Changes in Vitamin C Content of Different Parts;of Broccoli (Brassica oleracea var. italica) After Cooking

Abstract

　Broccoli (Brassica oleracea var. italica) has a high vitamin C (VC) content, which can be reduced during the cooking process. We therefore compared two methods, vacuum cooking and boiling, with respect to changes in VC content. We cut the broccoli, and divided it into 4 edible parts: the florets, branches, and inner and outer parts of the stalk. Thereafter, we applied the two cooking methods to the prepared broccoli samples, and analyzed the VC content using the post-column derivatization method. Samples were analyzed for total VC content/100g fresh weight. For raw samples, the VC content was greatest in the branches, followed by the inner stalk, florets, and outer stalk. Significantly more VC remained after vacuum cooking than boiling in all 4 parts based on the reduced VC content eluted out under vacuum cooking (p＜0.01). The sterilization process before vacuum-sealed packaging reduced the VC content in florets, whereas sterilization of the other 3 parts (branches, inner stalk, and outer stalk) showed minimal reduction of VC content (p＜0.05). We concluded that the major factors maintaining VC content during vacuum cooking are control of the outflow of VC in the cooking water and deactivation of enzyme decomposition of VC by sterilization.