Variations in the chemical composition of Norwegian cultivated brown algae Saccharina latissima and Alaria esculenta based on deployment and harvest times

Abstract

Brown algae exhibit large seasonal variation in their composition based on nutrient and sunlight access, as well as other environmental factors. The continued growth of brown algae cultivation in Europe is dependent on increased knowledge of these variances, to ensure optimal growth conditions, predict quality prior to harvest, and determine suitability of the biomasses' composition for different markets and applications. In the present study, cultivated sugar kelp (Saccharina latissima - SL) and winged kelp (Alaria esculenta - AE) were collected from seeded lines deployed at two different times (October 2020 and January 2021). Samples were collected from the two deployment groups throughout the harvesting season (April–June 2021) from a single site (Frøya, Norway). The collected biomasses were analyzed with respect to lamina elongation, dry matter content, ash content, elemental composition, soluble protein, amino acid composition, and monosaccharide composition. The results showed that SL was more influenced by deployment time compared to AE, where earlier deployed biomass showed larger lamina size, lower iodine content, and later accumulation of mannitol and laminarin. The study further showed the compositional variation in each of the species and deployment groups throughout the harvesting seasons, indicating ideal harvesting times for different applications of the biomass.