Near-critical extraction of sage, celery, and coriander seed

Near-critical extraction of coriander seed, Dalmatian sage, and celery was performed on a pilot-scale extraction apparatus. Sage and celery were extracted using liquid carbon dioxide to obtain oleoresins. Coriander seed was extracted at 250 bar and 40 degrees C. Coriander extract was fractionated into triglycerides and essential oils by using two separation stages at different pressures. Extractions were carried out using a range of particle diameters, carbon dioxide flow rates, and packed bed flow configurations to establish relationships between extract yield and extraction time/carbon dioxide usage. The particle diameter had the largest influence on both yield and extraction time for all materials. The flow rate and packed bed flow configuration affected only the rate of extraction of triglycerides. The extraction of essential oils/oleoresins was found to be intraparticle diffusion controlled, whilst triglycerides were found to be both film and particle diffusion controlled. A mathematical model was developed which satisfactorily predicts extract yields as a function of extraction time, flow rate, and particle diameter. The model contains only one adjustable parameter, the intraparticle diffusion coefficient, D-e, which is a constant for each herb.