Identification of Key Odour Components in Pig House Air using Hyphenated Gas Chromatography Olfactometry

P. Kai, A. Schäfer


The exposure to odorants from animal production facilities creates a serious problem in the
form of odour annoyance for the surrounding society and thus for the agricultural industry.
The identification of the key odour components responsible for the odour annoyance is
important in the search for odour reducing methods and could be useful for quantitative
purposes as well.
The objective of the present study was to investigate the application of the hyphenated gas
chromatography olfactometry technique (GCO) called Detection Frequency Analysis for the
identification of key odour components in an odorous air sample collected in a
grower/finisher pig house. Detection Frequency Analysis is based on a combination of gas
chromatography and a human panel sniffing to odours eluting from the gas chromatographic
The human sniffing panel detected 25 odours from a grower/finisher pig house air extract.
Subsequent gas chromatography mass spectrometry (GC-MS) analysis resulted in the
identification of propanoic acid, 2-methylpropanoic acid (iso-butanoic acid), butanoic acid,
octanoic acid, 4-methylphenol (p-cresol), indole, and possibly skatole. The odour components
identified in the present study are in agreement with published data on key odour
components. Many of the odours found by the odour panel could not be positively identified
by GC-MS, which suggests that the olfactory sense of the human subjects may have been
more sensitive than the applied GC-MS method.
The method applied in the present study does not take into account possible interactions
between odour components. Validation of the identified key odour components may be
performed by comparing a recombined odour based on a mixture of the identified key odour
components and a real odour sample.
Further studies will reveal if additional key odour components can be identified using GC
methods and if different animal categories and/or housing systems differ with regards to key
odour components.

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