Influence of the chemical structure on odor qualities and odor thresholds in homologous series of alka-1,5-dien-3-ones, alk-1-en-3-ones, alka-1,5-dien-3-ols, and alk-1-en-3-ols

Article abstract of DOI:10.1021/jf404885j

Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-ols and their corresponding ketones were evaluated by gas chromatography-olfactometry. In the series of the alk-1-en-3-ols and alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic, vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms. With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants, respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.

Full text of DOI:10.1021/jf404885j

Article
pubs.acs.org/JAFC
Influence of the Chemical Structure on Odor Qualities and Odor
Thresholds in Homologous Series of Alka-1,5-dien-3-ones, Alk-1-en-
3-ones, Alka-1,5-dien-3-ols, and Alk-1-en-3-ols
Katja Lorber,#,† Peter Schieberle,§ and Andrea Buettner*,#,†
#Department of Sensory Analytics, Fraunhofer Institute for Process Engineering and Packaging (IVV), Giggenhauser Strasse 35,
85354 Freising, Germany
†Department of Chemistry and Pharmacy, Emil Fischer Center, Friedrich-Alexander University Erlangen-Nurnberg, Schuhstrasse 19,
̈
91052 Erlangen, Germany
§Chair for Food Chemistry, Technical University of Munich, Lise-Meitner-Straße 34, 85354 Freising, Germany
S
* Supporting Information
ABSTRACT: Odor qualities and odor thresholds in air in homologous series of synthesized alk-1-en-3-ols and alka-1,5-dien-3-
ols and their corresponding ketones were evaluated by gas chromatography−olfactometry. In the series of the alk-1-en-3-ols and
alk-1-en-3-ones the odor quality changed successively from pungent for the compounds with five carbon atoms via metallic,
vegetable-like for the six- and seven-carbon odorants to mushroom-like for the compounds with eight and nine carbon atoms.
With further increase in chain length the mushroom-like impression decreased and changed to citrus-like, soapy, or herb-like. In
both series, two odor threshold minima were found for the six-carbon and also for the eight- and nine-carbon odorants,
respectively. In contrast to this, the odor qualities in the series of the (Z)- and (E)-alka-1,5-dien-3-ols and their corresponding
ketones did not change significantly with geranium-like, metallic odors and an increasing mushroom-like odor note with
increasing chain length. The lowest thresholds were found for the eight- and nine-carbon (Z)-compounds, respectively.
KEYWORDS: vinylketones, gas chromatography−olfactometry, odor threshold
present work was to provide sensory and analytical data on
homologues of these unsaturated oxo-compounds to sift out
new highly odor-active compounds and to ease their future
investigation. Specifically, the aim of the present study is to
provide comparative data on the respective odor qualities as
well as absolute odor thresholds in air to elucidate structure−
odor activity relationships of the target compounds.
Odor thresholds have been previously determined in
different ways. Besides the determination with odor delivery
tools as olfactometers,15−17 the odorant of interest is also
applied in defined concentrations (ng/L air, for example) to an
odor test room where the subject is placed.18 However, the
actual concentrations that are delivered by these techniques
have been commonly not proven by means of gas phase
determinations and have been demonstrated to be at times a
critical issue.19 Gas phase partitioning, as in the case of the
testing room scenario, as well as losses due to insufficient
vaporization, condensation, or adsorption in the delivery lines
of the odor dosing devices or depletion due to continuous
stripping of the delivered odorant from the source might be
potential reasons for errors, as could be recently demonstrated
by means of gas phase odorant determination involving proton
transfer reaction mass spectrometry (PTR-MS).19 Apart from
that, odorous contaminants may influence the threshold
INTRODUCTION
■
A broad variety of important food odorants originate from lipid
oxidation processes and are widely distributed in nature. The
highly odor-active compounds (Z)-octa-1,5-dien-3-one and oct-
1-en-3-one are two of these potent aroma compounds, eliciting
metallic, geranium-like, and mushroom-like odor qualities.
They were described as metallic oxidation products in dairy
products and in butter fat1,2 and as key odorants in
mushrooms3 and were identified later in numerous food
materials as important aroma contributors.4 (Z)-Octa-1,5-dien-
3-one was also found to participate in the formation of off-
flavors such as the reversion flavor of soybean oil5 or off-
odorant in milk.6 The enzymatic formation of these ketones as
well as their corresponding alcohols by lipoxygenase-catalyzed
conversion of linoleic and linolenic acid was shown
previously.3,7 Furthermore, the ketones were also found to
originate from the autoxidative decomposition of linoleate8 and
linolenate,9 respectively. Whereas (Z)-octa-1,5-dien-3-one
remained up to now the only (Z)-alka-1,5-dien-3-one found
in nature, several other homologous compounds from the series
of alk-1-en-3-ones and alk-1-en-3-ols were identified in foods,
such as pent-1-en-3-one, hex-1-en-3-one, hept-1-en-3-one, and
non-1-en-3-one.10−13 Interestingly, (Z)-undeca-1,5-dien-3-ol,
besides (Z)-octa-1,5-dien-3-ol, was reported as a fish aroma
constituent,14 indicating that other members of the series of the
(Z)-alka-1,5-dien-3-oxo compounds, and maybe also (E)-alka-
1,5-dien-3-oxo compounds, do possibly exist in nature.
