A Craft Beer & Brewing Magazine reader recently asked us the following question:
My beer has a bit of a creamed-corn flavor to it. What is causing it?
A creamed-corn or cooked-corn flavor is indicative of a compound called dimethyl sulfide (DMS). DMS is a by-product of malting, mashing, and fermentation, so it is present to some degree in all beers. However, it is more easily detected in lighter-colored ales and lagers, as it has a fairly low flavor threshold of 50–175 parts per billion.
All malts have a compound called S-methyl methionine (SMM), which is an amino acid formed during germination and kilning of barley malt as part of the malting process. This SMM is a precursor of DMS. Certain malts, such as 2-row malts, have less SMM than 6-row barley malt, and Pilsner malt has slightly higher SMM levels due to the low temperatures at which it is kilned. The malt house can reduce SMM slightly by under-modifying the malt or altering kilning temperatures. However, for the most part, SMM levels are outside the control of the brewer.