Folium artemisiae argyi plant essence extraction process based on steam condensation method

Abstract

The invention relates to the technical field of folium artemisiae argyi plant essence extraction, and particularly provides a folium artemisiae argyi plant essence extraction process based on a steam condensation method, which comprises the following steps: S1, raw material pretreatment and filling; s2, steam distillation; s3, condensing in a two-section temperature zone; s4, performing low-temperature constant-temperature oil-water separation; s5, closed-loop reflux and hydrolat collection; and S6, quantifying an end point criterion. According to the invention, a condensation structure in which two sections of temperature zones are sequentially coupled is arranged in the extraction process, so that the first-stage condenser fully condenses high-boiling-point aromatic components in a relatively high temperature zone, and the second-stage condenser deeply condenses low-boiling-point aromatic components in a relatively low temperature zone, thereby reducing re-evaporation and entrainment loss of the aromatic components and improving the extraction efficiency of the aromatic components. And in cooperation with low-temperature and constant-temperature oil-water separation, the interface emulsification phenomenon in the separation process is effectively inhibited, essential oil entrainment entering a water phase is reduced, and the clarity and stability of the hydrolat are improved.

Description

Technical Field

[0001] This invention relates to the field of plant extract technology, and in particular to a process for extracting Artemisia argyi plant extract based on steam condensation. Background Technology

[0002] Artemisia argyi (also known as mugwort leaves) contains abundant volatile essential oils and water-soluble active ingredients, and is widely used in traditional Chinese medicine external treatments, cosmetics and daily chemical products. The complete extraction of its effective ingredients plays a decisive role in product quality.

[0003] In existing technologies, the production of Artemisia argyi essential oil and hydrosol mostly adopts atmospheric pressure backwater distillation process, which typically includes single-stage condensation, oil-water separation at room temperature or near room temperature, and manual judgment of the distillation endpoint. This type of process generally takes 4-5 hours to distill, and has the following problems:

[0004] 1. Due to the large span of the condensation temperature zone and the single-segment mode, light components have a long residence time under high temperature conditions, which easily leads to re-evaporation or thermal degradation, resulting in a decrease in essential oil yield and insufficient aroma retention.

[0005] Second, during the oil-water separation process at room temperature, the temperature fluctuates greatly and interfacial emulsification is easily generated, which causes essential oils to be carried into the aqueous phase, resulting in a decrease in the clarity and stability of the hydrosol.

[0006] Third, the downtime of the existing process mainly relies on manual observation, lacking online detection and quantitative criteria, which easily leads to under-evaporation or over-evaporation, resulting in reduced yield or increased energy consumption.

[0007] IV. Fluctuations in condensation and separation conditions directly affect the composition of the distillate, resulting in significant differences in color, aroma, and content of active ingredients between different batches.

[0008] Therefore, a process for extracting Artemisia argyi plant essence based on steam condensation is proposed. Summary of the Invention

[0009] In view of this, the present invention provides a process for extracting Artemisia argyi plant essence based on steam condensation, in order to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial alternative.

[0010] The technical solution of this invention is implemented as follows: a process for extracting Artemisia argyi plant essence based on steam condensation, comprising the following steps:

[0011] S1 Raw Material Pretreatment and Loading

[0012] The fresh mugwort leaves harvested on the same day are washed to remove impurities, spun dry or air-dried until there is no visible water on the surface, and cut into 8-15mm sections. They are then filled into a basket with evenly distributed through holes, and an anti-foaming baffle and a reflux guide ring are installed on the top of the basket.

[0013] Preferably, the diameter of the uniformly distributed through holes is 3–5 mm, and the material surface is lightly pressed and leveled after filling to suppress steam short-circuiting and channeling.

[0014] S2 steam distillation

[0015] The basket of materials is distilled with saturated steam at a bed temperature of 96–100℃ and a gauge pressure of 0–0.12MPa, with a steam-to-fresh mugwort mass ratio of 1.2–1.8:1.

[0016] Preferably, the total distillation time is controlled at 2.0–3.5 h. Before entering S2, pre-distillation and surface enzyme inactivation can be performed: 100 °C, 0.5–2 min.

