Identification of phenolic components in dried spices and influence of irradiation

LC-ESI-MS analysis was used for identification of phenolic compounds in the methanolic extracts of commercially available dried oregano, sage and thyme. Rosmarinic acid, apigenin-glucuronide, luteolin-glucuronide, as well as quinic acid were present in all three spices. Whereas in thyme and sage only derivatives from flavonoid compounds were identified, in oregano also the aglycons eriodictyol, naringenin, hispidulin, apigenin and luteolin could be found. Some constituents, especially glucosides and glucuronides, were observed for the first time in the methanol extracts of these spices. To ascertain an irradiation influence (dose: 10kGy) the MS peak area counts of twenty constituents, among them 10 glycosides/glucuronides, were compared. Although the majority of those compounds exhibited a slight decrease with irradiation, the changes were not significant.