Gradient Extraction Method of Chili Flavor Compounds Based on Supercritical CO2

Abstract

The application discloses a supercritical CO2-based pepper flavor substance gradient extraction method and relates to the technical field of natural product extraction and separation. In order to solve the problems of single condition, volatile aroma, entrainer residue, fraction cross-contamination, insufficient CO2 and entrainer recovery during the supercritical CO2 extraction of pepper flavor substances, the application extracts volatile aroma fractions by using pure CO2 or CO2 containing 0-3v / v% ethanol through S300, extracts capsaicin fractions by using ethanol as an entrainer through S400, extracts pepper red pigment and fat-soluble flavor fractions by using a mixed entrainer of ethanol and ethyl acetate through S500, purifies the supercritical extraction kettle and pipeline by using pure CO2 before S400 and S500, connects the first separation kettle, the second separation kettle and the third separation kettle in series and sequentially decreases the pressure, enters the uncondensed CO2 into an adsorption trap, realizes the cyclic use of CO2 and the entrainer through S600, realizes the effects of selective extraction, segmented collection, high-purity separation and green cyclic production of volatile aroma, capsaicin and pepper red pigment.

Description

Technical Field

[0001] This invention relates to the field of natural product extraction and separation technology, and in particular to a gradient extraction method for chili flavor compounds based on supercritical CO2. Background Technology

[0002] Chili peppers contain abundant flavor compounds and functional components, mainly including volatile aroma components, capsaicinoids, and capsicum red pigments. Volatile aroma components such as hexanal, 2-methylbutyraldehyde, linalool, and β-ionone are important components constituting the characteristic aroma of chili peppers; however, they are highly heat-sensitive and easily oxidized, polymerized, or volatilized during high-temperature and long-term extraction. Capsaicinoids, including capsaicin, dihydrocapsaicin, and nordihydrocapsaicin, are the main source of the spiciness of chili peppers and have analgesic, antioxidant, and metabolism-boosting effects. Capsicum red pigments, including capsanthin, capsicum rubigin, and β-carotene, are important natural red pigments and fat-soluble antioxidants.

[0003] Existing methods for extracting flavor compounds from chili peppers mainly include solvent extraction, steam distillation, supercritical CO2 extraction, and ultrasound-assisted or enzyme-assisted extraction. While solvent extraction achieves high extraction rates, it carries a high risk of organic solvent residue, poor selectivity, and complex subsequent purification steps. Steam distillation is suitable for extracting volatile aromas, but high temperatures can easily destroy heat-sensitive aromas, and it is difficult to extract capsaicin and capsanthin simultaneously. Conventional supercritical CO2 extraction, using single pressure, single temperature, or single entrainer conditions, often suffers from the following problems: First, the adjustable range of CO2 polarity is limited, making it difficult to achieve simultaneous and efficient extraction of capsaicin and capsicum pigments with large differences in polarity. Second, the volatile aroma, capsaicin, and paprika oleoresin are mixed and extracted under the same conditions, making subsequent separation difficult and resulting in low product purity. Third, increasing temperature and pressure to improve extraction rate can easily lead to loss of volatile aroma and degradation of pigments; Fourth, the method of adding the entrainer is crude, and the residual entrainer in the pipeline and extraction vessel during gradient switching can easily cause cross-contamination of the distillate.

[0004] Therefore, there is an urgent need for a method that can selectively extract and collect in stages based on the polarity, volatility, and solubility characteristics of different flavor substances in chili peppers, so as to simultaneously achieve efficient extraction, high-purity separation, and protection of heat-sensitive components of volatile aromas, capsaicinoids, and capsicum pigments. Summary of the Invention

[0005] To address the problems of mixed extraction of volatile aromas, capsaicin, and capsanthin during existing supercritical CO2 extraction of chili flavor compounds due to single-condition extraction, cross-contamination of fractions caused by entrainer residues, and insufficient recovery of CO2 and entrainers, this invention designs a gradient extraction method for chili flavor compounds based on supercritical CO2. This invention sets up S100 for raw material pretreatment, S200 for loading and degassing, S300 for the first gradient extraction, S400 for the second gradient extraction, S500 for the third gradient extraction, and S600 for CO2 recovery and recycling. Specifically, S300 uses pure CO2 or CO2 containing 0-3 v / v% ethanol. CO2 is used to extract volatile aroma fractions. In S400, ethanol is used as an entrainer to extract capsaicin fractions. In S500, a mixture of ethanol and ethyl acetate is used as an entrainer to extract capsanthin and fat-soluble flavor fractions. Before S400 and S500, the supercritical extraction vessel and pipelines are purged with pure CO2. The first, second, and third separation vessels are connected in series with decreasing pressures. Uncondensed CO2 enters the adsorption trap. In S600, CO2 and the entrainer are recycled, achieving selective extraction, segmented collection, high-purity separation, and green circular production of volatile aromas, capsaicin, and capsanthin.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A gradient extraction method for chili flavor compounds based on supercritical CO2, comprising the following steps: S100. Remove impurities from the chili raw material, dry it to a moisture content of ≤8%, and pulverize it to 20-60 mesh to obtain chili powder; S200: The chili powder is loaded into a supercritical extraction vessel, and CO2 is introduced to replace the air in the supercritical extraction vessel. S300, First gradient extraction: CO2 containing 0-3 v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 8-15 MPa, the temperature at 31-40℃, and the CO2 flow rate at 10-30 L / h. The extraction is carried out for 20-60 min. The effluent from the first gradient extraction enters the first separation vessel for separation, and the volatile aroma fraction is collected. S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 min to raise the pressure in the supercritical extraction vessel to 16-26 MPa and the temperature in the supercritical extraction vessel to 40-55℃. Ethanol is mixed in as the second gradient entrainer to make the ethanol concentration reach 5-15 v / v%. The CO2 flow rate is controlled at 15-35 L / h. Extraction is carried out for 60-120 min. The effluent from the second gradient extraction enters the second separation vessel for separation, and the capsaicin fraction is collected. S500, Third Gradient Extraction: After the second gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 minutes to raise the pressure inside the supercritical extraction vessel to 28-40 MPa and the temperature inside the supercritical extraction vessel to 50-70℃. A mixed entrainer is added, and the CO2 flow rate is controlled at 20-40 L / h. Extraction is carried out for 90-180 minutes. The effluent from the third gradient extraction enters the third separation vessel for separation, and the capsicum red pigment and fat-soluble flavor fraction are collected. S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling.

