Abstract
We measured under various conditions the amount of total arsenic in cooked kombu and its soup for preparing kombu-tsukudani. We also examined the anti- oxidative capacity by using the peroxyl radical scavenging activity as its index. We found that the arsenic species eluted from kombu depended on the heating time and that its effect was strongly influenced by the seasoning added. The amount of total arsenic in kombu-tsukudani was less when it was cooked after replacing the soaking water with fresh water than with no replacement. However, the peroxyl radical scavenging activity in the water extract was maintained in the kombu-tsukudani when the soaking water was replaced with fresh water. The addition of vinegar and replacing the soaking water with fresh water reduced the total arsenic and retained unchanged the anti-oxidative capacity. This addition and replacement was clearly a good way of making kombu-tsukudani. The anti-oxidative capacity was also greatly increased when we added soy sauce and mirin, a type of seasoning, and condensed the boiled soup when making kombu-tsukudani.
