Extraction of Limonoids and Limonoid Glucosides with Supercritical Carbon Dioxide

Abstract

Supercritical carbon dioxide (SC-CO₂) extraction of limonoids and limonoid glucosides (LGs) from defatted Natsudaidai seed meals was examined under various conditions. The total amount limonoids extracted by SC-CO₂ was less than those extracted by organic solvent. Very little amount of limonin, deacetylnomilin and LGs were extracted by SC-CO₂. The results obtained with SC-CO₂ extraction with modification of entrainers indicated that acetone was the best entrainers among tested for extracting limonoids. However 70% ethanol was more efficient for LGs. Extraction pressure and the amount of CO₂ were important factors in this experiment. The extraction yield of limonids depended upon pressure, but were not affected by temperature. The yield increased with increasing pressure and sharp increase in nomilin extraction was observed between 250kg/cm² and 300kg/cm². The extraction of deacetylnomilin, nomilin and obacunone was sharply increaed till the 50 g-CO₂/g-seed level and remained relatively constant thereafter. The yield of limonin gradually increased with increasing amount of CO₂. The optimal extraction ratios of deacetylnomilin, limonin, nomilin and obacunone were 13.9%, 19.1%, 82.1% and 38.9%, respectively. On the other hand, a higher yield (81.0%-99.4%) of LGs was obtained, except for limonin glucoside.