A method for preparing Suaeda salsa seed oil by supercritical CO2 extraction

Abstract

The application belongs to the field of supercritical extraction, and particularly relates to a preparation method of supercritical CO2 extraction of seabuckthorn seed oil. The seabuckthorn seed oil is extracted from seabuckthorn seeds by supercritical extraction, and a green extraction method of the seabuckthorn seed oil is established. In the application, kaempferol and chlorogenic acid are compounded according to a specific proportion to be used as a carrier, the polarity range of supercritical CO2 is adjusted, the solubility of lipid components such as triglyceride and unsaturated fatty acid in the seabuckthorn seed oil is enhanced, and the lipid-soluble impurities in the seabuckthorn seeds are selectively combined through intermolecular hydrogen bonds and hydrophobic effects, so that the selectivity of the extraction system is improved.

Description

Technical Field

[0001] This invention belongs to the field of supercritical extraction, specifically relating to a method for preparing Suaeda salsa seed oil by supercritical CO2 extraction. Background Technology

[0002] Suaeda salsa is an annual herbaceous plant belonging to the genus Suaeda in the family Chenopodiaceae. It is widely distributed wild in the Bohai Rim region and inland saline-alkali lands. The seeds of Suaeda salsa contain up to 22.5% oil, and the naturally growing Suaeda salsa in Dongying City alone can produce 17,100 tons of Suaeda salsa seed oil annually. The fatty acid composition of Suaeda salsa seed oil contains over 70% linoleic acid, comparable to that of safflower seed oil.

[0003] Currently, the main extraction methods for Suaeda salsa seed oil include organic solvent extraction and physical pressing. Traditional organic solvent extraction, using petroleum ether and n-hexane as solvents, is the most commonly used method. However, this method carries the risk of solvent residue, making it difficult to meet the safety requirements for high-end edible and health-grade oils. Furthermore, the high extraction temperature severely damages the heat-sensitive active ingredients in Suaeda salsa seed oil, leading to significant losses of substances such as vitamin E and phytosterols. The oil is also prone to oxidation and darkening in color, and the extraction of intracellular bound oil is incomplete, resulting in low raw material utilization. In physical pressing, cold pressing yields low oil output and leaves a large amount of residual oil in the cake, resulting in significant resource waste. While hot pressing slightly improves the oil output, the high temperature triggers oil oxidation, polymerization, and Maillard reactions, causing excessive acid value and peroxide value, leading to a decline in oil flavor and quality. Additionally, the crude oil obtained by pressing contains more impurities, and subsequent refining processes such as degumming, decolorization, and deacidification are complex, further reducing the active ingredients.

[0004] Currently, supercritical CO2 extraction produces products with high purity, no solvent residue, and good retention of active ingredients. However, due to the weak polarity of CO2, it is less effective at extracting polar active ingredients. Furthermore, while current entrainers such as ethanol, methanol, acetone, and ethyl acetate can increase fluid polarity, enhance the solubility of polar components, and improve the overall extraction rate, their introduction easily disrupts the stable phase equilibrium of the supercritical CO2 system. This significantly increases the difficulty of controlling parameters such as extraction pressure, temperature, and flow rate, leading to large fluctuations in extraction efficiency and poor reproducibility, making stable industrial production difficult. Moreover, the use of entrainers significantly reduces the extraction selectivity of supercritical CO2. While dissolving the target polar components, it also extracts impurities such as pigments, colloids, and free fatty acids from the raw material, resulting in increased impurity content in the crude oil. This complicates subsequent refining steps such as degumming, decolorization, and deacidification, further increasing production costs and the loss of active ingredients. Therefore, establishing a green, stable, and simple supercritical extraction method is an urgent problem to be solved. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a novel method for preparing Suaeda salsa seed oil by supercritical CO2 extraction. This method yields Suaeda salsa seed oil with high purity and good stability, improves the selectivity of supercritical extraction, and reduces subsequent separation and recovery processes.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows: This invention provides a method for preparing Suaeda salsa seed oil by supercritical CO2 extraction, comprising the following steps: (1) After drying, the seeds of Suaeda salsa are crushed and then sieved to obtain Suaeda salsa seed powder; (2) Using kaempferol and chlorogenic acid as entrainers, supercritical CO2 extraction was performed on Suaeda salsa seed powder to obtain crude Suaeda salsa seed oil. (3) After centrifuging the crude product of Suaeda salsa seed oil, Suaeda salsa seed oil is obtained.

