Optimization of Mild Extraction Methods for the Efficient Recovery of Astaxanthin, a Strong Food Antioxidant Carotenoid from Microalgae

Microalgae represent an important source of bioactive compounds for food applications. In this study, multifunctional extracts from Haematococcus pluvialis (H. Pluvialis) microalga have been developed in order to be used as food additives. Total extracts were recovered by ultrasound assisted extraction using eco-friendly and food grade solvents. Five different ratios ranging from 1/100 to 1/5 g biomass/ mL solvent were studied in different ultrasound intensities in order to optimise the extraction of carotenoids, especially of astaxanthin. The produced extracts were analysed using High Pressure Liquid Chromatography (HPLC-DAD) and UV-Vis spectroscopy techniques. Acetone was the most efficient solvent for the extraction of carotenoids in all tested ratios. However, D-limonene and medium chain triglycerides extracts also gave a satisfying recovery of carotenoids. D-limonene was the preferred solvent since extracts with high amounts of carotenoids were recovered, permitting their direct use in food products and avoiding further condensation steps.