罗勒挥发油成分为萜烯类及其含氧衍生物，其中以丁香酚、芳樟醇、茴香脑、1,8一桉叶素、杜松烯醇的含量较高。与传统水蒸气蒸馏法相比，本工艺采用的超临界CO₂萃取法具有更好的选择性和更高的产量，可以避免有些对热敏感的化合物用水蒸气蒸馏法提取时受热分解而发生变化影响精油质量。其次，超临界流体萃取法提取时间短，产品无有机溶剂残留，超临界流体萃取法被广泛用于香精香料提取，也被公认为是用于食品添加剂安全的方法。

The volatile oil of basil consists of terpenes and their oxygen-containing derivatives, with higher contents of eugenol, linalool, anethole, 1,8-eucalyptol, and junipenol. Compared with the traditional steam distillation method, the supercritical CO2 extraction method used in this process has better selectivity and higher yield, which can avoid changes in the thermal decomposition of some heat sensitive compounds extracted by steam distillation method. Secondly, the supercritical fluid extraction method has a short extraction time and no organic solvent residue in the product. The supercritical fluid extraction method is widely used in the extraction of essence and fragrance, and is also recognized as a safe method for food additives.

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图1 超临界 CO₂流体萃取工艺流程图

Fig1 Supercritical CO₂ fluid extraction process flow chart

样品处理：罗勒采集后﹐阴干.实验时将罗勒按不同部位（叶、茎、种子)分类粉碎,过20目、40目筛,备用.

SFE—COz提取工艺：CO2钢瓶→压缩、冷冻系统→高压泵→萃取釜→解析釜Ⅰ→解析釜Ⅱ→贮罐(循环)

Sample processing: After collecting basil, dry it in the shade. During the experiment, classify and crush basil according to different parts (leaves, stems, seeds), pass through 20 mesh and 40 mesh sieves, and set aside

SFE COz extraction process: CO2 steel cylinder → compression and freezing system → high-pressure pump → extraction kettle → analysis kettle I → analysis kettle II → storage tank (circulation)

工艺操作：准确称取300 g 罗勒叶粉末,放入萃取釜中萃取﹒当工艺参数与设定参数一致时开始计时,每半小时从解析釜Ⅰ、解析釜Ⅱ各出料一次﹒用电子天平准确称出萃取物的重量.本工艺以萃取率为指标,研究压力、温度、萃取时间3个主要因素以及二氧化碳流量、解析压力、解析温度对萃取率的影响.其中,二氧化碳流量设定为150 L/h,解析釜Ⅰ:压力9 MPa、50℃;解析釜Ⅱ:压力6 MPa、40 ℃.

萃取率计算：(萃取重量/原料重量)×100%

Process operation: Accurately weigh 300 g of basil leaf powder and place it in an extraction kettle for extraction. When the process parameters are consistent with the set parameters, start timing and discharge the material from each analysis kettle I and II every half hour. Use an electronic balance to accurately weigh the weight of the extract. This process takes the extraction rate as the indicator and studies the three main factors of pressure, temperature, and extraction time, as well as the effects of carbon dioxide flow rate, analysis pressure, and analysis temperature on the extraction rate, The carbon dioxide flow rate is set to 150 L/h, and the analysis kettle I has a pressure of 9 MPa and 50 ℃; Analysis kettle II: pressure 6 MPa, 40 ℃

Extraction rate calculation: (extraction weight/raw material weight) × 100%

1.     原料颗粒度对萃取率的影响

1. The influence of raw material particle size on extraction rate

取白花罗勒叶粗粉、20目粉、40目粉﹐萃取参数16 MPa、45℃、1 h,结果见表1。结果表明原料粉碎后,可增加溶质分子与超临界二氧化碳的接触﹐减少传质阻力,但如果粉碎得太细会增加超临界二氧化碳通过的阻力,使萃取率下降。所以本工艺选取40目为条件。

Take crude powder of white flower basil leaves, 20 mesh powder, and 40 mesh powder, and extract them.The extraction parameters are 16 MPa, 45 ℃, and 1 hour. The results are shown in Table 1. The results show that after crushing the raw materials, the contact between solute molecules and supercritical carbon dioxide can be increased, reducing mass transfer resistance. However, if the crushing is too fine, it will increase the resistance of supercritical carbon dioxide passing through, resulting in a decrease in extraction rate. So this process selects 40 mesh as the condition.