However, due to their presumably low concentrations they
might not yet be identified. For this reason, the aim of the
Received: October 30, 2013
Revised: January 15, 2014
Accepted: January 15, 2014
Published: January 15, 2014
© 2014 American Chemical Society
1025
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
Figure 1. Synthetic routes leading to the (Z)-alka-1,5-dien-3-oxo compounds.
determination. A way to avoid such bias is to apply
determination by gas chromatography−olfactometry, thereby
involving an additional separation step so that odor threshold
determination can be focused solely on the substance of
interest. This methodology has been used for odor threshold
determination in a series of studies in conjunction with20,21 or
without22 an internal odorous standard, for example, (E)-dec-2-
enal,20,21 to correct for potential interindividual variations in
sensitivity or odorant delivery. The latter has been used in a
series of determinations until today and, accordingly, serves as a
reference technique that allows for comparison of odor
properties between substances and also between determina-
tions in different laboratories.23−25
Figure 2. Synthetic route leading to the alk-1-en-3-oxo compounds.
(Z)-Hepta-1,5-dien-3-ol, (Z)-Nona-1,5-dien-3-ol, (Z)-Dodeca-
1,5-dien-3-ol, (Z)-Hepta-1,5-dien-3-one, (Z)-Nona-1,5-dien-3-
one, (Z)-Dodeca-1,5-dien-3-one. The target compounds were
synthesized by stereospecific reduction of pent-3-yn-1-ol, hept-3-yn-
1-ol, or dec-3-yn-1-ol, respectively, as described previously for the
synthesis of (Z)-hex-3-en-1-ol,33,34 followed by oxidation of the
resulting (Z)-alk-3-en-1-ols to the corresponding (Z)-alk-3-enals using
Dess−Martin periodinane.31,32 A subsequent Grignard-type reaction of
the aldehydes with vinylmagnesium bromide gave the (Z)-alka-1,5-
dien-3-ols; their oxidation using Dess−Martin periodinane revealed
the corresponding dienone (Figure 1).
Accordingly, the following study has been based on this
approach for elaborating the respective odor properties of the
compounds investigated within this study.
(Z)-Deca-1,5-dien-3-ol, (Z)-Undeca-1,5-dien-3-ol, (Z)-Deca-
1,5-dien-3-one, (Z)-Undeca-1,5-dien-3-one. (Z)-Deca-1,5-dien-3-
one and (Z)-undeca-1,5-dien-3-one were synthesized by oxidation of
(Z)-oct-3-en-1-ol or (Z)-non-3-en-1-ol using Dess−Martin period-
inane31,32 followed by a Grignard-type reaction of the obtained
aldehydes with vinylmagnesium bromide to yield (Z)-deca-1,5-dien-3-
ol or (Z)-undeca-1,5-dien-3-ol. Subsequent oxidation with Dess−
Martin periodinane gave the corresponding ketones (Figure 1).
(Z)-Trideca-1,5-dien-3-ol, (Z)-Tetradeca-1,5-dien-3-ol, (Z)-Tri-
deca-1,5-dien-3-one, (Z)-Tetradeca-1,5-dien-3-one. (Z)-Trideca-
1,5-dien-3-ol and (Z)-tetradeca-1,5-dien-3-ol were synthesized by
reaction of s-trioxane with undec-1-en-3-ol or dodec-1-en-3-ol35
followed by a Wittig rearrangement36 to form the (Z)-undec-3-en-1-
ol or (Z)-dodec-3-en-1-ol. The latter compounds were oxidized using
Dess−Martin periodinane31,32 followed by a Grignard-type reaction of
the obtained aldehydes with vinylmagnesium bromide to yield (Z)-
trideca-1,5-dien-3-ol or (Z)-tetradeca-1,5-dien-3-ol. Dess−Martin
periodinane gave the corresponding ketones (Figure 1).
Dec-1-en-3-ol, Undec-1-en-3-ol, Dodec-1-en-3-ol, Tridec-1-
en-3-ol, Tetradec-1-en-3-ol, Dec-1-en-3-one, Undec-1-en-3-
one, Dodec-1-en-3-one, Tridec-1-en-3-one, Tetradec-1-en-3-
one. A Grignard-type reaction of octanal, nonanal, decanal, undecanal,
or dodecanal, respectively, with vinylmagnesium bromide gave the alk-
1-en-3-ols, and subsequent oxidation using Dess−Martin periodinane
yielded the corresponding alk-1-en-3-ones (Figure 2).
(E)-Hepta-1,5-dien-3-ol, (E)-Octa-1,5-dien-3-ol, (E)-Nona-1,5-
dien-3-ol, (E)-Deca-1,5-dien-3-ol, (E)-Undeca-1,5-dien-3-ol, (E)-
Dodeca-1,5-dien-3-ol, (E)-Hepta-1,5-dien-3-one, (E)-Octa-1,5-
dien-3-one, (E)-Nona-1,5-dien-3-one, (E)-Deca-1,5-dien-3-one,
MATERIALS AND METHODS
■
Chemicals. The following chemicals were purchased from the
suppliers given in parentheses: octanal, nonanal, decanal, undecanal,
undec-1-en-3-ol, dodec-1-en-3-ol, but-1-en-3-one, hex-1-en-3-ol, hept-
1-en-3-ol, oct-1-en-3-ol, pent-1-en-3-one, hexa-1,5-dien-3-ol, (Z)-hex-
3-en-1-ol, (E)-hex-3-en-1-ol, (Z)-non-3-en-1-ol, (E)-pent-3-enoic acid,
(E)-hept-3-enoic acid, (E)-oct-3-enoic acid, (E)-non-3-enoic acid, (E)-
dec-3-enoic acid, pent-3-in-1-ol, dec-3-in-1-ol, Dess−Martin period-
inane, malonic acid, s-trioxane, vinylic magnesiumbromide (Aldrich,
Steinheim, Germany); pent-1-en-3-ol, non-1-en-3-ol, oct-1-en-3-one,
(Z)-oct-3-en-1-ol, hept-3-yn-1-ol (Lancaster, Muhlheim, Germany).
