Peony seed oil prepared by a double-supercritical system, preparation method and application

Abstract

This disclosure provides a method for preparing peony seed oil using a dual supercritical system, along with its applications. The preparation method includes: Step 1, placing dried peony seed powder into an extraction vessel for supercritical CO2 extraction to obtain crude peony seed oil; Step 2, adding the crude peony seed oil, CALB lipase, and 1,3-propanediol together into a reaction vessel, sealing it, then introducing CO2, heating and pressurizing it to reach a supercritical state, starting stirring to begin the reaction, and after the reaction is complete, cooling and depressurizing, recovering the enzyme, and then centrifuging to obtain the target product. This method can significantly reduce the acid value of peony seed oil, resulting in a lighter color, milder odor, better stability, lower saturated fatty acid content, higher n-3 / n-6 value, and higher C20:4n6 (arachidonic acid, ARA) content, showing very broad application prospects, especially in the preparation of cosmetics and food.

Description

Technical Field

[0001] This disclosure belongs to the field of edible oil extraction technology, specifically relating to a method for preparing peony seed oil using a dual supercritical system, and its application. Background Technology

[0002] Peony seed oil is a natural woody plant oil extracted from the seeds of the oil peony through processes such as pressing and extraction. Peony seed oil is a unique and healthy edible oil in China. Due to its outstanding nutritional value and rare characteristics, it has received much attention in recent years and is hailed as "the gold of vegetable oils." It has an extremely high content of unsaturated fatty acids with a balanced fatty acid ratio, with a total unsaturated fatty acid content exceeding 90%. The content of α-linolenic acid (Omega-3) is particularly prominent, typically exceeding 40% or even 50%, and it also contains approximately 25%-30% linoleic acid (Omega-6) and approximately 20%-25% oleic acid (Omega-9). In addition, it contains abundant natural active substances such as vitamin E, phytosterols, polyphenols, and squalene. The extraction method of peony seed oil directly determines the quality of the oil, the degree of nutrient retention, and its safety. Currently, the mainstream extraction methods can be divided into three categories: physical pressing, solvent extraction, and novel extraction methods.

[0003] Pressing is the method of extracting oil from raw materials using physical mechanical pressure. This is currently the most common production method for high-quality peony seed oil, including hot pressing and cold pressing. Hot pressing involves steaming the material at high temperatures before pressing. Its advantages include high oil yield and rich aroma, but its disadvantages include protein denaturation, destruction of some heat-sensitive nutrients (such as vitamin E and some polyphenols), and the potential production of trace amounts of trans fatty acids. Cold pressing involves not steaming the material at high temperatures before pressing, or only subjecting it to gentle treatment at low temperatures (usually ≤60℃). This is the preferred process for producing high-end peony seed oil. Its advantages include maximizing the preservation of the oil's natural flavor, color, and bioactive substances such as vitamin E, squalene, and polyphenols, while avoiding the formation of harmful substances. Its disadvantages include a relatively lower oil yield and higher cost.

[0004] Solvent extraction utilizes the principle of "like dissolves like," employing a specific organic solvent (most commonly n-hexane) to soak or spray pre-treated (rolled) oilseeds, dissolving the oil. The solvent is then separated from the oil through processes such as distillation to obtain crude oil. This method boasts extremely high oil yield, with residual oil levels below 1%, and low production costs, making it suitable for large-scale industrial production. Disadvantages include: 1) the risk of trace solvent residue; 2) the need for high-temperature solvent removal, leading to significant loss of heat-sensitive nutrients; and 3) the crude oil must undergo full refining (degumming, deacidification, decolorization, and deodorization) before consumption, further diminishing its natural nutrients and flavor.

[0005] Novel extraction methods are currently a hot research and application area, overcoming the shortcomings of traditional methods. These include: 1. Supercritical CO2 fluid extraction. Under specific temperature and pressure, CO2 is brought to a supercritical fluid state. In this state, CO2 possesses the density of a liquid and the diffusivity of a gas, exhibiting a strong dissolving ability for oils and fats. By changing the pressure, the oils and fats can be separated from the CO2. Its advantages are: 1) Green and safe: CO2 is non-toxic, odorless, non-flammable, readily available, and completely evaporates during the process, leaving no solvent residue. 2) Low-temperature operation: Usually carried out near room temperature, it effectively protects heat-sensitive components such as α-linolenic acid and vitamin E. 3) Good selectivity: By adjusting the pressure and temperature, different components can be selectively extracted. The disadvantages are the huge equipment investment and high production costs. 2. Subcritical fluid extraction. Similar to supercritical, but using a subcritical solvent (below the critical temperature but liquefied under pressure), such as butane or propane. Its operating temperature is lower (room temperature or lower), providing better protection for heat-sensitive components; the equipment pressure and cost are lower than supercritical CO2. However, the solvent used is flammable and explosive, requiring high equipment safety standards. III. Water-enzyme method. This method utilizes the synergistic action of various enzymes, such as pectinase, cellulase, and protease, to break down the cell walls and lipid complexes of oilseed cells, thereby releasing the oil, which is then separated by centrifugation. This method is mild, environmentally friendly, safe, and pollution-free, and can simultaneously yield high-quality oil and protein. However, enzyme costs are high, the process is long, and the reaction rate is slow; currently, it is still in the laboratory research and pilot-scale stages and has not yet been widely applied industrially. Summary of the Invention

