Cinnamomum camphora leaf essential oil and application thereof in preparation of Cinnamomum camphora leaf essential oil preservative film

Abstract

The invention relates to cinnamomum camphora leaf essential oil and application thereof in preparation of a cinnamomum camphora leaf essential oil preservative film. The cinnamomum camphora leaf essential oil extracted from cinnamomum camphora leaves has antibacterial activity and antioxidant activity superior to those of cinnamomum camphora leaf essential oil of the same genus, the essential oil and ethyl alcohol are mixed to form a stable cinnamomum camphora leaf essential oil solution, and the stable cinnamomum camphora leaf essential oil solution and beta-cyclodextrin are included to obtain the cinnamomum camphora leaf essential oil microcapsule. Glycerol is added into the gelatinized starch aqueous solution, and then the cinnamomum camphora leaf essential oil microcapsules are added to prepare the cinnamomum camphora leaf essential oil preservative film. The cinnamomum camphora leaf essential oil preservative film prepared by the invention has antibacterial and antioxidant effects.

Description

Technical Field

[0001] The present application relates to the technical field of food preservation, and in particular to a camphor leaf essential oil and an application thereof in preparing a camphor leaf essential oil preservative film. Background Art

[0002] Camphora tenuipilis (Kosterm.) Y. Yang, Bing Liu & Zhi Yang) is a plant of the genus Camphora in the family Lauraceae. It is mainly distributed in the bushes, sparse forests or dense forests in the valleys or valleys in southern and western Yunnan, with an altitude of 580-2100 meters. In addition, the fresh leaves of Camphora tenuipilis can be chopped or mashed to make meat and raw seasoning and fragrance. It is a seasoning spice with ethnic characteristics in Xishuangbanna and has a long history of use. Due to habitat destruction and artificial felling, and the fact that Camphora tenuipilis is a cross-pollinated plant with a low fruiting rate and easy abortion, the wild population of Camphora tenuipilis is currently scarce and scattered, which has aggravated its endangered status. It is urgent to increase scientific research investment and provide scientific and technological support for its development and utilization. The early research on Camphora tenuipilis was mainly conducted by Cheng Biqiang and others in the 1980s and 1990s, which analyzed the chemical composition of its leaves, cultivated it, and compared some of its plant classifications. However, there are currently no reports on the pharmacological activities and functional evaluations of Cinnamomum pubescens leaf essential oils of different chemical types, which limits the product development and industrialization of Cinnamomum pubescens.

[0003] Essential oils, also known as volatile oils and aromatic oils, are a class of volatile and fat-soluble oily substances contained in aromatic plants. The chemical composition of essential oils is relatively complex. According to their structure, they can be divided into terpenoids, aromatic compounds, aliphatic compounds, sulfur-containing and nitrogen-containing heterocyclic compounds, and special compounds with macrolide structures. Essential oils have a variety of physiological activities, including antibacterial, anti-inflammatory, antiviral, analgesic, anti-tumor, mosquito repellent, penetration-promoting, and antioxidant. However, due to the disadvantages of volatility, unstable chemical properties, high preparation costs, and strong odors of many essential oils, their application in the food field is limited. How to achieve the effective use of essential oils in the food field has become an urgent problem to be solved.

[0004] Therefore, it is necessary to provide a kind of Cinnamomum pubescens leaf essential oil and the application of Cinnamomum pubescens leaf essential oil in the food field. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, the present application provides a camphor leaf essential oil and its application in preparing a camphor leaf essential oil preservative film. The camphor leaf essential oil has antibacterial activity and antioxidant activity that are superior to those of the same genus camphor leaf essential oil. The camphor leaf essential oil preservative film prepared using the camphor leaf essential oil has antibacterial and antioxidant effects.

[0006] The present application provides a method for preparing Cinnamomum pubescens leaf essential oil, comprising the following steps:

[0007] The leaves of Cinnamomum pubescens are added with water for distillation extraction, and the distillate is collected and dried to obtain the essential oil of Cinnamomum pubescens leaves.

