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Research article2007Peer reviewed

Effects of cultivar, lifting time and nitrogen fertiliser level on quercetin content in onion(Allium cepa L.) at lifting

Mogren LM, Olsson ME, Gertsson UE

Abstract

Commercial cultivars of onion (Allium cepa L.) were grown at Torslunda research station, Sweden with different levels of nitrogen fertiliser and lifted at different growth stages. Soon after lifting, before any drying or curing, tissue from the fleshy edible part of onions was extracted in ethanol and the raw extracts were analysed by high-performance liquid chromatography without any previous hydrolysis. It was confirmed that the main flavonoid compounds were quercetin monoglucoside and quercetin diglucoside, whereas only trace amounts of quercetin aglycone and other flavonoids were found. The greatest variation in quercetin content, in the range 100-500 mg kg(-1) fresh weight, occurred between years. The concentration of quercetin glucosides in the onions was strongly correlated (R-2 = 0.98) with the total amount of global radiation in August. Individual onions with fallen leaves had significantly higher concentrations of quercetin glucosides than individuals in the same row with erect leaves. Only minor differences were found between the three cultivars analysed. Higher levels of nitrogen fertiliser had only minor effects on onion yield and size and resulted in lower or equal amounts of quercetin glucosides. Nitrogen leakage from the soil, a potential source of environmental problems, could therefore be minimised by avoiding high nitrogen fertiliser levels with almost no effect on onion flavonol content. Late lifting of onions (80% fallen leaves) resulted in up to 45% higher concentrations of quercetin glucosides compared with early lifting (50% fallen leaves). (c) 2006 Society of Chemical Industry

Published in

Journal of the Science of Food and Agriculture
2007, Volume: 87, number: 3, pages: 470-476
Publisher: JOHN WILEY & SONS LTD

      SLU Authors

    • Mogren, Lars

      • Horticulture, Swedish University of Agricultural Sciences

      • Olsson, Marie

        • Horticulture, Swedish University of Agricultural Sciences

        • Gertsson, Ulla

          • Horticulture, Swedish University of Agricultural Sciences

        UKÄ Subject classification

        Food Science

        Publication identifier

        DOI: https://doi.org/10.1002/jsfa.2735

        Permanent link to this page (URI)

        https://res.slu.se/id/publ/14908