Pilot-scale production of lutein using Chlorella vulgaris

Abstract

Lutein is a carotenoid pigment which has applications in the food and nutraceutical sectors, both for its use as a colourant and for its applications as a nutraceutical. Microalgae are a promising source of lutein, however to meet market demand there is a need to develop technologies which can used for large-scale production. The effect of process conditions at a 5L scale were quantified, it was found that at low light intensities (160μmol photons m−2 s−1) the measured specific lutein concentration was 7.4±2.1mg g−1 which was greater than the concentration of 3.1±1.1mg g−1 obtained at higher (440μmol photons m−2 s−1) light intensities. Supplementation of the medium with nitrate led to significant increases in the maximum specific lutein concentration (10.4±5.5mg g−1) compared to medium without nitrate addition (4.3±2.9mg g−1). These conclusions were used to scale-up the process using 50L bubble column photo-bioreactors, it was found that the productivity was maximised (1.6mgL−1 day−1) using an air flow-rate of 1 vvm and 24h lighting. Finally, it was found that the process could be operated on a semi-continuous basis for 32 days, achieving high lutein concentrations (15–20mgL−1) with the performance of the system being consistent for this duration. Results from this work have clear application in the development of large-scale systems for the microalgal production of lutein.