[0006] A brief overview of this disclosure is given below to provide a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of this disclosure. It is not intended to identify key or essential parts of this disclosure, nor is it intended to limit its scope. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0007] To solve the above-mentioned technical problems, the technical solution provided in this disclosure is as follows:

[0008] In a first aspect, this disclosure provides a method for preparing peony seed oil using a dual supercritical system, comprising: Step 1: Place the dried peony seed powder into an extraction vessel and perform supercritical CO2 extraction to obtain crude peony seed oil. Step 2: Add the crude peony seed oil, CALB lipase, and 1,3-propanediol to a reaction vessel, seal it, then pass CO2 through it, heat and pressurize it to reach a supercritical state, start stirring to start the reaction, and after the reaction is completed, cool down and depressurize, recover the enzyme, and then centrifuge to obtain the target product, namely the finished peony seed oil.

[0009] Optionally, in step one, the supercritical CO2 extraction time is 0.5-2 h, the temperature is 30-45 °C, and the pressure is 20-35 MPa; preferably, the supercritical CO2 extraction time is 1 h, the temperature is 45 °C, and the pressure is 30 MPa.

[0010] Optionally, in step one, the particle size of the peony seed powder is 40 mesh (i.e., less than 0.425 mm).

[0011] Optionally, in step one, the peony seed powder is pre-dried, for example, dried at 60°C for 48 hours.

[0012] Optionally, in step two, the reaction conditions are: time 4-8 h, temperature 45-55℃, and pressure 20-22 MPa; more preferably, the reaction conditions are: time 4 h, temperature 55℃, and pressure 20 MPa.

[0013] Optionally, in step two, the centrifugation speed is 10,000 rpm and the time is 5 minutes.

[0014] In step two, the amount of substrate polyol should generally be excessive. Specifically, the amounts of crude peony seed oil and 1,3-propanediol should be determined based on the acid value of the crude peony seed oil (the number of carboxyl groups in the crude peony seed oil), and the amount of substrate 1,3-propanediol should ensure that the number of hydroxyl groups in it is greater than the number of carboxyl groups in the crude peony seed oil. Preferably, the mass ratio of crude peony seed oil to 1,3-propanediol is 15:1-2.

[0015] Optionally, in step two, the mass of CALB lipase is 2-5% of the substrate 1,3-propanediol; more preferably, the mass of CALB lipase is 5% of 1,3-propanediol.

[0016] Secondly, this disclosure also provides a peony seed oil prepared using the above method.

[0017] Thirdly, this disclosure also provides an application of the above-mentioned peony seed oil in the preparation of cosmetics, wherein the cosmetic is preferably a skin care essential oil.

[0018] Fourthly, this disclosure also provides an application of the above-mentioned peony seed oil in the preparation of food, preferably biscuits.

[0019] Compared to existing technologies, the beneficial effects of this disclosure include, but are not limited to: 1. The preparation method provided in this disclosure involves reacting crude peony seed oil obtained by supercritical extraction with immobilized CALB lipase and substrate 1,3-propanediol under supercritical CO2 conditions. In particular, the reaction conditions of 4 h, 55 °C, and 20 MPa can significantly reduce the acid value of the peony seed oil product, enabling it to meet the quality standard of GB / T 40622-2021.

[0020] 2. The peony seed oil prepared by the method disclosed herein has a lighter color and a milder odor, which is similar to commercially available peony seed oil.

[0021] 3. The peony seed oil prepared by the method provided in this disclosure has good stability after being treated with light and high temperature, which is superior to commercially available peony seed oil.