[0008] Optionally, the mass ratio of Cinnamomum pubescens leaves to the water is 1:(3-4); and the distillation extraction time is 4 hours.

[0009] The present application also provides the use of the Cinnamomum pubescens leaf essential oil prepared by the above-mentioned preparation method in the preparation of Cinnamomum pubescens leaf essential oil preservative film.

[0010] Optionally, the raw materials include microcapsules of Cinnamomum camphora leaf essential oil and a gelatinized starch aqueous solution; the mass ratio of the microcapsules of Cinnamomum camphora leaf essential oil to the gelatinized starch aqueous solution is (1-3):10;

[0011] The Cinnamomum pubescens leaf essential oil microcapsules use β-cyclodextrin as the wall material and a stable Cinnamomum pubescens leaf essential oil solution as the core material; the mass ratio of the β-cyclodextrin to the stable Cinnamomum pubescens leaf essential oil solution is (8-10):1.

[0012] Optionally, include the following steps:

[0013] The stable Cinnamomum pubescens leaf essential oil solution and β-cyclodextrin are included, filtered, and dried to obtain Cinnamomum pubescens leaf essential oil microcapsules; glycerol is added to the gelatinized starch aqueous solution at a preset temperature, and then the Cinnamomum pubescens leaf essential oil microcapsules are added to prepare the Cinnamomum pubescens leaf essential oil preservative film.

[0014] Optionally, the inclusion is carried out by stirring at 45°C for 30 min and then placing at 4°C for 24 h.

[0015] Optionally, the method for preparing a stable Cinnamomum pubescens leaf essential oil solution is to mix Cinnamomum pubescens leaf essential oil and anhydrous ethanol to prepare a stable essential oil solution; the mass ratio of the Cinnamomum pubescens leaf essential oil to the ethanol is 1:10.

[0016] Optionally, the method for preparing the gelatinized starch aqueous solution is to gelatinize potato starch, sodium carboxymethyl cellulose and water at 80-90° C. to obtain the gelatinized starch aqueous solution; the mass ratio of the potato starch, the sodium carboxymethyl cellulose and the water is 2:1:64.

[0017] Optionally, the preset temperature is 70-80°C.

[0018] β-cyclodextrin (β-CD) can effectively encapsulate the active ingredients in Cinnamomum camphora leaf essential oil through its unique ring structure, thereby enhancing its antibacterial and antioxidant effects. Essential oil components usually have low solubility and volatility. By combining with β-cyclodextrin, their solubility can be improved and their stability can be prolonged. After the Cinnamomum camphora leaf essential oil is encapsulated by β-cyclodextrin, the antioxidant components of the Cinnamomum camphora leaf essential oil can be released more sustainably, improving its antioxidant effect and effectively reducing the risk of volatilization or degradation. In addition, the hydrophilic inner cavity of β-cyclodextrin enables the hydrophobic components of the Cinnamomum camphora leaf essential oil to contact the organism more easily, thereby enhancing its bioavailability and activity. Therefore, the inclusion characteristics of β-cyclodextrin are highly compatible with Cinnamomum camphora leaf essential oil, which helps to maximize its antibacterial and antioxidant effects.

[0019] The technical solution provided by this application may have the following beneficial effects:

[0020] 1) The Cinnamomum pubescens leaf essential oil prepared in the present application has better antibacterial activity and antioxidant activity than the Cinnamomum camphora leaf essential oil of the same genus.

[0021] 2) The Cinnamomum pubescens leaf essential oil is included with β-cyclodextrin at a suitable temperature to maintain the antibacterial and antioxidant effects of the Cinnamomum pubescens leaf essential oil, and the prepared Cinnamomum pubescens leaf essential oil preservative film has antibacterial and antioxidant effects.

[0022] 3) The Cinnamomum pubescens essential oil cling film prepared using Cinnamomum pubescens essential oil lays a material foundation for further exploring the functions and biological activities of Cinnamomum pubescens essential oil, provides a scientific basis for the rational development and utilization of this plant resource, and ultimately provides a new resource for promoting the industrial development of cling film with antibacterial and antioxidant effects.

