A method for continuously extracting essential oil, pectin and hesperidin from orange peel

Abstract

The application discloses a method for continuously extracting essential oil, pectin and hesperidin from orange peel, and belongs to the technical field of food processing. The method adopts a mature superfine crushing technology in industry to break the cell wall of the orange peel, so that the essential oil, pectin and hesperidin and other substances are fully exposed from the original cell structure. Therefore, the significant difference in the solubility of the three substances in different mediums can be utilized under mild conditions to realize continuous operation and sequentially extract the essential oil, pectin and hesperidin, which are the three main functional components in the orange peel. The extraction rate of each product can reach or exceed the relatively optimal value reported in the current literature and patents. The extraction rate of the oil component in the orange peel is greater than 40% (relative to the total content), the extraction rate of the pectin in the orange peel is greater than 20% (relative to the dry substance), the extraction rate of the hesperidin in the orange peel is 1-2% (relative to the dry substance), and the purity of the hesperidin is not less than 97%.

Description

Technical Field

[0001] This invention relates to a method for the continuous extraction of essential oils, pectin and hesperidin from orange peel, belonging to the field of food processing technology. Background Technology

[0002] Citrus fruits are a major agricultural product, resulting in abundant citrus peel resources. Citrus peel essential oil is one of the most expensive varieties in the current fragrance and flavor market. It is mainly found in the oil sac of the outer peel of citrus fruits, typically comprising 0.5–2.0% of the fresh weight of the peel, and its main component is limonene. Pectin in citrus peel is mainly found in the middle layer of the cell walls. It is a heteropolysaccharide with a main chain structure of D-galacturonic acid linked by α-1,4 glycosidic bonds, and also contains hair-like side chains composed of more than ten neutral sugars. The pectin content in citrus peel is 20–30% (w / w, relative to dry weight). Hesperidin (dihydroflavonoid glycoside) in citrus peel is an important flavonoid compound with vitamin P-like activity; its content in citrus peel is generally about 1% (w / w, relative to dry citrus peel).

[0003] The most common methods for extracting essential oils, pectin, and hesperidin from orange peel are steam distillation, acid-heat extraction, and alkali-soluble acid precipitation, respectively. Steam distillation utilizes the principle that essential oils and water are immiscible. The orange peel is crushed, mixed with water, and heated for distillation. During distillation, the steam gradually carries away the essential oils, which are then collected in a container after phase separation. Acid-heat extraction of pectin is performed in an aqueous environment with a pH of 1–2, utilizing H+... + Acid hydrolysis of the cell wall fibers in orange peel exposes the pectin in the middle layer of the cell wall, which is then dissolved in hot water at a temperature >80°C. Hesperidin extraction is generally performed under strongly alkaline conditions (pH 12–13), utilizing alkaline catalysis to degrade pectin molecules, exposing hesperidin and converting it to Na+. + Hesperidin is converted into a salt form, which allows it to dissolve in a methanol solution. After adjusting the pH of the system to neutral, hesperidin reverts to its carboxylic acid form and crystallizes out in the solvent at low temperature.

[0004] The main problem with extracting citrus peel essential oil, pectin, and hesperidin is that the three extraction methods are independent and cannot be effectively linked; they are generally extracted independently. Achieving continuous extraction would involve significant energy consumption and pollution. For example, steam distillation is energy-intensive, acid-heat extraction of pectin produces a large amount of acidic wastewater, and adjusting the pH during hesperidin extraction requires the addition of large amounts of acid and alkali. Therefore, the currently widely used processes are characterized by high cost and significant pollution. Summary of the Invention

[0005] Technical issues:

[0006] The technical problem to be solved by the present invention is to provide a low-cost, green and environmentally friendly method for continuous extraction of essential oils, pectin and hesperidin from orange peel. Compared with the existing technology for extracting the three products separately, it can significantly save costs, shorten the process flow, reduce pollution, and the extraction rates of essential oils, pectin and hesperidin all reach or exceed the optimal values ​​reported in current literature and patent publications.