[0022] 4. The peony seed oil prepared by the dual supercritical system provided in this application has the following advantages: 1) lower saturated fatty acid content; 2) higher n-3 / n-6 value; 3) higher C20:4n6 (arachidonic acid, ARA) content; and has a very broad application prospect. Attached Figure Description

[0023] Figure 1 The photos are of three types of peony seed oil / crude oil: (1) finished peony seed oil sold on the market, (2) peony seed oil crude oil obtained by supercritical extraction, and (3) peony seed oil crude oil obtained by pressing. Figure 2 The photos are of five types of peony seed oil / crude oil: (1) commercially available peony seed oil, (2) peony seed oil prepared by a double supercritical system, (3) peony seed oil crude extracted by supercritical extraction, (4) peony seed oil crude obtained by pressing, and (5) peony seed oil obtained by pressing-supercritical enzyme catalysis. Detailed Implementation

[0024] This disclosure provides a method for preparing peony seed oil using a dual supercritical system, and its application. The specific implementation method is as follows.

[0025] In a first aspect, this disclosure provides a method for preparing peony seed oil using a dual supercritical system, comprising: Step 1: Place the dried peony seed powder into an extraction vessel and perform supercritical CO2 extraction to obtain crude peony seed oil. Step 2: Add the crude peony seed oil, CALB lipase, and 1,3-propanediol to a reaction vessel, seal it, then pass CO2 through it, heat and pressurize it to reach a supercritical state, start stirring to start the reaction, and after the reaction is completed, cool down and depressurize, recover the enzyme, and then centrifuge to obtain the target product, namely the finished peony seed oil.

[0026] Optionally, in step one, the supercritical CO2 extraction time is 0.5-2 h, the temperature is 30-45 °C, and the pressure is 20-35 MPa; preferably, the supercritical CO2 extraction time is 1 h, the temperature is 45 °C, and the pressure is 30 MPa.

[0027] Optionally, in step one, the particle size of the peony seed powder is 40 mesh (i.e., less than 0.425 mm).

[0028] Optionally, in step one, the peony seed powder is pre-dried, for example, dried at 60°C for 48 hours.

[0029] Optionally, in step two, the reaction conditions are: time 4-8 h, temperature 45-55℃, and pressure 20-22 MPa; more preferably, the reaction conditions are: time 4 h, temperature 55℃, and pressure 20 MPa.

[0030] Optionally, in step two, the centrifugation speed is 10,000 rpm and the time is 5 minutes.

[0031] In step two, the amount of substrate polyol should generally be excessive. Specifically, the amounts of crude peony seed oil and 1,3-propanediol should be determined based on the acid value of the crude peony seed oil (the number of carboxyl groups in the crude peony seed oil), and the amount of substrate 1,3-propanediol should ensure that the number of hydroxyl groups in it is greater than the number of carboxyl groups in the crude peony seed oil. Preferably, the mass ratio of crude peony seed oil to 1,3-propanediol is 15:1-2.

[0032] Optionally, in step two, the mass of CALB lipase is 2-5% of the substrate 1,3-propanediol; more preferably, the mass of CALB lipase is 5% of 1,3-propanediol.

[0033] Secondly, this disclosure also provides a peony seed oil prepared using the above method.

[0034] Thirdly, this disclosure also provides an application of the above-mentioned peony seed oil in the preparation of cosmetics, wherein the cosmetic is preferably a skin care essential oil.

[0035] Fourthly, this disclosure also provides an application of the above-mentioned peony seed oil in the preparation of food, preferably biscuits.

[0036] The following embodiments further illustrate the content of the present invention, but should not be construed as limiting the present disclosure. Any modifications or substitutions made to the methods, steps, or conditions of the present disclosure without departing from the spirit and substance of the present disclosure are within the scope of the present invention.

[0037] The technical solutions of this disclosure will be described below with reference to exemplary embodiments. Unless otherwise specified, the experimental methods used in the following embodiments and comparative examples are conventional methods.

[0038] Unless otherwise specified, all materials and reagents used in the following examples and comparative examples are commercially available.

[0039] I. Preparation Examples Example 1: Preparation of crude peony seed oil 1.1 Preparation of crude peony seed oil by supercritical CO2 extraction In this embodiment, crude peony seed oil is first prepared by supercritical CO2 extraction. The specific method is as follows: 1) Dry the peony seeds in an oven at 60℃ for 48 hours, then grind them into powder using a grinder, and pass the powder through a 40-mesh sieve. 2) Weigh 200g of peony seed powder and place it in the extraction vessel for supercritical CO2 extraction (extraction time: 1 h, extraction temperature: 45℃, extraction pressure: 30 MPa). After extraction, open the discharge valve of the separation vessel and collect the oil, which is the crude peony seed oil obtained through supercritical extraction. See [link to relevant documentation]. Figure 1 As shown in (2) of the text.