[0023] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0025] Figure 1 It is a schematic diagram of the actual application of the microcapsule preservative film of Cinnamomum pubescens essential oil shown in the present application. DETAILED DESCRIPTION

[0026] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0027] Example 1: Preparation of Cinnamomum camphora leaf essential oil by steam distillation

[0028] Take fresh Cinnamomum pubescens leaves, add 3-4 times of ultrapure water, steam distill for 4 hours, collect distillate, dry with anhydrous sodium sulfate to obtain Cinnamomum pubescens leaf essential oil, the yield is 0.1%-0.5%. After the Cinnamomum pubescens leaf essential oil is packed in a brown essential oil bottle, it is stored in a refrigerator at 4°C for later use.

[0029] Test Example 1: Antibacterial activity test of Cinnamomum pubescens leaf essential oil

[0030] Bacillus cereus, Bacillus subtilis, Escherichia coli, and Staphylococcus aureus were provided by the Microbial Culture Collection Center of the College of Life Sciences, Nanjing Agricultural University. Botrytis cinerea was isolated from rotten strawberry fruits and identified by ITS sequence analysis by Sangon Biotech (Shanghai) Co., Ltd.

[0031] (1) Antibacterial test

[0032] Take a 96-well culture plate and dilute the Cinnamomum pubescens leaf essential oil sample in a gradient manner. Set eight concentration gradients of 25 μL / mL, 12.5 μL / mL, 6.25 μL / mL, 3.13 μL / mL, 1.56 μL / mL, 0.78 μL / mL, 0.39 μL / mL, and 0.19 μL / mL. Add bacterial culture solution to each well to make the bacterial solution concentration about 5×10 5 CFU / mL; after culturing at 37℃ for 24 hours, add the colorimetric agent iodonitrotetrazolium violet solution to each well, then culture at 37℃ for 2 hours. The lowest concentration that does not turn red is the minimum inhibitory concentration (MIC) of the essential oil against bacteria. Pipette the non-colorizing solution into LB solid medium and culture at 37℃ for 24 hours. The lowest concentration that does not grow bacteria is the minimum bactericidal concentration (MBC) of the essential oil against bacteria. The experiment also sets up a blank medium control and a bacterial control.

[0033] (2) Antifungal test

[0034] The essential oil was added to the PDA medium to be solidified, and the essential oil was gradiently diluted with anhydrous ethanol, and four concentration gradients of 0.5μL / mL, 1μL / mL, 2μL / mL, and 4μL / mL were set. A 5mm cake was taken from the Botrytis cinerea grown for 5 days and inverted on the PDA medium, and the mycelial growth of Botrytis cinerea after two and four days of growth was recorded, and the relative inhibition rate of the essential oil on Botrytis cinerea was calculated. A blank control and anhydrous ethanol control were also set in the experiment.

[0035] Inhibition rate (%) = (CT) / C×100%

[0036] Wherein, C is the radial colony growth of the control pathogen (mm); T is the radial colony growth of the pathogen after treatment (mm).

[0037] The specific results are shown in Table 1 and Table 2:

[0038] Table 1 Antibacterial activity of Cinnamomum pubescens leaf essential oil

[0039]

[0040]

[0041] Note: The smaller the MIC and MBC values, the better the antibacterial activity of the essential oil.

[0042] Table 2 Antifungal activity of Cinnamomum pubescens leaf essential oil

[0043]

[0044] According to the test results in Tables 1 and 2, the inhibitory effect of Cinnamomum hainanensis leaf essential oil on Bacillus cereus, Bacillus subtilis and Escherichia coli is better than that of Cinnamomum camphora leaf essential oil of the same genus. At the same time, it can effectively inhibit the mycelial growth of Botrytis cinerea at a lower concentration. It is inferred that Cinnamomum hainanensis leaf essential oil has good antibacterial activity.