[0007] Technical solution:

[0008] To address the aforementioned technical problems, this invention provides a method for the continuous extraction of essential oils, pectin, and hesperidin from orange peel, the method comprising the following steps:

[0009] (1) Crush the orange peel;

[0010] (2) Extraction of essential oil: Ethanol was used as the extractant. After mixing with crushed orange peel raw material, the mixture was filtered to obtain ethanol extract. The ethanol extract was concentrated and then extracted to obtain dark brown essential oil.

[0011] (3) Extraction of pectin: The solid remaining after filtration in step (2) is mixed with water to obtain a reaction solution. The reaction solution is reacted at 60-90℃ and then the reaction is continued at 18-25℃. After the reaction is completed, the solution is filtered and the filtrate is collected as the pectin extract. The pectin extract is concentrated and ethanol is added to precipitate the pectin. The precipitate is collected after filtration and dried to obtain the pectin product.

[0012] (4) Extraction of hesperidin: Add glycerol-ethanol mixed solvent to the solid remaining after collecting pectin extract in step (3) and react. After the reaction is completed, filter and collect the filtrate. Adsorb the filtrate with non-polar macroporous adsorption resin. After the adsorption is completed, desorb the non-polar macroporous adsorption resin with ethanol. The resulting ethanol solution is the hesperidin extract. Concentrate and remove the ethanol to obtain the hesperidin product.

[0013] In one embodiment of the present invention, in step (1), the orange peel is crushed into particles with a particle size of less than 100 micrometers.

[0014] In one embodiment of the present invention, the dried orange peel is pulverized using an ultrafine pulverizer and the raw material is collected.

[0015] In one embodiment of the present invention, in step (2), ethanol is used as the extractant and mixed with crushed orange peel raw material at a ratio of 1:5 to 1:10. The mixture is reacted at 18 to 25°C and 100 to 300 rpm for 30 to 60 minutes. The liquid is filtered to collect the ethanol extract. The ethanol extract is then concentrated to prepare dark brown orange peel essential oil.

[0016] In one embodiment of the present invention, in step (2), the concentration method of the prepared ethanol extract is: vacuum distillation.

[0017] In one embodiment of the present invention, in step (3), the remaining solid after filtration is mixed with water at a ratio of (1:20) to (1:40) to obtain a reaction solution. The reaction solution is reacted at 60-90°C and 100-300 rpm for 10-60 min to inactivate endogenous pectinase. Then, it is reacted at 18-25°C and 100-300 rpm for 1-2 h. After filtration, the pectin extract is collected. The pectin extract is concentrated and ethanol is added to precipitate the pectin. After filtration, the pectin product is obtained.

[0018] In one embodiment of the present invention, in step (3), the reaction solution is reacted for 30 minutes at pH 5-6, 80°C, and 100-300 rpm to inactivate the endogenous pectinase. Then, it is reacted for 2 hours at 20°C and 100-300 rpm. The solution is filtered and the filtrate is collected to obtain the pectin extract.

[0019] In one embodiment of the present invention, the water is pure water.

[0020] In one embodiment of the present invention, in step (4), a glycerol-ethanol mixed solvent is added to the solid remaining after collecting the pectin extract in step (3), and the mixture is reacted at 18-25°C and 100-300 rpm for 1-3 hours, then filtered and the filtrate is collected; a non-polar macroporous adsorption resin is added to the filtrate, and the resin is adsorbed at 18-25°C for 1-3 hours, then the resin is collected, and then the resin is desorbed with ethanol for 1-3 hours, and the filtrate is collected by filtration, which is the hesperidin extract.

[0021] In one embodiment of the present invention, in step (4), a glycerol-ethanol mixed solvent is added to the solid remaining after collecting the pectin extract in step (3), and the mixture is reacted at 20°C and 200 rpm for 1 hour, then filtered and the filtrate is collected.

[0022] In one embodiment of the present invention, a non-polar macroporous adsorption resin is added to the prepared filtrate, adsorbed at 25°C for 1 hour, and the resin is recovered by filtration. Then the resin is added to ethanol for desorption for 1 hour, and the resulting ethanol solution is the hesperidin extract.

[0023] In one embodiment of the present invention, the nonpolar macroporous adsorption resin is D101, AB-8, or HD-100.

