Characterization of Methyl-Branched Aldehyde Analogs as Potent Odorants in Ripe Natural Cheeses

Abstract

12-Methyltridecanal has a unique beef-like odor and has been reported to be a potent odorant in ripe Gouda-type 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.