Supercritical carbon dioxide processing of pyrethrum oleoresin and pale

Abstract

Possible refining of crude hexane extract (CHE) from pyrethrum flowers and further refining of Pyrethrum Board of Kenya (PBK) pale product is investigated with both liquid and supercritical carbon dioxide. The experiments were carried out in a small pilot plant with a 200 mL extractor and three cyclonic separators in series. To understand the dynamics of pyrethrin extraction, CHE was extracted in a single step; pyrethrin concentration was found to be improved from 0.16 to 0.50 g/g. The effects of temperature and pressure on the quality of the extract were studied at 29 °C and 80 bar and at 40 °C and 100 bar. Liquid CO2 processing (29 °C, 80 bar) yielded slightly better product quality. A comparison study of CHE and PBK pale processing with supercritical CO2 (40 °C, 100 bar) showed that the final products were similar in terms of pyrethrin content. Extraction of both PBK pale and CHE in two steps with different operating conditions improved their purity.