[0024] In one embodiment of the present invention, the glycerol-ethanol mixed solvent is prepared by mixing glycerol and ethanol in a volume ratio of (7:3) to (3:7).

[0025] In one embodiment of the present invention, the ethanol is anhydrous ethanol.

[0026] The above-described method of the present invention is applied in the preparation of products containing orange peel essential oil, or in the preparation of products containing orange peel pectin, or in the preparation of products containing hesperidin.

[0027] Beneficial effects

[0028] (1) This invention uses industrially mature ultrafine pulverization technology to break the cell walls of orange peel, thereby fully exposing substances such as essential oil, pectin and hesperidin from the original cell structure. Therefore, under mild conditions, the significant difference in solubility of the three substances in different media can be used to achieve continuous operation and sequential extraction of the three main functional components of orange peel, namely essential oil, pectin and hesperidin. Moreover, the extraction rate of each product can reach or exceed the optimal value reported in current literature and patent publications.

[0029] (2) Using the method provided by this invention, relatively safe ethanol is used in the essential oil extraction process, and the extraction is completed in a short time at room temperature. Compared with the traditional steam distillation method, the extraction time of more than 10 hours required by steam distillation is shortened to less than 1 hour, which significantly shortens the extraction time and saves steam energy consumption. At the same time, using anhydrous ethanol as the extraction agent can also extract natural pigments such as carotenoids from orange peel, solving the problem of decolorization of subsequent pectin products. Furthermore, the extraction yield of oil components from orange peel using the method provided by this invention is greater than 40% (based on the total content).

[0030] (3) Using the method provided by this invention, during the pectin extraction process, the pectin molecules are fully exposed due to the destructive effect of ultrafine grinding on the cell wall, thus achieving short-time heating extraction of pectin at the natural pH of the system. Compared with the traditional acid-heating method for extracting pectin from orange peel, this technology does not require the addition of additional acid reagents or prolonged heating, reducing pollution and energy consumption. Furthermore, the extraction rate of pectin from orange peel using the method provided by this invention is greater than 20% (for dry matter).

[0031] (4) Using the method provided by this invention, since hesperidin is insoluble in anhydrous ethanol or water, hesperidin is not lost during the extraction of essential oils and pectin. In particular, after the extraction of essential oils and pectin, the dissolution effect of hesperidin is significantly reduced due to the reduced mass transfer resistance, making it easier to dissolve. This technology achieves room temperature extraction by selecting a highly safe and suitable solvent for hesperidin. Compared with the currently disclosed technology that requires the use of strong alkali to destroy the cell walls of orange peel before extracting hesperidin, this technology significantly reduces pollution, and the extraction rate of hesperidin from orange peel using the method provided by this invention is 1-2% (for dry matter), with a purity of not less than 97%. Attached Figure Description

[0032] Figure 1 : Technical flowchart of this invention.

[0033] Figure 2 HPLC chromatogram of hesperidin extracted in this invention. Detailed Implementation

[0034] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0035] The detection methods involved in the following embodiments are as follows:

[0036] Methods for determining essential oil extraction rate:

[0037] The mass of the essential oil obtained after complete removal of ethanol from the concentrate is m1; the total oil content m0 ​​in the orange peel was determined by Soxhlet extraction. Essential oil extraction rate (%) = m1 / m0 × 100.

[0038] Methods for detecting the main components in essential oils:

[0039] The main components in the essential oil were detected by gas chromatography, with operating parameters as described in ISO 3528:2012.

[0040] Method for determining pectin extraction rate:

[0041] The galacturonic acid content in the pectin extract was determined by the carbazole colorimetric method. The formula for calculating the pectin extraction rate is: Pectin extraction rate (%) = (mass of galacturonic acid in the extract / mass of raw material) × 100.

[0042] Methods for testing the purity of pectin:

[0043] Pectin purity was determined according to the national standard GB25533-2010 "National Food Safety Standard - Food Additives - Pectin", calculated as total galacturonic acid content. The specific testing method was the determination of total galacturonic acid and degree of amidation in A.4 of the national standard. Acid-insoluble ash content was measured by the ignition method described in GB25533-2010.

