Extraction of curcumin from Curcuma longa using meglumine and pyroglutamic acid, respectively, as solubilizer and hydrotrope

Abstract

In preceding papers, it could be shown that mixtures of water, ethanol, and triacetin can significantly boost the extraction of curcuminoids out of Curcuma longa, compared to the usually applied water–ethanol mixtures. To further improve it, additives can be beneficial. We show that meglumine and pyroglutamic acid are among the most promising of these additives. First, the influence of meglumine and pyroglutamic acid on the phase diagram of ternary mixtures consisting of water, ethanol and triacetin has been investigated: the addition of meglumine to the water phase only slightly increases the miscibility gap, whereas pyroglutamic acid increases it significantly in the oil-rich region. The solubility of curcumin could be significantly enhanced through the addition of meglumine. Extractions were successfully conducted extracting ~ 18 mg of curcuminoids per g Curcuma longa by adding 15 wt% of meglumine to the amount of water in the extraction mixtures consisting of water, ethanol and triacetin, which is an increase of ~ 20% compared to the best extraction mixture water/ethanol/triacetin from the previous study. A simple water/meglumine extraction was also investigated. Around 13 mg curcuminoids per g Curcuma longa could be extracted. Bisdemethoxycurcumin contributes 3.46 mg to the total amount, which is a very good extraction yield (increase of 19% compared to the best extraction mixture from the previous study). The purity of the extract reached 87% just by extracting with water and meglumine. For comparison, the same purity was achieved using the ternary water/ethanol/triacetin system, but only after freeze drying of the rhizomes before extraction.