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Metallic odour caused by vinyl ketones formed in the oxidation of butterfat. the identification of octa‐1, cis ‐5‐dien‐3‐one
Author(s) -
Swoboda Peter A. T.,
Peers Kenneth E.
Publication year - 1977
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740281111
Subject(s) - butterfat , chemistry , metal , dilution , organic chemistry , chromatography , nuclear chemistry , milk fat , physics , thermodynamics , linseed oil
Oct‐1‐en‐3‐one and the more potent octa‐1, cis ‐5‐dien‐3‐one have been identified as being responsible for the metallic odour which developed when a model system containing butterfat, α‐tocopherol and cupric palmitate was allowed to oxidise at 35°C for 35 h. These vinyl ketones were synthesised, their mass and n.m.r. spectra determined, and odour descriptions and odour thresholds assessed. Octa‐1, cis ‐5‐dien‐3‐one in aqueous solution could be detected at a dilution of 1 in 10 12 . Its metallic odour was also described as like geranium leaves. Oct‐1‐en‐3‐one (detectable at 1 in 10 10 dilution) was described as mushroom like at low concentrations and only exhibited a metallic odour at higher concentrations. Both compounds had an odour threshold concentration about five hundred times greater in groundnut oil than in water. The significance of these compounds is discussed with reference to the published literature and their formation from ( n ‐3) and ( n ‐ 6) polyenoic fatty acids.