[0044] Methods for determining the molecular weight of pectin:

[0045] The molecular weight of pectin was determined by high performance liquid chromatography (HPLC). The specific conditions were as follows: Shodex KS-802 and KS-804 columns were coupled together, with 0.1N NaNO3 as the mobile phase and a flow rate of 1.0 mL / min at room temperature.

[0046] Method for determining the extraction rate of hesperidin:

[0047] The hesperidin extraction rate was determined by colorimetry. The procedure was as follows: 300 μL of sample was added to 45 μL of 5% sodium nitrite, shaken, and allowed to stand for 6 min. Then, 45 μL of 10% aluminum nitrate was added, shaken, and allowed to stand for 6 min. Next, 600 μL of 4% sodium hydroxide was added, shaken, and allowed to stand for 20 min. Colorimetry was measured at 340 nm. A standard curve was constructed using hesperidin standard solutions at concentrations of 40, 80, 120, 160, and 200 μg / mL. The hesperidin extraction rate was calculated as follows: Hesperidin extraction rate (%) = (Mass of hesperidin in extract / Mass of raw material) × 100.

[0048] Methods for determining the purity of hesperidin:

[0049] According to the "Determination of Hesperidin in Buddha's Hand" section of the Chinese Pharmacopoeia (2015 edition), the purity of hesperidin was determined by HPLC. Specific conditions were: JADE-PAK ODS column, methanol:water:glacial acetic acid (33:63:2) as mobile phase, detection wavelength 284 nm, column temperature room temperature, and flow rate 1.0 mL / min.

[0050] Example 1: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0051] For detailed process flow, please refer to Figure 1 The specific steps are as follows:

[0052] (1) Crush the orange peel into particles with a particle size range of 80 to 100 micrometers;

[0053] (2) Anhydrous ethanol was used as the extractant and mixed with the crushed orange peel raw material prepared in step (1) at a ratio of 1:5. The mixture was stirred at 18-25°C for 50 minutes, filtered to obtain ethanol extract, and then concentrated to remove ethanol by vacuum distillation to obtain dark brown orange peel essential oil.

[0054] The essential oil extraction rate was measured to be 42% (relative to total content); the essential oil contains 150 volatile components, of which limonene accounts for 75%, and other major essential oil components include linalool (5%), β-myrcene (3%), 1,3-dihydroxyacetone (1.5%), methyl acetate (1.2%), etc.

[0055] (3) Continue to mix the remaining solid residue after filtration in step (2) with pure water at a ratio of 1:30 to obtain a reaction solution. Stir the reaction solution at 70°C for 30 minutes under pH 5.5 conditions, and then continue stirring at 25°C for 2 hours. Filter and collect the filtrate, which is the pectin extract.

[0056] The pectin extract was concentrated three times using vacuum evaporation, and then anhydrous ethanol was added until the ethanol concentration reached 60% (by volume), resulting in pectin precipitation. After filtration, the precipitate was dried and pulverized to obtain the pectin product. Testing showed that the pectin extraction rate was 25%, the galacturonic acid content in the pectin was 82%, the molecular weight was 198 kDa, and the insoluble ash content was <0.5%.

[0057] (4) Add a glycerol-anhydrous ethanol mixed solvent to the solid remaining after collecting the pectin extract in step (3) to obtain a mixed solvent for reaction. The glycerol-anhydrous ethanol mixed solvent is obtained by mixing glycerol and anhydrous ethanol at a volume ratio of 7:3. After stirring the obtained mixture at 18-25°C for 1 hour, filter and collect the filtrate. Then add D101 non-polar macroporous adsorption resin, adsorb at 25°C for 1 hour, filter and recover the resin, and then add the resin to anhydrous ethanol for desorption for 1 hour. The resulting anhydrous ethanol solution is the hesperidin extract.

[0058] After completely removing the anhydrous ethanol by concentration, the hesperidin product is obtained and analyzed according to the aforementioned analytical method (e.g. Figure 2 As shown in the figure, the hesperidin extraction rate was 1.5% and the purity was 97%.

