Catty odorant

A most challenging tainting problem was the occurrence of a catty note in some foods. Catty is used to describe the odor of tom cat urine. Pearce et al. [13] found that an unsaturated ketone, mesityl oxide, (4-methylpent-3-en-2-one) can react with sulfur compounds in a food, particularly hydrogen sulfide, to form a compound with a catty odor. This compound has been identified as 4-mercapto-methylpentan-2-one [14]. This reaction has been responsible for several tainting events in the industry. In one case, the mesityl oxide was a trace component (0.5%) in a solvent... 

Tertiary thiols (Table 5.35) are some of the most intensive aroma substances. They have a fruity odor at the very low concentrations in which they occur in foods. With increasing concentration, they smell of cat urine and are called catty odorants. Tertiary thiols have been detected in some fruits, olive oil, wine (Scheurebe) and roasted coffee (Table 5.35). They make important contributions to the aroma and are possibly formed by the addition of hydrogen sulfide to metabolites of isoprene metabolism. In beer. 

Blackcurrant absolute (Bourgeons de cassis absolute, cassis absolute) is obtained by solvent extraction via the concrete obtained from the dormant buds of the blackcurrant bush Ribes nigrum L. (Saxifragaceae). The yield is ca. 3%. Blackcurrant absolute is a dark green paste with the characteristic, powerful, penetrating odor of blackcurrants. The typical catty note is caused by a sulfurous trace constituent, 4-methoxy-2-methyl-2-butenethiol [80324-91-0] [286-288]. 

According to the latter authors, the pure substance has a sweaty, fruity odor, becoming black currantlike and catty in aqueous solution (ca 0.1 ppm). The odor and taste thresholds, 2-5 and 5-8 ppt respectively, are nearly ten times higher than those of prenyl mercaptan (Q.10). This mercaptan... 

Polak E., Fetison G., Fombon A.M. and Skalli A. (1988) Structure-odor relationships for catty smelling mercapto compounds in humans. J. Agric Food Chem. 36, 355-9. 

Furfurylthiol is the primary character impact compound for the aroma of roasted Arabica coffee (45). It has a threshold of 5 ppt and smells like freshly brewed coffee at concentrations between 0.01 and 0.5 ppb (46). At higher concentrations it exhibits a stale coffee, sulfury note. Other potent odorants in roasted coffee include 5-methylfurfurylthiol (0.05 ppb threshold), which smells meaty at 0.5-1 ppb, and changes character to a sulfury mercaptan note at higher levels (46). Furfuryl methyl disulfide has a sweet mocha coffee aroma (15). A key aromatic that markedly contributes to coffee aroma is 3-mercapto-3-methylbutyl formate. The pure compound has a blackcurrant-like, catty note, however, in the context of brewed coffee, it contributes roast coffee likeness (47,48). 

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