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Supercritical CO2 Fluid Extraction of Sardine Oil

Sardine

Sardine, also known as “sand mullet”, is a collective term for some squid. It is a warm-water fish in the offshore waters and is often distributed in low-latitude offshore areas.

Supercritical CO2 Fluid Extraction of Sardine Oil
Supercritical CO2 Fluid Extraction of Sardine Oil

Chinese sardines are mainly about ten species of small sardines, with the highest yield of golden sardines and small sardines.

Sardine’s nutrients

The composition of the sardine’s nutrients is: moisture 64.6%, protein 19.2%, fat 13.8%, carbohydrate 0.5%, minerals 1.9%.

Compared with common marine fish, sardines have low moisture content and high protein, fat and minerals.

Among them, minerals include calcium, magnesium, zinc, manganese, etc., as well as protein and various vitamins. They are rich in pentanepentaenoic acid (EPA) and docosahexaenoic acid (DHA). )etc.

These basic fatty acids help the blood flow in the body, maintain a healthy heart and prevent cardiovascular disease.

Extraction

At present, the extraction status of these lipid nutrients in various fish species is still high in cost, low in yield, and high in waste.

The use of traditional methods leads to waste of resources and low yield, while supercritical extraction uses high yield and good texture, although the cost will increase, but supercritical extraction will certainly be the mainstream way of fish oil extraction in the future.

Therefore, the extraction of sardine fish oil by supercritical method has potential value and prospect for the deep processing and comprehensive utilization of sardines.

Fish oil supercritical CO2 extraction machine
Supercritical CO2 extraction machine

Experiment

In this experiment, the sardine fish oil was extracted by supercritical extraction method, and the effects of extraction pressure, extraction temperature and extraction time on the extraction of sardine fish oil were investigated to obtain the best process of supercritical extraction of sardine fish oil, thereby reducing costs and improving The purpose of production. In order to provide some reference for the further development and utilization of sardines.

Extraction methods

At present, the extraction methods for various types of fish oil mainly include pressing method, organic solvent method, cooking method, enzymatic hydrolysis method, light alkali hydrolysis method and supercritical fluid extraction method.

The extraction status of these lipid nutrients in various fish species is still high in cost, low in yield, and high in waste.

The use of traditional methods leads to waste of resources and low yield, while supercritical extraction uses high yield and good texture, although the cost will increase, but supercritical extraction will certainly be the mainstream way of fish oil extraction in the future.

Therefore, the extraction of sardine fish oil by supercritical method has potential value and prospect for the deep processing and comprehensive utilization of sardines.

Advantages of supercritical CO2 extraction

Supercritical fluid extraction (SFE) is a new separation technique that extracts oil from fish raw materials by using a fluid in a supercritical state as an extractant.

Compared with traditional chemical methods, it has the advantages of high separation efficiency, low operating temperature, good product quality and no environmental pollution. However, the investment cost is high, and the method is only used when the product requirements are high.

The process of supercritical fluid extraction of sardine oil:

Selection of sardines – crushing – refrigeration – drying – weighing charge – supercritical extraction – obtaining fish oil

Effect of extraction pressure on the extraction rate

In the single factor experiment of supercritical extraction, the effect of extraction pressure on the extraction rate was investigated.

The extraction temperature was 37 °C, the extraction time was 2 h, the CO2 flow rate was 15 mL/min, and the extraction pressure was 2600-2800 psi (1 MPa ≈ 145 psi).

The effect of extraction rate on the extraction rate The effect of extraction pressure on the extraction rate is also a major parameter affecting the solubility of solute in supercritical CO2.

Under certain temperature conditions, when the pressure is at a lower level, the pressure increase increases the density of the CO2 fluid, and the solubility of the solute increases.

On the other hand, the mass transfer distance between the molecules is reduced to increase the mass transfer rate. Ideally, it is beneficial to the extraction.

Since the solubility of CO2 on fish oil is not proportional to the pressure, when the pressure is high, the extraction pressure is continuously increased.

Although the density of CO2 fluid and its solubility to solute increase slightly, the viscosity of carbon dioxide fluid increases, and the fluidity of mass Lowering, mass transfer is severely affected, resulting in a decrease in product yield.

That the extraction rate of sardine fish oil has a maximum value with pressure change, that is, it reaches a maximum at about 2800 psi, because the temperature is constant, the supercritical extraction pressure is increased, and the density of supercritical CO2 fluid is increased. The solubility capacity increases, so the extraction rate increases with the increase of pressure.

After the pressure is stronger than 2800 psi, the extraction rate decreases because the viscosity of CO2 fluid increases and the mass transfer rate decreases as the extraction pressure increases, resulting in a decrease in extraction rate.

Therefore, the appropriate pressure for extraction is around 2800 psi.

Effect of extraction temperature

In the single factor experiment of supercritical extraction, when the effect of temperature on the extraction rate was investigated, the extraction time was kept for 2 h, the extraction pressure was 2900 psi, the CO2 flow rate was 15 mL/min, and the extraction temperature was 35-44 °C.

When the extraction temperature is raised to 38 °C at 35 °C, the extraction rate is significantly improved, indicating that the effect of temperature on the CO2 diffusion coefficient and the increase in the solubility of the extract is stronger than the adverse effect of the decrease in the density of the CO2 fluid.

When the temperature is raised from 38 ° C to 44 ° C, the extraction rate decreases with increasing temperature, because the elevated temperature dominates the adverse effects of the decrease in the solubility and density of supercritical CO 2 , and thus the extraction rate decreases. Therefore, the extraction temperature is suitable for a temperature of about 38 °C.

Effect of extraction time

In the single factor experiment of supercritical extraction, the effect of time on the extraction rate was observed.

The extraction temperature was 38 °C, the extraction pressure was 2800 psi, the CO2 flow rate was 15 mL/min, and the extraction time was 1.5 h, 2 h, 2.5 h, 3 h, 3.5. h. Supercritical extraction time is a major parameter in the extraction of sardine fish oil.

The extraction time is too short, the extraction process of raw materials can not be completed completely, the extraction effect is poor, and the extraction time is too long, which is equivalent to using a large amount of energy consumption and logistics loss in exchange for micro extraction. The effect is improved.

The experimental results show that the suitable extraction time is about 3h.

Orthogonal experiment

Based on the previous single factor experiment, the main influencing factors affecting the extraction rate of sardine fish oil were extraction temperature, extraction time and extraction pressure.

The optimal process obtained by the orthogonal experimental results table increases the extraction rate from 0.2846% to 0.3359% under the condition of changing the time parameters, and the growth rate is the fastest at 2.5h-3h, so it can be orthogonal experiment and auxiliary experiment.

The optimum conditions for supercritical CO2 extraction of sardine fish oil were determined: dynamic extraction, pressure 2900 psi, extraction temperature 40 ° C, extraction time 3 h, extraction rate 0.3246%.

Summarize

  1. The sardine fish oil can be extracted by supercritical CO2 extraction, and the sardine fish oil is a fishy, transparent, pale yellow oil.
  2. Single factor experiments showed that the optimal process conditions for supercritical CO2 extraction of sardine fish oil were as follows: extraction temperature 38 ° C, extraction time 3 h, extraction pressure 2800 psi.
  3. The orthogonal experimental results show that the optimum conditions for supercritical CO2 extraction of sardine fish oil are: extraction temperature 40 ° C, extraction time 3 h, extraction pressure 2900 psi; fish oil yield under this condition is 0.3246%.