[0059] Example 2: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0060] The specific steps are as follows:

[0061] (1) Crush the orange peel into particles with a particle size range of 200-300 micrometers;

[0062] (2) Anhydrous ethanol was used as the extractant and mixed with the crushed orange peel raw material prepared in step (1) at a material-liquid ratio of 1:5. The mixture was stirred at 18-25°C for 50 minutes, filtered to obtain ethanol extract, and then concentrated to remove ethanol by vacuum distillation to obtain dark brown orange peel essential oil.

[0063] The essential oil extraction rate was measured to be 30% (total content); the essential oil contains 126 volatile components, of which limonene accounts for 78%, and other major essential oil components include linalool (3%), β-myrcene (2%), 1,3-dihydroxyacetone (1%), methyl acetate (1%), etc.

[0064] (3) Continue to mix the remaining solid residue after filtration in step (2) with pure water at a ratio of 1:30 to obtain a reaction solution. Stir the reaction solution at 70°C for 30 minutes under pH 5.2 conditions, and then continue stirring at 25°C for 2 hours. Filter and collect the filtrate, which is the pectin extract.

[0065] The pectin extract was concentrated three times using vacuum evaporation, and then anhydrous ethanol was added until the ethanol concentration reached 60% (by volume), resulting in pectin precipitate. After filtration, the precipitate was dried and pulverized to obtain the pectin product. Empirically, the pectin extraction rate was 8%, the galacturonic acid content in the pectin was 79%, the molecular weight was 223 kDa, and the insoluble ash content was <0.5%.

[0066] (4) Add glycerol-anhydrous ethanol mixed solvent to the solid remaining after collecting pectin extract in step (3) to obtain a mixed solution. The glycerol-anhydrous ethanol mixed solvent is obtained by mixing glycerol and anhydrous ethanol at a volume ratio of 7:3. Stir the obtained mixed solution at 18-25℃ for 1 hour, filter and collect the filtrate, then add D101 non-polar macroporous adsorption resin, adsorb at 18-25℃ for 1 hour, filter and recover the resin, then add the resin to anhydrous ethanol for desorption for 1 hour. The resulting anhydrous ethanol solution is hesperidin extract.

[0067] After the anhydrous ethanol was completely removed by concentration, the hesperidin product was obtained. The hesperidin extraction rate was 0.4% and the purity was 98% as determined by the aforementioned method.

[0068] Example 3: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0069] The specific steps are as follows:

[0070] (1) Crush the orange peel into particles with a particle size range of 20 to 80 micrometers;

[0071] (2) Anhydrous ethanol was used as the extractant and mixed with the crushed orange peel raw material prepared in step (1) at a material-liquid ratio of 1:5. The mixture was stirred at 18-25°C for 50 minutes, filtered to obtain ethanol extract, and then concentrated to remove ethanol by vacuum distillation to obtain dark brown orange peel essential oil.

[0072] The essential oil extraction rate was measured to be 50% (total content); the essential oil contains 153 volatile components, of which limonene accounts for 74%, and other major essential oil components include linalool (6%), β-myrcene (4%), 1,3-dihydroxyacetone (2%), methyl acetate (2%), etc.

[0073] (3) Continue to mix the remaining solid residue after filtration in step (2) with pure water at a ratio of 1:30 to obtain a reaction solution. Under pH 5.8 conditions, directly stir and extract the reaction solution at 18-25℃ for 2 hours, filter and take the filtrate to obtain pectin extract.

[0074] The pectin extract was concentrated three times using vacuum distillation, and then anhydrous ethanol was added until the ethanol ratio was 60% (by volume). There was almost no obvious precipitation, indicating that the pectin had been degraded by endogenous enzymes into low molecular weight soluble fragments with a molecular weight <5000 Da, and could not be used as normal pectin.

[0075] (4) Add glycerol-anhydrous ethanol mixed solvent to the solid remaining after collecting pectin extract in step (3) to obtain a mixed solution. The glycerol-anhydrous ethanol mixed solvent is obtained by mixing glycerol and anhydrous ethanol at a volume ratio of 7:3. Stir the obtained mixed solution at 18-25℃ for 1 hour, filter to collect the liquid part, then add D101 non-polar macroporous adsorption resin, adsorb at 18-25℃ for 1 hour, filter to recover the resin, and then add the resin to anhydrous ethanol for desorption for 1 hour. The resulting anhydrous ethanol solution is hesperidin extract.

