**9. Caffeine**

The best known N compound is caffeine (1,3,7-trimethylxanthine) because of its physiological effects (stimulation of the central nervous system, increased blood circulation, and respiration). It is mildly bitter in taste. 10% of the caffeine and about 6% of the chlorogenic acid are present in a coffee drink. During roasting, the caffeine level in beans is decreased. Synthetic caffeine and caffeine obtained by the decaffeination process are used by the pharmaceutical and soft drink industries. By methylation of xanthine, synthetic caffeine is obtained which is obtained from uric acid and formamide. Medicinally, caffeine is used as a CNS stimulant, usually combined with another therapeutic agent and in analgesic preparations.

Theobromine acts as diuretic and smooth muscle relaxant, but not routinely used. Theophylline is used as smooth muscle relaxant and is frequently dispensed in sustainable formulations to lower the side effects. It is also available as aminophylline (a more soluble preparation containing theophylline with ethylenediamine) and choline theophyllinate (theophylline and choline). The alkaloids may be isolated from natural sources or obtained by total or partial synthesis [5].

The purine alkaloids include caffeine, theobromine, and theophylline as shown in **Figure 1**. They have a limited distribution as alkaloids, but the origins are very

#### *A Detail Chemistry of Coffee and Its Analysis DOI: http://dx.doi.org/10.5772/intechopen.91725*

close with those of the purine bases like adenine and guanine, fundamental components of nucleosides, nucleotides, and the nucleic acids. Caffeine is mainly consumed in the form of beverages like tea, coffee, and cola and is most widely consumed and socially accepted natural stimulants. Theophylline is much more important as a drug compound because of its muscle relaxant properties, utilized in the relief of bronchial asthma when compared to caffeine, medicinally. The major constituent of cocoa and related chocolate products is theobromine.

Out of four nitrogen atoms, two are supplied by glutamine and a third by aspartic acid. The synthesis of the nucleotides AMP and GMP is by way of IMP and XMP, and the purine alkaloids then branch away via XMP. The loss of phosphate via methylation generates the nucleoside 7-methylxanthosine, which is then released from the sugar moiety. Furthermore, successive methylation on the nitrogen gives caffeine through theobromine, while a different methylation sequence can result in the formation of theophylline (**Table 2**) [6].

AMP = adenosine-50 -monophosphate. GMP = guanosine-5<sup>0</sup> -monophosphate. IMP = inosine-5<sup>0</sup> -monophosphate. XMP = xanthosine-5<sup>0</sup> -monophosphate.

Chlorogenic acids are the mainly rich acids of coffee.

like, earthy, sulfurous/roasty, and smoky/phenolic.

Green coffee contains trigonelline (N-methylnicotinic acid) up to 0.6% and is 50% decomposed during roasting. The degradants include nicotinic acid, pyridine,

The aroma profile of coffee is composed of the following notes: sweet/caramel-

Potassium is major in coffee ash (1.1%), calcium (0.2%), and magnesium (0.2%). The major anions includes phosphate (0.2%) and sulfate (0.1%), along with

The best known N compound is caffeine (1,3,7-trimethylxanthine) because of its physiological effects (stimulation of the central nervous system, increased blood circulation, and respiration). It is mildly bitter in taste. 10% of the caffeine and about 6% of the chlorogenic acid are present in a coffee drink. During roasting, the caffeine level in beans is decreased. Synthetic caffeine and caffeine obtained by the decaffeination process are used by the pharmaceutical and soft drink industries. By methylation of xanthine, synthetic caffeine is obtained which is obtained from uric acid and formamide. Medicinally, caffeine is used as a CNS stimulant, usually combined with another therapeutic agent and in analgesic preparations.

Theobromine acts as diuretic and smooth muscle relaxant, but not routinely used. Theophylline is used as smooth muscle relaxant and is frequently dispensed in sustainable formulations to lower the side effects. It is also available as aminophylline (a more soluble preparation containing theophylline with ethylenediamine) and choline theophyllinate (theophylline and choline). The alkaloids may be iso-

The purine alkaloids include caffeine, theobromine, and theophylline as shown in **Figure 1**. They have a limited distribution as alkaloids, but the origins are very

lated from natural sources or obtained by total or partial synthesis [5].

3-methyl pyridine, nicotinic acid, methyl ester, and other compounds.

**6. Trigonelline and nicotinic acid**

*Coffee - Production and Research*

**7. Aromatic principle**

traces of other elements [4].

**8. Minerals**

**9. Caffeine**

**82**

**Figure 1.** *Chemistry of the purine derivatives.*


**S.N. Method**

**85**

8 HPLC and

For HPLC: Shimadzu LC10A fitted

UV detector set at 273 nm

> with a C18 column as stationary

phase and acetonitrile

(10:90%) as mobile phase set at a

flow rate of 1 ml min1

For biosensor: amperometricbiosensor

the biological sensing element,

transducer,

detector systems HPLC with solid phase extraction

Caffeine was extracted from green

10–60 ppm

 Caffeine in tea, coffee, and

Crude black tea, green tea,

[15]

and coffee contained 7.04%,

4.88%, and 13.7% caffeine,

respectively,

purification

tea, and coffee contained

3.34%, 2.24%, and 5.20%

pure caffeine

 black tea, green

 whereas after

soft drinks

tea, black tea, and coffee and then

characterized

max (UV/vis), IR absorption bands, Rf (TLC), and RT (HPLC)

Crude caffeine was purified by

solid phase extraction

 by melting point, λ

(SPE)

HPLC model: Waters 515, with UV

detector (REX, Model pHS-25),

Visi TM-1 SPE

processor (Supelco) 50 mM

KH2PO4 (pH = 2)

Acetonitrile

was used as solvent as well as

mobile phase spectrophotometer

MDA was found to be 1115 and

1010 m2 mol1,

water and DCM

Transitional

caffeine in water and in

dichloromethane

and 10.80 1030 C m,

respectively

 are 10.40 1030

 dipole moments of

respectively,

 in

five samples by

HPLC

0.90–1.10%

 for

Caffeine in coffee beans

 UV/vis

five

independent

measurements

1.1 0.01% for Bench Maji,

1.01 0.04% for Gediyo

Yirga Chefe, 1.07 0.02%

for Tepi, and 1.19 0.02%

for Godere, respectively

HPLC:

1.10% for Bench Maji, 1.10%

for Gediyo Yirga Chefe,

1.00% for Gomma Limu, and

0.90% for Besema

measurements

 were

 were

spectrophotometer:

[16]

The molar decadic absorption

(MDA) coefficients

transitional

caffeine in water and

dichloromethane

obtained at 272 and 274.7 nm

 (DCM) were

 dipole moment of pure

 and

10. HPLC and UV UV/vis

 and methanol (40:8:2)

single-sample

9 HPLC

amplification,

 and

 comprising

 and water

biosensor

method

 **Experiment**

**Detection**

**Linearity**

**Application**

**Scientific outcome**

**Ref.no.**

**range**

0.01–0.1%w/v

Commercial

and cola drinks

 coffee samples

0.033–0.072%w/v

[14]

0.01–0.1%w/v

0.030–0.076%w/v

*A Detail Chemistry of Coffee and Its Analysis DOI: http://dx.doi.org/10.5772/intechopen.91725*

