European aquaculture of sugar kelp (Saccharina latissima) for food industries: iodine content and epiphytic animals as major problems

There is little use of cultivated kelp including Saccharina latissima (syn. Laminaria saccharina) in the European food industry, in contrast to the extensive use of Pyropia (syn. Porphyra) as Nori, e.g. in sushi restaurants. A major reason for this discrepancy is possibly the extremely high iodine content in laminarian species, i.e. 3-10 g I kg(-1) dry weight, in contrast to the situation in Pyropia with its approximately 10 times lower iodine content. Another serious problem for commercial use of S. latissima from rope culture for food is the presence of epiphytic animals on the blades from May onwards as an unwanted food addition. This investigation presents data on iodine content in commercial samples of S. latissima, with indications of lower iodine values from rope cultivation in the Kattegat (Baltic) at reduced salinities, and in general from tank cultivation, possibly mainly due to rapid iodine depletion of seawater in the tanks. Boiling dried blades for several minutes in fresh water resulted in a reduction of the iodine content to approximately one third of the initial value after 2 min. Results from rope cultures in a Norwegian fjord showed the presence of epiphytic animals from early May onwards in the sea, which ruined the food quality of the blades, but the complete absence of such animals throughout the year in parallel tank-grown S. latissima, probably mainly due to mechanical prevention of larval settlement in tank tumble culture.