Analysis of phytate in raw and cooked potatoes

The phytate (myo-inositol hexakisphosphate) contents of eight varieties of potato (Solanum tuberosum) stored at 4°C for approximately 3 months ranged from 0.111% to 0.269% of dry weight. The phytate was distributed evenly throughout raw unpeeled russet potatoes. There were no significant differences in phytate content between raw russet potatoes and those which had been boiled, baked or microwaved until fully cooked. French fries, potato chips and dehydrated potato flakes contained 0.174%, 0.095% and 0.205% phytate, respectively, on a dry weight basis. Only phytate was detected in raw russet potatoes, but smaller amounts of inositol pentakisphosphate were also present in the fries, chips and flakes. Sufficient phytate is consumed in cooked potatoes in the United States to comprise a substantial portion of the daily intake of this multifaceted phytochemical.