[0007] Furthermore, in S100, the drying is carried out by hot air drying, vacuum drying or microwave drying, the drying temperature is 40-60℃, and the powder is pulverized to 30-50 mesh.

[0008] Furthermore, S100 also includes enzyme-assisted pretreatment: chili powder is mixed with an aqueous solution of cellulase and pectinase, the amount of enzyme is 0.1-0.5% of the mass of chili powder, the pH is 4.5-5.5, the temperature is 40-50℃, the enzymatic hydrolysis is carried out for 1-2 hours, and then dried to a moisture content of ≤8%.

[0009] Furthermore, in the S300, the first gradient extraction pressure is 9-12 MPa, the first gradient extraction temperature is 32-38℃, the CO2 flow rate is 15-25 L / h, and the first gradient extraction time is 30-45 min.

[0010] Furthermore, in the S400, the second gradient extraction pressure is 18-24 MPa, the second gradient extraction temperature is 45-52℃, the ethanol concentration is 8-12 v / v%, the CO2 flow rate is 20-30 L / h, the second gradient extraction time is 75-100 min, the second separation vessel pressure is 5-6 MPa, and the second separation vessel temperature is 38-42℃.

[0011] Furthermore, in the S500, the third gradient extraction pressure is 30-36 MPa, the third gradient extraction temperature is 55-65℃, the CO2 flow rate is 25-35 L / h, the third gradient extraction time is 100-150 min, the third separation vessel pressure is 3-4 MPa, and the third separation vessel temperature is 45-52℃.

[0012] Furthermore, in S300, the pressure of the first separation vessel is 6.5-7.5 MPa, and the temperature of the first separation vessel is 28-32℃; In the S400, the pressure of the second separation vessel is 5-6 MPa, and the temperature of the second separation vessel is 38-42℃; In the S500, the pressure of the third separation vessel is 3-4 MPa, and the temperature of the third separation vessel is 45-52℃.

[0013] Furthermore, the mixed entrainer is ethanol and ethyl acetate, with a volume ratio of ethanol to ethyl acetate of 1:2-2:1, and a total concentration of the mixed entrainer of 12-20 v / v.

[0014] Furthermore, the first separation vessel, the second separation vessel, and the third separation vessel are connected in series, and the pressures of the first separation vessel, the second separation vessel, and the third separation vessel decrease sequentially. In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

[0015] Furthermore, the chili pepper raw material is one or more of the following: bird's eye chili, small red chili, Erjingtiao chili, lantern chili, and long chili. The capsaicin fraction includes capsaicin, dihydrocapsaicin, and nordihydrocapsaicin; the capsicum red pigment and fat-soluble flavor fraction include capsicum red pigment, capsicum rubigin, and β-carotene.

[0016] Compared with the prior art, the beneficial effects of the present invention are: I. This invention achieves the segmented collection of volatile aroma fractions, capsaicin fractions, capsanthin, and fat-soluble flavor fractions through programmed switching of first-gradient extraction, second-gradient extraction, and third-gradient extraction. The first gradient extraction uses CO2 containing 0-3 v / v% ethanol to preferentially extract volatile aroma fractions at 8-15 MPa and 31-40°C. The second gradient extraction uses ethanol as an entrainer to extract capsaicin fractions at 16-26 MPa and 40-55°C. The third gradient extraction uses a mixture of ethanol and ethyl acetate as an entrainer to extract capsaicin and fat-soluble flavor fractions at 28-40 MPa and 50-70°C. Before switching between the first, second, and third gradient extractions, the supercritical extraction vessel and pipelines are purged with pure CO2 to avoid cross-contamination of fractions caused by entrainer residues. The first, second, and third separation vessels are connected in series with decreasing pressures in sequence, allowing target products of different polarities and volatility to be separated in a predetermined order, improving the purity of capsaicin and capsaicin fractions, and solving the problem of subsequent separation difficulties caused by mixed extraction under single supercritical CO2 conditions.

