Effect of ultra high temperature processing and storage conditions on phenolic acid, avenanthramide, free fatty acid and volatile profiles from Australian oat grains

The present study examines the influence of ultra high temperature (UHT) treatment and storage conditions (22 and 40 °C) on the phenolic acid and avenanthramide composition of oat samples during 12-week shelf life. The evolution of free fatty acid and volatile compounds is also investigated due to their impact on storage quality. Ferulic acid is found as the most abundant phenolic acid in oat samples followed by p-coumaric acid. Chromatographic analysis also detects the presence of major avenanthramides (A, B and C), free fatty acids (palmitic, oleic and linoleic acids), and volatiles (hexanal and 2-pentyl furan) in our materials. Following UHT treatment, total phenolic content (TPC), phenolic acids, avenanthramides and free fatty acids were reduced. However, prolonged storage of the UHT-treated preparations at ambient temperature has a positive effect on the content of TPC, phenolic acids, avenanthramides, free fatty acids and volatile compounds. In contrast, extended storage at a higher temperature (40 °C) leads to a decrease in the TPC and phenolic acid content, with the levels of avenanthramides and volatiles increasing with time. Overall, UHT treatment and storage conditions have a considerable effect on the composition of bioactive compounds in oat samples of industrial interest.