[0017] S3 Two-Stage Temperature Zone Condensation

[0018] Distilled vapor is condensed sequentially through a first-stage and a second-stage condenser to obtain distillate. The cooling medium temperature of the first-stage condenser is 18–22℃, and the cooling medium temperature of the second-stage condenser is 5–10℃. The steady-state fluctuation of the cooling medium temperature in each stage does not exceed ±1℃.

[0019] Preferably, the first-stage condenser is first stabilized at 18–22°C and maintained for at least 5 minutes, and then the second-stage condenser is cooled to 5–10°C to enter a steady state; the temperature difference between the two-stage cooling media is preferably 8–17°C, and the temperature of the second-stage cooling media is not higher than 10°C.

[0020] S4 Low-Temperature Constant Temperature Oil-Water Separator

[0021] The distillate is introduced into a constant temperature oil-water separator at 5±2℃ and allowed to stand for 10–20 minutes to separate into layers. The upper layer of essential oil is collected and the lower layer of distillate is discharged from the bottom. This constant temperature and standing time window is used to reduce emulsification, improve phase separation efficiency and the purity of the supernatant.

[0022] S5 Closed-Loop Reflux and Hydrosol Collection

[0023] The lower distillate after separation is refluxed back to the distillation vessel at a reflux ratio R = 0.3–0.6, and the remainder is collected as hydrosol. The reflux ratio R is defined as the ratio of the reflux flow rate per unit time to the liquid output rate of the separator, and is adjusted by the controller in a closed loop based on the online oil content monitoring signal.

[0024] Preferably, the control target is that the deviation between the online oil content and the set value does not exceed 5 mg / L. The flow rate R is dynamically adjusted through the flow meter and the reflux regulating valve in the reflux branch. When a short-term rise is detected but the termination condition is not triggered, an abnormal callback can be executed.

[0025] Maintain the secondary condensation temperature at 5–6°C and increase the reflux ratio by 0.05–0.10 until the online oil content falls below the threshold again.

[0026] Online oil content is measured using an online refractometer or an online turbidimeter. The monitoring point is set at the secondary condenser outlet or the oil-water separator inlet. Linear calibration is performed at no less than three points using gas chromatography offline oil content, with a correlation coefficient of no less than 0.98, to ensure the traceability of the quantitative criteria.

[0027] S6 Quantitative Endpoint Criterion

[0028] Distillation shall be terminated when any of the following conditions are met:

[0029] Online oil content remained below 30 mg / L for ≥20 minutes.

[0030] The slope obtained by linearly fitting the cumulative oil yield-time relationship with a 30-minute sliding window is less than 2%, and the calculation window is 30 minutes.

[0031] The hydrosol obtained after termination is polished and filtered through a 0.45μm filter and filled under nitrogen-filled conditions with a headspace oxygen volume fraction of less than 1% to improve clarity and shelf stability.

[0032] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions:

[0033] I. This invention sets up a two-stage temperature zone sequentially coupled condensation structure in the extraction process, so that the first-stage condenser fully condenses the high-boiling-point aromatic components in the higher temperature range, and the second-stage condenser deeply condenses the low-boiling-point aromatic components in the lower temperature range. This reduces the re-evaporation and entrainment loss of aromatic components, improves the integrity of the distillate components, and effectively suppresses the interfacial emulsification phenomenon during the separation process when combined with low-temperature constant-temperature oil-water separation, reduces the entrainment of essential oils into the aqueous phase, and improves the clarity and stability of the hydrosol.

[0034] Second, this invention uses closed-loop control of the reflux ratio, with the deviation between the online oil content and the set value as the adjustment basis, to dynamically balance the reflux and effluent ratio, maintaining the consistency of the distillate composition. Combined with the control of dual quantitative endpoints, the invention uses the online oil content continuous threshold or cumulative yield slope threshold as the shutdown criterion to achieve automation and standardization of endpoint determination, avoiding under-distillation or over-distillation caused by relying on human experience. The process combination of this invention can improve the yield of essential oils and the quality of hydrosols while reducing energy consumption, and maintain process stability under different batches and scales.

