Feature annotation was based on the identification levels from Schymanski et al. but with Level 3 split into four sublevels. Features with a library match but for which the correct isomer structure was unknown were labeled as Level 3a. Features annotated using in silico fragmentation were assigned as Level 3b if a tentative structure was known, and Level 3c if the elucidated isomer was unknown. Finally, features that were putatively annotated by monoisotopic matching only were assigned a Level 3d. For polyphenol related features, a total of 8, 18, 70 and 112 features were assigned to Levels 3a-d, respectively. Additionally, 26 features were annotated as Level 2 and 11 features could be fully identify at Level 1. All of the identified and annotated polyphenolic features are listed in Table . From these 245 features, 89 were assigned to phenolic acids, 24 to flavonoids, and 132 to non-flavonoids. These results are displayed in Figure .