[0040] 1.2 Preparation of crude peony seed oil by pressing method This embodiment also employs a conventional physical pressing method to obtain crude peony seed oil without alkaline washing, degumming, or deodorization processes. The specific method is as follows: Peony seed kernel powder with a certain moisture content is added to the feeder, the feeding speed is set, the pressing pressure of the screw press is adjusted, and the pressing temperature is set. The oil press and feeder are started simultaneously. After pressing and extraction, the crude oil in the collection bottle is filtered to obtain peony seed oil. Each experiment is repeated four times, and the average oil yield is calculated. This embodiment uses the following optimal preparation process: pressure 4.6 MPa, feeding speed 1600 g / min. -1 The pressing temperature was 73℃, and the moisture content was 4.6%. The maximum oil yield was 23.11%, and the residual oil rate was 7.02%. For the crude peony seed oil obtained, see [link to relevant documentation]. Figure 1 As shown in (3) of the text.

[0041] The transparency, odor, acid value, and peroxide value (POV) of the following three oils were determined: (1) commercially available peony seed oil (Shun brand peony seed oil, Xuzhou Shun brand peony food Co., Ltd.), (2) crude peony seed oil obtained by supercritical extraction in this example, and (3) crude peony seed oil obtained by pressing in this example. The determination of transparency and odor was performed in accordance with GB / T 5525-2008 "Identification Methods for Transparency, Odor and Taste of Vegetable Oils". The determination of acid value was performed in accordance with GB 5009.229-2025 "National Food Safety Standard - Determination of Acid Value in Food" - Method 1 (Cold Solvent Method). The determination of peroxide value was performed in accordance with GB5009.227-2023 "National Food Safety Standard - Determination of Peroxide Value in Food" - Method 1 (Indicator Titration Method).

[0042] See test results Figure 1 See Table 1. Figure 1 Photographs of three types of peony seed oil are shown below: (1) commercially available finished peony seed oil; (2) crude peony seed oil obtained by supercritical extraction; and (3) crude peony seed oil obtained by pressing. It can be seen that, in terms of color, the commercially available finished oil is the lightest, the supercritical extracted crude oil is similar in color, and the pressed crude oil is the darkest. In terms of aroma, the commercially available finished oil has the faintest aroma, the supercritical extracted crude oil has a unique plant fragrance, and the pressed crude oil has the strongest aroma. Furthermore, the commercially available peony seed oil has the lowest acid value but the highest POV value, while the supercritical extracted crude oil and the pressed crude oil have relatively high acid values ​​but similar POV values.

[0043] Table 1. Physicochemical properties of three types of peony seed oil

[0044] Example 2: Refining of crude peony seed oil 2.1 Refining Peony Seed Oil from Crude Peony Seed Oil Extracted by Supercritical Extraction under Non-Supercritical Conditions via Enzymatic Catalysis The specific method is as follows: Excess glycerol, 1,3-propanediol, 1,3-butanediol, and crude peony seed oil extracted by supercritical extraction in Example 1 were reacted under magnetic heating and stirring (400 rpm) using CALB lipase catalysis at 55°C for 24 h. The product was then obtained by centrifugation (10,000 rpm, 5 min). Specific reaction parameters are shown in Table 2. The acid value and POV value of the crude oil before and after the enzyme-catalyzed reaction under non-supercritical conditions are shown in Table 3.

[0045] Table 2 Enzyme-catalyzed reaction conditions for supercritical extraction of crude peony seed oil under non-supercritical conditions.

[0046] Table 3. Acid value and POV value of crude peony seed oil extracted by supercritical extraction before and after enzyme catalysis under non-supercritical conditions.

[0047] As shown in Table 3, the acid value of crude peony seed oil obtained by supercritical extraction was the lowest after enzyme-catalyzed reaction with 1,3-propanediol, at 3.93 mg / g, a significant reduction of 85.0% compared to the initial value of 26.25 mg / g. However, it still did not meet the recommended national standard for peony seed oil (GB / T 40622-2021) (the acid value for the first-level standard is ≤2.5 mg / g based on KOH, and the acid value for the second-level standard is ≤3.0 mg / g). The POV values ​​of the oils obtained after enzyme-catalyzed reactions of crude peony seed oil obtained by supercritical extraction with the three substrate polyols all increased, but were still far lower than the POV value of commercially available peony seed oil (0.23 g / 100 g). Based on the degree of acid value reduction, 1,3-propanediol was the preferred reaction substrate.

