Apparatus for the quantitative analysis of the aroma of french bread and its loss during storage.

Based on the principles of static and dynamic headspace sampling, an apparatus was developed for the determination of the release of potent odorants from two types of baguette (industrial process or "intensifée" and traditional or "artisanal") differing in their odor profiles. We applied this apparatus to get an insight into the aroma changes of freshly baked French bread, which develops a stale off-flavor within four hours after baking. Model mixtures containing the odorants in the concentrations found by the headspace analysis were evaluated using the apparatus as an olfactometer. By comparing the odor profiles of the models with those of the baguettes, the quantitative data were confirmed. The results indicate that losses of methylpropanal, 2- and 3-methylbutanal and, on the other hand, an increase of hexanal and (E)-2-nonenal led to a stale off-flavor. Furthermore it was suggested that this apparatus is also suitable for precise flavor release studies of other foods.

Use of humidified air in optimizing APCI-MS response in breath analysis.

An atmospheric-pressure chemical ionization-mass spectrometer (APCI-MS) system was modified to introduce gaseous samples as well as to humidify sheath and auxiliary gases. Solutions of single odorants in pentane were evaporated inside a vessel in a dry environment (relative humidity 0-10%) and in a human-breath-like environment (relative humidity 88-98%) and subsequently analyzed in the positive ion mode. The results indicated that using dry nitrogen as sheath and auxiliary gases led to strong fragmentation of the molecules combined with a low sensitivity of detection. Humidification of both gases not only increased sensitivity but also resulted in the protonated molecular ion as the base peak in 5 of the 6 compounds studied (ethyl butyrate, 3-methyl-3-phenyl glycidic acid ethyl ester, gamma-decalactone, (E)-2-hexenal, and cinnamic aldehyde). Only hexanal, which formed a cluster (m/z 183), did not have the protonated molecular ion as base peak. It was found that the humidity of the sample itself did not have any influence on sensitivity or fragmentation.