Tea oil and preparation method thereof

Abstract

The invention relates to the field of vegetable oil, in particular to tea oil and a preparation method thereof.The tea oil is composed of a core material and a wall material; the core material is camellia oil; the wall material is composed of soybean protein isolate, chitosan and oleanolic acid-polyethylene glycol-tocopherol nanoparticles, the prepared tea oil has an extremely high embedding rate, the camellia oil is effectively wrapped in the wall material through the microcapsule technology, the reaction with oxygen is reduced, and therefore the storage stability of the tea oil is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of vegetable oils, specifically to a tea oil and its preparation method. Background Technology

[0002] Fatty acids are the main components of vegetable oils and play an important role in promoting human health. Linoleic acid, linolenic acid, and arachidonic acid are essential fatty acids for maintaining human functions. They cannot be synthesized by the human body and must be obtained from external sources. Tea oil contains approximately 90% unsaturated fatty acids, including 74%-87% oleic acid and 7%-14% linoleic acid. The diversity of unsaturated fatty acids and bioactive substances in tea oil gives it great nutritional value, but it also makes it susceptible to oxidation by factors such as oxygen, light, high temperature, metal ions, and microorganisms, easily forming aldehydes, acids, ketones, and other peroxides. This not only affects the quality of edible oils but also has adverse effects on human health. Encapsulating oils into microcapsules can prevent them from direct contact with the external environment and thus avoid oxidation and deterioration. However, the encapsulation rate of vegetable oil microcapsules prepared by current technology is low (approximately 70-80%), resulting in poor quality of the final product and difficulty in long-term stable storage. Summary of the Invention

[0003] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes a tea oil and its preparation method.

[0004] The technical solution adopted is as follows: A type of tea oil, composed of core material and wall material; The core material is camellia oil; The wall material is composed of soy protein isolate, chitosan, and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0005] Furthermore, the preparation method of the oleanolic acid-polyethylene glycol-tocopherol nanoparticles is as follows: The product of the esterification reaction of polyethylene glycol and oleanolic acid is dissolved together with tocopherol in dimethyl sulfoxide, then added dropwise to water. The resulting mixed solution is dialyzed and then freeze-dried.

[0006] Furthermore, the preparation method of the oleanolic acid-polyethylene glycol-tocopherol nanoparticles is as follows: Polyethylene glycol and oleanolic acid were dissolved in dichloromethane, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine were added. The mixture was stirred in an ice-water bath for 1-10 h, and then reacted at room temperature for 1-10 h. The reaction solution was washed with hydrochloric acid solution and then with water. The product was concentrated under reduced pressure and dissolved together with tocopherol in dimethyl sulfoxide. The product was then added dropwise to water. The resulting mixed solution was transferred to a dialysis bag and dialyzed in deionized water. Finally, it was freeze-dried.

[0007] Further, the mass ratio of the polyethylene glycol, the oleanolic acid and the tocopherol is 1-5:1-5:1-5.

[0008] The application provides a preparation method of tea oil. The oleanolic acid-polyethylene glycol-tocopherol nanoparticles are added into water in which soybean protein isolate is dissolved, ultrasonic dispersion is performed to make the nanoparticles uniformly dispersed, and then the pH value is adjusted to 6-7 to form an aqueous phase; the camellia oil is added into the aqueous phase, high-speed homogenization is performed to form an emulsion, the emulsion is added dropwise into a chitosan hydrochloride aqueous solution, the pH value of the solution is adjusted to 4-5, and water bath stirring is performed for 1-5 h to form a microcapsule solution, and finally spray drying is performed.

[0009] Further, the mass ratio of the oleanolic acid-polyethylene glycol-tocopherol nanoparticles, the soybean protein isolate and the chitosan hydrochloride is 1:1-3:1-3.

[0010] Further, the volume ratio of the camellia oil and the aqueous phase is 1:5-15.

[0011] Further, the rotating speed of high-speed homogenization is greater than or equal to 20000 r / min.

[0012] Further, the water bath temperature is 40-60 DEG C.

[0013] Further, the temperature of spray drying is 160-180 DEG C.

[0014] The application has the following beneficial effects: The application provides a kind of tea oil, the core material of tea oil is camellia oil, and the wall material is composed of soybean protein isolate, chitosan and oleanolic acid-polyethylene glycol-tocopherol nanoparticles, by effectively wrapping camellia oil inside the wall material, the reaction with oxygen is reduced, thereby the storage stability of tea oil is significantly improved.