̈
Syntheses. The identity of all intermediates and synthetic products
was determined by MS/EI, as well as their retention indices on at least
two capillary columns of different polarities (FFAP, SE-54 (DB5), and
OV-1701) (data available in Supporting Information Tables S1−S6).
Linear retention indices (RI) of the compounds were calculated as
previously described.26 Purity and concentration of all synthetic
products were determined according to the method described by
Milo,27 using methyl octanoate or any other ester of high GC purity
and a compound with the same effective carbon number as the
substance to be determined.28−30
Hex-1-en-3-one and (Z)-octa-1,5-dien-3-one were synthesized
according to the literature: Blank et al.,23 Ullrich and Grosch.9
Hexa-1,5-dien-3-one, Hept-1-en-3-one, Non-1-en-3-one.
Hexa-1,5-dien-3-one (Figure 1), hept-1-en-3-one, and non-1-en-3-
one (Figure 2) were synthesized by a Dess−Martin oxidation of the
corresponding alcohols using Dess−Martin periodinane.31,32
1026
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
Figure 3. Synthetic routes leading to the (E)-alka-1,5-dien-3-oxo compounds.
Table 1. Odor Qualities and Odor Thresholds of Homologous (Z)-Alka-1,5-dien-3-ones
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
by GC-O
data from lit.
previously identified in food
hexa-1,5-dien-3-one
geranium-, vegetable-like, metallic
geranium-like, metallic
geranium-like, metallic
herb-, mushroom-like
herb-, mushroom-like
herb-, mushroom-like
herb-, mushroom-like
herb-like, fresh
0.01
0.0006
0.003
0.06
nr
nr
nr
nr
(Z)-hepta-1,5-dien-3-one
(Z)-octa-1,5-dien-3-one
(Z)-nona-1,5-dien-3-one
(Z)-deca-1,5-dien-3-one
(Z)-undeca-1,5-dien-3-one
(Z)-dodeca-1,5-dien-3-one
(Z)-trideca-1,5-dien-3-one
(Z)-tetradeca-1,5-dien-3-one
0.003−0.0063
mushrooms,3 soybean oil,24 olive oil40
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
0.12
0.18
1.1
126
fresh, green, sweet
353
nr
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
(E)-Undeca-1,5-dien-3-one, (E)-Dodeca-1,5-dien-3-one. (E)-
Pent-3-enoic, (E)-hept-3-enoic, (E)-oct-3-enoic, (E)-non-3-enoic,
and (E)-dec-3-enoic acid were reduced to the corresponding (E)-
alk-3-en-1-ols37 (Figure 3). Those and (E)-hex-3-en-1-ol were oxidized
using Dess−Martin periodinane31,32 followed by a Grignard-type
reaction of the obtained aldehydes with vinylmagnesium bromide to
yield (E)-hepta-1,5-dien-3-ol, (E)-octa-1,5-dien-3-ol, (E)-nona-1,5-
dien-3-ol, (E)-deca-1,5-dien-3-ol, (E)-undeca-1,5-dien-3-ol, and (E)-
dodeca-1,5-dien-3-ol. Dess−Martin periodinane gave the correspond-
ing ketones.
(E)-Trideca-1,5-dien-3-ol, (E)-Tetradeca-1,5-dien-3-ol, (E)-Tri-
deca-1,5-dien-3-one, (E)-Tetradeca-1,5-dien-3-one. (E)-Trideca-
1,5-dien-3-ol, (E)-tetradeca-1,5-dien-3-ol, (E)-trideca-1,5-dien-3-one,
and (E)-tetradeca-1,5-dien-3-one were synthesized following two
different routes (Figure 3): The first route is identical with synthesis
of the corresponding (Z)-compounds. (E)-Trideca-1,5-dien-3-ol and
(E)-tetradeca-1,5-dien-3-ol were synthesized by reaction of s-trioxane
with undec-1-en-3-ol or dodec-1-en-3-ol35 followed by a Wittig
rearrangement36 to form the (E)-undec-3-en-1-ol or (E)-dodec-3-en-
1-ol. The obtained compounds were oxidized using Dess−Martin
periodinane31,32 followed by a Grignard-type reaction of the obtained
aldehydes with vinylmagnesium bromide to yield (E)-trideca-1,5-dien-
3-ol or (E)-tetradeca-1,5-dien-3-ol. Dess−Martin periodinane gave the
corresponding ketones. The second route starts with a Knoevenagel
condensation of malonic acid with nonanal or decanal to form (E)-
undec-3-enoic acid or (E)-dodec-3-enoic acid.38 After reduction of the
(E)-alk-3-enoic acid to the corresponding (E)-alk-3-en-1-ol, route 2
follows the same path as route 1.
