Process intensification of ultrasound assisted deep eutectic solvent-based extraction of astaxanthin-rich extract derived from the non-conventional bacterium Paracoccus carotinifaciens

Abstract

The objective of this work was to develop an integrated ultrasound-assisted deep eutectic solvent-based process for extracting astaxanthin-rich extracts (ARE) from dried biomass of the non-conventional aerobic Gram-negative marine bacterium P. carotinifaciens. Deep eutectic solvents (DES) composed of choline chloride (HBA) and carboxylic acids/alcohols (HBD) were used as alternative solvents, and the effects of processing intensification parameters on ARE extraction yield were studied. The investigated parameters included extraction temperature, solid/liquid ratio, amplitude level, ultrasound intensity, DES molar ratio, and extraction time. The efficient extraction period for achieving maximum yield of ARE was approximately 8 min, extraction temperature 65 ◦C, solid/liquid ratio 0.05 g/mL, amplitude level: 15 %. Sequential five re-extraction cycles were applied, and it was observed that in two cycles, more than 95 % of total ARE was recovered. The experimental results showed that the choline chloride:acetic acid (CC-C2) DES combined with US enhanced mass transfer, leading to a remarkable recovery yield increase of up to 900 % compared to the conventional procedure. These values were compared with the calculations of the activity coefficient at infinite dilution and the sigma profile delivered by COSMOSAC, concluding that this tool can be used to predict the behavior of DES for the recovery of ARE.