A novel sustainable approach for the extraction of value-added compounds from Hibiscus sabdariffa L. calyces by natural deep eutectic solvents.

Hibiscus sabdariffa L. is widely acknowledged as an important source of value-added compounds as natural pigments and bioactive compounds whose isolation is of great interest in food industry. Due to the incessant demand of green extraction procedures, NADESs have emerged in the last years as new green solvents alternative to the conventional organic ones. The feasibility of NADESs for the extraction of value-added compounds of H. sabdariffa has been assessed in this work for the first time. An extraction technique based on microwave assisted extraction (MAE) and the use of NADESs was proposed testing different deep eutectic solvents based on choline chloride (ChCl). Among them, oxalic acid based NADES exhibited a great selectivity for anthocyanins in particular as well as higher extraction yields of bioactive compounds was also observed, even greater than those observed by methanol. The effect of extraction variables such as liquid-solid ratio, temperature and water percentage were studied by Box-Behnken design and a response surface methodology. The statistical program pointed out the liquid-solid ratio of 1:30 mL mg-1, temperature of 75 °C and a water percentage of 55% as the conditions to maximize extraction within the experimental domain. Hence, NADES composed by oxalic acid and choline chloride resulted to be an effective green alternative tailor-made solvent to carry out selective extractions of value-added compounds from H. sabdariffa.