[0045] Test Example 2: Antioxidant activity test of Cinnamomum pubescens leaf essential oil

[0046] The total antioxidant capacity (ABTS method) kit, the total antioxidant capacity (DPPH method) kit and the total antioxidant capacity (FRAP method) kit were all purchased from Suzhou Keming Biotechnology Co., Ltd.

[0047] (1) Total antioxidant capacity (ABTS method) test

[0048] Take a 96-well plate, add 10 μL of samples of different concentrations to 190 μL ABTS+ solution, react at room temperature in the dark for 6 minutes, and measure the absorbance at 732 nm with an enzyme marker. Repeat the experiment 3 times for each sample and take the average value. Trolox is used as the standard, and the iron ion reducing capacity of the essential oil sample is expressed by Trolox-Equivalent Antioxidant Capacity (TEAC).

[0049] (2) Total antioxidant capacity (DPPH method) test

[0050] Add 10 μL of sample extracts of different concentrations to a 96-well plate, then add 190 μL of DPPH solution, react at room temperature in the dark for 20 minutes, and measure the absorbance at 515 nm using an enzyme marker. Repeat the experiment 3 times for each sample and take the average value. Trolox was used as the standard, and the total antioxidant capacity (DPPH method) of the essential oil sample was expressed by Trolox-Equivalent Antioxidant Capacity (TEAC).

[0051] (3) Total antioxidant capacity (FRAP method) test

[0052] Take a 96-well plate, add 10 μL of samples of different concentrations and 180 μL of TPTZ solution, mix well, react at 37°C for 10 minutes, and measure the absorbance at 593 nm using an enzyme marker. Repeat the experiment three times for each sample and take the average value. Trolox was used as the standard, and the total antioxidant capacity (FRAP method) of the essential oil sample was expressed by Trolox-Equivalent Antioxidant Capacity (TEAC).

[0053] The specific results are shown in Table 3:

[0054] Table 3 Antioxidant activity of Cinnamomum pubescens leaf essential oil

[0055]

[0056] Note: TEAC is the Trolox equivalent antioxidant capacity of Cinnamomum quinoa leaf essential oil and Cinnamomum camphora leaf essential oil. The larger the TEAC value, the stronger the antioxidant activity.

[0057] According to the test results in Table 3, the essential oil of Cinnamomum hainanensis leaves showed better antioxidant activity than that of Cinnamomum camphora leaves in DPPH, ABTS and FRAP antioxidant tests, indicating its good application prospect in antioxidant products.

[0058] Example 2: Preparation of Cinnamomum camphora leaf essential oil preservative film

[0059] 1) mixing Cinnamomum pubescens leaf essential oil and anhydrous ethanol to prepare a stable essential oil solution; the mass ratio of Cinnamomum pubescens leaf essential oil to the ethanol is 1:10;

[0060] 2) Using β-cyclodextrin as the wall material and a stable Cinnamomum camphora leaf essential oil solution as the core material; stirring the stable essential oil solution and β-cyclodextrin at 45° C. for 30 min, placing in a 4° C. refrigerator for 24 h for inclusion, then filtering with suction, and drying in an oven at 60° C. for 3 h to obtain Cinnamomum camphora leaf essential oil microcapsules; the Cinnamomum camphora leaf essential oil microcapsules are powdery solids; the mass ratio of β-cyclodextrin to the stable Cinnamomum camphora leaf essential oil solution is (8-10):1;

[0061] 3) gelatinizing potato starch, sodium carboxymethyl cellulose and deionized water at 80-90° C. to prepare a gelatinized starch aqueous solution; the mass ratio of potato starch, sodium carboxymethyl cellulose and water is 2:1:64;

[0062] 4) The preset temperature is 70-80° C., glycerol is added dropwise to the gelatinized starch aqueous solution, and then the Cinnamomum camphora leaf essential oil microcapsules are added, stirred until viscous, cast onto a plastic plate, and dried at room temperature for 48 hours to obtain the Cinnamomum camphora leaf essential oil preservative film; the mass ratio of the Cinnamomum camphora leaf essential oil microcapsules to the gelatinized starch aqueous solution is (1-3):10.