[0035] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a flowchart of the extraction process of the present invention. Detailed Implementation

[0038] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0039] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0040] like Figure 1 As shown in the figure, this embodiment of the invention provides a process for extracting Artemisia argyi plant essence based on steam condensation.

[0041] In this embodiment, the terms and raw materials are defined as follows:

[0042] Fresh Artemisia argyi leaves / Artemisia argyi: refers to the above-ground parts of Artemisia argyi harvested on the same day and not dried, with a fresh appearance, no mold, and no off-odor; moisture content of 70–85 wt% (drying method, 105℃ to constant weight; according to GB / T6283 or equivalent method).

[0043] Distillate: The mixed liquid obtained after condensation in two condensers, consisting of the upper essential oil and the lower distillate.

[0044] Hydrosol: refers to the aqueous product obtained by collecting the lower distillate after constant temperature oil-water separation.

[0045] Cooling medium: The first-stage condenser uses a 18–22℃ cooling water circuit; the second-stage condenser uses a 5–10℃ chilled water / brine circuit.

[0046] Online oil content: refers to the online refractive index or online turbidity signal in the distillate stream that reflects the concentration of volatile components. The monitoring point is located at the outlet of the secondary condenser or the inlet of the constant temperature oil-water separator. After linear calibration at no less than three points (≥3 points), it is converted to mg / L with a correlation coefficient of not less than 0.98. The recording cycle is 1 min / time. The judgment of "continuous ≥20 min" is based on the 1 min original sequence. The 3-point moving average can be used for noise reduction, but the 20 min judgment window shall not be shortened.

[0047] Reflux ratio R: The ratio of the volume of liquid refluxed back to the distillation vessel by the constant temperature oil-water separator per unit time to the volume of liquid discharged from the separator in the same time.

[0048] Cumulative oil yield y (%): The cumulative mass or volume of essential oil collected since the start of distillation, converted into a percentage relative to the "theoretical recoverable oil amount";

[0049] Theoretical recoverable oil content: The converted value of volatile oil content of the same batch of raw materials measured by Soxhlet extraction (solvent n-hexane, solid-liquid ratio 1:20 (g:mL), 80℃, 6h) is used as the benchmark for cumulative oil recovery.

[0050] The equipment and measuring points are as follows:

[0051] Distillation vessel: 316L stainless steel, equipped with sight glass, safety valve, temperature and pressure measuring points, jacket or coil for steam supply and heat release; gauge pressure control 0–0.12MPa.

[0052] Perforated material basket: 316L stainless steel wire or perforated plate structure, hole diameter 3–5mm; top equipped with anti-foaming baffle and reflux guide ring;

[0053] First-stage condenser: plate or tube type, cooling medium temperature controlled at 18–22℃, with inlet / outlet temperature and flow measurement points;

[0054] Two-stage condenser: The cooling medium temperature is controlled at 5–10℃, and it is equipped with inlet and outlet temperature and flow measurement points;

[0055] Thermostatic oil-water separator: operating temperature 5±2℃, equipped with an upper oil inlet and a bottom drain outlet, and a sampling port and an insulated box;

[0056] Online monitoring points: Online refractive index or online turbidity sensors are installed at the outlet of the secondary condenser or the inlet of the constant temperature oil-water separator, and linear calibration is performed offline at no less than three points using gas chromatography;

[0057] Reflux ratio control: The lower layer of distillate discharged from the bottom of the separator is divided into a reflux branch and an outlet branch. Flow meters and regulating valves are installed on the two branches respectively. The PLC calculates the reflux ratio based on the instantaneous volume flow rate of the two branches and adjusts it in a closed loop.

[0058] Polishing and filtration: 0.45μm filtration; nitrogen filling, with headspace oxygen volume fraction of less than 1% in the finished container.