[0076] After the anhydrous ethanol was completely removed by concentration, the hesperidin product was obtained. The hesperidin extraction rate was 1.2% and the purity was 97% as determined by the aforementioned method.

[0077] Example 4: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0078] The specific steps are as follows:

[0079] (1) Crush the orange peel into particles with a particle size range of 50 to 100 micrometers;

[0080] (2) Anhydrous ethanol was used as the extractant and mixed with the crushed orange peel raw material prepared in step (1) at a material-liquid ratio of 1:10. After stirring at 18-25°C for 60 minutes, the ethanol extract was obtained by filtration. The dark brown orange peel essential oil was obtained by concentrating and removing the ethanol by vacuum distillation.

[0081] The essential oil extraction rate was measured to be 50% (total content); the essential oil contains 148 volatile components, of which limonene accounts for 81%, and other major essential oil components include linalool (4%), β-myrcene (3%), 1,3-dihydroxyacetone (1%), methyl acetate (1%), etc.

[0082] (3) The solid residue remaining after filtration in step (2) is mixed with pure water at a ratio of 1:40 to obtain a reaction solution. Under pH 5.5 conditions, the reaction solution is stirred at 90°C for 10 minutes, and then stirred at 18-25°C for 1.5 hours. The solution is filtered and the filtrate is taken as the pectin extract. The pectin extract is concentrated 3 times by vacuum evaporation technology, and then anhydrous ethanol is added until the ethanol ratio is 60% (by volume) to obtain pectin precipitate. After filtration, the precipitate is dried and crushed to obtain the pectin product.

[0083] The pectin extraction rate was 22%, the galacturonic acid content in the pectin was 84%, the molecular weight was 200 kDa, and the insoluble ash content was <0.5%.

[0084] (4) Add glycerol-anhydrous ethanol mixed solvent to the solid remaining after collecting pectin extract in step (3) to obtain a mixture. The glycerol-anhydrous ethanol mixed solvent is obtained by mixing glycerol and anhydrous ethanol at a volume ratio of 9:1. After stirring the obtained mixture at 18-25°C for 1 hour, the system viscosity is too high and it cannot be filtered and separated smoothly, so hesperidin product cannot be obtained.

[0085] Example 5: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0086] The specific implementation method is the same as in Example 1, except that the resin selected is HD-100 non-polar macroporous resin.

[0087] The prepared dark brown orange peel essential oil had an extraction rate of 48% (total content). The essential oil contained 158 volatile components, of which limonene accounted for 72%. Other major essential oil components included linalool (5%), β-myrcene (5%), 1,3-dihydroxyacetone (3%), and methyl acetate (2%).

[0088] The pectin product obtained had an extraction rate of 25%, a galacturonic acid content of 82%, a molecular weight of 188 kDa, and an insoluble ash content of <0.5%.

[0089] The extraction rate of hesperidin was 1.4%, and the purity was 98%.

[0090] Example 6: Process for continuous extraction of essential oils, pectin and hesperidin from orange peel

[0091] The specific implementation method is the same as in Example 1, except that the resin selected is AB-8 non-polar macroporous resin;

[0092] The prepared dark brown orange peel essential oil had an extraction rate of 54% (total content). The essential oil contained 143 volatile components, of which limonene accounted for 76%. Other major essential oil components included linalool (8%), β-myrcene (3%), 1,3-dihydroxyacetone (3%), and methyl acetate (2%).

[0093] The pectin product obtained had an extraction rate of 21%, a galacturonic acid content of 76%, a molecular weight of 204 kDa, and an insoluble ash content of <0.5%.

[0094] The extraction rate of hesperidin was 1.3%, and the purity was 98%.

[0095] Comparative Example 1

[0096] The specific implementation method is the same as in Example 1, except that the resin is adjusted to 701 anion exchange resin.

[0097] The prepared dark brown orange peel essential oil had an extraction rate of 50% (total content). The essential oil contained 148 volatile components, of which limonene accounted for 81%. Other major essential oil components included linalool (4%), β-myrcene (3%), 1,3-dihydroxyacetone (1%), and methyl acetate (1%).

