Green coffee beans, chlorogenic acids

Clifford MN, Knight S, Surucu B and Kuhnert N. 2006a. Characterization by LC-MS(n) of four new classes of chlorogenic acids in green coffee beans dimethoxycinnamoylquinic acids, diferuloylquinic acids, caffeoyl-dimethoxycinnamoylquinic acids, and feruloyl-dimethoxycinnamoylquinic acids. J Agric Food Chem 54(6) 1957-1969. 

The ubiquitous plant compound chlorogenic acid (isolated from green coffee beans) is formed by transesterification with the glycoside cinnamoyl-glucose.187 Coumaroyl-CoA is converted into monomeric and dimeric amides with agmatine, which provides barley plants with resistance to mildew.188 Similar compounds with various polyamines and derived from p-coumaric, caffeic, ferulic, or sinapic acid appear to... 

Green coffee beans (Coffea arabica) are one of the richest dietary sources of chlorogenic acids. 5-O-Caffeoylquinic acid is the dominant chlorogenic acid accounting for 50% of the total. This is followed by 3-0- and 4-O-caffeoyl-quinic acid, the three analogous feruloylquinic acids and 3,4-0-, 3,5-0- and 4,5-O-dicaffeoylquinic acids (Fig. 1.32) [Clifford, 1999]. Levels decline ca. 80% during the roasting of coffee beans, but sizable amounts with substantial antioxidant activity are still found in the typical cup of coffee. 

O-Dicaffeoylquinic acid Figure 1.32 Main chlorogenic acids in green coffee beans. 

As an example, Urakova et al. compared the analysis of chlorogenic acid in green coffee bean extracts by thin layer chromatography on silica (i.e. normal-phase liquid chromatography) and by reversed-phase HPLC The validation data (LOD, LOQ, repeatability, and various precision parameters), the recoveries and the quantitative results were totally comparable. It can be assumed that both methods find the true value. Either method can be used, depending on the preference or instrumentation of a laboratory. 

Ohiokpehai O. (1982) Chlorogenic acid content of green coffee beans. Thesis, University of Surrey. 

Ohiokpehai O., Brumen G. and Clifford M.N. (1983) The chlorogenic acids content of some peculiar green coffee beans and the implications for beverage quality. 10th. Int. Colloq. Chem. Coffee (Salvador, Bahia 11-14.10.82) (ASIC, 1983), 177-86. 

TABLE 2 Chlorogenic Acids Identified in Green Coffee Beans (Robusta and Arabica) by Liquid Chromatography Tandem Mass Spectrometry ... 

Moreover, green coffee beans contain a number of chlorogenic acids such as derivatives of caffeoylquinic acid, dicaffeoylquinic acid, and feruloylquinic acid [428], whose amount and distribution in the coffee beans depend on the bean type and degree of ripeness. During the roasting process, a significant... 

Green and roasted coffees, for example, contain more than 50 esters of cinnamic acids. Their level in green coffee beans ranges from 4 to 14%. The main groups are caffeoylquinic, dicaffeoylquinic, feruloylquinic, p-coumaroylquinic and caffeoyl-feruloylquinic acids. Moreover, all esters and diesters of quinic acid are found in three types of positional isomers that include 3-0-esters, 4-0-esters and 5-0-esters. The main component is chlorogenic acid, that is 3-0-caffeoyl-L-quinic acid, but this name also refers to all the natural quinic acid esters. The structures of the basic esters and diesters of caffeoylquinic acids are given in formulae 8-82. 

Chfford M.N., Marks S., Knight S., Kuhnert N. Characterization by LC-MSn of four new classes of p-coumaric acid-containing diacyl chlorogenic acids in green coffee beans. Journal of Agricultural and Food Chemistry, 54 4095-4101 (2006). 

Figure 7.61 Green coffee beans contain high levels of chlorogenic acids which dec ...

More recently, a series of 11 chlorogenic acids has been recognized in green Robusta coffee beans.51... 

Each patent has somewhat different features and claims. We select one patent for more detailed discussion to highlight certain technical facets of the process. First we explain the (often misunderstood) effect of water on the extractability of caffeine by selective supercritical carbon dioxide. A number of references report that dry carbon dioxide cannot extract caffeine from dry coffee, either green or roasted, but moist carbon dioxide can. The inability of dry carbon dioxide to extract caffeine from coffee should not be misconstrued to mean that dry carbon dioxide cannot dissolve neat caffeine. This same moist-versus-dry effect is experienced if, for example, methylene chloride is used to extract caffeine from coffee. Dry methylene chloride cannot decaffein-ate dry coffee but moistened coffee can be decaffeinated. It is thought that the caffeine is chemically bound in a chlorogenic acid structure present in the coffee bean. Thus, water somehow acts as a chemical agent it frees caffeine from its bound form in the coffee matrix in both the carbon dioxide and the methylene chloride processes. 

Morishita H., Iwahashi H. and Kido R. (1989) Chlorogenic acids composition of green and roasted coffee beans. Bull. Fac. Edu. Wakayama Univ. Nat. Sci 38, 33-9. 

Cblford, M.N. and Jarvis, T. (1988) The chlorogenic acids content of green robusta coffee beans as a possible index of geographic origin. Food Chem., 9,291-298. 

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