[0015] Microcapsule technology uses high molecular materials to wrap gas, solid or liquid by film-forming or capsule-forming technology to form small particles with shell structure, in recent years, Pickering emulsion is used as a template to prepare microcapsules, which has attracted great attention. Pickering emulsion exhibits excellent ability to stabilize emulsion droplets due to the irreversibility of solid particles adsorbed at the water / oil interface, so Pickering emulsion template method is an excellent microcapsule preparation method that can stabilize the core material.

[0016] The hydroxyl group of the polyethylene glycol end group is connected with the carboxyl group of the oleanolic acid through esterification reaction in the application to prepare oleanolic acid-polyethylene glycol ester with amphiphilic property. The hydrophobic segment of the oleanolic acid-polyethylene glycol ester and the hydrophobic segment of the tocopherol are both hydrophobic, and can gradually gather in water. The hydrophilic segment is easy to disperse in water, so the oleanolic acid-polyethylene glycol-tocopherol nanoparticles are gathered into a core-shell structure in the aqueous solution, and the self-assembly process is completed to obtain the oleanolic acid-polyethylene glycol-tocopherol nanoparticles. The oleanolic acid-polyethylene glycol-tocopherol nanoparticles can be used as a nanoparticle stabilizer to stabilize the Pickering emulsion, and can participate in the electrostatic reaction of soybean protein isolate and chitosan hydrochloride, improve the compactness of the formed microcapsule structure, improve the embedding rate, and the oleanolic acid and the tocopherol both have certain antioxidant function, can reduce the oxidation and deterioration of tea oil, and the storage stability of the tea oil is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The acid value-time curve of the camellia oil without microencapsulation treatment and the samples prepared in Example 1 and Comparative Example 1-2.

[0018] Figure 2 The peroxide value-time curve of the camellia oil without microencapsulation treatment and the samples prepared in Example 1 and Comparative Example 1-2.

[0019] Figure 3 The micro-morphology diagram of the tea oil prepared in Example 1. DETAILED DESCRIPTION

[0020] Unless specific conditions are specified in the examples, the conventional conditions or the conditions recommended by the manufacturers are used. Unless the manufacturers of the reagents or instruments are specified, the conventional products available on the market are used. The technologies not mentioned in the application refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests, and the same processing steps and parameters are used.

[0021] Example 1: A tea oil composed of a core material and a shell material; The core material is camellia oil, and the shell material is composed of soybean protein isolate, chitosan and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0022] The preparation method of the tea oil is as follows: Polyethylene glycol 400 (10 mmol, 4 g) and oleanolic acid (10 mmol, 4.567 g) were dissolved in 200 ml of dry dichloromethane, and 0.6 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.4 g of 4-dimethylaminopyridine were added. After stirring in an ice water bath for 1 h, the ice water bath was removed and the reaction was carried out at room temperature for 10 h. The reaction solution was washed with 0.1 M hydrochloric acid solution three times and then with deionized water three times. The dichloromethane phase was separated and dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The obtained product was dissolved in 25 ml of dimethyl sulfoxide together with 2 g of tocopherol, and then slowly added dropwise into 500 ml of water. The obtained mixed solution was transferred into a dialysis bag (pore size 1.3 nm) and dialyzed in deionized water for 24 h. Finally, it was freeze-dried at -50℃ to obtain oleanolic acid-polyethylene glycol-tocopherol nanoparticles. 1 g of oleanolic acid-polyethylene glycol-tocopherol nanoparticles was added to 100 ml of deionized water containing 2 g of soybean protein isolate, and ultrasonic dispersion was carried out for 30 min to make it uniformly dispersed. The pH was adjusted to 6 to form an aqueous phase. 10 ml of camellia oil was added to the aqueous phase, and an emulsion was formed by high-speed homogenization at 20000 r / min for 10 min. The emulsion was added to 100 ml of deionized water containing 2 g of chitosan hydrochloride, and the pH of the solution was adjusted to 4. A water bath was stirred at 40℃ for 5 h to form a microcapsule solution, and finally spray drying was carried out at 160℃. Figure 1 The electron scanning microscope photograph of the tea oil prepared in this example showed that the surface was smooth and spherical.