[0007] Preferably, in step (1), the sample is passed through a 20-50 mesh sieve.

[0008] Preferably, in step (2), the mass ratio of kaempferol to chlorogenic acid is 3-5:1; and the volume ratio of the entrainer to CO2 is 1:15-20.

[0009] Preferably, in step (2), during the supercritical CO2 extraction process, the packing density of Suaeda salsa seed powder is 0.4–0.6 g / cm³. 3 The CO2 flow rate is 10 L / min, the entrainer flow rate is 1.0–2.0 L / min, the extraction temperature is 25℃–55℃, the extraction pressure is 20 MPa–50 MPa, and the extraction time is 0.5–3.0 hr.

[0010] The beneficial effects of this invention are as follows: (1) This invention uses supercritical extraction to extract Suaeda salsa seed oil from Suaeda salsa seeds, establishing a green extraction method for Suaeda salsa seed oil. This invention uses kaempferol and chlorogenic acid in a specific ratio as an entrainer to adjust the polarity range of supercritical CO2, so that it can not only enhance the solubility of lipid components such as triglycerides and unsaturated fatty acids in Suaeda salsa seed oil, but also selectively bind lipid-soluble impurities in Suaeda salsa seeds through intermolecular hydrogen bonds and hydrophobic interactions, thereby improving the selectivity of the extraction system.

[0011] (2) The extraction method provided by this invention can reduce the binding force between oil molecules and the cell wall of Suaeda salsa seeds, promote the desorption and dissolution of oil molecules from the intercellular spaces into the supercritical CO2 system, and improve the extraction efficiency. At the same time, it does not introduce new impurities, and the Suaeda salsa seed oil prepared has high purity, clear color, and pure taste. It can be directly applied to multiple fields such as food, health products, and cosmetics without the need for additional complex post-processing purification processes, which greatly reduces the quality loss of the product. Attached Figure Description

[0012] Figure 1 The effect of extraction temperature on the yield of Suaeda salsa seed oil; Figure 2 The effect of extraction pressure on the yield of Suaeda salsa seed oil; Figure 3 The effect of extraction time on the yield of Suaeda salsa seed oil; Figure 4 This is a graph showing the interaction between extraction pressure and extraction temperature. Figure 5 This is a graph showing the interaction between extraction pressure and extraction time. Figure 6 This is a graph showing the interaction between extraction temperature and extraction time. Detailed Implementation

[0013] The technical solution of the present invention will be further explained and described below through specific embodiments.

[0014] Example 1 (I) Extraction process of Suaeda salsa seed oil Suaeda salsa seeds drying → crushing → sieving → weighing → loading → extraction → crude Suaeda salsa seed oil → centrifugation → Suaeda salsa seed oil (II) The preparation method is as follows: Accurately weigh 10g of Suaeda salsa seed powder that has passed through a 20-mesh sieve, and load it into an extraction container (the packing density of the Suaeda salsa seed powder is 0.5 g / cm³). 3 Extraction was carried out, and the extraction temperature (25℃-55℃), extraction pressure (20MPa-50MPa), extraction time (0.5hr-3.0hr), CO2 flow rate (10 L / min), the flow rate of the entrainer (mass ratio of kaempferol to chlorogenic acid of 3.5:1) was 1.0 L / min, and the volume ratio of entrainer to CO2 was 1:15.

