Changes of phenolic content in rapeseed during preliminary drying

Abstract

Drying of rapeseed represents one of the most important elements in the complexity of actions defined as
the “post-cropping” process. This work investigates how drying of the rapeseed at low and high temperature
influences the bioactive compounds (phenolic acids). Samples of rapeseed (Kronos and Lisek variety) were
dried at 60, 80, 100, and 120C and low temperature (layer 2 and 12). In methanolic extracts total phenolic
content was determined using Folin-Ciocalteu reagent and composition of free phenolic acids was determined
by HPLC. Obtained results showed that the most unfavourable influence on the native hydrophilic antioxidant
content was observed after drying at 60 and 80oC. Seed dried at these temperatures are characterized by
highest decrease of total phenolic compounds and free phenolic acid content. Probably it is caused by the
activity of enzymes (phenoloxidaze) that display optimal functional activity at this temperature.