Oxazoles and oxazolines are a class of compounds which have been found in heated foodstuffs at low concentrations. They are characterized by possessing a five-membered ring with oxygen and nitrogen in the 1 and 3 positions, Their strong odor impact at low concentration suggests they may he important contributors to food aroma.
The occurrence of oxazoles in food flavor has been reviewed. More recently, oxazoles have been identified in baked potato, roasted peanuts, roasted beef, cocoa butter and fried chicken. Oxazoles have also been reported in various model systems, namely, furfural, hydrogen sulfide and ammonia, rhamnose and ammonia. D-glucose and ammonia, maltol and ammonia and diacetyl and alkyl- or sulfur-containing amino acids.
The aroma properties of fifteen 4,5-dialkyloxazoles have been reported. Most of the 4,5-dialkyloxazoles synthesized have green, vegetable-like aromas. It was also noted that 4- butyl-5-propyloxazole, 4-butyl-5-methyloxazole and 4-pentyl-5-methyloxazole were judged to have a strong bell pepper-like character. This observation indicates that the general structure for compounds possessing potent bell-pepper aroma
-CH = NC(R) = CX-
where R is a hydrocarbon chain about four carbons long and X is oxygen or sulfur, which was proposed by Buttery et al. could be extended to 4,5-dialkyloxazoles.