[0017] II. In the first gradient extraction, this invention prioritizes the extraction of volatile aroma fractions, reducing the oxidation and loss of heat-sensitive aroma components. The second gradient extraction uses medium pressure, medium temperature, and ethanol as an entrainer to improve the solubility and mass transfer efficiency of capsaicin compounds. The third gradient extraction uses high pressure, high temperature, and a mixed ethanol / ethyl acetate entrainer to improve the extraction rate of capsaicin and fat-soluble flavor substances. In S600, the CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling. The entrainer is recovered by distillation and recycled. This method reduces organic solvent residues and production costs, achieving green, continuous, and large-scale extraction of chili flavor substances, and solving the problems of large loss of heat-sensitive aromas, low extraction rates of capsaicin and capsaicin, and insufficient recovery of CO2 and entrainer in existing technologies. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0019] Figure 1 This is a flowchart illustrating the steps of the gradient extraction method for chili flavor compounds based on supercritical CO2 in this invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] It should be understood that, when used in this specification, the terms “comprising” and “including” indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “the” are intended to include the plural forms.

[0023] This invention provides a gradient extraction method for chili flavor compounds based on supercritical CO2, such as... Figure 1 As shown, the steps of this method are as follows: S100. Remove impurities from the chili raw material, dry it to a moisture content of ≤8%, and pulverize it to 20-60 mesh to obtain chili powder; S200: The chili powder is loaded into a supercritical extraction vessel, and CO2 is introduced to replace the air in the supercritical extraction vessel. S300, First gradient extraction: CO2 containing 0-3 v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 8-15 MPa, the temperature at 31-40℃, and the CO2 flow rate at 10-30 L / h. The extraction is carried out for 20-60 min. The effluent from the first gradient extraction enters the first separation vessel for separation, and the volatile aroma fraction is collected. S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 min to raise the pressure in the supercritical extraction vessel to 16-26 MPa and the temperature in the supercritical extraction vessel to 40-55℃. Ethanol is mixed in as the second gradient entrainer to make the ethanol concentration reach 5-15 v / v%. The CO2 flow rate is controlled at 15-35 L / h. Extraction is carried out for 60-120 min. The effluent from the second gradient extraction enters the second separation vessel for separation, and the capsaicin fraction is collected. S500, Third Gradient Extraction: After the second gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 minutes to raise the pressure inside the supercritical extraction vessel to 28-40 MPa and the temperature inside the supercritical extraction vessel to 50-70℃. A mixed entrainer is added, and the CO2 flow rate is controlled at 20-40 L / h. Extraction is carried out for 90-180 minutes. The effluent from the third gradient extraction enters the third separation vessel for separation, and the capsicum red pigment and fat-soluble flavor fraction are collected. S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling.

[0024] In this invention, the term v / v% refers to the percentage of the entrainer volumetric flow rate to the CO2 volumetric flow rate, where the CO2 volumetric flow rate is expressed by volume under standard conditions. The volatile aroma fractions obtained in this invention can be used in food flavorings, flavoring oils, and compound seasonings; capsaicin fractions can be used in health foods, topical analgesics, and functional additives; capsanthin and fat-soluble flavor fractions can be used in natural pigments, cosmetics, feed colorings, and antioxidants. Each fraction can be further refined as needed, for example, by molecular distillation, column chromatography, or membrane separation.

[0025] In this invention, unless otherwise specified, all raw materials, reagents, and equipment used are conventional commercially available products. The detection methods are as follows: volatile aroma fractions are detected using gas chromatography-mass spectrometry, and the aroma retention rate is calculated using the peak area normalization method; capsaicin fractions are detected using high-performance liquid chromatography, and the capsaicin extraction rate and capsaicin purity are calculated using the external standard method; capsaicin red pigment and fat-soluble flavor fractions are detected using ultraviolet-visible spectrophotometer, and the color value is calculated based on the absorbance at 460 nm; CO2 recovery rate is calculated using a flow meter and mass balance method; and entrainer recovery rate is calculated using the mass method before and after distillation.

[0026] Example 1 In this embodiment, dried Erjingtiao chili peppers are used as raw materials. After impurity removal, hot air drying, pulverization, and filling and degassing, the first gradient extraction, second gradient extraction, and third gradient extraction are carried out sequentially to collect volatile aroma fractions, capsaicin fractions, capsicum red pigments, and fat-soluble flavor fractions, respectively. The first, second, and third separation vessels are connected in series with decreasing pressures in sequence, and CO2 is recovered and circulated. Through three-stage gradient switching, pure CO2 purging before switching, and decreasing pressure in the separation vessels, selective extraction and segmented separation of chili flavor substances are achieved.

[0027] The specific steps are as follows: S100. Remove impurities from dried Erjingtiao chili peppers, dry them with hot air to a moisture content of 7%, and grind them to 40 mesh to obtain chili powder.

[0028] S200: Weigh 500g of chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0029] S300, First gradient extraction: Using pure CO2 as the first gradient extraction medium, the pressure inside the supercritical extraction vessel is controlled at 10 MPa, the temperature inside the supercritical extraction vessel is 32℃, and the CO2 flow rate is 20 L / h, and the extraction is carried out for 30 min; the effluent from the first gradient extraction enters the first separation vessel, and is separated under the conditions of 7 MPa pressure and 30℃ temperature in the first separation vessel, and the volatile aroma fraction is collected.

