Flavor dilution chromatogram

Figure 3. Flavor dilution (FD) chromatogram of the neutral/basic odorants in a pale lager beer. The numbering follows Figure 2. RI retention index on a silicone SE-54 GC stationary phase [adapted from ref. 18],...

These methods were developed to quantify and visualize the intensity of aroma as a chromatogram. A specific system named combined hedonic and response measurement (CHARM) was initially developed. Later on, aroma extract dilution analysis (AEDA) (Figure 3), a new method using a conventional GC-O system, was proposed. They share the same strategy aroma extract is diluted to a certain extent and then GC—O methodology is applied. In an AEDA procedure, if such a maximum extent of a dilution that allows the detection of a certain component is times diluted from the original sample, this component is referred to have a flavor dilution (FD) factor of . CHARM value corresponds to FD factor in a CHARM procedure. These values represent the contribution of the volatile the larger these values are, the more important they are considered as key components. 

These limitations are eliminated by the stepwise dilution of the volatile fraction with solvent, followed by the gas chromatographic/olfactometric analysis of each dilution. The process is continued until no more aroma substance can be detected by GC olfactometry. In this way, a dilution factor 2 (n = number of 1 -b 1 dilutions) is determined for each aroma substance that appears in the gas chromatogram. It is designated as the flavor dilution factor (FD factor) and indicates the number of parts of solvent required to dilute the aroma extract until the aroma value is reduced to one. 

In AEDA, the assessor indicates whether or not an aroma can be perceived and notes the sensory descriptor. The result is expressed as the flavor dilution (ED) factor that corresponds to the maximum dilution value detected, i.e., the peak height obtained in CharmAnalysis. The FD factor is a relative measure and represents the odor threshold of the compound at a given concentration. The data are presented in an FD chromatogram (Fig. 5) indicating the retention indices (x-axis) and FD factors in a logarithmic scale (y-axis). AEDA has been proposed as a screening method for potent odorants as the results are not corrected for losses during isolation (7). 

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