[0023] Bio-safety analysis: Zebrafish was used as a biological model to determine the bio-safety of tea oil. According to the test conditions of GB / T 13267-1991, the tea oil prepared in this example was prepared into a solution with a mass concentration of 100 mg / L. Experimental groups and blank control groups were set up, and the experiment lasted for 96 h. The intestinal, brain and liver tissues of zebrafish were collected, sterilized with 0.01 mol / L PBS solution and then preserved in 4% paraformaldehyde. After sealing and processing, they were placed under a microscope to observe the morphology of zebrafish tissues. It was observed that the brain and liver of zebrafish in the experimental group were relatively healthy, and the tissues were not damaged by toxicity, which was close to the state of the blank control group. The intestinal barrier of zebrafish in the experimental group was still intact, that is, the material did not have a significant impact on zebrafish itself. It showed that it had bio-safety, which could ensure its safety in the field of food or health care products, and had potential application value.

[0024] Example 2: A tea oil composed of a core material and a shell material; The core material is camellia oil, and the shell material is composed of soybean protein isolate, chitosan and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0025] The preparation method of tea oil is as follows: Polyethylene glycol 400 (10 mmol, 4 g) and oleanolic acid (10 mmol, 4.567 g) were dissolved in 200 ml dry dichloromethane, and 0.6 g 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.4 g 4-dimethylaminopyridine were added. The reaction was stirred in an ice water bath for 10 h, and then the ice water bath was removed and the reaction was stirred at room temperature for 1 h. The reaction solution was washed with 0.1 M hydrochloric acid solution three times and then with deionized water three times. The dichloromethane phase was separated, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained product was dissolved in 25 ml dimethyl sulfoxide together with 2 g tocopherol, and then 500 ml water was slowly added dropwise. The obtained mixed solution was transferred to a dialysis bag (pore size 1.3 nm) and dialyzed in deionized water for 24 h. Finally, freeze-drying at -50℃ was performed to obtain oleanolic acid-polyethylene glycol-tocopherol nanoparticles. 1 g of oleanolic acid-polyethylene glycol-tocopherol nanoparticles was added to 100 ml of deionized water in which 2 g of soybean protein isolate was dissolved, and ultrasonic dispersion was performed for 30 min to obtain a uniform dispersion. The pH was adjusted to 7, and 10 ml of camellia oil was added to the water phase. The mixture was homogenized at 20000 r / min for 10 min to form an emulsion. The emulsion was added to 100 ml of deionized water containing 2 g of chitosan hydrochloride, and the pH of the solution was adjusted to 5. The mixture was stirred in a water bath at 60℃ for 5 h to form a microcapsule solution. Finally, spray drying was performed at 180℃ to obtain the product.

[0026] Example 3: A tea oil, composed of a core material and a shell material; The core material is camellia oil, and the shell material is composed of soybean protein isolate, chitosan, and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0027] The preparation method of the tea oil is as follows: Polyethylene glycol 400 (10 mmol, 4 g) and oleanolic acid (10 mmol, 4.567 g) were dissolved in 200 ml dry dichloromethane, and 0.6 g 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.4 g 4-dimethylaminopyridine were added. The reaction was stirred in an ice water bath for 1 h, and then the ice water bath was removed and the reaction was stirred at room temperature for 10 h. The reaction solution was washed with 0.1 M hydrochloric acid solution three times and then with deionized water three times. The dichloromethane phase was separated, dried over anhydrous sodium sulfate, and concentrated under reduced pressure. The obtained product was dissolved in 25 ml dimethyl sulfoxide together with 2 g tocopherol, and then 500 ml water was slowly added dropwise. The obtained mixed solution was transferred to a dialysis bag (pore size 1.3 nm) and dialyzed in deionized water for 24 h. Finally, freeze-drying at -50℃ was performed to obtain oleanolic acid-polyethylene glycol-tocopherol nanoparticles. 1 g of oleanolic acid-polyethylene glycol-tocopherol nanoparticles was added to 100 ml of deionized water in which 3 g of soybean protein isolate was dissolved, and ultrasonic dispersion was performed for 30 min to obtain a uniform dispersion. The pH was adjusted to 6, and 10 ml of camellia oil was added to the aqueous phase. The emulsion was prepared by high-speed homogenization at 20000 r / min for 10 min. The emulsion was added to 100 ml of deionized water containing 3 g of chitosan hydrochloride, and the pH of the solution was adjusted to 4. The solution was stirred in a water bath at 40℃ for 5 h to form a microcapsule solution. Finally, spray drying was performed at 160℃ to obtain the product.