[0015] (III) Single-factor experiment Accurately weigh 10g of Suaeda salsa seed powder that has passed through a 20-mesh sieve, and load it into an extraction container (the packing density of the Suaeda salsa seed powder is 0.5 g / cm³). 3 Extraction was carried out to investigate the effects of extraction temperature (25℃-55℃), extraction pressure (20MPa-50MPa), extraction time (0.5hr-3.0hr), CO2 flow rate (10 L / min), and entrainer flow rate of 1.0 L / min on the yield of Suaeda salsa seed oil. The single-factor experimental design is shown in Table 1.

[0016] Table 1 Single-factor experimental design (iv) Response surface methodology Based on the single-factor experiments, extraction temperature, extraction pressure, and extraction time were selected as response variables, and the yield of Suaeda salsa seed oil was used as the response value. A four-factor, three-level response surface analysis experiment was designed using the Box-Behnken Design (BBD) principle. The factors and level codes of the response surface experiment design are shown in Table 2.

[0017] Table 2 Response Surface Experiment Factor Levels (V) Results and Analysis 1. Single-factor experiment 1.1 Effect of extraction temperature on the yield of Suaeda salsa seed oil For the extraction of Suaeda salsa seed oil, the extraction pressure was set at 28 MPa, the CO2 flow rate at 10 L / min, the extraction time at 90 min, and the extraction temperature range at 30℃-50℃. The yield of Suaeda salsa seed oil under different extraction temperature conditions is as follows: Figure 1 As shown, the yield of Suaeda salsa seed oil initially increases and then decreases with increasing extraction temperature, reaching its highest at 40℃. This is presumably because the rate of molecular thermal motion increases with temperature, increasing the probability of collisions between molecules and facilitating sufficient contact between the seed oil and supercritical CO2 gas, thus making the supercritical extraction process more efficient and rapid. However, as the extraction temperature continues to increase, the density of CO2 gas gradually decreases, reducing its solubility in the oil from the seeds and leading to a gradual decline in the yield. Therefore, further response surface methodology experiments were conducted at three temperature gradients: 40℃, 45℃, and 50℃ to optimize the extraction temperature response.

[0018] Calculation of Suaeda salsa seed oil yield: Suaeda salsa seed oil yield (%) = G1 / G2 × 100 In the formula: G1 is the total amount of extracted Suaeda salsa seed oil, g; G2 is the total amount of Suaeda salsa seeds, g.

[0019] 1.2 Effect of extraction pressure on the yield of Suaeda salsa seed oil The extraction temperature of Suaeda salsa seed oil was set at 40℃, CO2 flow rate at 10L / min, extraction time at 90min, and extraction pressure range at 20MPa-36MPa. The yield of Suaeda salsa seed oil under different extraction pressure conditions is as follows: Figure 2 As shown in the figure. Due to the characteristics of supercritical CO2, such as viscosity and diffusion coefficient, increasing the pressure can increase the CO2 fluid density, reduce the mass transfer distance between molecules, increase the mass transfer efficiency between molecules, and improve the extraction efficiency. However, if the pressure is too high, the material in the extractant is easily compacted by the high-pressure CO2 fluid, which reduces the solute diffusion coefficient and is not conducive to extraction, thus reducing the yield of Suaeda salsa seed oil. Therefore, further response surface optimization experiments were conducted on the extraction pressure response values ​​at three pressure gradients of 24 MPa, 28 MPa, and 32 MPa.

[0020] 1.3 Effect of extraction time on the yield of Suaeda salsa seed oil The extraction pressure of Suaeda salsa seed oil was set at 288 MPa, the extraction temperature at 40℃, the CO2 flow rate at 10 L / min, and the extraction time range was 60-180 min. The yield of Suaeda salsa seed oil under different extraction time conditions is as follows: Figure 3 As shown, the yield of Suaeda salsa seed oil increased significantly with increasing extraction time. At an extraction time of 150 min, the oil was almost completely extracted, reaching its maximum yield. Further extending the extraction time led to polymerization of the oil, and the oil in the extraction flask was also lost due to high-pressure gas being forced into the exhaust pipe. Therefore, subsequent response surface optimization experiments were conducted using three time gradients: 120, 150, and 180 min.

