title: Thermal degradation of onion quercetin glucosides under roasting conditions.
abstract: Flavonoids are an important constituent of the human diet. In recent years, they have gained much attention due to their physiological properties, leading to an enormous increase in research on cancer prevention and reduction of cardiovascular diseases. Unfortunately, there is limited information about the fate of flavonoid glycosides during thermal treatment such as cooking, frying, roasting, etc. Such processing techniques may have an impact on the flavonoid structure, resulting in changes of the bioavailability and activity of the flavonoids. In this study, the stability of selected model and onion quercetin glycosides under roasting conditions (180 degrees C) was determined. The influence of the kind and position of the sugar moiety was investigated. As onions contain large amounts of quercetin glycosides and are often subject to thermal processes in food production, their major glycosides were isolated using counter current chromatography and roasted. The thermal treatment led to a degradation of the quercetin glycosides. The main product is the aglycone quercetin, which remained stable during further roasting. During the roasting process of the quercetin diglucoside isolated from onion, the formation of a monoglycoside as an intermediate product was observed. This underlined that the stability of the glycosides is dependent on the kind and position of the sugar moiety.
authors.affiliation: Department of Food Analysis, Institute of Food Technology and Food Chemistry, Technical University of Berlin, Gustav Meyer Allee 25, D-13355 Berlin, Germany. Sascha.Rohn@TU-Berlin.de
authors.forename: Sascha
authors.initials: S
authors.lastname: Rohn
authors.forename: Nadja
authors.initials: N
authors.lastname: Buchner
authors.forename: Gregor
authors.initials: G
authors.lastname: Driemel
authors.forename: Morten
authors.initials: M
authors.lastname: Rauser
authors.forename: Lothar W
authors.initials: LW
authors.lastname: Kroh
mesh_terms: D004355:Drug Stability; D005960:Glucosides / Q000737:chemistry*; D006358:Hot Temperature; D019697:Onions / Q000737:chemistry*; D018517:Plant Roots / Q000737:chemistry; D011794:Quercetin / Q000737:chemistry*; D013329:Structure-Activity Relationship
chemical_list: D005960:Glucosides; D011794:Quercetin