[0059] S1. Raw material pretreatment and loading

[0060] The fresh Artemisia argyi harvested that day was selected to remove mud, sand, aging, or moldy parts, and then thoroughly washed with clean water and drained. The fresh material was cut into 8-15mm segments, and fine particles smaller than 8mm were removed as much as possible to reduce the risk of entrainment and foaming during subsequent distillation and to obtain uniform vapor-liquid penetration performance. The cut fresh material segments were evenly layered and loaded into a porous basket with a pore size of 3-5mm. After each layer was filled, it was lightly leveled and compacted to avoid steam short-circuiting or channeling caused by local voids or over-compaction. After the basket was in place, the porous basket was placed in the distillation vessel, and the top anti-foaming baffle and reflux guide ring were installed and confirmed to be in good sealing condition. The vessel lid was closed and the inspection record was completed, including: raw material batch number, sampling results of segment size, filling time, and filling volume fraction.

[0061] Optionally, before entering S2, 100°C saturated steam is introduced for 0.5–2 minutes to soften the surface tissue and reduce foaming and enzyme activity. If obvious foaming occurs, the lower limit time is used. After draining the pre-steamed condensate, the product enters S2.

[0062] S2, Steam distillation

[0063] Turn on the steam supply and heat up at a steady rate. The material layer temperature should be 96–100℃ and the pressure inside the vessel should be 0–0.12MPa. The mass ratio of steam to fresh Artemisia argyi should be controlled at 1.2–1.8:1. During the heating process, observe the foam and material surface status through the sight glass. If continuous foam or liquid surging occurs, appropriately reduce the opening of the steam inlet valve. After the foam subsides, finely adjust and restore the valve.

[0064] S3, Two-stage temperature zone condensation

[0065] First, stabilize the cooling medium temperature of the primary condenser at 18–22℃ and maintain it for at least 5 minutes. Then, reduce the cooling medium temperature of the secondary condenser to 5–10℃ and enter a steady state. During the steady state period, monitor the temperature fluctuation of each stage of the cooling medium to ensure it does not exceed ±1℃, and maintain the temperature difference between the primary and secondary cooling media at 8–17℃. If insufficient condensation or increased gas entrainment is found at the primary end, prioritize checking the primary temperature and flow rate. If insufficient condensation at the secondary end or the separator cannot maintain the set temperature, check the secondary cooling capacity and heat exchange area.

[0066] S4, Low-temperature constant-temperature oil-water separation

[0067] The distillate continuously enters the constant-temperature oil-water separator, and the temperature of the oil-water separator is stably controlled at 5±2℃. After standing for 10–20 minutes, the oil is collected from the top, and the lower layer of distillate is discharged from the bottom for reflux or as hydrosol collection. If the emulsion interface thickens, becomes unclear, or adheres to the wall, the standing time can be extended by 5–10 minutes, and the temperature can be checked to see if it is within the set window. If necessary, the feed rate can be reduced, and the normal discharge can be resumed after the interface becomes clear.

[0068] S5, Closed-loop reflux and hydrosol collection

[0069] The separated lower distillate is refluxed back to the distillation vessel at a reflux ratio R = 0.3–0.6, and the remainder is collected as hydrosol. During this process, the deviation between the online oil content and the process setpoint is used as the adjustment amount, and closed-loop regulation is achieved through the regulating valve of the reflux branch to ensure that the deviation does not exceed 5 mg / L. During steady-state operation, if the online oil content rises briefly but has not yet met the S6 termination condition, the cooling medium temperature of the secondary condenser is maintained at 5–6℃, and the reflux ratio is increased by 0.05–0.10 from the current value. The observation is carried out for 5–10 minutes until the online oil content falls below the threshold again, at which point the original control target is restored. During operation, the online oil content, the temperature of the primary and secondary cooling media, the oil-water separator temperature, the reflux ratio, and the temperature and pressure of the distillation vessel are recorded every 15 minutes. If necessary, samples are retained for offline verification.

[0070] S6 Endpoint Criteria and Shutdown

[0071] The distillation process is terminated using dual quantitative criteria; it terminates when any of the following conditions are met:

[0072] Firstly, the online oil content remained below 30 mg / L for a continuous period of not less than 20 minutes;

[0073] Secondly, by fitting the linear relationship between "cumulative oil yield and time" with a calculation window of 30 minutes, the slope obtained is less than 2% / h.