High-Resolution Gas Chromatography−Olfactometry
(HRGC-O) and HRGC−Mass Spectrometry (HRGC-MS). HRGC
analyses were performed with a type 8000 gas chromatograph (Fisons
Instruments, Mainz, Germany) and a Trace GC Ultra (Thermo Fisher
Scientific GmbH, Dreieich, Germany) by using the following
capillaries: FFAP (30 m × 0.32 mm fused silica capillary, free fatty
acid phase FFAP, 0.25 μm; Chrompack, Muhlheim, Germany), SE-54
̈
(DB5) (30 m × 0.32 mm fused silica capillary DB-5, 0.25 μm; J&W
Scientific, Fisons Instruments), and OV-1701 (30 m × 0.32 mm fused
silica capillary, DB-1701, 0.25 μm; Chrompack). The (Z)-alka-1,5-
dien-3-oxo and alk-1-en-3-oxo samples were applied by the on-column
injection technique at 35 °C (Supporting Information Tables S1, S3,
S4, and S6). After 2 min, the temperature of the oven was raised at 40
°C/min to 50 °C (SE-54, OV-1701) or 60 °C (FFAP), respectively,
held for 2 min isothermally, then raised at 6 °C/min to 180 °C, and
finally raised at 10 °C/min to 230 °C and held for 10 min. The flow
rate of the carrier gas helium was 2.5 mL/min. The (E)-alka-1,5-dien-
3-oxo compounds were applied by the column injection technique at
40 °C (Supporting Information Tables S2 and S5). After 2 min, the
temperature of the oven was raised at 10 °C/min to 240 °C, then
raised at 40 °C/min to 280 °C (SE-54 (DB5)) or at 10 °C/min to 240
°C (FFAP), respectively, and held for 5 min. The flow rate of the
carrier gas helium was 2.5 mL/min (DB5) or 1.3 mL/min (FFAP). At
the end of the capillary, the effluent was split in a ratio 1:1 (by vol)
into an FID and a sniffing port using two deactivated but uncoated
fused silica capillaries (50 cm × 0.32 mm). The FID and the sniffing
port were held at 220 and 240 °C, respectively. S analyses were
performed with an MS-95 S (Finnigan, Bremen, Germany) in tandem,
an Agilent MSD 5975C (Agilent Technologies, Waldbronn,
1027
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
Table 2. Odor Qualities and Odor Thresholds of Homologous (E)-Alka-1,5-dien-3-ones
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
by GC-O
data from lit.
previously identified in food
hexa-1,5-dien-3-one
geranium-, vegetable-like, metallic
geranium-like, metallic
geranium-like
0.01
0.9
1.4
2.8
18
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
(E)-hepta-1,5-dien-3-one
(E)-octa-1,5-dien-3-one
(E)-nona-1,5-dien-3-one
(E)-deca-1,5-dien-3-one
(E)-undeca-1,5-dien-3-one
(E)-dodeca-1,5-dien-3-one
(E)-trideca-1,5-dien-3-one
(E)-tetradeca-1,5-dien-3-one
geranium-like, flowery
geranium-like
geranium-like, flowery
citrus-like
7.9
36
citrus-like, green
92
citrus-, plastic-like
192
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
Table 3. Odor Qualities and Odor Thresholds of Homologous Alk-1-en-3-ones
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
pungent, fish-like
metallic
by GC-O
data from lit.
2022
previously identified in food
pent-1-en-3-one
hex-1-en-3-one
hept-1-en-3-one
oct-1-en-3-one
0.17
0.02
0.08
0.04
0.008
0.08
0.15
33
banana,10,41 black tea,42 tomato,43 olive oil40
0.02−0.04,23 0.722
artichoke,11 honey,23 dill,44 butter oil45
grapefruit juice12
vegetable-like, metallic
mushroom-like, metallic
mushroom-like
0.722
0.03−1.12,24,25 0.122
artichoke,11 mushrooms,41 soybean oil,44 olive oil40
non-1-en-3-one
dec-1-en-2-one
undec-1-en-3-one
dodec-1-en-3-one
tridec-1-en-3-one
tetradec-1-en-3-one
0.008,40 0.0222
raspberry,42 yogurt,46 sheep meat40
mushroom-, geranium-, herb-like
herb-, citrus-like, soapy
herb-, citrus-like, soapy
citrus-like, soapy
122
nr
122
nr
18022
nr
white bread47
nr
166
soapy, plastic-like
771
nr
nr
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
Table 4. Odor Qualities and Odor Thresholds of Homologous Alka-1,5-dien-3-ols
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
by GC-O data from lit.
previously identified in food
hexa-1,5-dien-3-ol
geranium-, vegetable-like, metallic
geranium-like
37.4
4.7
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
(Z)-hepta-1,5-dien-3-ol
(Z)-octa-1,5-dien-3-ol
(Z)-nona-1,5-dien-3-ol
(Z)-deca-1,5-dien-3-ol
(Z)-undeca-1,5-dien-3-ol
(Z)-dodeca-1,5-dien-3-ol
(Z)-trideca-1,5-dien-3-ol
(Z)-tetradeca-1,5-dien-3-ol
nr
geranium-like
1.3
mushroom,3,48 fish14,49
herb-, geranium-, mushroom-like
herb-, geranium-, mushroom-like
herb-, geranium-, mushroom-like
herb-, geranium-, mushroom-like
geranium-like, fresh
4.2
nr
7.1
nr
20.7
fish14,49
nr
143
173
nr
fresh, green
284
nr
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
Germany), and a Thermo ITQ 900 (Thermo Fisher Scientific,
Dreieich, Germany) with the capillaries described above. Mass spectra
in the electron impact mode (MS/EI) were generated at 70 eV.
