Determination of the diffusion coefficient while extractiing oil from evening primrose seeds using high hydrostatic pressure

The purpose of research is to study the dependence of the effective diffusion coefficient De on the external hydrostatic pressure P when extracting oil from ground seeds (meal) of evening primrose using the EVHD method at a constant (room) temperature. Tasks: to obtain experimental dependences of the oil concentration in the extract (Cp) on the extraction time t (Cp (t)) and pressure P (Cp (P)); using the experimental dependences Cp (t) and Cp (P) at room temperature, calculate the dependence of the effective diffusion coefficient De on pressure P (De (P)). Seeds of evening primrose (Oenothera biennis L.) were obtained from the Znak Zemli plant nursery in the village of Lapino, the Moscow Region. In order to increase the contact surface between the seed particles and the solvent, the seeds were crushed in a planetary ball mill until particles were obtained, the average diameter of the projected area of which was equal to dav = 0,2 ± 0,03 mm. As an extractant, in accordance with the requirements of the pharmacopoeial article FS 42-3071-00, an organic solvent of 70 % ethanol was chosen. Extraction with ethanol of crushed seeds of VGD was carried out on a laboratory automated installation. The ratio of evening primrose aggregates (mass, g) to the amount of solvent (volume, ml) is 1:11 and 1:23 (or 1:10 and 1:20 in a mass ratio). Mixtures of aggregates and solvents were packed in sealed polyethylene capsules, after which they were subjected to the VGD effect in the range from 25 to 300 MPa at an ambient temperature of 25 ± 2 °C, exposure time was 20 min. The results of experimental and theoretical studies of the EVHD process during the extraction of oil from ground seeds of evening primrose at a constant temperature are presented. Experimental dependences of the oil concentration in the extract on the extraction time and pressure were obtained, on the basis of which the dependence of the effective diffusion coefficient on pressure was calculated.