[0048] 2.2 Refining peony seed oil from crude peony seed oil obtained by pressing under non-supercritical conditions using enzyme-catalyzed reaction The specific method is as follows: excess glycerol, 1,3-propanediol, 1,3-butanediol, and crude peony seed oil obtained by pressing in Example 1 were reacted under magnetic heating and stirring (400 rpm), catalyzed by CALB lipase, at 55°C for 24 h, and then centrifuged (10000 rpm, 5 min) to obtain the target product. The specific reaction parameters are shown in Table 4 below.

[0049] Table 4 Enzyme-catalyzed reaction conditions of crude peony seed oil obtained by pressing under non-supercritical conditions.

[0050] Table 5. Acid value and POV value of crude peony seed oil obtained by pressing before and after enzyme catalysis under non-supercritical conditions.

[0051] Table 5 shows that the crude peony seed oil obtained by pressing, after being catalyzed by 1,3-propanediol enzyme, had the lowest acid value, at 1.78 mg / g, a significant reduction from 12.28 mg / g before the reaction, representing a reduction rate of 85.5%. The POV values ​​of the crude peony seed oil obtained by pressing, after being catalyzed by the three alcohols respectively, all increased, but were still far lower than the POV value of commercially available peony seed oil (0.23 g / 100 g). However, the crude peony seed oil obtained by pressing, even after refining under non-supercritical conditions using enzyme catalysis, still had a relatively dark color, failing to meet the standard requirements.

[0052] 2.3 Refining Peony Seed Oil from Crude Peony Seed Oil Extracted by Supercritical Extraction via Enzyme Catalysis under Supercritical Conditions The specific method is as follows: Crude peony seed oil extracted by supercritical fluid extraction is added to a reaction vessel along with pre-prepared immobilized enzyme and substrate. The vessel is then sealed, and CO2 is introduced into the sealed reaction vessel to raise the temperature and pressure to reach a supercritical state. The stirrer is turned on, and the reaction is carried out under the set conditions, with the progress monitored in real time. After the reaction is completed, the temperature is lowered and the pressure is released. The enzyme is recovered (the enzyme after the reaction is collected, vortexed with n-hexane three times, dried, and can be reused). The product is then obtained by centrifugation (10,000 rpm, 5 min).

[0053] 2.3.1 Effect of reaction time: The reaction conditions are shown in Table 6 below. 1,3-propanediol was used as the substrate, and CALB lipase was used as the catalysis. Acid value was used as the indicator. The best results are shown in Group 2. The acid values ​​of the oils obtained from Groups 2 and 3 have reached the first-grade quality standard (≤2.5mg / g) in GB / T 40622-2021 Peony Seed Oil. The acid value of the oil obtained from Group 4 has reached the second-grade quality standard (≤3.0) in GB / T 40622-2021 Peony Seed Oil.

[0054] Table 6

[0055] 2.3.2 Effect of reaction temperature: The reaction conditions are shown in Table 7 below. 1,3-propanediol was used as the substrate, and CALB lipase was used as the catalyst. Acid value was used as the indicator. The best results are shown in Group 2. The acid values ​​of the oils obtained from Group 2 and Group 3 have reached the first-class quality standard (≤2.5) in GB / T 40622-2021 Peony Seed Oil.

[0056] Table 7

[0057] 2.3.3 Effect of reaction pressure: The reaction conditions are shown in Table 8 below. 1,3-propanediol was used as the substrate, and CALB lipase was used as the catalysis. Acid value was used as the indicator. The best results are shown in Group 4. The acid value of the refined peony seed oil in Groups 4 and 5 has reached the first-class quality standard (≤2.5) in GB / T 40622-2021 Peony Seed Oil.

[0058] Table 8

[0059] It can be seen that, using 1,3-propanediol as a substrate and CALB lipase as a catalyst, the optimal reaction conditions are: reaction time of 4 h, temperature of 55 °C, and extraction pressure of 20 MPa.

[0060] 2.3.4 Effects of enzymes: Experimental Method: Immobilized enzymes (CALB, RML, and Lipozyme IM 20), reaction substrates (glycerol, 1,3-propanediol, and 1,3-butanediol), and crude peony seed oil extracted via supercritical fluid extraction were prepared and added to a reaction vessel. The vessel was sealed, and CO2 was introduced into the sealed reaction vessel. The temperature and pressure were increased to reach a supercritical state. The stirrer was turned on, and the reaction conditions were adjusted to the set parameters, with the progress monitored in real time. After the reaction was completed, the temperature was lowered and the pressure released. The enzymes were recovered, and the product was obtained by centrifugation (10,000 rpm, 5 min). The acid value of the product was then determined.

[0061] Reaction conditions: 45g of crude peony seed oil obtained by supercritical extraction, 0.3g of enzyme, 6g of 1,3-propanediol as substrate, 4 h of reaction time, 55℃ of temperature, and 20 MPa of pressure. The optimal results are shown in Group 1 (see Table 9 below).

