Aroma Compounds Formed from Carbohydrate Metabolism

3 Aroma Compounds Formed from Carbohydrate Metabolism 

Returning briefly to Table 4.1, one can see that a large variety of volatile flavors can be traced to carbohydrate metabolism. If one considers plant metabolism, it is clearly established that plants obtain all of their energy directly from photosynthesis. The photosynthetic pathways involve turning CO2 into sugars that are metabolized into other plant needs, e.g., lipids and amino acids. Therefore, one may state that nearly all plant flavors come indirectly from carbohydrate metabolism since all of the other flavor precursors come from carbohydrate metabolism. However, there are few flavor constituents that come directly from carbohydrate metabolism. Terpenes, for example, arise both from carbohydrate and lipid metabolism. 

FIGURE 4.7 Pathways for the formation of phenolic acids and phenol esters in banana. El, L-phenylalanine-ammonia-lyase E2, cinnamic-acid-hydroxylase E3, phenolase E4, meth-yltransferase. (From Tressl, R., F. Drawer , J. Agric. Food Chem., 21, p. 560, 1973. With permission.) 

FIGURE 4.8 Biosynthetic pathway for the formation of isopentenyl diphosphate. (From Little, D.B., R.B. Croteau, Flavor Chemistry 30 Years of Progress, R. Teranishi, E.L. Wick, I. Homstein, Fids., Kulwer Academ., New York, 1999, p. 239. With permission.) 

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