Articles
SUPPRESSION OF UNPLEASANT ODOR EMISSION FROM CUT GYPSOPHILA PANICULATA L. INFLORESCENCES BY ISOVALERATE ESTER FORMATION
Article number
766_66
Pages
493 – 500
Language
English
Abstract
The inflorescences of perennial gypsophila emit an unpleasant odor that makes them undesirable for indoor use.
The responsible compound is known to be 3-methylbutyric acid (isovaleric acid). To reduce the substrate availability and specificity of enzyme esterification (alcohol acetyltransferase; AAT), we investigated the reduction of the emission of methylbutyric acids a precursor of isovaleric acid, which alcohols to isovalerate esters.
Sensory evaluation revealed that the inflorescences treated exogenously with 0.05% isoamyl alcohol, benzyl alcohol and 2-phenylethyl alcohol had a weaker unpleasant odor than the control and this coincided with a decrease in methylbutyric acid emission.
Moreover, application of isoamyl alcohol facilitated the production of isoamyl isovalerate and consequently decreased methylbutyric acid emission.
Ethyl alcohol treatment was not effective to reduce the methylbutyric acid emission.
In the cell-free extract of open florets, only isoamyl alcohol was highly reactive with isovaleryl-CoA and ethyl alcohol was the least reactive.
Placing cut inflorescences under an anaerobic (N2) condition strongly suppressed the emission of methylbutyric acids and transferring them to an aerobic condition increased emissions of isoamyl alcohol and isoamyl isovalerate.
These results suggest that the substrate specificity of AAT and poor availability of reactive alcohol substrates, i.e., isoamyl alcohol, are two major factors limiting the volatile ester emission in gypsophila inflorescences.
The responsible compound is known to be 3-methylbutyric acid (isovaleric acid). To reduce the substrate availability and specificity of enzyme esterification (alcohol acetyltransferase; AAT), we investigated the reduction of the emission of methylbutyric acids a precursor of isovaleric acid, which alcohols to isovalerate esters.
Sensory evaluation revealed that the inflorescences treated exogenously with 0.05% isoamyl alcohol, benzyl alcohol and 2-phenylethyl alcohol had a weaker unpleasant odor than the control and this coincided with a decrease in methylbutyric acid emission.
Moreover, application of isoamyl alcohol facilitated the production of isoamyl isovalerate and consequently decreased methylbutyric acid emission.
Ethyl alcohol treatment was not effective to reduce the methylbutyric acid emission.
In the cell-free extract of open florets, only isoamyl alcohol was highly reactive with isovaleryl-CoA and ethyl alcohol was the least reactive.
Placing cut inflorescences under an anaerobic (N2) condition strongly suppressed the emission of methylbutyric acids and transferring them to an aerobic condition increased emissions of isoamyl alcohol and isoamyl isovalerate.
These results suggest that the substrate specificity of AAT and poor availability of reactive alcohol substrates, i.e., isoamyl alcohol, are two major factors limiting the volatile ester emission in gypsophila inflorescences.
Publication
Authors
M. Doi, H. Nimitkeatkai, K. Inamoto, Y. Ueda
Keywords
alcohol acetyltransferase, Gypsophila paniculata L., isoamyl alcohol, isovaleryl-CoA, methylbutyric acid
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