[0062] Table 9. Acid value of refined peony seed oil catalyzed by three lipases

[0063] As shown in Table 9, the acid value of peony seed oil refined by CALB catalysis under supercritical CO2 conditions was the lowest, at 1.8 mg / g, which was 93.1% lower than the acid value of crude oil before the reaction, which was 26.25 mg / g.

[0064] 2.3.5 Effect of the type of polyol as reaction substrate The reaction conditions are shown in Table 10 below. CALB lipase was used as the catalyst, and the acid value was used as the indicator. The best results are shown in Group 1. The acid value of the oil obtained in Group 1 has reached the first-class quality standard (≤2.5) in GB / T 40622-2021 Peony Seed Oil.

[0065] Table 10 Purification reaction conditions and product acid values ​​of polyols with different substrates

[0066] As shown in Table 10, 1,3-propanediol is the substrate for refining peony seed oil with the lowest acid value, so 1,3-propanediol is selected as the reaction substrate.

[0067] 2.4 Refining peony seed oil from crude peony seed oil obtained by pressing under supercritical conditions using enzyme-catalyzed reaction The specific method is as follows: 15g of crude peony seed oil obtained by pressing was added to a reaction vessel along with 0.05g of CALB lipase and 1g of 1,3-propanediol substrate. The vessel was sealed, and CO2 was introduced into the sealed reaction vessel. The temperature and pressure were increased to reach a supercritical state, and the stirrer was turned on. The reaction was carried out under optimal conditions (reaction time of 4 h, temperature of 55℃, and pressure of 20 MPa), and the progress was monitored in real time. After the reaction was completed, the temperature was lowered and the pressure was released. The enzyme was recovered, and the product was obtained by centrifugation (10,000 rpm, 5 min). The acid value of the refined peony seed oil was 1.61 mg / g, the POV value was 0.1g / 100g, and the yield was 97.67%.

[0068] Example 3 Performance Testing The peony seed oil prepared under the optimal conditions explored above (i.e., the crude peony seed oil extracted by supercritical CO2 was purified again under supercritical CO2 conditions using 1,3-propanediol as a substrate and CALB lipase as a catalyst, with a reaction time of 4 h, a temperature of 55 °C, and a pressure of 20 MPa) was further tested for various indicators.

[0069] 1. Transparency and odor test: The test method is described above. The results are shown in Table 11 and... Figure 2 .

[0070] Color sorting: In terms of transparency, commercially available peony seed oil finished product < peony seed oil prepared by a double supercritical system < peony seed oil crude extracted by supercritical extraction < peony seed oil obtained by pressing-supercritical enzyme catalysis < peony seed oil crude obtained by pressing.

[0071] Aroma ranking: Commercially available peony seed oil (finished product) < Peony seed oil prepared by a dual supercritical system < Crude peony seed oil extracted by supercritical extraction < Peony seed oil obtained by pressing-supercritical enzyme catalysis < Crude peony seed oil obtained by pressing.

[0072] Acid value ranking: Commercially available peony seed oil finished product < Peony seed oil obtained by pressing-supercritical enzyme catalysis < Peony seed oil prepared by double supercritical system < Crude peony seed oil obtained by pressing < Crude peony seed oil obtained by supercritical extraction.

[0073] Table 11

[0074] In addition, as can be seen from Table 11, although the POV value of the peony seed oil prepared by this dual supercritical system did not reach the first-level quality standard (≤0.15) in GB / T40622-2021 Peony Seed Oil, it did reach the second-level quality standard (≤0.25).

[0075] 2. Stability test (1) The effect of temperature on POV value, the measurement index is POV value.

[0076] Specific method: Peony seed oil prepared under a dual supercritical system and commercially available peony seed oil were placed in a sealed, light-protected environment at 55°C. The POV of the peony seed oil was measured periodically, and the measurement was repeated three times under the same conditions. The lower the POV, the slower the oxidation rate of the peony seed oil. POV value unit: g / 100g.

[0077] Table 1. POV values ​​of two types of peony seed oil at 255℃

[0078] The test results are shown in Table 12. Under the initial conditions, the POV value of the peony seed oil prepared under the dual supercritical system was significantly lower than that of commercially available peony seed oil. After heating at 55℃ for 8 hours, the POV value was measured every 2 hours. The POV values ​​of both gradually increased. Finally, the POV value of the peony seed oil prepared under the dual supercritical system was comparable to that of commercially available peony seed oil.

[0079] (2) The effect of light on POV value, the measurement index is POV value.

