What is the primary source of DMS in brewing?

Dimethyl Sulfide (DMS) is a compound that can contribute to off-flavors in beer, often described as having a sweet, corn-like aroma. The primary source of DMS in brewing is lighter malts. These malts contain higher levels of the precursor compound S-methylmethionine (SMM), which can convert to DMS during the malting and brewing processes, especially when the wort is boiled or if the boil is insufficient.

When lighter malts are used, some DMS can form during the kilning of the malt. If the wort is not boiled vigorously or for a sufficient time, DMS can remain in the final beer. While other types of malts can influence flavor profiles in different ways, darker malts do not generally contribute to DMS as they are kilned at higher temperatures, which breaks down SMM more effectively and reduces DMS formation.

Understanding the role of different malt types in DMS production is crucial for brewers, as controlling the amount of DMS is important for achieving the desired flavor profile in the final product.