Astaxanthin, is a kind of terpene unsaturated compound, is pink, it is a kind of carotenoid. Astaxanthin has many very important biological functions, such as preventing ultraviolet radiation, improving immunity, and preventing cardiovascular diseases.
The supercritical fluid extraction method has a simple process, no residual solvent, high extraction rate, and no environmental pollution. In this paper, the supercritical CO extraction method is used for the extraction of astaxanthin.
CO2 extraction process
Accurately weigh 4.7647g crayfish shell powder sample and place it in the extraction kettle, put the filter cotton and filter discs into the extraction kettle before loading the sample, and cover the extraction kettle cover. After the preparation work is completed, the extraction test  is carried out. The set extraction pressure is 30MPa, the CO2 flow rate is 30L/h, the separation temperature is 40°C, the entrainer is 1 times the amount of 95% ethanol, the extraction time is 120min, the extraction temperature is 50°C, and the extract is red liquid.
Choice of CO2 flow
The fixed extraction temperature is 50℃, 95% ethanol is the entrainer, the extraction pressure is 30MPa, the sample particle size is 0.425mm, the separation temperature is 40℃, the extraction time is 2h, and the CO2 flow rate is 10, 20 respectively. Under the conditions of, 30, 40, 50L/h, explore the effect of CO2 flow rate on astaxanthin yield. When CO2 flow rate is 10~30L/h, the astaxanthin yield in the sample increases with the increase in flow rate, but when the flow rate reaches At 30L/h, the increase in astaxanthin yield in the sample tends to be flat.
Considering that an excessive increase in the CO2 flow rate will lead to an increase in production costs, therefore, the CO2 flow rate is selected as 30L/h.
Selection of extraction temperature
With other conditions unchanged, the extraction temperature was selected to be 30, 35, 40, 45, and 50°C to study the effect of temperature on the yield of astaxanthin.
When the extraction temperature is in the range of 40~50℃, the yield of astaxanthin increases with the increase of temperature. When the extraction temperature is 50℃, the yield reaches the maximum; when the extraction temperature exceeds 50℃, the yield decreases as the temperature increases. the trend of.
Generally speaking, as the temperature rises, the solubility of astaxanthin in the extractant will increase, which is beneficial to the extraction. However, when the temperature is too high, it will also cause the loss of the extractant to increase, resulting in the production of astaxanthin. The extraction rate is reduced, which is unfavorable for extraction. Therefore, the optimal extraction temperature condition is 50°C.
The choice of cosolvent
With other conditions unchanged, we investigated the entrainment of 0.5 times the amount of 95% ethanol, 1 times the amount of 95% ethanol, 2 times the amount of 95% ethanol, 1 times the amount of 30% ethyl acetate, and 2 times the amount of 30% ethyl acetate. The effect of the agent on the extraction rate of astaxanthin.
With the increase of the entrainer dose, the yield of astaxanthin increased, but when the entrainer was increased to 1 time, the yield did not increase. For different entrainers, the extraction rate of 30% ethyl acetate solution as the entrainer is obviously slightly higher than that of 95% ethanol. But considering that ethyl acetate will remain in the sample, it is difficult to remove, and ethanol will be completely volatilized, so choose 1 times the amount of 95% ethanol as the entrainer.
Selection of extraction pressure
With other conditions unchanged, the effects of extraction pressures of 30, 35, 40, 45, and 50 MPa on the yield of astaxanthin were investigated. When the pressure was 20 to 30 MPa, the yield gradually increased, and the yield when the pressure reached 30 MPa. It is the highest value. When the pressure reaches 30 MPa, the yield increase is not obvious. Considering the cost, the supercritical extraction pressure is selected as 30 MPa.
Selection of material particle size
Under the condition of other conditions unchanged, choose the material size to extract astaxanthin from crayfish under the conditions of 2.000, 0.850, 0.425, 0.180mm, respectively, and explore the influence of the material size on the yield of astaxanthin. The material size is 0.180~ At 2.000mm, the yield gradually increases, and when the particle size of the material is 0.425mm, the astaxanthin extraction rate reaches the highest value.
Because the smaller the particle size of the sample, the larger the contact area with the extraction solvent, and the higher the astaxanthin yield. However, particles with too fine particle size are easy to agglomerate, which affects the extraction effect. Therefore, the best material particle size is 0.425. mm.
Selection of separation temperature
When other conditions remain unchanged, set the separation temperature to 25, 30, 35, 40, and 45°C to discuss the effect of the separation temperature on the yield of astaxanthin.
As the separation temperature increases, the yield of astaxanthin gradually increases. A higher yield can be obtained when the separation temperature is 40°C, but the temperature continues to rise, and the yield shows a downward trend. When the temperature exceeds 40°C, the molecular weight The increase of the attractive force between the molecules reduces the molecular distance, but the molecules are in motion, which will prevent the molecules from approaching all the time and reach equilibrium. The higher the temperature, the greater the molecular kinetic energy, which will increase the molecular distance, which is not good for extraction. , And consume more energy, therefore, choose the appropriate separation temperature is 40 ℃.
Selection of extraction time
With other conditions unchanged, set the extraction time to 1.0, 1.5, 2.0, 2.5, and 3.0h respectively to study the effect of different extraction times on the yield of astaxanthin. When the extraction time is 1~2h, the yield gradually increases. When the extraction time reaches 2h, a higher yield can be obtained, but the extraction time continues to increase, the yield shows a gentle trend, and consumes more energy, so the best extraction time is selected as 2h.
To sum up
High performance liquid chromatography was used to detect the content of astaxanthin in shrimp shells, and finally the yield of astaxanthin in the sample was 26.13μg/g.
The precision and recovery rate tests were conducted 6 times respectively, and the relative standard deviation was 0.10%, and the average recovery rate was 99.0%, both of which were within the scope of the national standard and conformed to the national standard.
Astaxanthin has a good linear relationship in the linear range of 0-12μg/mL, and the detection limit is 0.01μg/mL. High performance liquid chromatography is easy to operate, low consumption, high sensitivity, high precision, and good recovery rate. It can be used as a detection method for astaxanthin.
The supercritical CO2 extraction method is used as the extraction method of astaxanthin. In consideration of economic benefits, the CO2 flow rate is 30L/h, and the astaxanthin yield reaches the maximum when the extraction temperature is 50℃, and the entrainer is 1 times the amount of 95 The extraction effect is best in% ethanol. Considering the production cost, the supercritical extraction pressure is 30MPa and the material particle size is 0.425μm when the yield is the highest. The most suitable separation temperature is 40℃, and the extraction time is 2h, and the yield reaches the maximum. value.
It shows that the optimization of extraction conditions is scientific and reliable, and can provide a basis for the extraction of astaxanthin.
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