Trigonelline coffee

About 50—80% of the trigonelline is decomposed during roasting. Trigonelline is a probable source for niacin [59-67-6] but also a source of some of the aromatic nitrogen compounds such as pyridines, pyrroles, and bicycHc compounds found in coffee aroma (16). Certain acids, such as acetic, formic. 

Pyridine is formed from trigonelline during roasting.3 It is presumed to contribute to the flavor, especially in the darker coffee roasts.15... 

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... 

Determinations of nicotinamide in green and roasted Robusta coffee are indicative of its much increased content in coffee roasted at or below 240°C. The values are 3 and 46 mg/100 g for green and roasted coffee, respectively.183 At least part of this increase is from trigonelline as it decomposes on roasting. 

The products from trigonelline seen in roasted coffee.3... 

Robusta coffee has undesirable flavor agents that can be masked by the addition of L-aspartyl-L-phenylalaninemethyl ester.218 The methylxanthine stimulant properties of coffee can be antagonized by spraying freshly roasted coffee beans with nicotinamide and nicotinic acid,219 quinolinic acid, or trigonelline.220... 

Viani, R., Horman, I., Determination of trigonelline in coffee, Coll. Int. Chim. Cafes 7, 273, 1975. (CA85 190824x)... 

Saldana MDA. 1997. Extraction of caffeine, trigonelline and chlorogenic acid from Brazilian coffee beans using supercritical CO2 MSc. Thesis, UNICAMP, Campinas, Brazil. 

Anti-adhesive effect. Green and roasted coffee, used in a treatment mixture and as a pretreatment on beads, inhibited the Strep tococcus mutans sucrose-independent adsorption to saliva-coated hydroxyapatite beads. The inhibition of Salmonelb mutans adsorption indicated that coffee-active molecules may adsorb to a host surface, preventing the tooth receptor from interacting with any bacterial adhesions. Among the known tested coffee components, trigonelline and nicotinic and chlorogenic acids are very... 

In general, niacin is widespread in foodstuffs (93,94). Cereals, seeds, meat, and fish are good food sources of niacin. The niacin content of coffee beans is primarily a product of the roasting process, which converts trigonelline (1-methylnicotinic acid) to nicotinic acid (95). 

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. 

Many pyrroles have been identified in roasted coffee. Regarding their formation in coffee pyridine, pyrrole and N-methyl-2-formylpyrrole are trigonellin derivatives 3 and 4 typical pyrroles from primary amino acids and 6 to 8 hydroxyproline derived Maillard products ( 26 ). ... 

Smith (1963a) and Feldman et al. (1969) underlined the importance of non-volatile compounds to the flavor of coffee. The comparison between the composition of green and of roasted coffee showed an important decrease in the content of proteins, chlorogenic acid and sucrose on roasting. Fractionation and analysis of the aroma precursors in green coffee have also been studied by Russwurm (1970) who considers that the non-volatile constituents of green coffee that may be involved in flavor formation are carbohydrates, proteins, peptides and free amino acids, polyamines and tryptamines, lipids, phenolic acids, trigonelline and various non-volatile acids. 

De Maria et al. (1995, 1996c) have described a simultaneous determination of total chlorogenic acids, trigonelline and caffeine in green coffee by high-performance gel filtration chromatography. They also... 

Mazzafera (1991) examined 28 coffee species for their trigonelline content. For the arabicas it is mainly around 2%, the extremes in other varieties being ca 0.8 and 3.0%, higher than the values generally reported. The differences are probably due to different methods of determination. Stennert and Maier (1994) reported literature values in agreement with their own values of 0.88% (average) for seven green arabicas and 0.67 % for three robustas. 

It was formed in the pyrolysis of proline and 4-hydroxyproline (Merritt et al., 1970) and is one of the pyrolysis products of trigonelline (Viani and Horman, 1974). Baltes and Bochmann (1987b) found 1-methylpyrrole in all their serine/threonine/sucrose reactions as well as in coffee. 

Ouweland et al., 1978) or directly by the pyrolysis of amino acids (Fujimaki et al., 1969). Another important, if not the main, precursor of pyridines in roasted coffee is trigonelline (see Section 2.1.1.2), a product isolated by Goi ter (1910), identical to the product isolated from the seeds of Trigonella foenum-graecum. Viani and Horman (1974, 1976) identified 12 pyridinic compounds after pyrolysis of trigonelline, six of which have now been identified in roasted coffee (4-methylpyridine is noted as identified in coffee, but it is not present in the lists of quoted publications, and to our knowledge its identification has not yet been reported in the literature). The presence of four other alkyl derivatives and of two N-methylnicotinamides have not yet been confirmed in the flavor. The authors have also isolated two piperidylpyridines, 3-phenylpyridine and two of its methyl derivatives, as well as four unsubstituted and dimethyl-substituted dipyridyl compounds. 

For Viani and Horman (1974), pyridine represents 25% of the pyrolysis products of a trigonelline monohydrate sample. Pyridine has been found in model reactions between glucose and amino acids (Kato et al., 1973b), when heating serine and/or threonine with or without sucrose under coffee-roasting conditions (Baltes and Bochmann, 1987d who found it also in coffee). Mottram (1991) explained the possible formation of pyridine by reaction of ammonia on 2,4-pentadienal. 

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