The impact of different light conditions during culture on the nitrogen, protein, colour, total phenolic content (TPC) and amino acid profile of Palmaria palmata biomass was investigated. P. palmata was cultured using different light regimes, i.e., white (1 and 2), red, blue and green over 12 days. A significant decrease (p < 0.05) in total nitrogen (TN), non-protein nitrogen (NPN) and protein nitrogen (PN) was observed on day 6 while an increase was observed on day 12 in P. palmata samples cultured under blue light. The protein content (nitrogen conversion factor of 4.7) of the initial sample on day 0 was 15.0% (w/w) dw whereas a maximum protein content of 16.7% (w/w) was obtained during exposure to blue light following 12 days culture, corresponding to an 11.2% increase in protein content. Electrophoretic along with amino acid profile and score analyses showed light-related changes in protein composition. The lighting regime used during culture also influenced the colour parameters (lightness L*, redness a*, yellowness b* and colour difference ΔE) of milled algal biomass along with the TPC. Judicious selection of lighting regime during culture may allow the targeted production of sustainable high-quality proteins from P. palmata.
Keywords: Palmaria palmata; amino acid; light regime; nitrogen; protein; red seaweed.