[0021] 2. Optimization Experiment of Response Surface Analysis for Suaeda salsa Seed Oil Extraction 2.1 Response Surface Design To further investigate the effects of interactions among various factors on the yield of Suaeda salsa seed oil, the extraction process was optimized using response surface methodology. Based on a Box-Behnken experimental design, four factors with the greatest impact on the yield of Suaeda salsa seed oil—extraction pressure (A), extraction temperature (B), and extraction time (C)—were selected for a three-factor, three-level response surface methodology experiment. The factor levels and results of the response surface methodology experiment are shown in Tables 3 and 4, respectively.

[0022] Table 3. Response Surface Experiment Factor Levels and Coding Table 4. Response Surface Experimental Design and Results 2.2 Response Surface Experiment Results and Variance Analysis Using Design-Expert 10.0.3 software, regression fitting was performed on each factor. Based on Table 4, the following multiple quadratic regression equation was obtained: Suaeda salsa seed oil yield (%): Y=20.44+1.47A-1.07B+2.33C+1.03AB-0.86AC-0.05BC-3. 23A2-1.36B2-1.25C2 The results of the ANOVA on the regression equation are shown in Table 4. The F-value is used to test the significance of each variable's influence on the response value; the larger the F-value, the higher the significance of the corresponding variable. The model is considered statistically significant when the significance test probability P < 0.05. Table 5 shows that the order of influence of extraction process conditions on the yield of Suaeda salsa seed oil is: C > A > B, i.e., extraction time > extraction pressure > extraction temperature. The model's coefficient of determination R0...2 The value of 0.9800 indicates that the model has high significance, and the AdjR value is also high. 2 The value of 0.9455 explains 94.55% of the experimental response variation. This experimental model fits the real data well and has practical guiding significance. Therefore, this model can be used to analyze and predict the optimal extraction process conditions for supercritical CO2 extraction of Suaeda salsa seed oil.

[0023] Table 5. Analysis of variance results of the fitted regression equation for the response yield. Note: p<0.01 indicates that the difference is highly significant; p<0.05 indicates a significant difference. 2.3 Response Surface Analysis Figures 4 to 6 The response surface of the interactions between the factors determined by the regression equation is displayed. This surface represents the influence of each factor on the response value during enzymatic hydrolysis, and its projection is represented by a contour plot. The relationship between extraction pressure (A, MPa), extraction temperature (B, ℃), and extraction time (C, min) on the oil yield % (Y) is visually represented in the contour plot and response surface plot. The form of the contour lines indicates the degree of interaction between the two variables. As can be seen from the figure, the interaction between the three factors has a significant impact on Y, which is consistent with the results of the analysis of variance in Table 5.

[0024] To comprehensively consider the interaction between various extraction factors on the yield of Suaeda salsa seed oil, and to further determine the optimal process conditions for supercritical extraction, with the maximum yield of Suaeda salsa seed oil as the optimization objective, based on the results of the Design-Expert 10.0.3 software, the optimal extraction process for the yield of Suaeda salsa seed oil under the combined influence of extraction temperature, extraction pressure, and extraction time is: extraction temperature 40.313℃, extraction pressure 29.341 MPa, and extraction time 142.184 min. Under these conditions, the model predicts a yield of 21.348% for Suaeda salsa seed oil.

[0025] 2.4 Response surface methodology for optimal process conditions experimental verification Based on the software prediction results and considering the accuracy and feasibility of setting actual process conditions, an extraction temperature of 40℃, an extraction pressure of 29MPa, and an extraction time of 140min were selected as the conditions for the extraction and preparation of Suaeda salsa seed oil. Three repeated experiments were conducted, with an average yield of 21.15%. These experimental results are very close to the model predictions, indicating that the optimal preparation process for Suaeda salsa seed oil extraction based on this response surface methodology is effective and feasible.

