Amino acids phenylpropenoyl

Stark T, Justus H, Hofinann T (2006) Quantitative analysis of N-phenylpropenoyl-L-amino acids in roasted coffee and cocoa powder by means of a stable isotope dilution assay. J Agric Food Chem 54 2859-2867... 

Stark T, Hofmann T (2005) Isolation, structure determination, synthesis, and sensory activity of iV-phenylpropenoyl-L-amino acids from cocoa (Theobroma cacao). J Agric Food Chem 53 5419-5428... 

AT-phenylpropenoyl amino acids (2-17) have been identified as the key contributors to the astringent taste of non-fermented cocoa beans and cocoa products. Besides the already known (E) -N- [ 3, 4 -dihydroxycinnamoyl-3-hydroxy-L-tyrosine (known as clovamide), (E)-Ar-(4Chydroxycinnamoyl)-L-tyrosine (deoxy-clovamide) and (E)-AT-(3, 4 -dihydroxycinnamoyl)-L-tyrosine, seven additional amides derived from cinnamic, 4-coumaric, caffeic and feruHc acids, namely, (- -)-(E)-N-(cinnamoyl)-L-aspartic acid, (-f)-( )-N-(4 -hydroxycinnamoyl)-L-aspartic add, (- -)-( )-iV-(3, 4 -dihydroxydnnamoyl)-L-aspartic add, (-l-)-(E)-N-(4 -hydroxy-3 methoxydnnamoyl)-L-aspartic acid, (-)-( )- /-(4 -hydroxydnnamoyl)-L-glutamic add, (-)-( )-N-(3, 4 -di-hydroxycinnamoyl)-L-glutamic add and (-)-( )-N-(4 -hydr-oxycinnamoyl)-3-hydroxy-L-tyrosine, were recently identified. 

Exposure to light rapidly converted ( )-isomers of N-phenylpropenoyl amino acids into the corresponding (Z)-isomers. 

Fresh cocoa beans, the seeds of cacao tree (Theobroma cacao, StercuUaceae), have a sour odour and a sour, bitter and astringent taste. The main contributors to the bitter taste are purine alkaloids. The astringent taste of cocoa products is mainly influenced by oligomeric procyanidins, flavan-3-ol-C-glycopyranosides (see Section 8.3.6.2.2) and N-phenylpropenoyl amino acids (see Section 2.2.1.2.1). 

---