[0080] Specific method: Peony seed oil prepared under a dual supercritical system and commercially available peony seed oil were placed at room temperature and sealed. The POV of the peony seed oil was measured periodically under light conditions, and the measurement was repeated three times under the same conditions. The lower the POV, the slower the oxidation rate. POV value unit: g / 100g.

[0081] Table 13 POV values ​​of two types of peony seed oil under light conditions

[0082] The test results are shown in Table 13. Under the initial conditions, the POV value of the peony seed oil prepared under the dual supercritical system was significantly lower than that of commercially available peony seed oil. After heating under light for 8 hours, the POV value was measured every 2 hours. The POV values ​​of both gradually increased. Finally, the POV value of the peony seed oil prepared under the dual supercritical system was lower than that of commercially available peony seed oil.

[0083] 3. Evaluation Indicators for Extraction Process Performance The performance evaluation indicators of peony seed oil extraction process were assessed: crude oil extraction rate, refined oil yield, and extraction time. The test methods are described below. The results are shown in Table 13.

[0084] (1) Extraction rate, also known as oil yield, refers to the percentage of crude peony seed oil obtained from extraction relative to the mass of raw peony seed input, reflecting the actual oil production capacity per unit mass of raw material.

[0085] Calculation formula: Extraction rate (%) = Mass of crude peony seed oil actually extracted (g) / Mass of peony seed raw material input (g) × 100%.

[0086] (2) Yield refers to the percentage of the mass of oil refined by a certain extraction / preparation process relative to the total mass of crude oil input, reflecting the loss of oil due to the extraction / preparation process.

[0087] Calculation formula: Yield (%) = Mass of refined peony seed oil actually extracted (g) / Total mass of crude peony seed oil input (g) × 100%.

[0088] (3) Time consumption refers to the total process time required to obtain the target peony seed oil product from the formal start of the extraction / preparation operation to the end of the process, reflecting the efficiency and industrial feasibility of the extraction method.

[0089] Table 14

[0090] As can be seen from Table 14, the extraction rate / yield of supercritical related processes (dual supercritical and supercritical extraction) is significantly higher than that of traditional processes (commercially available finished oil and pressing). Among them, supercritical extraction has the highest crude oil extraction rate. The yield of supercritical related processes is almost complete recovery of raw oil, while the yield of traditional processes is significantly lower. The yield of peony seed oil prepared by the dual supercritical system is 98.33%, indicating that the enzyme-catalyzed reaction refining method under supercritical conditions disclosed in this application causes less loss to crude oil.

[0091] 4. Fatty acid composition The proportions of various fatty acids and the composition of major fatty acids in peony seed oil prepared by the dual supercritical system and commercially available peony seed oil are shown in Table 15 below.

[0092] Table 15

[0093] It is known that the peony seed oil prepared by the dual supercritical system provided in this application has the following advantages: 1) Lower saturated fatty acid content. 2) Higher n-3 / n-6 value. Commercially available peony seed oil: (C18:3 n3 + C20:5 n3) / (C18:2 + C20:4n6 + C20:3 n6) ≈ 1.578, while the peony seed oil prepared by dual supercritical system: (C18:3n3 + C20:5n3) / (C18:2 + C20:4n6 + C20:3n6) ≈ 1.645. The peony seed oil prepared by dual supercritical system has a slightly higher n3 / n6 ratio. The slightly higher n-3 / n-6 value of the oil helps to enhance overall health, promote wound healing, and is also more beneficial for formulas for sensitive skin, eczema, and dermatitis. 3) Higher content of C20:4n6 (arachidonic acid, ARA). C20:4n6 is an important component in infant formula, supporting brain and retinal development. It is also a key component for skin barrier repair and inflammation regulation, and has anti-inflammatory and repairing effects in cosmetics. Potential applications of peony seed oil prepared using a dual supercritical system include: 1) In infant skincare products. It contains ARA, offering anti-inflammatory and soothing benefits, and is low in SFA, making it safer; 2) In sensitive skin repair products. Its high n3 / n6 and high ARA content provides potent anti-inflammatory effects; 3) As a functional edible oil, it is low in fat, high in n3, and contains ARA, making it suitable for healthy diets.

[0094] Application examples The peony seed oil prepared by the dual supercritical system provided in this application can be used not only as a functional edible oil, but also processed into deep-processed products such as microcapsules, microemulsions, nanoemulsion gels, biscuits, daily chemical products, and soft capsules, and has a very broad application prospect.

