Celery is a kind of vegetable with rich nutrition, which is loved by people. Celery seeds have unique flavor and are used to make various condiments.
Celery seeds have rich oil content and can be used to make edible oils.
Supercritical CO2 extraction technology is a new technology in food industry. Compared with traditional solvent extraction methods, it has the advantages of no chemical residue, no pollution, avoiding high temperature deterioration of extracts, maintaining active substances, simple process, low energy consumption, non-toxicity of extracts and easy recovery.
Method for Supercritical CO2 Extraction Celery Seed Essential Oil
The effects of particle size, pressure, temperature, flow rate and time on the extraction rate of celery seed oil were investigated.
Effect of Crushing Fineness on Oil Yield
Under the conditions of 45 °C , 2 h and 15L/h CO2 flow rate, the extraction was carried out at different particle sizes, and the results were shown in the figure.
Celery seed oil exists in the cells of seeds, with less oil in the seed coat and more oil in the seed kernels. In order to increase the contact area between CO2 and seeds and reduce the diffusion distance between extractant and extractant in the biological matrix, it is necessary to grind it to the appropriate size according to the raw materials.
It can be seen from the figure that the particle size decreases and the oil yield increases, but too fine particle size is easy to cause caking and clogging the filter screen, so the particle size can not be too fine. It is appropriate to use about 60 mesh.
Effect of Extraction Pressure on Oil Yield
The results of extraction under different pressures are shown in the figure below at 45 °C , 2 h and 15L/h CO2 flow rate.
When the temperature is constant, the polarity of supercritical CO2 increases with the increase of pressure, which affects the binding ability with solute.
When the pressure increases, it is beneficial to increase the solubility of celery seed oil in CO2.
To obtain high pressure, it is necessary to increase equipment investment, energy consumption and maintenance costs and affect the purity of celery seed oil.
It can be seen from the figure that when the pressure is near 10 MPa, the oil yield of celery seed is very low, and when the pressure exceeds 150 MPa, the oil yield is very high; when the pressure is higher than 20 MPa, the oil yield increases slightly, but the oil quality is turbid.
According to the experimental results, the optimum extraction pressure was 15-20 MPa.
Effect of Extraction Temperature on Oil Yield
The results of extraction at different temperatures at 45 °C , 2 h and 15L/h .
The extraction rate decreases with the increase of temperature because the solvent density decreases with the increase of temperature, which outweighs the effect caused by the increase of solvent vapor pressure due to the increase of temperature.
The extraction effect at the time is better than that at 45 °C .
Effect of co2 flow rate
The results of extraction under different CO2 flow rates at 45 °C , 2 h and 15L/h are shown in the figure.
Experiments were carried out at solvent flow rates of 1.1 kg/h and 3 kg/h, respectively.
The results show that the increase of solvent flow rate increases with the same extraction time. The extraction time can be shortened by increasing solvent flow rate to obtain the same yield.
The extraction time of CO2 was less than 1.1 kg/h at the flow rate of 3 kg/h (15l/h).
The quality of celery seed oil extracted by supercritical CO2 fluid is better than that by cold pressing and solvent methods, and the process is more simple and convenient.
The optimum extraction conditions of CO2 fluid are as follows: temperature 45 °C , pressure 20 MPa, particle size 60 mesh, flow rate 15 l/h.