Thiopropanone

Thiopropanone, also known as propanethial S-oxide, is an organic sulfur compound with the chemical formula C3H6SO. It is a volatile chemical that is produced by the enzymatic breakdown of certain sulfur-containing amino acids found in plants, particularly those in the Allium genus, such as onions and garlic. This compound is a key contributor to the characteristic aroma and flavor of these vegetables.

The biosynthesis of thiopropanone involves a series of enzymatic reactions. When the plant tissue is damaged, enzymes like alliinase are released, which act on S-alk(en)ylcysteine sulfoxides. This initial reaction produces a sulfenic acid intermediate, which then undergoes rearrangement to form the thiopropanal S-oxide. Further enzymatic or non-enzymatic reactions can lead to the formation of various volatile sulfur compounds, including thiopropanone.

Thiopropanone itself is a reactive molecule and can undergo further transformations. It is known to be unstable and can decompose or react with other compounds present. Its presence and concentration are important factors influencing the sensory qualities of foods like onions, garlic, and leeks. Research into these compounds is ongoing to better understand their role in food chemistry and potentially for applications in flavorings and fragrances.