Czech J. Food Sci., 2015, 33(5):405-409 | DOI: 10.17221/622/2014-CJFS

The "Breme" red onion: effects of home-storage methods on quercetin and quercetin-glycoside contentsFood Chemistry and Safety

Elena DOZIO¹, Alessandra BARASSI², Alessandro RAVELLI³, Ilaria ANGELI³, Franco LODI³, Gian Vico MELZI d'ERIL², Massimiliano M. CORSI ROMANELLI^1,4

¹ Department of Biomedical Sciences for Health

² Department of Sciences for Health

³ Department of Biomedical, Surgical and Oral Sciences, Forensic Toxicology Section, University of Milan, Milan, Italy

⁴ Service of Laboratory Medicine 1-Clinical Pathology, Department of Health Services of Diagnosis and Treatment-Laboratory Medicine, I.R.C.C.S. Policlinico San Donato, Milan, Italy

The "Breme" onion is a red-skinned cultivar growing in the northwest Italy. To date, its nutrient composition has not been described. In this study, we quantified the contents of quercetin (Q) and its glycosides and we studied their stability in the dependence on the local home-storage methods storage at 4°C and freezing. Quercetin-3,4'-O-diglycoside (3,4'-Qdg) was the most abundant form, followed by quercetin-4'-O-diglycoside (4'-Qmg ) and Q. We observed the reduction in the contents of all the analysed flavonols after storage at 4°C and after storage in frozen state. No changes have been observed in the ratio Q/3,4'-Qdg + 4'-Qmg, as well as in 3,4'-Qdg /4'-Qmg between the fresh, stored at 4°C, and frozen onions. This could suggest an overall condition of instability, not the activation of a selective deglycosylation pathway. In conclusion, our study shows that the "Breme" onion is mainly rich in 3,4'-Qdg and that home-storage methods do not preserve the stability of some important health-promoting molecules.

Keywords: Breme onion; home-storage methods; HPLC-MS, MS; quercetin; quercetin glycosides

Published: October 31, 2015  Show citation