To elucidate the effect of processing methods on the iron content of hijiki produced from the west coast of the Izu Peninsula, we analyzed the iron content and tested its correlation with the boiling time in an iron pot or the boiling and holding times in the iron pot. The iron content of the dry material of hijiki averaged 112.0±50.2 mg/100 g dry matter, and the iron content of the products processed in the iron pot was higher than that of the dry material, averaging 112.0±50.2 mg/100 g. There was no correlation between the iron content of the products and the boiling time, whereas a positive correlation was found between the boiling and holding times in the iron pot. Based on our findings, hijiki products from the west coast of the Izu Peninsula that were processed in an iron pot had a higher iron content than other sources of hijiki, and it was due not only to the length of the boiling time in the iron pot, but also the length of the holding time.
