The material investigated consisted of fresh kale (B. oleracea L.
var acephala) leaves; leaves after blanching; leaves after cooking to
consumption consistency; frozen products stored at a temperature
of 20 C and 30 C; sterilized canned products; leaves after hot
air-drying and after freeze-drying. The various products were
evaluated after 12 months of storage. The kale cultivar under
investigation was Winterbor F1, produced by the Dutch firm Bejo
Zaden b.v. (Netherlands). Kale was grown from seedlings planted in
an experimental field located in southern Poland