Optimum Technological Conditions for Supercritical CO2 Extraction of Natural Ve
Wheat germ is the most abundant food resource in nature containing natural Ve. The content of V in wheat germ is 69mg/100g, and the activity of alpha-tocopherol is the highest. In recent years, the research of natural vitamin E has developed rapidly in China. At present, the main extraction methods are esterification, enzymatic, saponification, organic solvent (low alcohols or ketones) extraction and supercritical fluid extraction. The technological conditions of supercritical CO2 fluid extraction of natural Ve were studied and the optimum combination of technological conditions was obtained in order to provide theoretical basis for the application of the new separation technology in the industrial production of natural Ve.
According to the principle of supercritical fluid extraction (SFE), the main factors affecting the extraction of natural Ve from wheat germ by SFE were analyzed, including extraction pressure, temperature, time, CO2 flow rate, moisture content of wheat germ, particle size, Ve species and structural characteristics. The relationship between extraction amount of natural Ve and various factors was studied by orthogonal test and single factor test. The optimum conditions were determined as follows: extraction pressure 29-36 MPa, temperature 38-40 C, time 2-3 h, CO2 flow rate 16 kg/h, water content 5.0% in wheat germ and particle size 20-30 mesh.
Wheat germ drying crushing sieving weighing filling sealing heating up and pressurizing to set extraction conditions supercritical CO2 fluid extraction cycle decompression separation wheat germ oil centrifugal separation distillation refined wheat germ oil determination of Ve content.
Fresh wheat germ was heated and dried for 20-30 minutes in an electrothermal constant temperature drying chamber at l10-ll5 C and 1.5 cm thickness. After removal, it was crushed by a multi-functional grinder and superfine powder was removed by a standard screen of l0-30 mesh. Weighing 500 g wheat germ, filling in extraction kettle, then opening CO2 cylinder (need to keep outlet pressure above 5.OMPa), adjusting extraction temperature and separation temperature to set temperature, then opening plunger reciprocating pump to press to set extraction pressure, adjusting CO2 flow rate by adjusting frequency converter, then closing CO2 cylinder, so that Supercritical CO2 fluid is extracted under the set pressure, temperature and flow rate. When the extraction time is reached, the pressure reducing valves of separator I and II are adjusted to normal pressure, so that CO2 loses its solubility, and wheat germ oil is collected. Finally, impurities are separated by centrifugal separator and refined wheat is obtained by distillation column distillation. At last, the extraction rate of Ve was determined by ammonium ceric sulfate method.
According to the experimental results of supercritical CO2 extraction of natural VE from wheat germ, the following conclusions can be drawn: the main factors affecting the extraction of natural Ve by supercritical CO2 fluid are extraction pressure > extraction temperature > extraction time > CO2 flow rate, and the optimum operating conditions are: extraction pressure, temperature, time and CO2 flow rate are 29-32 Mpa, 38-42 Mpa, respectively. Temperature, 2.0h, 16kg/h; The extraction amount of natural Ve increased with the decrease of water content of wheat germ, but decreased when the water content of wheat germ was less than 5.0%. This was because the water content of wheat germ was 5.0%. In SCF-CO2 extraction, there was no thin water film near continuous phase on the surface of wheat germ, which prevented the diffusion and mass transfer of Ve to SCF-CO2 phase. Ve can be used as a carrier to promote the extraction of Ve. Ve extraction increases with the decrease of wheat germ particle size, but the extraction decreases when the grain size is too fine. This is due to the blockage of dissolution channel caused by excessive bulk density, poor permeability and the decrease of extraction effect, so the grinding particle size of Wheat germ is 30 mesh. Appropriate.