Evaluation of different cell disruption processes on encysted cells of Haematococcus pluvialis: effects on astaxanthin recovery and implications for bio-availability

Although Haematococcus pluvialis is one of the most important natural sources of the carotenoid astaxanthin as a pigmentor for the aquaculture industry, the thick sporopollenin cell wall in the cysts hinders astaxanthin extraction and its subsequent bio-availability to fish. A range of physical and chemical processes were tested to promote the disruption of the encysted cells. The efficacy of these processes was evaluated in terms of astaxanthin recovery, which was assessed by determining the extent of leaching of astaxanthin into an organic solvent. The processes tested were: autoclave 30 min, 121 °C, 1 atm; HCl 0.1 M, 15 min and 30 min; NaOH 0.1 M, 15 min and 30 min; enzymatic treatment with a mixture of 0.1% protease K and 0.5% driselase in a phosphate buffer, pH 5.8, 30 °C, for one hour; spray drying, inlet 180 °C, outlet 115 °C; and mechanical disruption, with a cell homogeniser developed for this purpose. The mechanical (homogenisation) and autoclave treatments were the most effective in terms of extraction and availability.