Sustainable approaches for the curcumin extraction from Curcuma longa employing green solvents.

Curcumin is a highly valued compound in the global market due to its extensive
applications in the food, beverage, pharmaceutical, and cosmetic industries. It is
primarily obtained from turmeric, and its extraction can be achieved through various
techniques ranging from conventional soaking methods to advanced processes such as
supercritical fluid extraction. Each method has its own advantages and limitations.
Among these, solvent extraction is commonly preferred because it is relatively simple
and cost-effective. However, many conventional solvents are derived from petroleum
sources and are considered hazardous due to their potential adverse effects on human
health and the environment.
Therefore, there is an increasing need to develop alternative, sustainable, and
environmentally friendly extraction techniques. In this study, bio-based and/or
biodegradable green solvents were employed along with sustainable extraction
approaches such as enzyme-assisted extraction and ultrasound-assisted extraction
(UAE). Turmeric rhizomes were processed into powder and pre-treated with two
different enzymes, namely Viscozyme and Cellulase. The reaction conditions were
optimized using the Taguchi method within the framework of Response Surface
Methodology (RSM) to minimize the number of experimental runs. A total of nine
runs were obtained for each enzyme. All experimental runs involved solvents such as
acetone, ethyl acetate, 2-MeTHF, CPME, and DMC.
The results indicated that parameters such as solvent type, pH, incubation time, and
enzyme concentration play a crucial role in curcumin extraction. In several cases, the
green solvents demonstrated superior extraction efficiency compared to the control
solvents acetone and ethyl acetate. Furthermore, a higher percentage of curcuminoids
was observed in ultrasound-assisted extraction compared to conventional hot
extraction. In vitro biological assays including total phenolic content (TPC), total
flavonoid content (TFC), DPPH radical scavenging activity, ABTS assay, ferric
reducing antioxidant power (FRAP), and total antioxidant capacity (TAC) were
performed. Interestingly, samples obtained through hot extraction exhibited slightly
higher biological activity compared to those obtained through UAE. Samples showing
the highest biological activity were further analyzed using HPLC, and the percentage
of curcumin obtained was found to be consistent with the values determined by the
UV-Vis method.