Panelists were trained volunteers from the University of Erlangen
(Erlangen, Germany), exhibiting no known illness at the time of
examination and with audited olfactory function. In preceding weekly
training sessions the assessors were trained for at least half a year in
recognizing orthonasally about 90 selected known odorants at different
concentrations according to their odor qualities and in naming these
according to an in-house developed flavor language.
Odor Quality Determination. The odor qualities were
determined during GC-O evaluation and were related to odor
qualities of commercially available reference compounds, such as Z-
octa-1,5-dien-3-one (geranium like) or pent-1-en-3-ol (pungent) and
pent-1-en-3-one (pungent, fish-like).
RESULTS AND DISCUSSION
■
The odor threshold values in air and the odor qualities of the
homologous (Z)-alka-1,5-dien-3-ones, (E)-alka-1,5-dien-3-ones,
and alk-1-en-3-ones are given in Tables 1, 2, and 3. The data of
the corresponding alcohols are given in Tables 4, 5, and 6. With
regard to the bis-unsaturated compounds, we found a very low
odor threshold minimum with 0.6 mg/L air for the seven-
carbon compound of the (Z)-alka-1,5-dien-3-ones, thus being
Odor Threshold Values. Thresholds in air were determined by
GC-O with (E)-2-decenal as internal standard20 (Tables 1−6). The
thresholds were determined by two panelists. HRGC was performed
on capillary SE-54 (DB5) and capillary FFAP as already described.
1028
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
Table 5. Odor Qualities and Odor Thresholds of Homologous (E)-Alka-1,5-dien-3-ols
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
by GC-O
data from lit.
previously identified in food
hexa-1,5-dien-3-ol
geranium-, vegetable-like, metallic
geranium-like
37.4
4.9
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
nr
(E)-hepta-1,5-dien-3-ol
(E)-octa-1,5-dien-3-ol
(E)-nona-1,5-dien-3-ol
(E)-deca-1,5-dien-3-ol
(E)-undeca-1,5-dien-3-ol
(E)-dodeca-1,5-dien-3-ol
(E)-trideca-1,5-dien-3-ol
(E)-tetradeca-1,5-dien-3-ol
geranium-like, green
geranium-like
36.2
13
geranium-like, green
green, geranium-like
green, geranium-like
sweet, fresh, citrus-like
fresh, flowery, green
4.1
133.6
165
191.1
310.6
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
Table 6. Odor Qualities and Odor Thresholds of Homologous Alk-1-en-3-ols
a
threshold in air (ng/L)
b
c
c
odorant
odor quality
pungent
by GC-O
data from lit.
previously identified in food
pent-1-en-3-ol
hex-1-en-3-ol
46
2.3
4300,50 66022
banana,10,41 dill herb,51 chicken fat,52 fish,14,49 black tea53,54
pungent, glue-like
vegetable-like, metallic
mushroom-like
mushroom-like
herb-, citrus-like
herb-, citrus-like
herb-, citrus-like
citrus-like
7022
7022
banana,41 dill herb,51 black tea42
hept-1-en-3-ol
oct-1-en-3-ol
40.4
1.4
banana,10,41 dill herb51
110,22 4841
4022
banana,10,41 fish14,49
non-1-en-3-ol
dec-1-en-3-ol
2.7
banana10,41
20.3
22.9
285
1616
4381
37022
nr
nr
nr
nr
undec-1-en-3-ol
dodec-1-en-3-ol
tridec-1-en-3-ol
tetradec-1-en-3-ol
37022
370022
nr
citrus-, plastic-like
nr
nr
a
b
c
Odor thresholds in air were determined as described by Ullrich and Grosch.20 Odor quality as perceived at the sniffing port. nr, compound or
odor threshold was not reported previously.
the most odor-active compound of all odorants under
investigation. All (Z)-alka-1,5-dien-3-ones elicited a geranium-
like odor quality, with the short-chain compounds possessing a
merely metallic odor note, whereas an increase of the chain
length results in a more herb- and mushroom-like odor quality.
This change in odor qualities went along with an increase in the
odor thresholds up to a factor of about 103. The same change in
odor quality was observed for the homologous (Z)-alka-1,5-
dien-3-ols. However, the minimum in the odor thresholds was
not so pronounced for the seven-carbon compound. Generally,
the most odor-active alkadienols in this series were the
odorants with 7−10 carbon atoms with odor thresholds from
1 to 10 ng/L air. The odor thresholds then increased by a factor
of about 102 from (Z)-deca-1,5-dien-3-ol to (Z)-dodeca-1,5-
dien-3-ol.
