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Quercetin content in yellow onion (Allium cepa L.)

effects of cultivation methods, curing and storage

Mogren, Lars (2006). Quercetin content in yellow onion (Allium cepa L.). Diss. (sammanfattning/summary) Alnarp : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae, 1652-6880 ; 2006:96
ISBN 91-576-7145-1
[Doctoral thesis]

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Abstract

Flavonoids are polyphenolic substances that are common in many fruits and vegetables and may have positive protective effects against e.g. cardiovascular disease and some forms of cancer. These effects have mainly been attributed to their antioxidative properties. One of the most common flavonoids in food plants is quercetin, of which yellow onion (Allium cepa L.) is one of our main dietary sources. The effects of cultivars, nitrogen fertiliser level, lifting time, curing, cultivation system and storage conditions on the quercetin content in yellow onion are investigated in this thesis. Analyses were performed using reversed-phase HPLC after extraction of raw onion samples in ethanol. The main determinant of quercetin level was found to be the amount of global solar radiation during the end of the bulbing phase in August. Annual variations in quercetin content were higher than any treatment effect within each year. Cultivar differences in quercetin levels were significant but inconsistent. Early lifting, when 50% of the onions had fallen leaves, resulted in onions with better keeping quality and equal quercetin content compared with onions with later lifting times. Minimised split application of nitrogen fertilisers reduced the risk of mineral nutrient leaching without lowering the yield or quercetin content. Field curing generally resulted in significant increases in quercetin content compared with levels at lifting. The role of onion size for quercetin content was inconsistent but of minor importance. Quercetin levels were stable during cold storage at constant temperature. No significant differences were found between inorganically fertilised and organically fertilised onions of the same cultivar or between directly sown and transplanted onions. Quercetin content and soil water content within the field were not correlated.

Authors/Creators:Mogren, Lars
Title:Quercetin content in yellow onion (Allium cepa L.)
Subtitle:effects of cultivation methods, curing and storage
Year of publishing :2006
Volume:2006:96
Number of Pages:42
Papers/manuscripts:
NumberReferences
ALLI. Mogren, L.M., Olsson, M.E. & Gertsson, U.E. 2006. Effects of cultivar, lifting time and nitrogen fertiliser level on quercetin content in onion (Allium cepa L.) at lifting. Journal of the Science of Food and Agriculture. In press. II. Mogren, L.M., Olsson, M.E. & Gertsson, U.E. 2006. Quercetin content in field-cured onions (Allium cepa L.): Effects of cultivar, lifting time, and nitrogen fertilizer level. Journal of Agricultural and Food Chemistry 54, 6185-6191. III. Mogren, L.M., Olsson, M.E. & Gertsson, U.E. 2006. Quercetin content in stored onions (Allium cepa L.): Effects of storage conditions, cultivar, lifting time and nitrogen fertiliser level. Submitted. IV. Mogren, L.M., Olsson, M.E., Caspersen, S. & Gertsson, U.E. 2006. Quercetin content in organically fertilized onions (Allium cepa L.): Effects of mycorrhizal inoculation and fertilizer placement. Manuscript.
Place of Publication:Alnarp
Associated Programs and Other Stakeholders:Z - SLU - Libray > Odla mera
ISBN for printed version:91-576-7145-1
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:allium cepa, quercetin, organic fertilizers, inorganic fertilizers, polyphenols, hplc, antioxidants, controlled atmosphere storage, cropping systems
Keywords:fertiliser level, flavonoids, polyphenols, antioxidants, lifting stage, global radiation, organic fertiliser, inorganic fertiliser, HPLC, onion, Allium cepa, cultivar, nitrogen, quercetin, storage
URN:NBN:urn:nbn:se:slu:epsilon-1268
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-1268
ID Code:1246
Department:?? 4806 ??
Deposited By: Lars Mogren
Deposited On:08 Nov 2006 00:00
Metadata Last Modified:22 Mar 2015 15:12

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