[0028] Example 4: A tea oil, composed of a core material and a shell material; The core material is camellia oil, and the shell material is composed of soybean protein isolate, chitosan, and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0029] The preparation method of the tea oil is as follows: Polyethylene glycol 400 (10 mmol, 4 g) and oleanolic acid (10 mmol, 4.567 g) were dissolved in 200 ml of dry dichloromethane, and 0.6 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 0.4 g of 4-dimethylaminopyridine were added. The reaction was stirred in an ice water bath for 1 h, and then the ice water bath was removed and the reaction was stirred at room temperature for 10 h. The reaction solution was washed with 0.1 M hydrochloric acid solution three times and then with deionized water three times. The dichloromethane phase was separated and dried over anhydrous sodium sulfate, and then concentrated under reduced pressure. The obtained product was dissolved in 25 ml of dimethyl sulfoxide together with 2 g of tocopherol, and then slowly added dropwise to 500 ml of water. The obtained mixed solution was transferred to a dialysis bag (pore size 1.3 nm) and dialyzed in deionized water for 24 h, and then freeze-dried at -50°C to obtain oleanolic acid-polyethylene glycol-tocopherol nanoparticles. 1 g of oleanolic acid-polyethylene glycol-tocopherol nanoparticles was added to 100 ml of deionized water in which 1 g of soybean protein isolate was dissolved, and then ultrasonicated for 30 min to disperse uniformly. The pH was adjusted to 6, and 10 ml of camellia oil was added to the water phase. The emulsion was formed by high-speed homogenization at 20000 r / min for 10 min, and then added dropwise to 100 ml of deionized water containing 1 g of chitosan hydrochloride. The pH of the solution was adjusted to 4, and the microcapsule solution was formed by stirring in a 40°C water bath for 5 h. Finally, spray drying was performed at 160°C.

[0030] Comparative Example 1 The same as Example 1, except that oleanolic acid-polyethylene glycol-tocopherol nanoparticles were not added.

[0031] The preparation method of camellia oil is as follows: 100 ml of deionized water in which 2 g of soybean protein isolate was dissolved was ultrasonicated for 30 min, and then the pH was adjusted to 6 to form a water phase. 10 ml of camellia oil was added to the water phase, and the emulsion was formed by high-speed homogenization at 20000 r / min for 10 min. The emulsion was added dropwise to 100 ml of deionized water containing 2 g of chitosan hydrochloride, and then the pH of the solution was adjusted to 4. The microcapsule solution was formed by stirring in a 40°C water bath for 5 h, and then spray drying was performed at 160°C.

[0032] Comparative Example 2 The same as Example 1, except that nano-microcrystalline cellulose was used instead of oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

[0033] The preparation method of camellia oil is as follows: 1g nanocrystalline cellulose was added to 100ml deionized water in which 2g soy protein isolate was dissolved, and ultrasonic dispersion was performed for 30min to make it uniformly dispersed, then the pH was adjusted to 6 to form an aqueous phase, 10ml camellia oil was added to the aqueous phase, and high-speed homogenization was performed at 20000r / min for 10min to form an emulsion, the emulsion was added dropwise to 100ml deionized water containing 2g chitosan hydrochloride, and then the pH of the solution was adjusted to 4, and stirring was performed in a 40℃ water bath for 5h to form a microcapsule solution, and finally spray drying was performed at 160℃.

[0034] Performance test: The camellia oil prepared in Examples 1-4 and Comparative Examples 1-2 was used as a test sample for performance testing.