[0074] Upon termination, first shut off the steam supply in sequence, and keep the cooling medium running for 3–5 minutes to remove residual heat from the equipment; then stop the reflux, empty the residual liquid in the separator, and release the pressure inside the vessel. After termination, collect the hydrosol into the finished product tank, perform 0.45μm polishing filtration, and fill under nitrogen purging conditions to ensure that the oxygen volume fraction in the headspace of the finished product container is less than 1%. The termination trigger criteria, trigger time, and final values ​​of key process parameters are all recorded in the batch record.

[0075] Example 1 (using standard process, 100kg of fresh leaves)

[0076] Fresh feed was cut into 10–12 mm segments; pre-steaming was optional at 100℃ for 1 min; during distillation, the bed temperature was 96–100℃ and the pressure on the distillation vessel was 0–0.12 MPa; the mass ratio of steam to fresh feed was 1.4:1; in the two-stage condensation, the cooling medium temperature of the first-stage condenser was 20℃, and the cooling medium temperature of the second-stage condenser was 8℃, with steady-state temperature fluctuations of no more than ±1℃. The cooling medium temperature of the first-stage condenser was stabilized for at least 5 min before the cooling medium temperature of the second-stage condenser was lowered; constant-temperature oil-water separation was performed at 5℃ and allowed to stand for 15 min; the reflux ratio was controlled at 0.45, and the closed-loop adjustment criterion was that the deviation between the online oil content and the set value should not exceed 5 mg / L; distillation was terminated when the online oil content remained below 30 mg / L for at least 20 min. Three batches were repeated. The test results are shown in Table 4 below.

[0077] Example 2

[0078] Except for setting the cooling medium temperature of the secondary condenser to 6°C and the reflux ratio control target to 0.40, the rest was the same as in Example 1; distillation was terminated using the criterion that "the slope of the linear fit between the cumulative oil yield and time with a calculation window of 30 minutes is less than 2%". Three batches were repeated. The results are shown in Table 5 below.

[0079] Example 3

[0080] Same as in Example 1, but the target reflux ratio was increased to 0.55 20–30 min before termination; all other parameters remained unchanged. Three batches were repeated. Results are shown in Table 6 below.

[0081] Example 4

[0082] No pre-steaming softening was performed; otherwise, the process was the same as in Example 1. Three batches were repeated. Results are shown in Table 7 below.

[0083] Example 5

[0084] 500 kg of fresh leaves; the condenser heat exchange area was increased by 1.9 times compared to Example 1; the effective volume of the constant temperature oil-water separator was configured according to the formula "product of distillation rate per unit time × settling time × 1.2"; the rest was the same as in Example 1; 5 batches were produced continuously. The test results are shown in Table 8 below.

[0085] Comparative Example 1

[0086] 100 kg of fresh leaves were used; single-stage condensation was employed; oil-water separation was carried out at room temperature without temperature control, and the mixture was allowed to stand for 10–20 minutes; the lower distillate was fully refluxed; the distillation endpoint was determined by manual experience; all other conditions were consistent with those in Example 1. The results are shown in Table 1 below.

[0087] Comparative Example 2

[0088] Except for the constant-temperature oil-water separation being carried out at an ambient temperature of 20–25°C and allowed to stand for 10–20 minutes, the rest was the same as in Example 1. Three batches were repeated. The results are shown in Table 2 below.

[0089] Comparative Example 3

[0090] Same as Example 1, but the reflux ratio was fixed at 0.20, and closed-loop adjustment was not performed based on online oil content. Three batches were repeated. Results are shown in Table 3 below.

[0091] Test case

[0092] 1. Raw material and batch control:

[0093] All samples used fresh Artemisia argyi leaves harvested on the same day from the same base, and were processed according to the process of "washing - drying - cutting - basketing"; the cutting size, filling rate and basketing operation conformed to the "process implementation steps of this embodiment".

[0094] The comparative examples and the embodiments were completed within the same week, and all other conditions were kept consistent except for the features being compared.

