Seasonal variation in the composition and antioxidant potential of Codium tomentosum and Ulva lacinulata produced in a land-based integrated multi-trophic aquaculture system

Abstract In the context of the blue bioeconomy, macroalgae have gained widespread recognition in Europe as a renewable raw material with a wide range of uses, while also providing important ecosystem services. To reach its full potential, the macroalgae industry must diversify the species exploited. The green macroalgae Ulva lacinulata and Codium tomentosum are among several species currently cultivated at ALGAplus’ land-based integrated multi-trophic aquaculture (IMTA) system inserted in Ria de Aveiro, Portugal. This study aims to evaluate seasonal changes in the composition and antioxidant potential of the two cultivated species to assess their value as sea vegetables. To achieve this, samples of U. lacinulata and C. tomentosum were collected during different seasons and analyzed. The nutritional and mineral composition showed some marked differences across species and seasons. Ulva lacinulata contained more protein and dietary fiber, while C. tomentosum had a higher lipid content, particularly in polyunsaturated fatty acids. Codium tomentosum contained more minerals than U. lacinulata , except for magnesium and iron. Ulva lacinulata was richer in chlorophylls, carotenoids, and total phenols. Additionally, U. lacinulata displayed a higher antioxidant potential against ABTS +• and O 2 •- . The levels of heavy metals, namely, lead, cadmium, and mercury were below the limit defined for dietary supplements by EU regulations. Moreover, the levels of inorganic arsenic were below the limit recommended for edible macroalgae sold in France. According to current knowledge, recommendations and regulations, both species appear to have good potential as sea vegetables.