Production of a carotenoid-rich product by alginate entrapment and fluid-bed drying of Dunaliella salina

A new carotenoid-rich product was formed by entrapment of Dunaliella salina in calcium alginate beads of different alginate concentrations, followed by drying in a fluid-bed dryer. The drying process yielded β-carotene recoveries of between 79 and 89% and produced a change in the 9-cis/all-trans ratio of β-carotene isomers. The carotenoid stability of the product was dependant on both the storage conditions and alginate content (range 3.3-7.3 g litre^-1) of the beads. In the presence of light and oxygen total carotenoid degraded following a first order kinetic model with degradation constants between 0.016 and 0.039 days^-1, with the lowest degradation occurring with the lowest alginate concentration. Product stored in the dark and flushed with nitrogen produced first-order degradation constants of 0.012 and 0.020 days^-1 for the two higher alginate concentrations; that with the lowest alginate content showed no noticeable degradation after 58 days storage. During storage, the 9-cis isomer was significantly more unstable showing a relative loss under all conditions, degrading almost completely when stored in the presence of light and oxygen and reaching an equilibrium ratio with the all-trans isomer when stored in the dark and flushed with nitrogen.