表1 原料颗粒度对萃取率的影响

Table1 The influence of raw material particle size on extraction rate

2.     萃取压力对萃取率的影响

2.The effect of extraction pressure on extraction rate

图2为40℃时二氧化碳流体的密度一压力关系.由图2可见,在7.0～20.O MPa区域内压力对密度的影响非常显著.本工艺考察了不同压力(12、16、20 MPa)下、萃取时间1.5 h、萃取温度45℃时的萃取率,结果见图3,结果显示16 MPa时萃取率最高,为最佳提取压力。

Figure 2 shows the density pressure relationship of carbon dioxide fluid at 40 ℃. As can be seen from Figure 2, The effect of pressure on density is very significant in the range of 7.0-20 MPa. This process investigated the extraction rate at different pressures (12, 16, 20 MPa), extraction time of 1.5 hours, and extraction temperature of 45 ℃. The results are shown in Figure 3, which shows that the extraction rate is highest at 16 MPa, which is the optimal extraction pressure.

图2 CO₂密度-压力关系

Fig2 CO₂ density pressure relationship

图3 压力对萃取率的影响

Fig3 The influence of pressure on extraction rate

3.      萃取温度对萃取率的影响

3. The influence of extraction temperature on extraction rate

本工艺考察了同一压力(16 MPa)下﹐不同温度(35、40、45℃)时的萃取率,结果如图4,因此45℃时萃取率最高,为最佳萃取温度。

This process investigated the extraction rates at different temperatures (35, 40, 45 ℃) under the same pressure (16 MPa), as shown in Figure 3. Therefore, the extraction rate is highest at 45 ℃, which is the optimal extraction temperature.

图4 温度对萃取率的影响

Fig4 The influence of temperature on extraction rate

4.      萃取时间对萃取率的影响

4. The effect of extraction time on extraction rate

从图5发现,前2h萃取率随时间变化较明显,在延长萃取时间,萃取率变化不显著。因此,实验最佳萃取时间为2.0 h.

From Figure 5, it can be observed that the extraction rate changes significantly with time in the first 2 hours, and the change in extraction rate is not significant when the extraction time is extended. Therefore, the optimal extraction time for the experiment is 2.0 hours.

图5 萃取时间对萃取率的影响

Fig5 The influence of extraction time on extraction rate

5.      其他因素

5. Other factors

影响二氧化碳超临界流体萃取的其他因素有:解析压力﹐解析温度,CO₂流量等.本工艺设计解析釜Ⅰ参数为:9 MPa ,50℃;解析釜Ⅱ参数为:6 MPa、40 ℃.二级分离最佳萃取率为2.27%、1.99%.另外,实验过程中,CO₂流量在150 L/h左右。

Other factors that affect supercritical fluid extraction of carbon dioxide include analytical pressure, analytical temperature, CO₂ flow rate, etc. In this process the parameters of the designed analytical vessel I are 9 MPa and 50 ℃; The parameters of the analytical kettle II are 6 MPa and 40 ℃. The optimal extraction rates for secondary separation are 2.27% and 1.99%. Additionally, during the experiment, the CO₂ flow rate was around 150 L/h.

结论：最佳工艺条件为16 MPa, 45 ℃、2 h.二级分离解析釜Ⅰ参数为9 MPa、 50℃,解析釜Ⅱ参数为:6 MPa、40 ℃;二级分离最佳萃取率为2.27%、1.99%.

Conclusion: The optimal process conditions are 16 MPa, 45 ℃, and 2 hours. The parameters of secondary separation and analysis kettle I are 9 MPa and 50 ℃, and the parameters of analysis kettle II are 6 MPa and 40 ℃; The optimal extraction rates for secondary separation are 2.27% and 1.99%, respectively

超临界流体在各大领域中都能得到广泛的应用。在化学反应中，超临界流体可以作为溶剂或反应介质，用于合成有机化合物、高分子材料和纳米材料等。由于超临界流体的介电常数和溶剂化能力会随着压力的增加而发生变化，因此可以用来控制化学反应的速率和方向，提高产物的纯度和选择性。

在天然产物萃取方面，超临界流体可以有效地萃取植物、动物和微生物中的活性成分，如色素、香料、油脂和药用成分等。相比于传统的萃取方法，超临界流体萃取具有更高的提取效率和选择性，能够获得更好的产品质量和经济效益。Supercritical fluids can be widely applied in various fields. In chemical reactions, supercritical fluids can serve as solvents or reaction media for the synthesis of organic compounds, polymer materials, and nanomaterials. Due to the fact that the dielectric constant and solvation ability of supercritical fluids change with increasing pressure, they can be used to control the rate and direction of chemical reactions, improve product purity and selectivity.

In terms of natural product extraction, supercritical fluid can effectively extract active ingredients from plants, animals, and microorganisms, such as pigments, spices, oils, and medicinal ingredients. Compared to traditional extraction methods, supercritical fluid extraction has higher extraction efficiency and selectivity, which can achieve better product quality and economic benefits.