[0026] Comparative Example 1 Accurately weigh 10g of Suaeda salsa seed powder that has passed through a 20-mesh sieve, and load it into an extraction container (the packing density of the Suaeda salsa seed powder is 0.5 g / cm³). 3 Extraction was carried out, and the extraction temperature (40℃), extraction pressure (29MPa), extraction time (140min), CO2 flow rate (10 L / min), the flow rate of the entrainer (kaempferol) was 1.0 L / min, and the volume ratio of entrainer to CO2 was 1:15.

[0027] When kaempferol was used as the entrainer alone, the average yield was 18.18% in three repeated experiments.

[0028] Comparative Example 2 Accurately weigh 10g of Suaeda salsa seed powder that has passed through a 20-mesh sieve, and load it into an extraction container (the packing density of the Suaeda salsa seed powder is 0.5 g / cm³). 3 Extraction was carried out, and the extraction temperature (40℃), extraction pressure (29MPa), extraction time (140min), CO2 flow rate (10 L / min), and the flow rate of entrainer (ethanol) was 1.0 L / min, with a volume ratio of entrainer to CO2 of 1:15 were investigated.

[0029] When ethanol was used as the entrainer, the average yield was 18.79% in three repeated experiments.

[0030] Example 1: Analysis of Fatty Acid Components in Suaeda salsa Seed Oil Fatty acid methyl esterification: Weigh 0.1g of Suaeda salsa seed oil sample and add it to a 10mL capped glass bottle. Add 4mL of 2% sodium hydroxide-methanol solution and heat in an 80℃ water bath for 15min. Then add 3.5mL of 15% boron trifluoride-methanol solution and heat in an 80℃ water bath for 2min. Rinse with running water and cool to room temperature. Accurately add 1mL of n-hexane, shake well, and then add 2mL of saturated sodium chloride aqueous solution. Centrifuge at 5000r / min for 5min. Collect the supernatant solution, filter through a membrane, and transfer to a sample vial for injection.

[0031] Gas chromatography detection conditions: Detector: Flame Ionization Detector (FID); Column: Agilent DB-23 quartz capillary column, 60 m long, 0.25 mm inner diameter, 0.25 μm film thickness; Carrier gas: High-purity hydrogen, high-purity nitrogen, and air; Carrier gas flow rate: 3 ml / min; Split ratio: 50:1; Injector and detector temperatures: 250 °C and 280 °C, respectively; Injection volume: 1 μL.

[0032] Nineteen fatty acids were detected in the fatty acid composition of the Suaeda salsa seed oil extracted in Example 1. Among them, cis-linoleic acid, cis-oleic acid, cis-9,12,15-octadecanoic acid were relatively abundant, with linoleic acid having the highest relative content at 74%. In contrast, in Comparative Example 1, the relative content of linoleic acid was only 63%.

Claims

1. A method for preparing Suaeda salsa seed oil by supercritical CO2 extraction, characterized in that, Includes the following steps: (1) After drying, the seeds of Suaeda salsa are crushed and then sieved to obtain Suaeda salsa seed powder; (2) Using kaempferol and chlorogenic acid as entrainers, supercritical CO2 extraction was performed on Suaeda salsa seed powder to obtain crude Suaeda salsa seed oil. (3) After centrifuging the crude product of Suaeda salsa seed oil, Suaeda salsa seed oil is obtained.

2. The preparation method according to claim 1, characterized in that, In step (1), the sample is passed through a 20-50 mesh sieve.

3. The preparation method according to claim 1 or 2, characterized in that, In step (2), the mass ratio of kaempferol to chlorogenic acid is 3-5:1; the volume ratio of the entrainer to CO2 is 1:15-20.

4. The preparation method according to claim 1 or 3, characterized in that, In step (2), during the supercritical CO2 extraction process, the packing density of Suaeda salsa seed powder is 0.4–0.6 g / cm³. 3 The CO2 flow rate is 10 L / min, the entrainer flow rate is 1.0–2.0 L / min, the extraction temperature is 25℃–55℃, the extraction pressure is 20 MPa–50 MPa, and the extraction time is 0.5–3.0 hr.

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