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G. N. ZEHENTBAUER, Department of Food Science & Nutrition, University of Minnesota, 1334 Eckles Ave, St. Paul, MI 55108 and G. A. Reineccius.

For more than 20 years, cheddar cheese has been a subject of aroma research. During this time, more than 230 volatiles have been identified regardless of their specific contribution to the overall aroma. Recently, the Aroma-Extract-Dilution-Assay (AEDA), combined with GC Olfactometry of Static Headspace Samples (GCO-H), has been applied to screen for potent odorants in mild cheddar cheese. However, based on sensory evaluation, additional compounds are needed to accurately reproduce the aroma of regular-fat mild cheddar cheese.

In order to find these additional compounds, a recently published screening method called Dynamic-Headspace-Dilution-Assay (DHDA) has been applied.

Based on the principle of dynamic headspace sampling the dilution was performed by a stepwise decrease of the purge time (starting at 30 min=FD 1 to a final purge time of 20 sec=FD 90) using a constant purge flow. Each dilution was sniffed three times and the odorous compounds were marked on the GC-chromatogram. Subsequently the odorants were identified on the basis of odor quality, linear retention indices on two different columns, and mass spectra.

In addition to previous data obtained by AEDA and GCO-H, odorants showing the highest FD-factor during DHDA were identified as dimethyl trisulfide, 1-octen-3-one, (E)-2-nonenal, (Z)-2-nonenal, (Z)-1,5-octadien-3-one, (Z)-4-heptenal and 2-acetyl-1-pyrroline.

The results show that a combination of AEDA and GCO-H might not always be sufficient to identify key odorants in food. In the case that a sufficient simulation cannot be obtained, we believe that DHDA is a suitable tool to provide a third perspective in order to evaluate the importance of odorants in a complex food system.