[0063] Comparative Example 1:

[0064] The difference between the preparation of Cinnamomum pubescens leaf essential oil microcapsules in Comparative Example 1 and Example 2 is that the inclusion is carried out at 65° C. in step 2).

[0065] Comparative Example 2: Chitosan is used as the wall material for inclusion

[0066] 1) mixing Cinnamomum pubescens leaf essential oil and anhydrous ethanol to prepare a stable essential oil solution; the mass ratio of Cinnamomum pubescens leaf essential oil to the ethanol is 1:10;

[0067] 2) Chitosan is used as the wall material and the stable camphor leaf essential oil solution is used as the core material; chitosan is mixed with water and dissolved in a 50°C water bath for 3 hours. Then it is cooled to room temperature, an appropriate amount of 1% Tween 80 is added as an emulsifier, and stirred at room temperature for 15 minutes. Then the stable essential oil solution is added and stirred for 30 minutes. Finally, centrifuge at 13000rpm / min for 10 minutes, take the precipitate, and freeze-dry to obtain the camphor leaf essential oil microcapsules. The camphor leaf essential oil microcapsules are slightly yellow powder solids; the mass ratio of chitosan to the stable camphor leaf essential oil solution is (3-5):1.

[0068] Comparative Example 3

[0069] The difference between Comparative Example 3 and Example 2 is that in step 4) of Comparative Example 3, the mass ratio of the Cinnamomum pubescens leaf essential oil microcapsules to the gelatinized starch aqueous solution is (5-10):10.

[0070] Test Example 3: Microcapsule recovery rate experiment

[0071] The microcapsule recovery test is the ratio of the weight of the microcapsules obtained (dry basis) to the total mass of the core and wall materials used to formulate the microcapsules.

[0072] Microcapsule recovery rate (%) = weight of obtained microcapsules / weight of materials used to prepare microcapsules × 100%.

[0073] The experimental results are shown in Table 4.

[0074] Table 4 Experimental results of recovery rate of microcapsules of camphor leaf essential oil of Example 2, Comparative Example 1 and Comparative Example 2

[0075]

[0076] As shown in Table 4, the recovery rate of microcapsules included at 45°C in Example 2 is 84.32%, while the recovery rate of microcapsules included at 65°C in Comparative Example 1 is 56.55%, which shows that too high a temperature will greatly reduce the effective utilization rate of the essential oil. In Example 2, β-cyclodextrin is used as the wall material for inclusion, while the recovery rate of microcapsules included with chitosan as the wall material in Comparative Example 2 is 65.13%, which shows that using chitosan as the wall material will reduce the recovery rate of microcapsules, indicating that using chitosan as the wall material for inclusion of Cinnamomum camphora essential oil has a good effect.

[0077] The test value of the recovery rate of essential oil microcapsules shows the preparation effect of essential oil microcapsules. The more effective the preparation method and material use of essential oil microcapsules are, the less waste there is in the microencapsulation process, and therefore the higher the value is. Since essential oils are volatile and are usually relatively expensive raw materials, if the recovery rate is low, it will cause waste of raw materials and increase production costs. A higher recovery rate means that more products that meet the requirements can be obtained with the same raw material input. Therefore, in this application, the microcapsule recovery rate can reach 84.32% at 45°C and with β-cyclodextrin as the wall material, indicating that the preparation effect of preparing the essential oil of fine camphor leaf essential oil into microcapsule essential oil in this application is good.

[0078] Test Example 4: Test of tensile properties of camphor leaf essential oil cling film

[0079] The tensile mechanical properties of the camphor leaf essential oil cling film were tested using a 4×75 mm dumbbell-shaped film specimen. The tensile speed was 10 mm / min, the gauge length was 20 mm, and the environmental test was performed at a relative humidity of RH = 50% and a temperature of 25°C.

