The aroma concentrates of the three maturation stages of Gouda-type cheeses were prepared by combining the solvent extraction and the solvent assisted flavor evaporation techniques. The aroma extract dilution analysis applied to the volatile fraction revealed 31 odorants that were identified or tentatively identified from the 38 odor-active peaks with FD factors between 43 and 48. By comparison with the FD factors in the three maturation stages of the cheeses, 16 odorants, including 12-methyltridecanal, which is a newly identified odorant from the cheese, increased with the increasing maturation stage of the cheese. In addition, many iso- and anteiso-methyl-branched long-chain aliphatic aldehydes could be identified as the analogs of 12-methyltridecanal, which have a unique odor note. It may be then expected that these aldehydes were able to influence the flavor of the highly ripened Gouda cheese, since these compounds also increased with the increasing maturation stage.

To clarify the characteristic sweet aroma of Wagyu (Japanese Black Cattle), aroma extraction dilution analysis (AEDA) was applied to the volatile fractions of Wagyu and Australia beefs. Some 20 odor-active peaks were detected, and 17 odorants were identified or tentatively identified. Among the perceived odorants, most of them were newly identified from the Wagyu beef. The main constituents of the potent odorants were aldehydes and ketones, which are known as the degradation products of polyunsaturated fatty acids that were significantly included in the lipids of the Wagyu. In addition, the most potent odorant was trans-4,5-epoxy-(E)-2-decenal, which is known to be the oxidation product of polyunsaturated acids, such as linoleic acid and arachidonic acid, that were significantly included in the lipids of the Wagyu. Accordingly, these findings strongly suggested that the kind of fatty acid constituting lipids of the Wagyu plays an important role in the formation of the characteristic aroma of the Wagyu beef.

12-Methyltridecanal has a unique beef-like odor and has been reported to be a potent odorant in ripe Goudatype cheeses. In addition, many iso-and anteiso-methyl-branched aldehydes have been identified as analogs of 12-methyltridecanal. The objective of this study was to clarify the properties of these aldehydes in natural cheeses. The odor thresholds of methyl-branched aldehydes gave a minimum value of 14 carbon atoms, and 12-methyltridecanal had the lowest threshold. Furthermore, in the region of low odor threshold, methyl-branched aldehydes showed beef-like notes. These results suggest that the specifically low threshold and unique odor quality of 12-methyltridecanal play an important role in the aroma of Gouda. Furthermore, the increases in methyl-branched aldehydes during long-term maturation were observed with different semi-hard type cheeses. This result suggests that the phenomenon of the increase in methyl-branched aldehydes from long-term maturation was applicable for many other cheeses made via the maturational process in addition to Gouda. Cheese lipids were fractionated, and the amounts of methyl-branched aldehydes generated by hydrolysis in each fraction showed that the precursor was concentrated in simple lipid fractions. This result suggests that the methyl-branched aldehyde precursor in the cheese differs from that in beef.

The aim of this study was to develop a new approach that can be used to estimate the elution characteristics of odorants from chewing gum into saliva during chewing using a chewing apparatus and to apply the approach to the prediction of their elution ratios. The odorants eluted from the model chewing gum were analyzed by a gas chromatography-flame ionization detector using the adsorptive column method and Headspace-solid phase microextraction (HS-SPME). It was found that the quantitative data obtained from each analytical method are in proportion and that the measured value obtained from HS-SPME, which is easy to operate, could convert the quantitative data obtained from the adsorptive column method. Therefore, it was demonstrated that the amounts of odorants eluted from chewing gum and their release curves could be easily determined by a combination of the two methods. In addition, it was recognized that there was a good overall regression coefficient between the elution ratio of the odorants in the model chewing gum after a 20-min chewing run and the difference between the retention indices on the polar and apolar stationary phase of GC columns (ΔI). Therefore, ΔI is the most important factor for predicting the elution ratio of odorants in chewing gum during chewing.Keywords: flavor release, elution characteristic, chewing gum, chewing apparatus *To whom correspondence should be addressed. E-mail: itobe.takafumi@ogawa.net IntroductionFlavor is one of the primary factors determining the quality of a foodstuff. Flavor is a more important factor for the quality of chewing gum than for that of other foodstuffs, because the flavor of chewing gum is strongly required as an excellent characteristic of in-mouth release, which is the immediate flavor impression and the duration of perception of odorants during chewing, in addition to an excellent odor quality and an appropriate intensity. The sensory response to an added flavor in chewing gum is mainly affected by the rate and extent of the in-mouth flavor release during consumption, and the driving forces of the release are the partition between the different phases (chewing gum -saliva -air) and mass transfer velocity (De Roos, 1990;De Roos, 2000;Harrison, 2000). Therefore, detailed understanding of the in-mouth release characteristics of odorants in chewing gum during chewing is extremely important for the production of high quality chewing gum products.