EVALUATION OF CURCUMINOIDS, POLYPHENOLS AND ANTIOXIDANT CAPACITY IN RESIDUES FROM THE DISTILLATION PROCESS OF ESSENTIAL OILS OF CURCUMA LONGA L.

Abstract

Agro-industrial wastes produced in various extractive processes cause and exacerbate environmental problems. One process that generates thousands of tons of biomass annually is the distillation of essential oils, where small quantities of the oil and high amounts of waste are obtained. Turmeric essential oil is marketed all over the planet. In the process, a residual cake is produced that is often discarded without considering the secondary metabolites that can still be reused. This research quantifies the remaining curcuminoids and polyphenols in the residual cake and their antioxidant activity by spectrophotometric methods. Concerning the presence of secondary metabolites, it is valid to highlight the concentration of
curcuminoids still preserved in the residue because these are not significantly affected in the distillation process and therefore maintain a concentration of 51.750 ± 0.060 mg/g, considering the medicinal value of these secondary metabolites, it would be interesting to analyze a later insertion in natural drugs. 
The high antioxidant capacity with oxidation inhibition indexes IC 50 of 13.3 µg/mL using the DPPH methodology and 7.0 µg/mL by ABTS is also noteworthy. The concentration of phenolic compounds such as flavonoids, anthocyanins, and simple phenols was considerably reduced, which was to be expected because these compounds are thermolabile. The results demonstrate the metabolic value of the residual cake produced in the distillation of turmeric and the possibility of medicinal or industrial reuse as dyes or cosmetics.