[0098] The pectin product obtained had an extraction rate of 23%, a galacturonic acid content of 78%, a molecular weight of 205 kDa, and an insoluble ash content of <0.5%.

[0099] The extraction rate of hesperidin was 1.4%, but the purity of the obtained hesperidin was low, only 23%.

[0100] Comparative Example 2

[0101] The specific implementation method is the same as in Example 1, except that the resin is adjusted to be 732 cation exchange resin.

[0102] The prepared dark brown orange peel essential oil had an extraction rate of 48% (total content). The essential oil contained 156 volatile components, of which limonene accounted for 78%. Other major essential oil components included linalool (5%), β-myrcene (4%), 1,3-dihydroxyacetone (3%), and methyl acetate (1%).

[0103] The pectin product obtained had an extraction rate of 24%, a galacturonic acid content of 80%, a molecular weight of 195 kDa, and an insoluble ash content of <0.5%.

[0104] The extraction rate of hesperidin was 1.4%, but the purity of the obtained hesperidin was low, only 18%.

[0105] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for continuously extracting essential oils, pectin, and hesperidin from orange peel, characterized in that, The method includes the following steps: (1) Crush the orange peel into particles smaller than 100 micrometers; (2) Extraction of essential oil: Anhydrous ethanol was used as the extractant and mixed with crushed orange peel raw material. The mixture was reacted at 18~25℃ and 100~300 rpm for 30~60 min and then filtered to obtain ethanol extract. The ethanol extract was concentrated and then extracted to obtain dark brown essential oil. (3) Extraction of pectin: Mix the solid remaining after filtration in step (2) with water to obtain a reaction solution. After reacting the reaction solution at 60~90℃, continue the reaction at 18~25℃. After the reaction is completed, filter and collect the filtrate to obtain the pectin extract. Concentrate the pectin extract and add ethanol to precipitate the pectin. After filtration, collect the precipitate and dry it to obtain the pectin product. (4) Extraction of hesperidin: Add glycerol-anhydrous ethanol mixed solvent to the solid remaining after collecting pectin extract in step (3) and react at 18~25℃ and 100~300 rpm for 1~3 h. After the reaction, filter and collect the filtrate. Adsorb the filtrate with non-polar macroporous adsorption resin at 18~25℃ for 1~3 h and collect the resin. Then desorb the non-polar macroporous adsorption resin with ethanol for 1~3 h. The resulting ethanol solution is the hesperidin extract. Concentrate and remove the ethanol to obtain the hesperidin product. The glycerol-anhydrous ethanol mixed solvent is prepared by mixing glycerol and ethanol in a volume ratio of (7:3)~(3:7).

2. The method as described in claim 1, characterized in that, In step (2), anhydrous ethanol is used as the extractant and mixed with the crushed orange peel raw material at a ratio of 1:5 to 1:

10.

3. The method as described in claim 1, characterized in that, In step (2), the concentration method of the prepared ethanol extract is vacuum distillation.

4. The method as described in claim 1, characterized in that, In step (3), the solid remaining after extracting the essential oil is mixed with water at a ratio of (1:20) to (1:40) to obtain a reaction solution. The reaction solution is reacted at 60-90℃ and 100-300 rpm for 10-60 min to inactivate the endogenous pectinase. Then, it is reacted at 18-25℃ and 100-300 rpm for 1-2 h. After filtration, the pectin extract is collected. The pectin extract is concentrated and ethanol is added to precipitate the pectin. After filtration, the pectin product is obtained.

5. The method as described in claim 1, characterized in that, The method for adsorbing the filtrate with the non-polar macroporous adsorption resin in step (4) is to add the non-polar macroporous adsorption resin to the prepared filtrate, adsorb at 25°C for 1 hour, filter and recover the resin, and then add the resin to ethanol for desorption for 1 hour. The resulting ethanol solution is the hesperidin extract.

6. The method as described in claim 1, characterized in that, The non-polar macroporous adsorption resin is D101, AB-8, or HPD-100.

7. The use of the method according to any one of claims 1 to 6 in the preparation of a product containing orange peel essential oil, or in the preparation of a product containing orange peel pectin, or in the preparation of a product containing hesperidin.

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