Signe H. Nissen1,2, Louise J. Pedersen1,2, Annette Bruun2,3, Jens Søndergaard4 and Trine K. Dalsgaard1,2,5
1 Dept. of Food Science, Aarhus University, Agro Food Park 48, 8200 Aarhus N, Denmark 2 CBIO, Aarhus University Centre for Circular Bioeconomy, 8000 Aarhus C, Denmark 3 Department of Ecoscience, Aarhus University, CF Møllers Alle 3, 8000 Aarhus C, Denmark 4 Department of Ecoscience, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark 5 CiFOOD, Aarhus University Centre for Innovative Food Research, 8000 Aarhus C, Denmark
The green seaweed Ulva is a promising protein source for food production. Various factors can affect the biochemical composition, which can complicate the utilisation on a commercial scale, where a uniform biomass supply is advantageous. This study investigates the composition of Ulva spp. harvested in a Danish fjord in May, June and August 2021. The August harvest was furthermore divided into different colours (Light green, green and dark green/black) to explore a relation between colour and composition, which have not been documented so far. Dry matter (DM), crude protein (CP), fat, ash, and element composition were investigated. DM was highest in May and August (15%), whereas the June harvest was lower (7%). For the different colour fractions, DM increased with a darker colour. The CP and ash contents were highest in the dark biomass (15% and 34%, respectively) and concerning season variation, the May harvest showed the highest content (20% CP and 40% ash), which correlates with a predominantly dark colour. The ash content decreased with a lighter colour. The June harvest was mostly light green, corresponding with the lower CP content in the light green fraction from August (June 6% and light green 7% CP). Fat content ranged between 0.9-2.2% and a higher fat content was correlated with a lighter biomass colour. P and K was highest in the green fraction, whereas the darker biomass was higher in all other elements. This study shows that colour coding can be used as an indicator for the chemical composition.