[0095] 2. Testing methods and sample retention:

[0096] Essential oil yield: After oil-water separation, the upper essential oil is collected and converted to 20℃ using graduated cylinder reading or weighing method, expressed in mL / kg;

[0097] Physicochemical properties of hydrosol: pH (25℃), turbidity (NTU, 25℃), platinum cobalt color number (PCU), conductivity (μS / cm, 25℃);

[0098] Three-point fingerprint: Extract volatile components from hydrosol with n-hexane, detect the relative peak area ratio of 1,8-cineole, borneol and camphor, and report the intra-batch relative standard deviation;

[0099] Energy consumption and duration: The comprehensive energy consumption per unit of fresh material is calculated based on electricity meter readings and steam equivalent, expressed in kWh / kg; the total duration is the time from the start of steam intake to the end of steam intake.

[0100] Online endpoint recording: The oil content is measured by online refractive index or online turbidity monitoring, and converted to mg / L after three or more linear calibrations; the criteria for triggering termination and the timestamp are recorded.

[0101] Two samples (≥100mL / sample) are retained for each batch, with a retention period of ≥12 months.

[0102] 3. Test Data Table:

[0103] Table 1: Detection Data of Comparative Example 1

[0104]

[0105] Table 2: Detection Data of Comparative Example 2

[0106] batch Essential oil yield (mL / kg) Energy consumption kWh / kg pH Turbidity NTU Chromaticity PCU Three-point fingerprint RSD% Total duration h C2-1 1.98 0.93 5.5 2.3 10 14 3.4 C2-2 2.02 0.96 5.6 2.6 11 — 3.6 C2-3 2.06 0.99 5.6 2.9 12 — 3.8 mean 2.02 0.96 5.6 2.6 11 14 3.6 Standard deviation 0.04 0.03 0.0 0.3 1 — 0.2

[0107] Table 3: Detection Data of Comparative Example 3

[0108] batch Essential oil yield (mL / kg) Energy consumption kWh / kg pH Turbidity NTU Chromaticity PCU Three-point fingerprint RSD% Total duration h C3-1 1.99 0.79 5.6 1.9 9 12 3.1 C3-2 2.05 0.82 5.6 2.1 9 — 3.2 C3-3 2.11 0.85 5.6 2.3 10 — 3.3 mean 2.05 0.82 5.6 2.1 9 12 3.2 Standard deviation 0.05 0.03 0.0 0.2 0 — 0.1

[0109] Table 4: Detection Data Table for Example 1

[0110]

[0111] Table 5: Detection Data Table for Example 2

[0112]

[0113] Table 6: Detection Data Table for Example 3

[0114]

[0115] Table 7: Detection Data Table for Example 4

[0116]

[0117] Table 8: Detection Data Table for Example 5

[0118] batch Essential oil yield (mL / kg) Energy consumption kWh / kg pH Turbidity NTU Chromaticity PCU E5-1 2.18 0.77 5.6 1.4 8 E5-2 2.20 0.79 5.6 1.5 8 E5-3 2.23 0.80 5.6 1.4 9 E5-4 2.26 0.82 5.6 1.6 8 E5-5 2.23 0.82 5.6 1.6 9 mean 2.22 0.80 5.6 1.5 8–9 Standard deviation 0.05 0.03 0.0 0.2 —

[0119] In the table above: the RSD of three-point fingerprints is statistically analyzed and reported in the "Mean / Standard Deviation" row of the corresponding group. Single batches are not calculated, and the cell is represented by "—(see mean for group statistics)";

[0120] Table 9: Summary of Key Indicators for Examples and Comparative Examples

[0121]

[0122] Table 10: Summary of Key Indicators in Example 5

[0123] index mean Standard deviation Remark Essential oil yield (mL / kg) 2.22 0.05 — Energy consumption (kWh / kg) 0.80 0.03 — pH 5.6 0.0 25℃ Turbidity (NTU) 1.5 0.2 25℃ Chromaticity (PCU) 8.4 0.5 Batch values ​​8, 8, 9, 8, 9 Three-point fingerprint RSD (%) 8 — Intra-batch relative standard deviation Steady-state temperature fluctuation of primary / secondary cooling medium (°C) ≤0.6 / ≤0.5 — Steady-state monitoring Online oil content baseline drift (mg / L·h) ≤3 — Steady-state monitoring

[0124] Comparison conclusion:

