Abstract
The aim of this work was to evaluate the potential of ultrasound (US), alone or in combination with mild heating and/or EDTA towards reduction of As, Cd, I, and Hg content of Laminaria hyperborea. Concentrations of As, Cd, I, and Hg of 56.29, 0.596, 7340, and <0.01 mg kg−1 of dry weight, respectively, were found in L. hyperborea blades. Treatment with US at 50 °C increased approx. 2-fold the amount of As released, although did not affect significantly the content of Cd or I, as compared to control (no US) samples. Reducing the temperature to 8 °C significantly decreased the effect of US, but heating at 80 °C did not cause a significant effect as compared to treatments at 50 °C. On the other hand, treatment with 0.1 N EDTA at 50 °C enhanced the percentage of Cd released by approximately 7-fold, regardless of sonication. In the present work, the combination of US and EDTA at 50 °C for 5 min led to a significant reduction of the As (32%), Cd (52%) and I (31%) content in L. hyperborea, thus improving the product’s safety for consumers.
Highlights
Seaweeds have constituted a very relevant and recognized part of the diet in certain parts of the world, such as Japan, China and Korea, for centuries or even millennia [1]
Despite the content of Hg being below the IPC-MS detection limit, the levels determined for the remaining compounds fall within the concentration ranges reported in the literature for L. hyperborea and other brown macroalgae [16,23,48,49,50,51]
To avoid interferences in the analytical determinations derived from such a high biological variability in the raw material, the amount of heavy metals and iodine released into the rinsing media was measured rather than the remaining levels in the blades after the respective treatments, as already described elsewhere [46]
Summary
Seaweeds have constituted a very relevant and recognized part of the diet in certain parts of the world, such as Japan, China and Korea, for centuries or even millennia [1]. Health-promoting effects have been associated to direct seaweed consumption and the use of their extracts/components as processing aids (e.g., as hydrocolloids, emulsifiers and/or gelling agents) and dietary supplements [5,7,8,9,10,11]. Their substantial bio-sorption and bio-accumulation capacity [12], that of brown algae species such as Laminaria hyperborea, may increase the dietary exposure to potentially harmful compounds. It should be noted that levels of heavy metals and iodine in seaweeds have been reported to substantially vary across species, location, season, and growth-related factors [21,22,23,24]
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