[0030] S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 22 MPa and the temperature inside the supercritical extraction vessel is increased to 48℃, and ethanol is mixed into the CO2 online as the second gradient entrainer to make the ethanol concentration reach 8 v / v%. The CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min; the effluent from the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5 MPa pressure and 40℃ temperature in the second separation vessel to collect the capsaicin fraction.

[0031] S500, Third Gradient Extraction: After the second gradient extraction, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 32 MPa and the temperature inside the supercritical extraction vessel is increased to 60℃, and a mixed entrainer of ethanol and ethyl acetate is added online to the CO2. The volume ratio of ethanol to ethyl acetate is 1:1, and the total concentration of the mixed entrainer is 15 v / v%. The CO2 flow rate is controlled at 30 L / h, and the extraction is carried out for 120 min; the effluent from the third gradient extraction enters the third separation vessel, and separation is carried out under the conditions of 3 MPa pressure and 50℃ temperature in the third separation vessel, collecting capsicum red pigment and fat-soluble flavor fraction.

[0032] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0033] In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

[0034] Test results: The volatile aroma fraction was analyzed by GC-MS, and the aroma retention rate was 86.2%; the capsaicin fraction was analyzed by HPLC, and the capsaicin extraction rate was 95.6%, with a capsaicin purity of 92.3%; the capsaicin red pigment and fat-soluble flavor fraction were analyzed by UV-Vis, with a color value of 221 and a capsaicin red pigment extraction rate of 94.1%; the CO2 recovery rate was 96.2%, and the entrainer recovery rate was 91.5%; no volatile aroma components from the first gradient were detected in the second gradient capsaicin fraction, and no capsaicin compounds were detected in the third gradient capsaicin red pigment and fat-soluble flavor fraction.

[0035] Example 2 This embodiment uses dried chili peppers as raw material. After drying, pulverizing, and filling with air, the mixture undergoes a first-gradient extraction with CO2 containing 2v / v% ethanol, a second-gradient extraction with ethanol, and a third-gradient extraction with a mixture of ethanol and ethyl acetate as an entrainer. Volatile aroma fractions, capsaicin fractions, capsanthin, and fat-soluble flavor fractions are collected separately. The separation vessels are connected in series with decreasing pressure, and CO2 is recycled. By optimizing the pressure, temperature, flow rate, time, and entrainer concentration for each gradient, the extraction rate, purity, and color value are improved.

[0036] The specific steps are as follows: S100. Remove impurities from dried chili peppers, dry them with hot air at 50℃ until the moisture content is 6%, and then grind them to 40 mesh to obtain chili powder.

[0037] S200: Weigh 500g of chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0038] S300, First gradient extraction: CO2 containing 2v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 10MPa, the temperature inside the supercritical extraction vessel is 35℃, and the CO2 flow rate is 20L / h. Extraction is carried out for 40min. The effluent from the first gradient extraction enters the first separation vessel and is separated under the conditions of 7MPa pressure and 30℃ temperature. The volatile aroma fraction is collected.

[0039] S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 20 MPa and the temperature inside the supercritical extraction vessel is increased to 48℃, and ethanol is mixed into the CO2 online as the second gradient entrainer to make the ethanol concentration reach 10 v / v%, and the CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min; the effluent of the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5.5 MPa pressure and 40℃ temperature in the second separation vessel, and the capsaicin fraction is collected.

[0040] S500, Third Gradient Extraction: After the second gradient extraction, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 32 MPa and the temperature inside the supercritical extraction vessel is increased to 60℃, and a mixed entrainer of ethanol and ethyl acetate is added online to the CO2. The volume ratio of ethanol to ethyl acetate is 1:1, and the total concentration of the mixed entrainer is 15 v / v%. The CO2 flow rate is controlled at 30 L / h, and the extraction is carried out for 120 min; the effluent from the third gradient extraction enters the third separation vessel, and separation is carried out under the conditions of 3.5 MPa pressure and 50℃ temperature in the third separation vessel, collecting capsicum red pigment and fat-soluble flavor fraction.

[0041] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0042] In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

[0043] Test results: The volatile aroma fraction was analyzed by GC-MS, and the aroma retention rate was 88.4%; the capsaicin fraction was analyzed by HPLC, and the capsaicin extraction rate was 96.5%, with a capsaicin purity of 93.1%; the capsaicin red pigment and fat-soluble flavor fraction were analyzed by UV-Vis, with a color value of 225 and a capsaicin red pigment extraction rate of 95.0%; the CO2 recovery rate was 96.5%, and the entrainer recovery rate was 92.3%; no volatile aroma components from the first gradient were detected in the second gradient capsaicin fraction, and no capsaicin compounds were detected in the third gradient capsaicin red pigment and fat-soluble flavor fraction.

[0044] Example 3 In this embodiment, dried small red chili peppers are used as raw materials. Cellulase and pectinase are added to S100 for pretreatment. After enzymatic hydrolysis, the mixture is dried, pulverized, and loaded with exhaust gas. Then, the first, second, and third gradient extractions are performed sequentially to collect volatile aroma fractions, capsaicin fractions, capsicum red pigments, and fat-soluble flavor fractions, respectively. The separation vessels are connected in series with decreasing pressure and CO2 is recovered and circulated. Enzyme-assisted pretreatment destroys the cell wall structure, thereby improving the mass transfer efficiency and extraction efficiency of chili flavor substances.

