Extraction and milking of astaxanthin from Haematococcus pluvialis cultures†
The microalga Haematococcus pluvialis is capable of accumulating natural astaxanthin when subjected to external stress and shifted towards a red-cyst phase, characterized by a robust and multilayered cell wall. In the present study, still-unexplored solvents were applied for extracting astaxanthin from H. pluvialis, directly from algae culture and without any pre-treatment of the cells. Among the tested solvents, some of them (e.g. ethyl acetate and 2-methyltehydrofuran) gave excellent astaxanthin recovery (>80%) in a short time (30 min) and others (e.g. isoamyl acetate, well known as a human-compatible solvent and already in use as a food additive) gave an astaxanthin recovery close to 90% in 1 hour and thus they are exploitable in the natural astaxanthin market. Almond oil is proved to be able to extract astaxanthin and keep H. pluvialis alive, without affecting the algal photosynthetic activity, providing the possibility to milk and regeneratively cultivate H. pluvialis and avoid an uneconomical loss of biomass.