Cinnamon (scientific name: Cinnamomum zeylanicum Bl.) is a plant of the genus Eucalyptus, an evergreen tree, which is a flavor or Chinese herbal medicine.
Cinnamon oil has a strong aroma and spicy odor and is widely used in foods and daily cosmetic fragrances.
Cinnamon oil is one of the products of China’s important export earning, and has a long-standing reputation in the world.
At present, China’s cinnamon oil production usually adopts steam distillation. This production method has low oil rate, heat-sensitive components are easily decomposed, and has high energy consumption and low productivity, which restricts the production and development of cassia oil and causes great resources.
So it is necessary to find an efficient extraction method of cinnamon oil.
In this study, supercritical extraction experiments on cinnamon were carried out using the latest extraction technology, supercritical carbon dioxide extraction technology. The aim was to obtain the best supercritical extraction process and some necessary physical parameters to lay the foundation for large-scale process production.
Using orthogonal test design, the extraction yield of cinnamon oil is the evaluation index, which affects the four factor variables of extraction yield (temperature, pressure, CO2 flow, bulk density), each factor takes three levels, according to orthogonal Experimental design L9 (34).
Supercritical co2 extraction of cinnamon for 2 to 3 hours basically reaches the extraction limit, and the extension of time has little meaning, and in dynamic extraction, co2 has good fluidity, high solubility, and strong ability to carry substances, for the extraction of common plant materials.
3~4h has basically reached the extraction limit, so this experiment selected a fixed 3h as the extraction time, and did not further study the influence of time factors.
Effect of temperature on the extraction of cinnamon essential oil
At a certain pressure, the extraction temperature affects the extraction yield by affecting the combination and dissociation of organic molecules and CO2 molecules.
The extraction temperature also affects the overall thermal effect of the extraction process.
On the one hand, the higher the extraction temperature, the smaller the density of CO2 fluid, the worse the solubility of organic matter and the lower the ability of carrying substances.
On the other hand, the higher the extraction temperature, the faster the fluid mass transfer speed. The former is not conducive to extraction, and the latter is conducive to extraction.
In this experiment, through the orthogonal experiment, we can know that the range of temperature factor is the smallest, which means that in this experiment, compared with other factors, temperature has the smallest influence on the extraction rate of Cinnamon by supercritical CO2 extraction.
Combined with the orthogonal experiment, the extraction temperature of 40 ℃ is better.
Effect of pressure on the extraction of cinnamon essential oil
The polarity of supercritical co2 increases with the increase of pressure, which affects the binding capacity of supercritical co2 and solute.
In this experiment, the range of pressure factor is the largest, which indicates that the pressure has the greatest influence on the extraction yield of cinnamon.
The results show that with the increase of pressure, the extraction yield also increases.
Considering the higher pressure, the cost and power consumption of extraction equipment will increase greatly.
Therefore, from the perspective of practical application, 35MPa can meet the requirements, so the extraction pressure of 35MPa is better.
Effect of co2 flow rate on the extraction of cinnamon essential oil
With the increase of co2 flow rate, the extraction yield is decreasing under different extraction co2 flow rate.
This is mainly because the increase of co2 flow rate reduces the contact time between co2 and raw materials, which is not conducive to the improvement of extraction yield. On the other hand, through the knowledge of chemical kinetics, we know that the increase of co2 flow rate will accelerate the speed of material layer and improve the mass transfer rate, which will improve the extraction speed.
It can be seen from this experiment and previous exploratory experiments that under various operating conditions, supercritical CO2 extraction of cinnamon for 2-3H has basically reached the extraction limit, and the extraction rate has no obvious change in unit time after prolonging the time.
Moreover, in dynamic extraction, the capacity of CO2 fluidity, solubility and carrying substance has been very good, and CO2 flow will increase CO2 consumption and cost, so by increasing dioxygen It is not advisable to increase the extraction speed by the flow rate of carbonization.
Considering comprehensively, the co2 flow rate of 30kg / h is better.
Effect of bulk density of raw materials on the extraction of cinnamon essential oil
Under different packing density of raw materials, with the increase of packing density of raw materials, the extraction yield decreases. This is mainly because the excessive packing density of raw materials makes the permeability worse, so that CO2 can only pass through the material layer along the route with low resistance, and the material is broken down (many small holes are produced), which makes the extraction significantly uneven.
At the same time, under the condition of high packing density, the moisture content in cinnamon powder is fast due to the effect of pressure. It will affect the extraction of cinnamon oil and increase the bulk density, which means it will take more time and energy to crush the raw materials.
Therefore, it is suggested that the bulk density of raw materials should be (0.44 ± 0.02) g / ml.
Through the comprehensive analysis of the orthogonal test results, the better technological conditions were obtained:
Extraction temperature 40 ℃, extraction pressure 35 MPa, CO2 flow rate 30 kg / h, bulk density (0.44 ± 0.02) g / ml.
The results showed that the extraction rate of cinnamon oil was 5.8% – 6.0%, the aroma of cinnamon oil was good, the appearance of cinnamon oil was brownish red, the color of cinnamon oil was darker than that of conventional steam distillation, the extraction rate of cinnamon oil by supercritical co2 extraction was more than 5 times of that by steam distillation, and the extraction time was also greatly shortened.
The temperature is low, the whole extraction and separation process is carried out in dark field, avoiding the decomposition, precipitation and other changes in the conventional extraction process, and maintaining the original characteristics of the components in cinnamon oil to the greatest extent.
Supercritical co2 extraction is a better technology to extract and separate plant essential oil.
Using supercritical co2 extraction to extract cinnamon, the oil yield is more than 5 times of that of ordinary steam distillation, and the extraction time is shortened.
The obtained oil has natural color and pure fragrance.
In the range of the experimental conditions, the best operating conditions were:
Extraction temperature 40 ℃, extraction pressure 35 MPa, CO2 flow rate 30 kg / h, bulk density (0.44 ± 0.02) g / ml. This method is easy to operate, safe and non-toxic, and there is no residual solvent problem, so it has a good development prospect.