[Aluminum contents in dried and cooked sea vegetables]

Regarding aluminum contents in sea vegetables, dried hijiki (an edible brown algae), dried wakame (seaweed) and dried konbu (kelp) contained 1.08mg/g, 17.7 to 149 micrograms/g, and 4.23 to 24.5 micrograms/g, of aluminum, respectively. With hijiki, especially, having a high aluminum content. Hijiki reconstituted by water immersion contained 450 to 678 micrograms/g, of aluminum. Thus, aluminum in dried hijiki was decreased by 40 to 66% by water immersion. The immersion water of blanched and salted wakame and fruit-bearing leaf wakame contained 4.67 to 6.92 micrograms and 1.00 microgram of aluminum, respectively. The migration ratio of aluminum was 8 approximately 12% for blanched and salted wakame and was 1% for fruit-bearing leaf wakame. The immersion water of Hidaka konbu contained 16.1 to 21.4 micrograms of aluminum, while that of Rishiri konbu contained 4.79 to 7.36 micrograms of aluminum. Thus, 22 to 57% of aluminum migrated into the konbu immersion water. Aluminum scarcely migrated into the supernatant of the immersion water. Compared with the cold water immersion method, a high aluminum migration ratio was achieved in the heat extraction method. It was estimated that the aluminum intake from reconstituted hijiki (dry weight: 5g) was about 2.2 to 3.4mg, which amounted to 50 to 75% of the daily aluminum intake of a typical Japanese diet.