2-Methoxy-3,5-dimethylpyrazine
2-Methoxy-3,5-dimethylpyrazine is a heterocyclic organic compound, part of methoxypyrazine class. It has a highly potent aroma with a strong musty, moldy, or earthy scent. It is best known as a source of cork taint in wine, secondary in importance to 2,4,6-trichloroanisole.
Natural occurrence
2-Methoxy-3,5-dimethylpyrazine has been identified as a natural product and a volatile organic compound responsible for off-odors in various products. It is a significant contributor to the "fungal must" or "corky" taint in wine, which is distinct from the smell caused by TCA. The compound is not only found in cork stoppers but can also be present in oak wood used for barrel making. Its presence has also been detected in coffee.The bacterium Rhizobium excellensis, which is widespread in the soil, is capable of producing 2-methoxy-3,5-dimethylpyrazine from amino acid precursors such as L-leucine and L-alanine. The compound has also been identified as the cause of musty odors in public water supplies.