RESUMO O perfil dos compostos bioativos em bebidas café depende das espécies e variedades de café, métodos de plantio e processamento pós-colheita, processo de torra e também do método de preparação da bebida. O trabalho teve como objetivo estudar os teores de caveol e cafestol - diterpenos do café com efeitos conhecidos a saúde - comparando bebidas de café preparadas usando métodos usuais de preparo (filtrada, espresso e café solúvel). As bebidas filtradas (pano ou papel), espresso e café solúvel foram obtidas de grãos com torra média da espécie Coffea arabica (tipo 2). Cinco repetições genuínas de cada bebida foram preparadas e os extratos foram liofilizados. Os diterpenos foram quantificados por CLUE. Os resultados foram relatados em mg de diterpeno por g de sólidos ou por dose padrão de 50 mL. O teor de sólidos das bebidas de café variou de 2,06 a 2,46 g 100 mL-1. Todas as bebidas apresentaram baixo teor de diterpenos: 0,05 a 0,16 mg de kahweol e 0,11 a 0,14 mg de cafestol 50 mL-1. A bebida instantânea mostrou o menor teor de kahweol e ausência de cafestol, redução relacionada ao processo de produção de café solúvel. O teor de diterpenos foi semelhante em cafés espresso e filtrados em papel. O café filtrado em pano apresentou menor teor de sólidos, mas níveis mais elevados de diterpenos (em mg g-1 de sólidos). Teores similares de cafestol e kahweol (mg 50 mL-1) foram observados nas bebidas filtradas e no espresso.

ABSTRACT The profile of bioactive compounds in coffee brews depends on the coffee bean species and varieties, harvesting and post-harvesting practices, roasting processes, and also on the brewing method. The present research aimed to study the contents of cafestol and kahweol - coffee diterpenes with a known impact on human health - comparing coffee beverages prepared using common brewing methods (filtered, espresso, and instant coffee brews). Filtered (cloth-filtered and paper-filtered), espresso and instant brews were obtained from a medium-roasted Coffea arabica coffee (NY 2). Five genuine replicates of each coffee brew were prepared, and the extracts were lyophilized. A validated UPLC-based method provided the content of diterpenes. The results were reported in mg of diterpene per g of solids or per a standard dose of 50 mL of coffee brew. Solids content of coffee brews ranged from 2.06 to 2.46 g 100 mL-1. All coffee brews presented low diterpene contents: 0.05 to 0.16 mg of kahweol and 0.11 to 0.14 mg of cafestol 50 mL-1. Instant coffee brew showed the lowest content of kahweol and absence of cafestol; this reduction was related to the production process of soluble coffee. Diterpenes content was similar in espresso and paper-filtered brews. The cloth-filtered coffee had lower solids content, but higher levels of diterpenes (in mg g-1 of solids). Similar cafestol and kahweol contents (mg 50 mL-1) were observed in filtered and espresso brews.

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.

A reverse phase liquid chromatography method was developed for simultaneous determination of trigonelline, caffeine, nicotinic and chlorogenic (5-CQA) acids in roasted coffee. A gradient of acetic acid/acetonitrile was used as mobile phase and detection was carried out in the UV. The samples were extracted with acetonitrile/water (5:95 v/v) at 80 ºC/10 min. Good recovery (89 to 104%), repeatability and linearity were obtained. Detection limits of 0.01, 0.15, 0.04 and 0.04 mg mL-1 were observed for nicotinic acid, trigonelline, 5-CQA and caffeine. The method, applied to arabica and robusta coffees with different degrees of roasting, was efficient and fast (~35 min) and also allowed identification of cinnamic acids.