[0045] The specific steps are as follows: S100. Remove impurities from dried small red chilies and grind them to 40 mesh to obtain chili powder. Mix the chili powder with an aqueous solution of cellulase and pectinase, with a mass ratio of cellulase to pectinase of 1:1, a total enzyme dosage of 0.3% of the chili powder mass, a pH of 5.0, a temperature of 45℃, and perform enzymatic hydrolysis for 1.5 hours. Then, vacuum dry the mixture until the moisture content is ≤8%, grind it to 40 mesh, and obtain enzyme-assisted pretreated chili powder.

[0046] S200: Weigh 500g of enzyme-assisted pretreated chili powder and put it into a 1L supercritical extraction vessel. Then, purge the air in the supercritical extraction vessel with CO2 for 3 minutes.

[0047] S300, First gradient extraction: CO2 containing 2v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 10MPa, the temperature inside the supercritical extraction vessel is 35℃, and the CO2 flow rate is 20L / h. Extraction is carried out for 40min. The effluent from the first gradient extraction enters the first separation vessel and is separated under the conditions of 7MPa pressure and 30℃ temperature. The volatile aroma fraction is collected.

[0048] S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 20 MPa and the temperature inside the supercritical extraction vessel is increased to 48℃, and ethanol is mixed into the CO2 online as the second gradient entrainer to make the ethanol concentration reach 10 v / v%, and the CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min; the effluent of the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5.5 MPa pressure and 40℃ temperature in the second separation vessel, and the capsaicin fraction is collected.

[0049] S500, Third Gradient Extraction: After the second gradient extraction, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 32 MPa and the temperature inside the supercritical extraction vessel is increased to 60℃, and a mixed entrainer of ethanol and ethyl acetate is added online to the CO2. The volume ratio of ethanol to ethyl acetate is 1:1, and the total concentration of the mixed entrainer is 15 v / v%. The CO2 flow rate is controlled at 30 L / h, and the extraction is carried out for 120 min; the effluent from the third gradient extraction enters the third separation vessel, and separation is carried out under the conditions of 3.5 MPa pressure and 50℃ temperature in the third separation vessel, collecting capsicum red pigment and fat-soluble flavor fraction.

[0050] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0051] In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

[0052] Test results: The volatile aroma fraction was analyzed by GC-MS, and the aroma retention rate was 90.1%; the capsaicin fraction was analyzed by HPLC, and the capsaicin extraction rate was 97.3%, with a capsaicin purity of 93.8%; the capsaicin red pigment and fat-soluble flavor fraction were analyzed by UV-Vis, with a color value of 230 and a capsaicin red pigment extraction rate of 96.2%; the CO2 recovery rate was 97.0%, and the entrainer recovery rate was 93.1%; no volatile aroma components from the first gradient were detected in the second gradient capsaicin fraction, and no capsaicin compounds were detected in the third gradient capsaicin red pigment and fat-soluble flavor fraction.

[0053] Example 4 In this embodiment, a mixture of chili peppers (including bird's eye chili and Erjingtiao chili) is used as raw material. After drying, pulverizing, and filling with air, the mixture undergoes sequential extraction using a first, second, and third gradient. Volatile aroma fractions, capsaicin fractions, capsicum pigments, and fat-soluble flavor fractions are collected, respectively. The third gradient uses a mixed entrainer of ethanol and ethyl acetate in a 1:2 volume ratio. The separators are connected in series with decreasing pressure, and CO2 is recovered and recycled. By blending different chili raw materials and adjusting the proportion of the mixed entrainer, segmented extraction of flavor substances from various chili raw materials is achieved.

[0054] The specific steps are as follows: S100. Mix chili peppers, small red chili peppers, and Erjingtiao chili peppers in a mass ratio of 1:1:1, remove impurities, dry to a moisture content of 7%, and grind to 40 mesh to obtain mixed chili powder.

[0055] S200: Weigh 500g of mixed chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0056] S300, First gradient extraction: CO2 containing 1v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 11MPa, the temperature inside the supercritical extraction vessel is 34℃, and the CO2 flow rate is 18L / h. The extraction time is 35min. The effluent from the first gradient extraction enters the first separation vessel and is separated under the conditions of 7MPa pressure and 30℃ temperature. The volatile aroma fraction is collected.

[0057] S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 22 MPa and the temperature inside the supercritical extraction vessel is increased to 50℃, and ethanol is mixed into the CO2 online as the second gradient entrainer to make the ethanol concentration reach 10 v / v%, and the CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min; the effluent from the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5.5 MPa pressure and 40℃ temperature in the second separation vessel, and the capsaicin fraction is collected.

[0058] S500, Third Gradient Extraction: After the second gradient extraction, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 34 MPa and the temperature inside the supercritical extraction vessel is increased to 62℃, and a mixed entrainer of ethanol and ethyl acetate is added online to the CO2. The volume ratio of ethanol to ethyl acetate is 1:2, and the total concentration of the mixed entrainer is 18 v / v%. The CO2 flow rate is controlled at 32 L / h, and the extraction is carried out for 130 min; the effluent from the third gradient extraction enters the third separation vessel, and separation is carried out under the conditions of 3.5 MPa pressure and 50℃ temperature in the third separation vessel, collecting capsicum red pigment and fat-soluble flavor fraction.

