Quinic acid lactone, coffee

CA109 Hucke, J., and H. G. Maier. Quinic acid lactone in coffee. Z Lebensm-Unters Forsch 1985 180(6) 479-484. 

Caffeine and the quinic acid lactones listed in Table 21.13 are the bitter substances in the coffee drink. Accordingly, these lactones are almost exclusively responsible for the bitter note of a decaffeinated coffee drink (Table 21.13). Although the concentrations of the lactones III-VII, IX and X in the drink are lower than their threshold concentrations (cf. Table 21.13), they still additively contribute to the bitter taste (cf. 5.1.2 additive effect). 

Table 21.13. Bitter quinic acid lactones in a decaffeinated coffee drink ...

Chlorogenic acid lactones are produced in roasted coffee and range from 1.5 to 3.5 g/kg in commercial roasted coffee samples. Two lactones that have been identified in roasted coffee are 3-caffeoyl- and 4-caffeoyl-quinic acid-y-lactone.60... 

The y-quinide G.15, the lactone of the main quinic acid (E.52) formed during roasting was identified in roasted coffee (chlorogenic lactones have been found in green coffee, see Section 2.1.4). The identification of isomers of this lactone was described by Maier s group (Scholz and Maier, 1990 Scholz-Bottcher et al., 1991 Scholz-Bottcher and Maier, 1992). The formation of the main lactone reached a maximum with a medium roast, whereas the minor isomers increased regularly. 

Scholz-Bottcher B.M. and Maier H.G. (1992) Isomers of quinic acid and quinides in roasted coffee indicators for the degree of roast 14th Int. Colloq. Chem. Coffee (San Francisco, 14-19.7.1991) (ASIC, 1992), 220-9. Scholz-Bottcher B.M., Ernst L. and Maier H.G. (1991) New stereoisomers of quinic acid and their lactones. Liebigs Ann. Chem. 1029—36. 

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