Also, all (E)-alka-1,5-dien-3-ones elicited a geranium leaf-like
odor quality. The short-chain compounds possessed a pungent
and green odor note. An increase in the chain length resulted in
a more citrus- and plastic-like odor. As in the case of the (Z)-
compounds, this change was accompanied with an increase in
the odor thresholds. The same changes in odor quality were
observed for the homologous (E)-alka-1,5-dien-3-ols.
odorants with eight and nine carbon atoms. This change went
along with two minima in the odor thresholds. The first one
was observed for the pungent six-carbon compounds, followed
by an increase in the odor threshold for hept-1-ene- odorants,
and then a second minimum for the mushroom-like smelling
eight- and nine-carbon compounds, respectively. A further
increase of the chain length resulted in an increasing citrus-like,
soapy, and herb-like odor quality as well as a significant increase
in their odor thresholds by a factor of about 103 in both
homologous series. Generally, the odor thresholds in air of the
alk-1-ene and alka-1,5-diene carbonyl compounds were
significantly lower than those of their corresponding alcohols.
Overall, most of the odor thresholds determined within the
present study are in very close agreement with others
previously reported for compounds that had been already
investigated, for example, oct-1-en-3-one (Table 3). However,
we observed a notable deviation from some reported values, for
example, pent-1-en-3-one and oct-1-en-3-ol (Tables 3 and 6).
In the case of these substances, odor thresholds provided by
Koszinowski and Piringer39 were higher by a factor of about
100−120, which may arise from the fact that in the previous
study another approach of odor threshold determination was
used based on GC-O but not utilizing an internal referencing
substance such as (E)-2-decenal.
Whereas the overall geranium-like odor of the (Z)- and (E)-
alka-1,5-dien-3-oxo compounds varied only slightly between
homologues, the odor qualities of the alk-1-en-3-oxo
compounds changed significantly with increasing chain length.
The five- and six-carbon compounds were mainly described as
pungent and glue-like but not mushroom-like. An increase of
the chain length first led to a change to a metallic odor quality
and then to the characteristic mushroom-like smells for the
Overall, the results show that most of the investigated
compounds in the homologous series of the (Z)-alka-1,5-dien-
3-ones, (E)-alka-1,5-dien-3-ones, and alk-1-en-3-ones as well as
their corresponding alcohols exhibit very low odor thresholds
or very high odor potencies, respectively. Therefore, some of
these compounds are possibly naturally occurring odorants but
1029
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
and gas chromatography olfactometry. J. Agric. Food Chem. 1996, 44,
3919−3925.
were not yet identified in food materials perhaps due to their
low concentrations. Our investigations now provide analytical
data on these compounds such as retention indices as well as an
evaluation of their odor qualities and odor thresholds, which
can aid at their future analysis.
(14) Yajima, I.; Nakamura, M.; Sakakibara, H.; Ide, J.; Yanai, T.;
Hayashi, K. Volatile flavor components of dried bonito (Katsuobushi).
II. From the neutral fraction. Agric. Biol. Chem. 1983, 47, 1755−1760.
(15) Bodyak, N.; Slotnick, B. Performance of mice in an automated
olfactometer: odor detection, discrimination and odor memory. Chem.
Senses 1999, 24, 637−645.
ASSOCIATED CONTENT
* Supporting Information
■
S
(16) Dravnieks, A.; Schmidtsdorff, W.; Meilgaard, M. Odor
thresholds by forced-choice dynamic triangle olfactometry: reprodu-
cibility and methods of calculation. J. Air Pollut. Control Assoc. 1986,
36, 900−905.
(17) Encen, T. The sense of smell. Annu. Rev. Psychol. 1973, 24,
187−206.
(18) Leonardos, G.; Kendall, D.; Barnard, N. Odor threshold
determinations of 53 odorant chemicals. J. Air Pollut. Control Assoc.
1969, 19, 91−95.
(19) Beauchamp, J.; Frasnelli, J.; Buettner, A.; Scheibe, M.; Hansel,
A.; Hummel, T. Characterization of an olfactometer by proton-
transfer-reaction mass spectrometry. Meas. Sci. Technol. 2010, 21,
025801/1−025801/9.
(20) Ullrich, F.; Grosch, W. Identification of the most intense volatile
flavor compounds formed during autoxidation of linoleic acid. Z.
Lebensm.-Unters. Forsch. 1987, 184, 277−282.
(21) Buettner, A.; Schieberle, P. Aroma properties of a homologous
series of 2,3-epoxyalkanals and trans-4,5-epoxyalk-2-enals. J. Agric.
Food Chem. 2001, 49, 3881−3884.
(22) Koszinowski, J.; Piringer, O. Importance of oxidation products
of unsaturated hydrocarbons in the sensorial properties of food
packing. Part 1: Oxygen derivates of 1-alkenes. Dtsch. Lebensm.-
Rundsch. 1983, 79, 179−183.
Mass spectroscopic data for all investigated compounds. This
material is available free of charge via the Internet at http://
pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*(A.B.) Phone: +49-9131-85 22739. E-mail: andrea.buettner@
fau.de.
■
Notes
The authors declare no competing financial interest.
ABBREVIATIONS USED
■
FID, flame ionization detector; GC-O, gas chromatography−
olfactometry; HRGC-MS, high-resolution gas chromatogra-
phy−mass spectrometry; HRGC-O, high-resolution gas
chromatography−olfactometry; MS/EI, mass spectrometry/
electron ionization; o.n, overnight; RI, retention index; rt,
Room temperature
REFERENCES
(23) Blank, I.; Fischer, K. H.; Grosch, W. Intensive neutral odorants
of linden honey. Differences from honeys of other botanical origin. Z.