[0095] Example 1: Preparation of skincare essential oil. Main components (mass percentage): 80% peony seed oil, 6% peony flower essential oil, 8% functional components, 2.4% glycerin, 3.6% hyaluronic acid; wherein the functional components are: 30% peony seed shell extract, 15% Cortex Moutan extract, 15% rutin, 5% vitamin E, and 15% ababadin, dissolved in 20% ethanol. Preparation method: Add the above main components according to the ratio, then stir at 60 rpm for 2 hours, incubate at room temperature for 30 days, and filter through a 1000-mesh sieve to obtain the skincare essential oil product. This product has multiple functions, such as whitening white spots, delaying melanin deposition, whitening skin, activating human skin surface cells, delaying aging, and isolating ultraviolet rays.

[0096] Example 2: Making cookies. The optimal recipe for Peony Whole Wheat Kelp Cookies is: 190g low-gluten flour, 45g peony seed oil, 20g wheat flour, 12g seaweed powder, 50g sugar, 55g margarine, 0.6g baking soda, 50g egg, 2g salt, 5g whole milk powder, and 20g purified water; baking time 13 minutes, baking temperature 130-140℃.

[0097] Comparative Example This comparative example further refines crude peony seed oil obtained through supercritical extraction under supercritical CO2 conditions, but without using substrate alcohol or CALB lipase. The treatment time is 4 h, the temperature is 55℃, and the pressure is 20 MPa. The specific method is as follows: 45 g of crude peony seed oil obtained through supercritical extraction is added to a reaction vessel. CO2 is introduced into the sealed reaction vessel, and the temperature and pressure are increased to reach a supercritical state. The stirrer is turned on, and the reaction is adjusted to the predetermined conditions mentioned above. After the reaction is completed, the temperature is lowered and the pressure is released, followed by centrifugation (10000 rpm, 5 min) to obtain the target product. The acid value of the refined peony seed oil in this comparative example is 25.1 mg / g. In contrast, the acid value of the crude peony seed oil obtained through supercritical extraction is 26.25 mg / g, indicating a very limited effect in reducing the acid value.

[0098] Finally, it should be noted that, if any, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0099] Although this disclosure has been described above through specific embodiments, it should be understood that those skilled in the art can devise various modifications, improvements, or equivalents to this disclosure within the spirit and scope of the appended solutions. Such modifications, improvements, or equivalents should also be considered to be included within the scope of protection claimed in this disclosure.

Claims

1. A method for preparing peony seed oil using a dual supercritical system, characterized in that, include: Step 1: Place the dried peony seed powder into an extraction vessel and perform supercritical CO2 extraction to obtain crude peony seed oil. Step 2: Add the crude peony seed oil, CALB lipase, and 1,3-propanediol to a reaction vessel, seal it, then introduce CO2, heat and pressurize it to reach a supercritical state, start stirring to start the reaction, and after the reaction is completed, cool down and depressurize, recover the enzyme, and then centrifuge to obtain the target product.

2. The method for preparing peony seed oil using a dual supercritical system according to claim 1, characterized in that, In step one, the supercritical CO2 extraction time is 0.5-2 h, the temperature is 30-45 °C, and the pressure is 20-35 MPa; preferably, the supercritical CO2 extraction time is 1 h, the temperature is 45 °C, and the pressure is 30 MPa.

3. The method for preparing peony seed oil using a dual supercritical system according to claim 1 or 2, characterized in that, In step one, the particle size of peony seed powder is less than 0.425mm.

4. The method for preparing peony seed oil using a dual supercritical system according to any one of claims 1-3, characterized in that, In step one, the peony seed powder is pre-dried, for example, dried at 60°C for 48 hours.

5. The method for preparing peony seed oil using a dual supercritical system according to any one of claims 1-4, characterized in that, In step two, the reaction conditions are: time 4-8 h, temperature 45-55℃, and pressure 20-22 MPa; more preferably, time 4 h, temperature 55℃, and pressure 20 MPa. Optionally, in step two, the centrifugation speed is 10,000 rpm and the time is 5 minutes.

6. The method for preparing peony seed oil using a dual supercritical system according to any one of claims 1-5, characterized in that, In step two, the mass ratio of crude peony seed oil to 1,3-propanediol is 15:1-2.

7. The method for preparing peony seed oil using a dual supercritical system according to any one of claims 1-6, characterized in that, In step two, the mass of CALB lipase is 2-5% of the substrate 1,3-propanediol; more preferably, the mass of CALB lipase is 5% of 1,3-propanediol.

8. A peony seed oil, prepared by the method described in any one of claims 1-7.

9. An application of the peony seed oil as described in claim 8 in the preparation of cosmetics, wherein the cosmetic is preferably a skin care essential oil.

10. An application of the peony seed oil as described in claim 8 in the preparation of food, wherein the food is preferably biscuits.

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