The confusion in the interpretation of some aroma chemicals’ molecular structures causes confusion among the users of these products. Several important cases, including keto-enol tautomerisation of α-diketones, isomerisation of α-angelica lactone, and the exact substitution pattern of pyrazines, will be discussed. The analytical methods used to unravel the correct molecular structures were GC, GCMS and 15N-NMR spectroscopy, and particularly polarization-transfer for sensitivity enhancement (INEPT), and 2D-correlation techniques.
α-Diketones α-Diketones are an important group of aroma chemicals that are characterized by two adjacent keto functionalities. Their structure consists of four to seven carbon atoms, as illustrated in in Figure 1.
The flavor characteristics of α-diketones range from creamy, sweet, buttery, caramely and milky, to fruity, roasted and burnt. This group of natural products occurs in many food flavors, including butter, milk, fruits, wine, roasted products, vinegar, yogurt, coffee, raspberry and cheddar cheese.