Lebensm.-Unters. Forsch. 1989, 189, 426−433.
■
(1) Stark, W.; Forss, D. A. A compound responsible for metallic
flavor in dairy products. I. Isolation and identification. J. Dairy Res.
1962, 29, 173−180.
(24) Guth, H.; Grosch, W. Comparison of stored soya-bean and
rapeseed oils by aroma extract dilution analysis. Lebensm.-Wiss. Technol.
1990, 23, 59−65.
(2) Swoboda, P. A. T.; Peers, K. E. Metallic odor caused by vinyl
ketones formed in the oxidation of butterfat. The identification of
octa-1,cis-5-dien-3-one. J. Sci. Food Agric. 1977, 28, 1019−1024.
(3) Tressl, R.; Bahri, D.; Engel, K. H. Formation of eight-carbon and
ten-carbon components in mushrooms (Agaricus campestris). J. Agric.
Food Chem. 1982, 30, 89−93.
(4) Nijssen, L. M.; Visscher, C. A.; Maarse, H.; Willemsen, L. Volatile
Compounds in Foods; TNO Nutrition and Food Research Institute:
Zeist, The Netherlands, 1996.
(25) Boerger, D.; Buettner, A.; Schieberle, P. State-of-the-Art in
Flavour Chemistry and Biology; Deutsche Forschungsanstalt fur
̈
Lebensmittelchemie: Eisenach, Germany, 2005.
(26) Halang, W. A.; Langlais, R.; Kugler, E. Cubic spline
interpolation for the calculation of retention indices in temperature-
programmed gas-liquid chromatography. Anal. Chem. 1978, 50, 1829−
1832.
(27) Milo, C. Identification and quantification of aroma compounds.
Curr. Protoc. Food Anal. Chem. 2001, G1.3.1−G1.3.12.
(28) Jones, F. W. Estimation of flame-ionization detector relative
response factors for oligomers of alkyl and aryl ether polyethoxylates
using the effective carbon number concept. J. Chromatogr. Sci. 1998,
36, 223−226.
(5) Ullrich, F.; Grosch, W. Flavor deterioration of soya-bean oil:
identification of intense odor compounds formed during flavor
reversion. Fat Sci. Technol. 1988, 90, 332−336.
(6) Spitzer, J.; Buettner, A. Characterization of aroma changes in
human milk during storage at −19°C. Food Chem. 2010, 120, 240−
246.
(29) Morvai, M.; Palyka, I.; Molnar-Perl, I. Flame ionization detector
response factors using the effective carbon number concept in the
quantitative analysis of esters. J. Chromatogr. Sci. 1992, 30, 448−452.
(30) Scanlon, J. T.; Willis, D. E. Calculation of flame ionization
detector relative response factors using the effective carbon number
concept. J. Chromatogr. Sci. 1985, 23, 333−340.
(31) Fielder, S.; Rowan, D. D. The synthesis of 3,4-2H2-3Z-hexenal
and 6,6,6-2H3-3Z-hexenal. J. Labelled Compds. Radiopharm. 1995, 36,
465−470.
(32) van den Nieuwendijk, A. M. C. H.; Kriek, N. M. A. J.; Brussee,
J.; van Boom, J. H.; van der Gen, A. Stereoselective synthesis of
(2R,5R)- and (2S,5R)-5-hydroxylysine. Eur. J. Org. Chem. 2000, 2000,
3683−3691.
(33) Brown, H. C.; Brown, C. A. Reaction of sodium borohydride
with nickel acetate in ethanol solution; a highly selective nickel
hydrogenation catalyst. J. Am. Chem. Soc. 1963, 85, 1005−1006.
(34) Brown, C. A.; Ahuja, V. K. P-2 nickel catalyst with
ethylenediamine, a novel system for highly stereospecific reduction
of alkynes to cis-olefins. J. Chem. Soc., Chem. Commun. 1973, 553−554.
(7) De Lumen, B. O.; Stone, E. J.; Kazeniac, S. J.; Forsythe, R. H.
Formation of volatile flavor compounds in green beans from linoleic
and linolenic acids. J. Food Sci. 1978, 43, 698−702, 708.
(8) Grosch, W. In Reactions of Hydroperoxides. Products of Low
Molecular Weight; Academic: New York, 1987; pp 95−139.
(9) Ullrich, F.; Grosch, W. Identification of the most intense odor
compounds formed during autoxidation of methyl linolenate at room
temperature. JAOCS, J. Am. Oil Chem. Soc. 1988, 65, 1313−1317.
(10) Tressl, R.; Drawert, F.; Heimann, W.; Emberger, R. Gas
chromatographic survey of aromatic materials of bananas. Z.
Naturforsch. B 1969, 24, 781−783.
(11) Buttery, R. G.; Guadagni, D. G.; Ling, L. C. Volatile aroma
components of cooked artichoke. J. Agric. Food Chem. 1978, 26, 791−
793.
(12) Buettner, A.; Schieberle, P. Characterization of the most odor-
active volatiles in fresh, hand-squeezed juice of grapefruit (Citrus
paradisi Macfayden). J. Agric. Food Chem. 1999, 47, 5189−5193.
