Raw edible seaweed harvested in the Galician coast (Northwestern Spain), including two red seaweed types (Dulse and Nori), three brown seaweed (Ko
mbu, Waka
me and Sea Spaghetti), one green seaweed (Sea Lettuce) and one
microalgae (Spirulina platensis) were studied to assess trace ele
ments bioavailability using an in vitro
method (si
mulated gastric and intestinal digestion/dialysis). Si
milarly, a cooked seaweed sa
mple (canned in brine) consisting of a
mixture of two brown seaweed (Sea Spaghetti and Furbelows) and a derived product (Agar–Agar) fro
m the red seaweed Gelidiu
mm sesquipedale, were also included in the study. The total trace ele
ment content as well as the non-dialyzable fractions was carried out after a
microwave acid digestion of the seaweed sa
mples by inductively coupled plas
ma-
mass spectro
metry (ICP-MS). The dialyzable fraction was deter
mined without any pre-treat
ment by ICP-MS.
PIPES buffer solution at a pH of 7.0 and dialysis membranes of 10 kDa molecular weight cut off (MWCO) were used for intestinal digestion. Accuracy of the method was assessed by analyzing a NIES-09 certified reference material (Sargasso seaweed). The accuracy of the in vitro procedure was established by a mass balance study which led to good accuracy of the whole in vitro process, after statistical evaluation (95 % confidence interval). The highest dialyzability percentages (100 ± 0.2 % ) were obtained for Dulse in Mn and V.