In general, white cabbage heads are cultivated in an open field.
Only the minor part of the leaves of round compact cabbages is
exposed to sun light and secondary plant compound formation,
such as polyphenols, are only influenced in the outer leaves by
UV-B radiation. However, the outer leaves carry no weight in food
production, such as coleslaw or sauerkraut. In addition, in most
cases, the outer leaves will be discarded prior to cabbage processing
and treated as waste as described by Nilnakara, Chiewchan, and
Devahastin (2009). However, cabbage processing sometimes
includes further postharvest processing steps like sun exposure
(‘plant withering’ before fermentation) as used for the traditional
Chinese cabbage fermentation (also named ‘pickling‘ of headless
cabbages like pak choi), and this might influence the contents of
bioactive compounds