Production of Arthrospira platensis BEA 005B: Biomass characterisation and use as a colouring additive in macarons

The present study aimed at (i) producing the microalga Arthrospira platensis BEA 005B using 80 m2 raceway reactors and (ii) to assess the potential use of the produced biomass as a food colour in macarons. The biomass production was carried out during winter and the productivity of the system ranged between 8 and 10 g m−2·day−1 depending on the depth of the culture (0.10–0.20 m). Illumina sequencing revealed that A. platensis represented over 85% of the prokaryotic populations; other alkaliphile strains were also identified. The produced biomass was mainly composed of protein (57.0 g·100 g−1) and contained natural and valuable pigments including chlorophylls (6.7 mg·100 g−1), carotenoids (1.8 mg·100 g−1), phycocyanins (115.4 mg·100 g−1), and allophycocyanins (36.9 mg·100 g−1). The effect of pH variations and thermal processing (121 °C, 15 min) on the colour of the biomass and on the stability of the main pigments was studied. The produced biomass was used to mimic the colour of two synthetic pigments used in green macarons. The lowest colour difference between the commercial and the microalgae-containing macarons was around 5 at a concentration of 3.5 mg g−1. The pigmentation capacity of the biomass was so high that the small quantities added did not affect the nutritional value of the macarons.