[0080] The experimental results are shown in Table 5.

[0081] Table 5: Test results of tensile properties of Example 2 and Comparative Example 1 Cinnamomum camphora leaf essential oil cling film

[0082] performance Example 2 Comparative Example 3 Tensile strength(MPa) 26.8 14.7

[0083] The results showed that adding excessive amount of essential oil microcapsules would greatly reduce the tensile properties of Cinnamomum pubescens essential oil cling film.

[0084] Test Example 5: Practical application of microcapsule cling film containing essential oil from camphor tree leaves

[0085] The orange segments were wrapped with the commonly used PE cling film and the microcapsule cling film of camphor leaf essential oil. The moldy conditions after six and twelve days were as follows Figure 1 shown.

[0086] according to Figure 1 The test results showed that after six days, the orange segments wrapped with Cinnamomum pubescens essential oil plastic wrap did not become moldy, while the orange segments wrapped with PE film and general starch film became moldy to varying degrees. After twelve days, the orange segments wrapped with Cinnamomum pubescens essential oil plastic wrap only became slightly moldy, while the orange segments wrapped with PE film and general starch film became seriously moldy. This shows that Cinnamomum pubescens essential oil played a role in preserving food, and its microcapsule plastic wrap has good application potential in food preservation.

[0087] In general, the essential oil of Cinnamomum pubescens leaves has good antibacterial and antioxidant activities, and the plastic wrap prepared from it can also effectively inhibit the mildew of fruits.

[0088] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for preparing Cinnamomum camphora leaf essential oil, characterized in that: The following steps are involved: The leaves of Cinnamomum pubescens are added with water for distillation extraction, and the distillate is collected and dried to obtain the essential oil of Cinnamomum pubescens leaves.

2. The preparation method according to claim 1, characterized in that: The mass ratio of the Cinnamomum pubescens leaves to the water is 1:(3-4); and the distillation extraction time is 4 hours.

3. Application of the fine hairy camphor leaf essential oil prepared by the preparation method according to claim 1 or 2 in preparing the fine hairy camphor leaf essential oil preservative film.

4. The use according to claim 3, characterized in that: The raw materials include microcapsules of camphor leaf essential oil and a gelatinized starch aqueous solution; the mass ratio of the microcapsules of camphor leaf essential oil to the gelatinized starch aqueous solution is (1-3):10; The Cinnamomum pubescens leaf essential oil microcapsules use β-cyclodextrin as the wall material and a stable Cinnamomum pubescens leaf essential oil solution as the core material; the mass ratio of the β-cyclodextrin to the stable Cinnamomum pubescens leaf essential oil solution is (8-10):

1.

5. The use according to claim 4, characterized in that: The following steps are involved: The stable Cinnamomum pubescens leaf essential oil solution and β-cyclodextrin are included, filtered, and dried to obtain Cinnamomum pubescens leaf essential oil microcapsules; glycerol is added to the gelatinized starch aqueous solution at a preset temperature, and then the Cinnamomum pubescens leaf essential oil microcapsules are added to prepare the Cinnamomum pubescens leaf essential oil preservative film.

6. The use according to claim 5, characterized in that: The inclusion process is performed by stirring at 45°C for 30 minutes and then placing at 4°C for 24 hours.

7. The use according to claim 5, characterized in that: The preparation method of the stable Cinnamomum pubescens leaf essential oil solution comprises mixing Cinnamomum pubescens leaf essential oil and anhydrous ethanol to prepare a stable essential oil solution; the mass ratio of the Cinnamomum pubescens leaf essential oil to the ethanol is 1:

10.

8. The use according to claim 5, characterized in that: The preparation method of the gelatinized starch aqueous solution is to gelatinize potato starch, sodium carboxymethyl cellulose and water at 80-90° C. to obtain the gelatinized starch aqueous solution; the mass ratio of the potato starch, the sodium carboxymethyl cellulose and the water is 2:1:

64.

9. The use according to claim 5, characterized in that: The preset temperature is 70-80°C.

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