Key Odorants in Japanese Roasted Barley Tea (Mugi-Cha) - Differences between Roasted Barley Tea Prepared from Naked Barley and Roasted Barley Tea Prepared from Hulled Barley.

The volatiles isolated by solvent extraction and solvent-assisted flavor evaporation (SAFE) from roasted barley tea, either prepared from hulled barley or from naked barley, were subjected to a comparative aroma extract dilution analysis which resulted in 27 odor-active compounds with flavor dilution factors (FD factors) of 64-1024. Additional 5 odorants were detected by static headspace analysis. Quantitation of these 32 compounds revealed 22 and 23 odorants in the naked and in the hulled barley tea, respectively, that exceeded their odor threshold values. On the basis of these data, the aroma of both barley tea variants was successfully reconstituted with reference compounds. The calculation of odor activity values (OAV = concentration/odor threshold value) and omission tests suggested 2-methoxyphenol (OAVs 69 and 160) and trans-isoeugenol (OAVs 1.4 and 31) as key compounds responsible for the stronger smoky note in the hulled barley tea. Further important odorants in the naked and in the hulled barley tea included 2-acetylpyrazine (OAVs 23 and 16), 2-acetyl-1-pyrroline (OAVs 19 and 16), and 3-methylbutanal (OAVs 12 and 15).