Green extraction of xanthophyll esters from marigold using 2-methyltetrahydrofuran: Process optimisation through response surface methodology

Xanthophyll esters derived from marigold flowers are high value natural pigments with applications in the food, nutraceutical, cosmetic, and pharmaceutical industries. The present study investigated the extraction of xanthophyll esters from enzymatically pre-treated marigold flowers using 2-methyltetrahydrofuran as a biobased and renewable solvent. Preliminary screening of five green solvents- methyl tert-butyl ether (MTBE), isopropyl acetate (IPA), dimethyl carbonate (DMC), cyclopentyl methyl ether (CPME), and 2-Methyltetrahydrofuran(2-MeTHF). Among them, 2-MeTHF was identified as the most efficient, achieving a xanthophyll ester extraction percentage (XEEP) of 83.29%. Subsequently, extraction conditions were optimized using a five factor, Box-Behnken design (BBD) under Response Surface Methodology (RSM). The effect of five process variables- moisture (%), particle size (µm), solvent volume (mL), extraction temperature (°C), and extraction time (h) on Xanthophyll ester extraction percentage (XEEP) were evaluated. The optimized conditions were moisture content of 11.20%, particle size of 106.01 µm, solvent volume of 32.57 mL, and extraction time of 3.73 h. Under these conditions, the predicted XEEP was 100%, while the experimentally obtained value was 98.62%. The results demonstrate that 2-MeTHF is an effective and sustainable alternative to conventional organic solvents for the extraction of xanthophyll esters from marigold flowers and offers significant potential for industrial scale applications.