Science Byte

Famously presents itself in cheddar, where does the sulfur smell come from?

“Sulfur”, “struck match”, and “boiled egg” are common descriptors used with some cheeses, especially some cheddars. These terms are all trying to capture the sulfury aroma/flavor that makes Vermont cheddar famous. While aged cheddar is the most prominent example, sulfur is important to the overall aroma profile of many different cheeses.

There are many volatile sulfur-containing compounds that make up “sulfur” aroma. A few example include: methanethiol, dimethyl disulfide, dimethyl trisulfide, and hydrogen sulfide. These compounds can all be found in sulfury cheese. Aside from cheddar, the aroma of many surface ripened cheeses are due, in-part, to sulfur compounds. Sometimes the aroma presents itself as "broccoli" or "cauliflower" notes.


Methanethiol, one of the sulfur compounds responsible for cheese sulfur aroma

The origins of these sulfur compounds are sulfur-containing amino acids. As we’ve discussed before, amino acids are what proteins are made of. Therefore, one could say sulfur aroma gets its start due to protein-breakdown. Microbes, like starter culture, can munch on the sulfur amino acids and produce the smelly sulfur compounds. Sulfur-containing amino acids include methionine and cysteine.


Sulfur-containing amino acids, methionine (left) and cysteine (right)


While we often talk about flavors and aromas being caused by certain compounds, it’s important to remember that the unique taste and aroma of cheese is caused by a whole menagerie of chemicals. Cheese flavor is definitely a case of the whole being greater than the sum of its parts.