Stability of total folates/vitamin B9 in irradiated watercress and buckler sorrel during refrigerated storage

The suitability of post-packaging gamma radiation treatment for preserving total folates or vitamin B9 in watercress (Nasturtium officinale R. Br.) and buckler sorrel (Rumex induratus Boiss. & Reut.) during storage at 4 °C was evaluated. Comparable amounts of total folates were found in fresh, non-stored samples of both species. In watercress, the irradiation treatment of up to 5 kGy reduced the loss of total folates caused by 7 days of storage. In turn, the 12-day storage period did not affect the total folate content of buckler sorrel (while the 2 kGy dose decreased the initial levels), evidencing that packaging and refrigeration are enough for preservation. These results suggest that the suitability of post-packaging irradiation for preserving total folates may depend not only on the applied dose but also on the plant matrix under analysis. In addition, new data useful to complete food composition tables or databases is provided.