[0059] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0060] In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

[0061] Test results: The volatile aroma fraction was analyzed by GC-MS, and the aroma retention rate was 87.5%; the capsaicin fraction was analyzed by HPLC, and the capsaicin extraction rate was 95.1%, with a capsaicin purity of 91.2%; the capsaicin red pigment and fat-soluble flavor fraction were analyzed by UV-Vis, and the color value was 218, with a capsaicin red pigment extraction rate of 93.5%; the CO2 recovery rate was 96.0%, and the entrainer recovery rate was 91.8%; no volatile aroma components from the first gradient were detected in the second gradient capsaicin fraction, and no capsaicin compounds were detected in the third gradient capsaicin red pigment and fat-soluble flavor fraction.

[0062] Comparative Example 1 This comparative example employed single-condition supercritical CO2 extraction without a three-stage gradient extraction. Using dried Erjingtiao chili peppers as raw material, after drying, pulverizing, and degassing, extraction was performed at 30 MPa, 55℃, ethanol concentration of 10 v / v%, and CO2 flow rate of 25 L / h for 150 min. All extracts were collected using a single-stage separator. Through single-condition extraction, volatile aromas, capsaicin, and capsanthin were extracted under the same conditions.

[0063] The specific steps are as follows: S100. Remove impurities from dried Erjingtiao chili peppers, dry them with hot air to a moisture content of 7%, and grind them to 40 mesh to obtain chili powder.

[0064] S200: Weigh 500g of chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0065] S300, Single-condition extraction: Set the supercritical extraction vessel pressure to 30MPa and the supercritical extraction vessel temperature to 55℃, add ethanol online to CO2 to achieve an ethanol concentration of 10v / v%, control the CO2 flow rate to 25L / h, and extract for 150min.

[0066] S400: Separation was carried out using a single separation vessel at 5 MPa and 40 °C, and all extracts were collected.

[0067] Test results: The total extract mass was 22.5 g, the volatile aroma recovery rate was 58.4%, the capsaicin extraction rate was 71.2%, the capsaicin purity was 63.5%, the capsicum red pigment color value was 148, the capsicum red pigment extraction rate was 68.5%, the CO2 recovery rate was 83.1%, and the entrainer recovery rate was 87.4%. Capsaicin, capsicum red pigment, and volatile aromas were mixed in the same extract, making subsequent separation steps complex. Compared with Example 1, single-condition supercritical CO2 extraction resulted in a decrease in capsaicin extraction rate, capsaicin purity, capsicum red pigment color value, capsicum red pigment extraction rate, and volatile aroma recovery rate. Capsaicin, capsicum red pigment, and volatile aromas could not be collected in fractions.

[0068] Comparative Example 2 This comparative example uses a three-stage gradient extraction process but does not perform pure CO2 purging before gradient switching. Using dried Erjingtiao chili peppers as raw material, steps S100, S200, S300, S400, S500, and S600 are the same as in Example 1. The difference is that pure CO2 purging is not performed before S400 and S500. By omitting the purging step, entrainer residues enter the next gradient, causing cross-contamination of the fractions.

[0069] The specific steps are as follows: S100. Remove impurities from dried Erjingtiao chili peppers, dry them with hot air to a moisture content of 7%, and grind them to 40 mesh to obtain chili powder.

[0070] S200: Weigh 500g of chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0071] S300, First gradient extraction: Using pure CO2 as the first gradient extraction medium, the pressure inside the supercritical extraction vessel is controlled at 10 MPa, the temperature inside the supercritical extraction vessel is 32℃, and the CO2 flow rate is 20 L / h, and the extraction is carried out for 30 min; the effluent from the first gradient extraction enters the first separation vessel, and is separated under the conditions of 7 MPa pressure and 30℃ temperature in the first separation vessel, and the volatile aroma fraction is collected.

[0072] S400, Second Gradient Extraction: After the first gradient extraction is completed, without pure CO2 purging, the pressure inside the supercritical extraction vessel is increased to 22 MPa and the temperature inside the supercritical extraction vessel is increased to 48°C. Ethanol is mixed into the CO2 online as the second gradient entrainer, so that the ethanol concentration reaches 8 v / v%. The CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min. The effluent from the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5 MPa pressure and 40°C temperature in the second separation vessel to collect the capsaicin fraction.

[0073] S500, Third Gradient Extraction: After the second gradient extraction, without pure CO2 purging, the pressure inside the supercritical extraction vessel is increased to 32 MPa and the temperature inside the supercritical extraction vessel is increased to 60°C. A mixed entrainer of ethanol and ethyl acetate is added online to the CO2, with a volume ratio of ethanol to ethyl acetate of 1:1 and a total concentration of 15 v / v%. The CO2 flow rate is controlled at 30 L / h, and the extraction is carried out for 120 min. The effluent from the third gradient extraction enters the third separation vessel, where it is separated under the conditions of a pressure of 3 MPa and a temperature of 50°C. Capsicum red pigment and fat-soluble flavor fraction are collected.

