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The amounts of nicotinic acid, trigonelline, 5-CQA, caffeine, kahweol and cafestol in 38 commercial roasted coffees ranged from 0.02 to 0.04; 0.22 to 0.96; 0.14 to 1.20; 1.00 to 2.02; 0.10 to 0.80 and 0.25 to 0.55 g/100 g, respectively. Evaluation of color and content of thermo-labile compounds indicated similarity in roasting degree. Differences in the levels of diterpenes and caffeine, components less influenced by the roasting degree, could be mainly explained by the species used (arabica and robusta). Gourmet coffees showed high concentrations of diterpenes, trigonelline and 5-CQA and low levels of caffeine, indicating high proportion of arabica coffee.

Different topics related to the kind and variety of coffee with commercial value, specially of the chemical composition of the green and toasted grain and particularly of the composition of the lipid fraction, are firstly revised. Secondly, the possible relationship between coffee consumption and some risk factors of cardiovascular diseases are also analysed, searching for the effect of different kinds of coffee, ways of preparation and the presence of the cafestol and kahweol diterpens on the level of serum lipids and lipoproteins on consumers. Among other conclusions, the loss of the hypercholesterolemic effect when the boiled preparations are filtered is noted.

The extraction of kahweol and cafestol involves saponification reaction. This step is important for the efficiency of the extraction as the diterpenes are susceptible to structural changes during hydrolysis. The microwave-assisted saponification has been successfully used in different matrices, but there is no previous report of the use of this technique in the saponification of diterpenes. Therefore, the effect of microwave-assisted saponification on the extraction of kahweol and cafestol in roasted coffee was evaluated. A 32 factorial experimental design was used in order to evaluate the effect of temperature (70, 80, and 90 ºC) and reaction time (4, 8, and 12 min). The quantification of diterpenes was performed by high-performance liquid chromatography and the results were compared to with those obtained by a method, which uses thermostatic bath for saponification. Temperature and time had a significant effect (p < 0.05) on diterpenes levels. For simultaneous saponification of kahweol and cafestol, the optimal reaction conditions were 80 ºC / 12 min. The use of microwave-assisted procedure lead to lower yields of kahweol (24%) and cafestol (35%) compared to reference method. However a significant reduction of reaction time (80%) was achieved, and the procedure also has the advantage of controlled process conditions and the possibility of extended scale.