Assessment of the flavour of fresh uncooked onions by taste-panels and analysis of flavour precursors, pyruvate and sugars

Flavour in fresh onions is dominated by volatile sulphenic and thiosulphenic acids that are liberated once alk(en)yl cysteine sulphoxide (ACSO) flavour precursors are cleaved by the enzyme alliinase after tissue disruption. The levels of pyruvate and ACSOs in over 100 samples of onions marketed in t...

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Bibliographic Details
Published in:Journal of the science of food and agriculture 2005-01, Vol.85 (1), p.112-120
Main Authors: Crowther, Timothy, Collin, Hamish A, Smith, Brian, Tomsett, A Brian, O'Connor, David, Jones, Meriel G
Format: Article
Language:English
Subjects:
Allium cepa
Biological and medical sciences
Flavors
flavour
flavour precursors
Food industries
Food science
Fruit and vegetable industries
Fundamental and applied biological sciences. Psychology
marketing
Onions
pyruvate
strength
sugars
taste-panels
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Summary:Flavour in fresh onions is dominated by volatile sulphenic and thiosulphenic acids that are liberated once alk(en)yl cysteine sulphoxide (ACSO) flavour precursors are cleaved by the enzyme alliinase after tissue disruption. The levels of pyruvate and ACSOs in over 100 samples of onions marketed in the UK were measured, and compared with assessment by taste‐panels. There was a linear relationship between the content of ACSOs and pyruvate. Measurements of pyruvate indicated that the marketing classification of some types of onion did not correspond to their pyruvate levels. A significant linear relationship was found between a sensory measure of strength and pyruvate over the range 1.2–9.3 µmol pyruvate g−1 fresh weight. In most cases, when a flavour classification of sweet, mild or strong was applied to a sample of onions based on pyruvate content, the taste‐panels agreed with the categorization. The taste‐panels were unable to identify a sweet flavour in onions, except at low levels of pyruvate. Taste‐panels were able to define a likeability character (attractiveness of flavour) for onions, which correlated with the level of pyruvate. However, for some varieties, the flavour classification or likeability did not correspond to predictions based on pyruvate levels alone. Pyruvate measurements were seen as a suitable method for routine quality control once the characteristics of a variety of onion had been established, but initial evaluations should include well‐designed taste‐panel assessments. Copyright © 2004 Society of Chemical Industry
ISSN:0022-5142
1097-0010
DOI:10.1002/jsfa.1966