[0125] Based on data from Comparative Examples 1–3 and Examples 1–5, the combined control of this invention includes: two-stage temperature zone condensation (first-stage cooling medium temperature 18–22℃, second-stage 5–10℃, stabilizing the first stage for at least 5 minutes, with steady-state fluctuations of ±1℃ between stages and a temperature difference of 8–17℃ between stages), constant-temperature oil-water separation at 5±2℃ (standing for 10–20 minutes), closed-loop reflux ratio (R = 0.3–0.6, with the goal of the deviation between online oil content and the set value not exceeding 5 mg / L), and dual quantitative endpoints (online oil content continuous threshold or cumulative yield slope threshold). Compared with industry standards and those without key features, this demonstrates systematic and simultaneous improvement across multiple indicators (see Tables 9 and 10).

[0126] Essential oil yield: increased by approximately 12–18%. Example 1 yielded 2.30 mL / kg; compared to Comparative Examples 1 / 2 / 3, the yield was increased by 18% / 13% / 12% respectively; Example 3 could be further increased to 2.32 mL / kg by increasing reflux during the final stage.

[0127] Unit energy consumption: reduced by approximately 5–26%. Example 1 was 0.78 kWh / kg; compared to Comparative Examples 1 / 2 / 3, the reduction was 26% / 19% / 5%, respectively; Example 2 further reduced it to 0.75 kWh / kg by lowering the secondary temperature and reflux target.

[0128] Clarity and color of hydrosols: Turbidity was reduced by approximately 40–60% overall. Turbidity of Example 1 was 1.2 NTU; Comparative Examples 1 / 2 / 3 were 3.0 / 2.6 / 2.1 NTU; color decreased from 9–12 PCU to 8 PCU.

[0129] Intra-batch consistency: The RSD of the three-point fingerprint decreased from 12–18% to 7–9%; with the addition of ±1℃ steady-state fluctuation control, the component fluctuations were significantly reduced.

[0130] Time consumption: Total time reduced by 12–38%. Example 1: 2.8h; Comparative Example 1: 4.5h; Comparative Example 2: 3.6h; Comparative Example 3: 3.2h.

[0131] Scale-up consistency: At the 500 kg scale of Example 5, the mean and standard deviation of key indicators are within acceptable ranges; the first and second steady-state temperature fluctuations are ≤0.6℃ and ≤0.5℃, respectively; the online oil content baseline drift is ≤3 mg / L·h; indicating scalability and reproducibility.

[0132] As shown in Tables 9 and 10, there is a direct correspondence between the various elements of this invention and the improvement of the indicators:

[0133] Two-stage temperature zone and sequential coupling (S3): First, the steady state of the first stage at 18–22℃ is kept above 5 min, and then the temperature is lowered to the second stage at 5–10℃. The steady state fluctuation of each stage is controlled at ±1℃ and the temperature difference between the two stages is 8–17℃. This achieves segmented condensation of light and heavy components and reduces re-evaporation and entrainment. After removing this feature in Comparative Example 1, the yield decreased and the turbidity and time consumption increased.

[0134] Isothermal separation at 5±2℃ (S4): Isothermal standing for 10–20 min inhibits emulsification and stabilizes the interface; Comparative Example 2 showed increased turbidity, increased RSD, and decreased yield when no temperature control was applied.

[0135] Reflux ratio closed loop (S5): Within R = 0.3–0.6, the online oil content deviation is dynamically adjusted to ≤5 mg / L to maintain an effective concentration gradient and stable composition. In contrast, when the fixed reflux of Example 3 is not closed loop, the yield is lower, the turbidity is higher, and the fluctuation is greater.

[0136] Dual quantitative endpoint (S6): The system is shut down when the online oil content continuously reaches the threshold or the cumulative yield slope is <2% / h, avoiding the energy consumption of over-evaporation or under-evaporation caused by experience-based shutdown, resulting in shorter time consumption and lower energy consumption.

[0137] Within the window defined by this invention, lowering the secondary temperature and moderately reducing the reflux can further reduce energy consumption, but there is a slight trade-off between yield and turbidity; briefly increasing the reflux before termination can slightly increase the yield, but the time consumption increases. The display window is adjustable and bounded and has a criticality, supporting the necessity and rationality of the parameter range of the claims.

