Farming a wild seaweed and changes to its composition, bioactivity, and bioaccessibility: The Saccorhiza polyschides case study

The nutritional value, elemental and fatty acid composition as well as key biological activities were determined in a large brown seaweed species (Saccorhiza polyschides, abundant in European shores), taking into account the effects of wild vs farmed and land-based vs open sea Integrated Multi-Trophic Aquaculture (IMTA) system dichotomies.The results showed that S. polyschides has significant amounts of relevant nutrients, some biological activity (anti-inflammatory), high contents of the essential elements Se (1.07–1.79 mg/kg dw) and I (367–522 mg/kg dw), and a high bioaccessibility of I. However, As levels should be monitored, given their high bioaccessibility (∼60–70% range), and I levels may translate into excessive I intake if too much seaweed is consumed (if daily consumption of dried S. polyschides exceeds 3 g dw). Regarding the wild-farmed dichotomy, wild S. polyschides had a moderately higher nutritional value, including a better ω3/ω6 ratio, but a lower Se content than farmed S. polyschides, 0.80 ± 0.01 vs 0.58–0.69 and 1.07 ± 0.05 vs 1.16–1.79 mg/kg dw, respectively. Furthermore, bioaccessibility of elements was not much affected by cultivation. Concerning land-based vs open sea IMTA, in comparison to S. polyschides in earthen ponds, lower Hg and Pb contamination, but higher Cd levels were determined in the seaweed cultivated in open sea. S. polyschides farming per se did not have a large deleterious impact on the characteristics of this edible seaweed and may ensure the production of large amounts of algal biomass for feed, food, and nutraceutical applications.