(13) Roberts, D. D.; Acree, T. E. Effects of heating and cream
addition on fresh raspberry aroma using a retronasal aroma simulator
1030
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031

Journal of Agricultural and Food Chemistry
Article
(35) Bedford, C. D.; Harris, R. N., III; Howd, R. A.; Goff, D. A.;
Koolpe, G. A.; Petesch, M.; Koplovitz, I.; Sultan, W. E.; Musallam, H.
A. Quaternary salts of 2-[(hydroxyimino)methyl]imidazole. 3. Syn-
thesis and evaluation of (alkenyloxy)-, (alkynyloxy)-, and
(aralykyloxy)methyl quaternized 2-[(hydroxyimino)methyl]-1-alkyli-
midazolium halides as reactivators and therapy for soman intoxication.
J. Med. Chem. 1989, 32, 504−516.
(36) Macia, B.; Gomez, C.; Yus, M. [2,3]-Wittig rearrangement by a
chlorine-lithium exchange. Tetrahedron Lett. 2005, 46, 6101−6104.
(37) Donde, Y.; Nguyen, J. H.; Burk, R. M. Preparation of substituted
cyclopentanes having prostaglandin activity for the treatment of
glaucoma. WO2009061811A1, 2009.
(38) Rao, B.; Vijayalakshmi, P.; Subbarao, R. Synthesis of long-chain
(E)-3-alkenoic acids by the Knoevenagel condensation of aliphatic
aldehydes with malonic acid. J. Am. Oil Chem. Soc. 1993, 70, 297−299.
(39) Koszinowski, J.; Piringer, O. Evaluation of off-odors in food
packaging − the role of conjugated unsaturated carbonyl compounds.
J. Plast. Film Sheeting 1986, 2, 40−50.
(40) Reiners, J.; Grosch, W. Odorants of virgin olive oils with
different flavor profiles. J. Agric. Food Chem. 1998, 46, 2754−2763.
(41) Tressl, R.; Drawert, F.; Heimann, W.; Emberger, R. Biogenesis
of aroma substances in plants and fruits. VI. Esters, alcohols, carbonyl
compounds, and pheno ether as constituents of banana aroma. Z.
Lebensm.-Unters. Forsch. 1970, 142, 313−321.
(42) Mick, W.; Schreier, P. Additional volatiles of black tea aroma. J.
Agric. Food Chem. 1984, 32, 924−929.
(43) Buttery, R. G.; Teranishi, R.; Ling, L. C. Fresh tomato aroma
volatiles: a quantitative study. J. Agric. Food Chem. 1987, 35, 540−544.
(44) Blank, I.; Grosch, W. Evaluation of potent odorants in dill seed
and dill herb (Anethum graveolens L.) by aroma extract dilution
analysis. J. Food Sci. 1991, 56, 63−67.
(45) Widder, S.; Sen, A.; Grosch, W. Changes in the flavor of butter
oil during storage. Identification of potent odorants. Z. Lebensm.-
Unters. Forsch. 1991, 193, 32−35.
(46) Ott, A.; Fay, L. B.; Chaintreau, A. Determination and origin of
the aroma impact compounds of yogurt flavor. J. Agric. Food Chem.
1997, 45, 850−858.
(47) Obretenov, T.; Khadzhieva, P. Gas chromatographic-mass
spectral analysis of aroma compounds of bread. Z. Lebensm.-Unters.
Forsch. 1977, 165, 195−199.
(48) Vanhaelen, M.; Vanhaelen-Fastre, R.; Geeraerts, J. Occurrence
in mushrooms (Homobasidiomycetes) of cis- and trans-octa-1,5-dien-
3-ol, attractants to the cheese mite Tyrophagus putrescentiae (Schrank)
(Acarina, Acaridae). Experientia 1980, 36, 406−407.
(49) Sakakibara, H.; Ide, J.; Yanai, T.; Yajima, I.; Hayashi, K. Volatile
flavor compounds of some kinds of dried and smoked fish. Agric. Biol.
Chem. 1990, 54, 9−16.
(50) Hall, G.; Andersson, J. Volatile fat oxidation products. I.
Determination of odor thresholds and odor intensity functions by
dynamic olfactometry. Lebensm.-Wiss. Technol. 1983, 16, 354−361.
(51) Schreier, P.; Drawert, F.; Heindze, I. The quantitative
composition of natural and technologically changed aromas of plants.
VIII. Volatile constituents of fresh dill herb, Anethum graveolens, L.
(Umbelliferae). Lebensm.-Wiss. Technol. 1981, 14, 150−152.
(52) Noleau, I.; Toulemonde, B. Volatile components of roasted
chicken fat. Lebensm.-Wiss. Technol. 1987, 20, 37−41.
(53) Fischer, N.; Nitz, S.; Drawert, F. Bound flavor compounds in
plants. Part 2. Free and bound flavor compounds in green and black
tea (Camellia sinensis). Z. Lebensm.-Unters. Forsch. 1987, 185, 195−201.
(54) Owuor, P. O. Comparison of gas chromatographic volatile
profiling methods for assessing the flavor quality of Kenyan black teas.
J. Sci. Food Agric. 1992, 59, 189−197.
1031
dx.doi.org/10.1021/jf404885j | J. Agric. Food Chem. 2014, 62, 1025−1031