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 sourc es of the carotenoid astaxanthin as a pigmentor for the aquaculture industr y, the thick sporopollenin cell wall in the cysts hinders astaxanthin extra ction and its subsequent bio-availability to fish. A range of physical and chemical processes were tested to promote the disruption of the encysted ce lls. The efficacy of these processes was evaluated in terms of astaxanthin recovery, which was assessed by determining the extent of leaching of astax anthin into an organic solvent. The processes tested were: autoclave 30 min , 121 degreesC, 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% dri selase in a phosphate buffer, pH 5.8, 30 degreesC, for one hour; spray dryi ng, inlet 180 degreesC, outlet 115 degreesC; and mechanical disruption, wit h a cell homogeniser developed for this purpose. The mechanical (homogenisa tion) and autoclave treatments were the most effective in terms of extracti on and availability.