Radiocesium and potassium decreases in wild edible plants by food processing

Abstract

It is more than 4 years since March 11, 2011, and, at this stage, foods that exceed the standard limits of radiocesium are mainly from the wild. Hence, one of the public’s main concerns is how to decrease ingestion of radiocesium from foods they have collected from the wild as well as from their home-grown fruits because radioactivities in these food materials have not been monitored. In this study, we focused on wild edible plants and fruits, and the effects of washing, boiling, and pealing to remove radiocesium were observed. Samples were collected in 2013 and 2014 from Chiba and Fukushima Prefectures, e.g., young bamboo shoots, giant butterbur, and chestnuts. Wild edible plants were separated into three portions to make raw, washed, and boiled samples. For fruit samples (i.e., persimmon, loquat, and Japanese apricot), fruit parts were separated into skin, flesh, and seeds. It was found that washing of plants is not effective in removing both 137Cs and 40K, and that boiling provided different removal effects on plant tissues. The retention factors of 137Cs and 40K for thinner plant body sample (leaves) tended to be higher than those for thicker plant body types, e.g., giant butterbur petiole and bamboo shoots. Thus, the boiling time as well as the crop thickness affects radiocesium retention in processed foods. For fruits, Cs concentration was higher in skin than in fruit flesh for persimmon and loquat; however, Japanese apricot showed different distribution.