[0074] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0075] Test results: The volatile aroma retention rate was 79.3%, the capsaicin extraction rate was 85.5%, the capsaicin purity was 82.1%, the capsaicin color value was 180.5, the capsaicin extraction rate was 86.3%, the CO2 recovery rate was 87.2%, and the entrainer recovery rate was 88.6%. The first-gradient volatile aroma components were detected in the second-gradient capsaicin fraction, and capsaicin compounds were detected in the third-gradient capsaicin and fat-soluble flavor fractions, indicating cross-contamination of the fractions.

[0076] Comparative Example 3 In this comparative example, only ethanol was used as the entrainer in the third-gradient extraction, without using a mixture of ethanol and ethyl acetate. Using dried Erjingtiao chili peppers as raw material, S100, S200, S300, S400, and S600 were the same as in Example 1, except that only 15 v / v% ethanol was used in S500. By changing the type of entrainer in the third gradient, the effect of the mixed entrainer on the extraction rate and color value of capsicum pigment was verified.

[0077] The specific steps are as follows: S100. Remove impurities from dried Erjingtiao chili peppers, dry them with hot air to a moisture content of 7%, and grind them to 40 mesh to obtain chili powder.

[0078] S200: Weigh 500g of chili powder and put it into a 1L supercritical extraction vessel. Then, introduce CO2 to replace the air in the supercritical extraction vessel for 3 minutes.

[0079] S300, First gradient extraction: Using pure CO2 as the first gradient extraction medium, the pressure inside the supercritical extraction vessel is controlled at 10 MPa, the temperature inside the supercritical extraction vessel is 32℃, and the CO2 flow rate is 20 L / h, and the extraction is carried out for 30 min; the effluent from the first gradient extraction enters the first separation vessel, and is separated under the conditions of 7 MPa pressure and 30℃ temperature in the first separation vessel, and the volatile aroma fraction is collected.

[0080] S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 22 MPa and the temperature inside the supercritical extraction vessel is increased to 48℃, and ethanol is mixed into the CO2 online as the second gradient entrainer to make the ethanol concentration reach 8 v / v%. The CO2 flow rate is controlled at 25 L / h, and the extraction is carried out for 90 min; the effluent from the second gradient extraction enters the second separation vessel, and is separated under the conditions of 5 MPa pressure and 40℃ temperature in the second separation vessel to collect the capsaicin fraction.

[0081] S500, Third Gradient Extraction: After the second gradient extraction, the supercritical extraction vessel and pipeline are purged with pure CO2 for 5 min; the pressure inside the supercritical extraction vessel is increased to 32 MPa and the temperature inside the supercritical extraction vessel is increased to 60℃, and ethanol is mixed into the CO2 online as the third gradient entrainer, with an ethanol concentration of 15 v / v%, and the CO2 flow rate is controlled at 30 L / h, and the extraction is carried out for 120 min; the effluent from the third gradient extraction enters the third separation vessel, and is separated under the conditions of a pressure of 3 MPa and a temperature of 50℃ in the third separation vessel, and the capsicum red pigment and fat-soluble flavor fraction are collected.

[0082] S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling; the entrainer is recovered by distillation and then recycled.

[0083] Test results: The volatile aroma retention rate was 85.1%, the capsaicin extraction rate was 88.2%, the capsaicin purity was 85.2%, the capsaicin color value was 158.6, the capsaicin extraction rate was 74.3%, the CO2 recovery rate was 89.8%, and the entrainer recovery rate was 88.1%. No capsaicin compounds were detected in the third-gradient capsaicin and fat-soluble flavor fractions, and no first-gradient volatile aroma components were detected in the second-gradient capsaicin fraction.

[0084] To facilitate comparison of the technical effects of the various embodiments and comparative examples, the above test results are summarized in Table 1: Table 1: Summary of test results for each embodiment and comparative example As shown in Table 1, Examples 1 to 4 showed no cross-contamination of distillates, with aroma retention rates of 86.2% to 90.1%, capsaicin extraction rates of 95.1% to 97.3%, capsaicin purity of 91.2% to 93.8%, capsaicin color value of 218 to 230, capsaicin extraction rates of 93.5% to 96.2%, CO2 recovery rates of 96.0% to 97.0%, and entrainer recovery rates of 91.5% to 93.1%. Comparative Example 1, using single-condition extraction, saw aroma retention rates decrease to 58.4%, capsaicin purity to 63.5%, and capsaicin color value to 148, with mixed extraction of volatile aromas, capsaicin compounds, and capsaicin. Comparative Example 2, omitting pure CO2 purging before gradient switching, resulted in cross-contamination of distillates, with capsaicin purity decreasing to 82.1% and capsaicin color value decreasing to 180.5. In Comparative Example 3, using only ethanol as an entrainer in the third gradient, the capsaicin extraction rate decreased to 74.3%, and the capsaicin color value decreased to 158.6. Table 1 shows that the three-stage gradient extraction, pure CO2 purging before gradient switching, the use of a mixed entrainer of ethanol and ethyl acetate, the series connection of the first to third separation vessels with progressively decreasing pressures, and CO2 recovery recycling collectively achieve selective extraction, segmented collection, high-purity separation, protection of heat-sensitive aromas, and green circular production of chili flavor compounds. In Example 3, enzyme-assisted pretreatment further improved aroma retention, capsaicin extraction rate, and capsaicin color value. Example 4 demonstrates that gradient extraction can be achieved by combining different chili raw materials and adjusting the proportion of the mixed entrainer.

