparing the dry distillation oil of jujube kernel shell according to claim 1, wherein: In step (2), the temperature of the first-stage condenser is 0-80°C, and the temperature of the second-stage condenser is 10-30°C.
5. The method for preparing the dry distillation oil of jujube kernel shell according to claim 1, wherein: In step (3), the centrifugal speed is 5000-8000 r / min, and the centrifugal time is 20-30 minutes.
6. The method for preparing the dry distillation oil of sour jujube kernel shell according to claim 1, wherein: In step (3), the rotary evaporation temperature for water removal and purification is set to 70-100° C. and the rotary evaporation time is 30-90 minutes.
7. Use of the dry distillation oil of jujube kernel shell prepared by the method according to any one of claims 1 to 6 in the preparation of antibacterial products.
8. The use of the dry distillation oil of jujube kernel shell according to claim 7 in the preparation of antibacterial products, characterized in that: The minimum inhibitory concentration of the dry distillation oil to Staphylococcus aureus and Escherichia coli is 3%, and the minimum bactericidal concentration to Staphylococcus aureus and Escherichia coli is 12%.
9. The use of the dry distillation oil of sour jujube kernel shell according to claim 7 in the preparation of antibacterial products, characterized in that: The antibacterial product is an antibacterial spray or an antibacterial lotion or an antibacterial coating for medical dressings.