Blanching of Two Commercial Norwegian Brown Algae for Reduction of Iodine and Other Compounds of Importance for Food Safety and Quality

Two commercially utilized kelp species, winged kelp (<i>Alaria esculenta</i>) and sugar kelp (<i>Saccharina latissima</i>), can accumulate high amounts of iodine and thereby pose a health concern if consumed in excess. Water blanching is used industrially to reduce the iodine content. This study aimed to optimize the blanching conditions to reduce the energy consumption and environmental impact by investigating the parameters of temperature, duration, use of sea or fresh water, biomass-to-water ratio, and recycling of water. The study investigated the impact of the blanching conditions on composition of the biomass, including nutrient content and potential toxic elements. The iodine content was reduced to 5% of the initial content for <i>S. latissima</i> and to 8% for <i>A. esculenta</i> at the optimal conditions in the present study, which was blanching in seawater at 80 °C for 2 min. Using tap water at the same conditions resulted in a reduction to 7 and 11% of the initial content. The content of arsenic in blanched winged kelp was reduced to levels below the maximum allowed content in feed, whereas the content in blanched sugar kelp remained above this level. This study provides a comprehensive set of data on blanching of the two kelp species, with high relevance for the industrial scale-up of kelp processing.