Flavor compounds major classes

The volatile compounds formed by the Maillard reaction are only one group of flavor compounds in foods. Schutte (1) presents a brief summary of the major classes and their modes of formation from precursors. Some of them can be formed by different pathways. An example is the furans, which can be formed by non-enzymatic browning reaction but also by biotransformation. 

Recognition of the presence of glycosidically-conjugated flavor precursors in fruits of all major horticultural classes has, in the last few years, stimulated much interest in these compounds. Advances in research on glycosidic flavor precursors of plant-derived foods has been the subject of several recent reviews (1-4). 

Nishimura and Mihara (1990) investigated 2-hydroxy-2-cyclopenten-l-ones in a steam-distilled coffee extract and identified ten compounds of this class, seven of them being reported for the first time in a natural flavor and some even being original chemicals. Procedures used for their syntheses are described. All the 2-hydroxy-2-cyclopenten-l-ones were also identified in a model reaction, when sucrose, the major component of green coffee, was heated with alkali in aqueous solution. Some had been previously found in maple syrup or tobacco. We are reminded that Gianturco et al. (1963) mentioned for the first time the presence of these typical, sweet, caramel-like and burnt compounds in a roasted coffee extract. 

Flavoring agents are the largest class of food additives. At the present time, over a thousand synthetic and natural flavors are available. The majority of these are concentrates or extracts from the material whose flavor is desired. These flavoring agents are often complex mixtures of fens fo hundreds of compounds. 

The preceding sections on sensory characters of organics cover only the major organic groupings widely encountered in flavor work and is by no means exhaustive. Discussing each compound class in detail would require a book in itself. It is intended merely to draw attention to the enormous range of aromatic effects that can be derived from synthetic chemicals and in no way is a substitute for practical exposure to the odor and flavor characteristics of the chemicals permitted for use in foods. 

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