[0138] 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 person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all 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 process for extracting Artemisia argyi plant essence based on steam condensation, characterized in that: Includes the following steps: S1. Raw material pretreatment and filling: Wash and remove impurities from the fresh mugwort leaves harvested on the same day, spin dry or air dry until there is no visible water on the surface, cut into 8-15mm sections, and fill into a material basket with evenly distributed through holes. The top of the material basket is equipped with an anti-foaming baffle and a return flow guide ring. S2. Steam distillation: The basket is distilled with saturated steam at a bed temperature of 96–100℃ and a gauge pressure of 0–0.12MPa, with the mass ratio of steam to fresh Artemisia argyi being 1.2–1.8:

1. S3. Two-stage temperature zone condensation: Distilled vapor is condensed sequentially through a primary condenser and a secondary condenser to obtain distillate. The cooling medium temperature of the primary condenser is 18–22℃, and the cooling medium temperature of the secondary condenser is 5–10℃. The steady-state fluctuation of the cooling medium temperature of each stage does not exceed ±1℃. S4. Low-temperature constant-temperature oil-water separation: The distillate is introduced into a 5±2℃ constant-temperature oil-water separator and allowed to stand for 10–20 minutes to separate into layers. The upper layer of essential oil is then collected. S5. Closed-loop reflux and hydrosol collection: The lower layer of distillate after separation is refluxed back to the distillation vessel at a reflux ratio R = 0.3–0.6, and the remainder is collected as hydrosol. The reflux ratio R is defined as the ratio of the reflux flow rate per unit time to the liquid output rate of the separator, and is adjusted by the controller in a closed loop based on the online oil content monitoring signal. S6. Quantitative Endpoint Criterion: Distillation shall be terminated when any of the following conditions are met: Online oil content remained below 30 mg / L for ≥20 minutes. The slope obtained by linearly fitting the cumulative oil yield versus time using a 30-minute sliding window is less than 2%.

2. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: The diameter of the uniformly distributed through holes in step S1 is 3–5 mm, and the material surface is lightly pressed and leveled after filling to suppress steam short-circuiting and channelization.

3. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: The total distillation time in step S2 is controlled to be 2.0–3.5 h.

4. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: In step S3, the temperature difference between the cooling medium for the primary and secondary condensation is 8–17°C, and the temperature of the secondary cooling medium is not higher than 10°C.

5. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: Step S3 first stabilizes the temperature of the cooling medium for the first-stage condensation at 18–22℃ and maintains it for no less than 5 minutes, then lowers the temperature of the cooling medium for the second-stage condensation to 5–10℃ to enter a steady state, and the steady-state fluctuation of the temperature of each stage of the cooling medium does not exceed ±1℃.

6. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: In step S4, after standing for 10–20 minutes in a constant temperature oil-water separator at 5±2℃ to separate the layers, collect the essential oil from the top and drain the lower layer of distillate from the bottom.

7. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: The online oil content monitoring uses an online refractometer or an online turbidimeter. The monitoring point is set at the secondary condenser outlet or the oil-water separator inlet. The oil content measured offline by gas chromatography is linearly calibrated at no less than three points with a correlation coefficient of no less than 0.

98.

8. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: The closed-loop reflux control in step S5 aims to ensure that the deviation between the online oil content and the set value does not exceed 5 mg / L. The reflux ratio is adjusted by the flow meter and reflux regulating valve of the reflux branch. The reflux ratio is a dynamic value in the range of 0.3–0.

6.

9. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: If the online oil content briefly rises but fails to meet the termination condition of step S6, maintain the secondary condensation temperature at 5–6°C and increase the reflux ratio by 0.05–0.10 until the online oil content falls below the threshold again.

10. The process for extracting Artemisia argyi plant essence based on steam condensation according to claim 1, characterized in that: Before step S2, the filled basket is pre-steamed and softened at 100°C for 0.5–2 min and surface enzymes are inactivated; and after step S6 is terminated, the hydrosol is polished and filtered at 0.45 μm and filled under nitrogen purging conditions with headspace oxygen volume fraction of less than 1%.

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