Compounds contributing to the characteristic aroma of malted barley

The volatiles from malt, sampled at stages during roasting, were examined by GC odor-port evaluation and by GC-MS. The technique of odor dilution was applied to volatile extracts from samples exhibiting strong malt-like characteristics. Seven odors from the GC column persisted through several dilutions. 3- and 2-methylbutanal were responsible for the odors with the highest dilution factors which had malty characteristics. The other five odors were malty or cereal-like; ethylmethylpyrazines and maltol may contribute to these odors, but other compounds responsible were present at very low concentrations and have not yet been identified. The levels of 2- and 3-methylbutanal increased dramatically in malt during roasting.