A whitish powder sometimes occurs on some of our sea vegetables, most often on sugar kelp and Alaria, and less often on dulse.  The product may arrive in this condition or it may develop during storage.  This is nothing to worry about!  People sometimes mistake this powder for mold, but it probably is not. To learn more about whether mold occurs on dried seaweed, click on this link "Moldy Seaweed" for a downloadable PDF on the topic, complete with photos.
As sea vegetables dry, salts and sugars often precipitate to the surface from the internal tissues. These salts and sugars are easily rinsed off, but they can also be safely eaten as is.  In kelp, the principle sugar is mannitol and the salts are predominantly potassium and sodium. Mannitol is less sweet than most other sugars, but it still adds a subtle flavor quality. Along with kelps’ high mineral content and naturally occurring glutamate, mannitol is why kelp makes beans taste so great, cook so quickly and digest so easily!
While we are more skilled than ever at handling all our sea veggies from harvest to packaging, they are not ultra-processed to the point of total control. This is actually one of their unique selling points: minimally processed whole foods, enzymes intact.