[0085] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A gradient extraction method for chili flavor compounds based on supercritical CO2, characterized in that, The steps of this method are as follows: S100. Remove impurities from the chili raw material, dry it to a moisture content of ≤8%, and pulverize it to 20-60 mesh to obtain chili powder; S200: The chili powder is loaded into a supercritical extraction vessel, and CO2 is introduced to replace the air in the supercritical extraction vessel. S300, First gradient extraction: CO2 containing 0-3 v / v% ethanol is used as the first gradient extraction medium. The pressure inside the supercritical extraction vessel is controlled at 8-15 MPa, the temperature at 31-40℃, and the CO2 flow rate at 10-30 L / h. The extraction is carried out for 20-60 min. The effluent from the first gradient extraction enters the first separation vessel for separation, and the volatile aroma fraction is collected. S400, Second Gradient Extraction: After the first gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 min to raise the pressure in the supercritical extraction vessel to 16-26 MPa and the temperature in the supercritical extraction vessel to 40-55℃. Ethanol is mixed in as the second gradient entrainer to make the ethanol concentration reach 5-15 v / v%. The CO2 flow rate is controlled at 15-35 L / h. Extraction is carried out for 60-120 min. The effluent from the second gradient extraction enters the second separation vessel for separation, and the capsaicin fraction is collected. S500, Third Gradient Extraction: After the second gradient extraction is completed, the supercritical extraction vessel and pipeline are purged with pure CO2 for 1-10 minutes to raise the pressure inside the supercritical extraction vessel to 28-40 MPa and the temperature inside the supercritical extraction vessel to 50-70℃. A mixed entrainer is added, and the CO2 flow rate is controlled at 20-40 L / h. Extraction is carried out for 90-180 minutes. The effluent from the third gradient extraction enters the third separation vessel for separation, and the capsicum red pigment and fat-soluble flavor fraction are collected. S600: The CO2 discharged from the first, second, and third separation vessels is purified, dried, condensed, and compressed before being returned to the supercritical extraction vessel for recycling.

2. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, In S100, drying is carried out by hot air drying, vacuum drying or microwave drying, with a drying temperature of 40-60℃, and the material is pulverized to 30-50 mesh.

3. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, The S100 also includes an enzyme-assisted pretreatment: chili powder is mixed with an aqueous solution of cellulase and pectinase, the amount of enzyme is 0.1-0.5% of the mass of chili powder, the pH is 4.5-5.5, the temperature is 40-50℃, the enzymatic hydrolysis is carried out for 1-2 hours, and then dried to a moisture content of ≤8%.

4. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, In the S300, the first gradient extraction pressure is 9-12 MPa, the first gradient extraction temperature is 32-38℃, the CO2 flow rate is 15-25 L / h, and the first gradient extraction time is 30-45 min.

5. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, In the S400, the second gradient extraction pressure is 18-24 MPa, the second gradient extraction temperature is 45-52℃, the ethanol concentration is 8-12 v / v%, the CO2 flow rate is 20-30 L / h, the second gradient extraction time is 75-100 min, the second separation vessel pressure is 5-6 MPa, and the second separation vessel temperature is 38-42℃.

6. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, In the S500, the third gradient extraction pressure is 30-36 MPa, the third gradient extraction temperature is 55-65℃, the CO2 flow rate is 25-35 L / h, the third gradient extraction time is 100-150 min, the third separation vessel pressure is 3-4 MPa, and the third separation vessel temperature is 45-52℃.

7. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, In the S300, the pressure of the first separation vessel is 6.5-7.5 MPa, and the temperature of the first separation vessel is 28-32℃; In the S400, the pressure of the second separation vessel is 5-6 MPa, and the temperature of the second separation vessel is 38-42℃; In the S500, the pressure of the third separation vessel is 3-4 MPa, and the temperature of the third separation vessel is 45-52℃.

8. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 6, characterized in that, The mixed entrainer is ethanol and ethyl acetate, with a volume ratio of ethanol to ethyl acetate of 1:2-2:1, and a total concentration of the mixed entrainer of 12-20 v / v.

9. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, The first separation vessel, the second separation vessel, and the third separation vessel are connected in series. In S300, S400 and S500, the first gradient extraction effluent enters the first separation vessel, the second gradient extraction effluent enters the second separation vessel, and the third gradient extraction effluent enters the third separation vessel through the switching valve, while the uncondensed CO2 enters the adsorption collector.

10. The gradient extraction method for chili flavor compounds based on supercritical CO2 according to claim 1, characterized in that, The chili pepper raw material is one or more of the following: bird's eye chili, small red chili, Erjingtiao chili, lantern chili, and long chili. The capsaicin fraction includes capsaicin, dihydrocapsaicin, and nordihydrocapsaicin; the capsicum red pigment and fat-soluble flavor fraction include capsicum red pigment, capsicum rubigin, and β-carotene.

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