Green coffee acids

The principal CGA isomers identified in green coffee include three caffeoylquinic acid isomers, 3-CQA [327-97-9], 4-CQA [905-99-7], and 5-CQA [906-33-2], three dicaffeoylquinic acid isomers, 3,4-diCQA [14534-61-3], 3,5-diCQA [2450-53-5], and 4,5-diCQA [57378-72-0], and three feruloylquinic acid isomers, 3-FQA [1899-29-2], 4-FQA, and 5-FQA [40242-06-6]. The total CGA level is somewhat higher in robustas compared to arabicas. The 5-CQA is the predominant isomer both in arabicas, ie, 4—5% dry basis (db), and in robustas, 5—6% db, and is known to form in vitro and possibly in vivo complexes with caffeine [58-08-2]. Greater compositional differences between robustas and arabicas are found in the minor CGA isomers, eg, 3,4-diCQA, 5-FQA,... 

The surface of the green coffee contains a cuticular wax layer (0.2—0.3% db) for both varieties. The wax contains insoluble hydroxytryptamides derived from 5-hydroxytryptamine [61 7-2] and saturated C18—C22 fatty acids. 

Methods for the decaffeination of green coffee beans, mainly with solvents after a steaming, have already been described. Even with the selective adsorption techniques to remove only caffeine, it is unlikely that the full character of the starting beans can be realized in a final decaffeinated beverage the result is that Robusta coffees are generally used to prepare decaffeinated coffee. The cost is kept down and the treatment, anyway, reduces any harsh or bitter flavor that the Robusta coffee may have had. The resulting beverage will be relatively caffeine-free, but Robusta coffee will contribute more soluble carbohydrates, phenols, and volatile fatty acids, and much less of the diterpenes found in Arabica coffees. 

Model systems indicate that aldehydes may also be produced by the action of polyphenoloxidases on amino acids in the presence of catechin, all of which are present in coffee beans at some stage between green and roasted. For example, valine yields isobutanal, leucine yields isopentanal, and isoleucine yields 2-methyl-butanal.14 Some of these aldehydes probably undergo condensation reactions in the acidic medium of the roasted bean when moisture is present.15 Some dienals in green coffee beans have recently been identified as (E,E)-2,4- and (E,Z)-2,4-nonadienal and (E,E)-2,4- and (E,Z)-2,4-decadienal.18... 

The treatment and environment of green coffee beans affects the concentrations of both caffeoyl- and feruloyl quinic acids,52 and several decomposition products have been recognized. Some of these products, in this case from steam-treated green coffee beans, are given in Figure 5.53... 

Amino acid Green coffee (%) Roasted coffee (%) (17.6% roast)... 

An acid phosphatase and a trypsin inhibitor94 also are presumed to form part of the protein complement in green coffee. 

Green coffee beans, as expected, contain storage polysaccharides such as starch, and structural support compounds such as cellulose and lignin. Mono- and di-saccharides are represented, as well as the related compounds quinic acid and myo inositol. 

The presence of tocopherols,114 as well as caffeic acid,108 accounts for the remarkable stability of green coffee bean oils toward oxidation. In coffee beans from different origins, a-tocopherol concentrations are in the range 89 to 188 pg/kg and (p + y)-tocopherol concentrations are in the range 252 to 530 pg/kg.114 Since p- and y-tocopherols have better antioxidant properties than a-tocopherol,114 it is not surprising to see coffee oil patented as an antioxidant material.115117... 

Trigonelline is present in green coffee (1 %),15 but it is rapidly decomposed on roasting so that only about 0.1% trigonelline is present in a deeply roasted coffee.161 The products of trigonelline breakdown are evident in roasted coffee and include nicotinic acid and its methylester, pyridine, and p-picoline (Figure 17).3... 

Several vitamins have been recognized in green coffee beans, as might be expected in a plant seed. A relatively high ascorbic acid content is associated with fine-grade coffee beans to be used as seeds.162 Vitamin E has already been mentioned as a component of coffee oil.114... 

Wajda, P., Walczyk, C., Relation between acid value of extracted fatty matter and age of green coffee beans, J. Sci. Food Agric., 29, 377, 1978. (CA89 145281q)... 

Melo, M., Amorim, H. V., Chemistry of Brazilian green coffee and the quality of the beverage. VI, The uv and visible spectral analysis and chlorogenic acids content in TCA soluble buffer extracts, Turrialba, 25, 243, 1975. (CA84 57533q)... 

Pereira, A., Pereira, M, M., Free amino acids in green coffee from Huambo (Angola). Separation and identification by electrophoresis and thin layer chromatography, Coll. Sc 1. Int. Cafe, 8, 545, 1977. (CA92 196460s)... 

Arnold, U., Ludwig, E., Kuehn, R., Moeschwitzer, U., Analysis of free amino acids in green coffee beans, Part 1, Determination of amino acids after precolumn derivatization using 9-fluorenylmethylchloroformate, Z. Lebensm.-Forsch. 199(1), 22, 1994. (CA121 132515y)... 

Berndt, W., Meier-Cabell, E., Properties of some proteins as well as acid phosphatase from green coffee, Coll, Int, Chlm, Cafes, 7, 225, 1975. (CA85 155547n)... 

Richter, H., Obermann, H., Spiteller G., A new kauran-18-oic acid glucopyranosylester from green coffee beans, Chem. Ber., 110, 1963, 1977. (CA87 68579x)... 

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. 

Amino acid duplications, in sulfonamide resistance, 23 505 Amino acid inhibitors, 13 300-302 Amino acid racemization dating, 5 752 Amino acid residues, 9 494 26 376 Amino acids, 2 554-618 20 447 achiral derivatizing agents, 6 96t analysis, 2 596-600 analysis in green coffee, 7 253t analysis in roasted, brewed, and instant coffee, 7 255t... 

Ferreira. Development of an HPLC/ CA090 diode-array detector method for simultaneous determination of seven hydroxyl-cinnamic acids in green coffee. J LiqChromRelTechnol 1997 20(13) CA091... 

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... 

A reversed-phase HPLC procedure was proposed for the determination of seven phenolic acids in green coffee samples (144). The sample preparation technique involved extraction, alkaline hydrolysis, and liquid/liquid extraction. The chromatographic separation was achieved us-... 

High-performance gel filtration chromatography was used to separate trigonelline, chloro-genic acid (CGA), and CF in green coffee by De Maria et al. (281). The method has the advantage, with respect to RP-HPLC, of an aqueous eluent. 

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. 

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