The Volatile Constituents of the Coffee Flower (Coffea arabica L.)

Abstract

Although coee beans have been well studied, the volatile constituents of the coee¯ower have not previously been investigated. An extract of coee¯ower (Coea arabica L.) was analyzed by GC±MS and found to contain a signi®cant number of nitrogen-containing aromatic compounds as well as phenylethane derivatives. The novel epoxygeraniols (2,3-epoxygeraniol and 6,7-epoxygeraniol) were also detected as minor components. These epoxides were estimated to be an approximately equal mixture of both enantiomers by chiral GC analysis. Optically active 2,3-epoxygeraniols were synthesized by Sharpless's asymmetric epoxydation (AE), and 6,7-epoxygeraniols were prepared utilizing Sharpless's asymmetric dihydroxylation (AD) as a key step in high optical purities (96±99% ee). Epoxygeraniols were found to possess rosy and muguet-like aromas reminiscent of the living¯ower. Considerable dierences of aroma were perceived between the enantiomers. # 1997 by John Wiley & Sons, Ltd.

Novel phenolic glycosides, adenophorasides A–E, from Adenophora roots

“…It is well known that cyanogenic glycosides are found in many natural sources such as plants of the family Rosaceae and Gramineae and are biosynthesized from their corresponding amino acids via phenylacetonitrile. To our knowledge, only a few phenylacetonitriles have been isolated from natural sources: phenylacetonitrile [21], 4-[b-D-glucopyranosyl-(1?3)-a-L-rhamnopyranosyl]-phenylacetonitrile [22], niazirin [23], niazirinin [23], and niaziridin [24]. This is the first report of phenylacetonitrile isolation from plants of the family Campanulaceae.…”

Synthesis of the fragrance terpene epoxides and selective monocyclization promoted by camphor and oxone®

“…It is noteworthy that the Shi epoxidation of citronellol using dioxirane derived from chiral ketone 6 analogue yielded (-)-6,7-epoxy-citronellol with 48% ee (Table 1 entry 9). [19,20] The (-)-6(S),7-diol and (+)-6(R),7-diol were converted to the (+)-6 (R),7-epoxy-and (-)-6(S),7-epoxy-geranol respectively in two steps, through mesylation and further nucleophilic elimination on treatment with base (Table 1, entry 14). [19,20] The (-)-6(S),7-diol and (+)-6(R),7-diol were converted to the (+)-6 (R),7-epoxy-and (-)-6(S),7-epoxy-geranol respectively in two steps, through mesylation and further nucleophilic elimination on treatment with base (Table 1, entry 14).…”

“…13h Alternatively, catalytic asymmetric dihydroxylation of geranyl acetate in the presence of AD-mix-β at 0°C for 24 h gave (-)-6(S),7dihydroxy-geraneol, whereas AD-mix-α gave (+)-6(R),7-diol. [18,19] Similar treatment of farnesyl acetate through terminal double bond dihydroxylation, mesylation and base catalysed elimination yielded 10(S),11-epoxy-farnesyl acetate ( Table 1, entry 17). [18,19] Similar treatment of farnesyl acetate through terminal double bond dihydroxylation, mesylation and base catalysed elimination yielded 10(S),11-epoxy-farnesyl acetate ( Table 1, entry 17).…”

“…Acyclic monoterpenes (R)-citronellol (16), (R)-citronellyl acetate (17), geranyl acetate (18) and sesqueterpene farnesyl acetate (19) yielded the corresponding terminal mono-epoxides 22-25 respectively ( Table 2). The epoxidation of (+)-dihydro-β-ionol yielded the corresponding epoxide (-)-15…”

The compositional basis of coffee flavour

“…Some of the compounds being investigated, particularly the volatile terpenes, have not previously been quantified accurately although their presence and peak abundance have been reported previously (Del Terra et al, 2013, Gonzalez-Rios et al, 2007, Mondello et al, 2005, Akiyama et al, 2008. Mostly found in coffee flowers and berries, terpenes are known to remain in the roasted coffee beans and corresponding brews (Stashenko et al, 2013, Emura et al, 1997, Akiyama et al, 2008. As known contributors the boquet of wines and beers, these monoterpenes are also likely to influence coffee flavour.…”