[0035] ① Embedding rate test: 1g of the test sample was weighed into a 50ml centrifuge tube, 10ml of n-hexane was added, shaken for 60s, centrifuged at 10000r / min for 3min, 5ml of supernatant was taken and diluted to 10ml with n-hexane. The absorbance at A 229 was measured, and the surface oil content M1 was calculated by a standard curve. 1.0g of the test sample was weighed and added to 10ml of hot water, shaken for 20min, then treated with 20ml of n-hexane for 30min to make the oil dissolve, centrifuged at 10000r / min for 10min, 1ml of supernatant was taken and diluted to 10ml with n-hexane, the absorbance at A 229 was measured, and the total oil content M2 of the microcapsules was calculated, and the embedding rate was calculated according to the following formula: Embedding rate = (1-M1 / M2) x 100% The test results are shown in Table 1 below: As shown in Table 1 above, the camellia oil prepared by the method of the present application has a very high embedding rate, and the microcapsule technology effectively wraps the camellia oil inside the wall material, reducing the reaction with oxygen, thereby significantly improving the storage stability of the camellia oil.

[0036] ② Oxidation stability test: a certain amount of camellia oil and the test samples in Examples 1 and Comparative Examples 1-2 were added to 250ml conical flasks, and placed in a (62±1)℃ electric heating constant temperature drying oven for accelerated oxidation test of oil, and sampled every 24h, and the acid value (AV) and peroxide value (POV) were measured according to GB 5009.229-2016 "National Food Safety Standard Determination of Acid Value in Food" and GB 5009.227-2016 "National Food Safety Standard Determination of Peroxide Value in Food", respectively, and the test results are shown in Figure 1 and Figure 2 .

[0037] From Figures 1-2It can be seen that the tea oil prepared by the microcapsule technology in the present application in Example 1 has better storage stability than the uncoated camellia oil and the samples prepared in Comparative Examples 1-2.

[0038] The above examples are only used to illustrate the technical solutions of the present application, but not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can still be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A type of tea oil, characterized in that, It consists of a core material and a wall material; The core material is camellia oil; The wall material is composed of soy protein isolate, chitosan, and oleanolic acid-polyethylene glycol-tocopherol nanoparticles.

2. The tea oil as described in claim 1, characterized in that, The preparation method of the oleanolic acid-polyethylene glycol-tocopherol nanoparticles is as follows: The product of the esterification reaction of polyethylene glycol and oleanolic acid, together with tocopherol, is dissolved in dimethyl sulfoxide, then added dropwise to water. The resulting mixed solution is dialyzed and then freeze-dried.

3. The tea oil as described in claim 2, characterized in that, The preparation method of the oleanolic acid-polyethylene glycol-tocopherol nanoparticles is as follows: Polyethylene glycol and oleanolic acid were dissolved in dichloromethane, and then 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and 4-dimethylaminopyridine were added. The mixture was stirred in an ice-water bath for 1-10 h, and then reacted at room temperature for 1-10 h. The reaction solution was washed with hydrochloric acid solution and then with water. The product was concentrated under reduced pressure and dissolved together with tocopherol in dimethyl sulfoxide. The product was then added dropwise to water. The resulting mixed solution was transferred to a dialysis bag and dialyzed in deionized water. Finally, it was freeze-dried.

4. The tea oil as described in claim 3, characterized in that, The mass ratio of polyethylene glycol, oleanolic acid and tocopherol is 1-5:1-5:1-5.

5. A method for preparing tea oil according to any one of claims 1-4, characterized in that, Specifically as follows: Oleanolic acid-polyethylene glycol-tocopherol nanoparticles were added to water containing dissolved soy protein isolate. After ultrasonication to disperse the nanoparticles evenly, the pH was adjusted to 6-7 to form an aqueous phase. Camellia oil was added to the aqueous phase and homogenized at high speed to form an emulsion. The emulsion was then added dropwise to a chitosan hydrochloride aqueous solution. The pH of the solution was adjusted to 4-5, and the solution was stirred in a water bath for 1-5 hours to form a microcapsule solution. Finally, the solution was spray-dried.

6. The method for preparing tea oil as described in claim 5, characterized in that, The mass ratio of oleanolic acid-polyethylene glycol-tocopherol nanoparticles, soy protein isolate, and chitosan hydrochloride is 1:1-3:1-3.

7. The method for preparing tea oil as described in claim 5, characterized in that, The volume ratio of camellia oil to water is 1:5-15.

8. The method for preparing tea oil as described in claim 5, characterized in that, The rotational speed during high-speed homogenization is ≥20000 r / min.

9. The method for preparing tea oil as described in claim 5, characterized in that, The water bath temperature is 40-60℃.

10. The method for preparing tea oil as described in claim 5, characterized in that, The spray drying temperature is 160-180℃.

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