Abstract
Lettuce wrapped in unperforated PE film, perforated PE film, stretch film and without wrapping was stored at 1, 6, 20 and 28°C. Freshly harvested lettuce and after one day of storage, independently on storage conditions, did not contains nitrites„ During storage of lettuce at 1°C only one time small quantities of nitrites (4.3 mg NO2/kg fresh matter) were found - after twelve days storage in perforated PE film. Storage of lettuce longer than 7 days at 6°C caused formation of nitrites. Lettuce stored at 20 and 28°C in unperforated PE film contained nitrites already after 2 or 3 days of storage. Decline of nitrates during storage of lettuce was independent from film used to wrapping.