No abstract

The Bourbon coffee cultivar has a high potential for producing a quality beverage, which is highly valued in specialty coffee markets. The objective of this study was to verify the occurrence of more promising genotypes for the production of specialty coffees in three different environments. In addition, the chemical composition of the grains was studied with a view toward relating these compounds to the genotypes and environments and to the interaction of these factors.The experimental design included three Brazilian locations in combination with different Arabica coffees, including eleven bourbon and three commercial genotypes. Trigonelline, caffeine and 5-caffeoylquinic acid (5-CQA) from coffee bean samples were analyzed by HPLC, and sensory analyses were performed by professional cuppers accredited by the Coffee Quality Institute. A group of Bourbon genotypes with potential for the production of specialty coffees was identified for each environment assessed. The trigonelline content allowed for discrimination among the three environments studied.

The influence of green coffee genotype on the bioactive compounds and the in vitro antioxidant capacity against the principal reactive oxygen (ROO(•), H2O2, HO(•), and HOCl) and nitrogen (NO(•) and ONOO(-)) species of biological relevance was investigated. This is the first report on the capacity of green coffee to scavenge H2O2, HOCl, and NO(•). Variations in the contents of total chlorogenic acids (22.9-37.9 g/100 g), cinnamoyl-amino acid conjugates (0.03-1.12 g/100 g), trigonelline (3.1-6.7 g/100 g), and caffeine (3.9-11.8 g/100 g) were found. Hydrophilic extracts of Coffea canephora and Coffea kapakata were the most potent scavengers of ROO(•), H2O2, HO(•), NO(•), and ONOO(-) due to their chlorogenic acid contents, which were, on average, 30% higher than those found in Coffea arabica and Coffea racemosa. The results showed that genotype is a determinant characteristic in the bioactive compound contents and consequently in the antioxidant capacity of green coffee.

RESUMOEste trabalho teve por objetivo caracterizar seis variedades de C. canephora do Banco de Germoplasma de Café do Instituto Agronômico, em Campinas. Para tanto, considerou-se a caracterização química de quarenta e sete exemplares analisando-se as variáveis sólidos solúveis, lipídios, trigonelina, ácidos clorogênicos e cafeína nas sementes. Observou-se a existência de grande variação entre e dentro dos diferentes materiais analisados, com valores extremos de 24,53% a 30,68% para sólidos solúveis; 6,61% a 12,27% para lipídios; 0,73% a 1,59% para trigonelina; 3,30% a 6,30% para ácidos clorogênicos e 1,94% a 3,29% para cafeína, indicando a possibilidade de seleção de plantas de interesse para o melhoramento dessa espécie.Palavras-chave: cafeína, componentes químicos, café robusta, diversidade genética, trigonelina. ABSTRACT CHEMICAL DIVERSITY IN COFFEE PLANTS OF COFFEA CANEPHORAThe objective of this work was to characterize six C. canephora varieties from the Coffee Germoplasma Collection of Instituto Agronômico, in Campinas, Brazil. For this a chemical characterization of forthy seven examples was performed. Soluble solids, lipids, trigonelline, chlorogenic acids and caffeine contents were evaluated on seeds. The results demonstrated the occurrance of great variation among and within the analyzed materials, with values ranging from 24,53% to 30,68% for soluble solids; 6,61% to 12,27% for lipids; 0,73% to 1,59% for trigonelline; 3,30% to 6,30% for chlorogenic acids and 1,94% to 3,29% for caffeine. These results indicate the possibility of selection of superior plants for the improvement of the specie.Key words: caffeine, chemical components, robust coffee, chemical diversity, trigonelline.( 1 ) Recebido para publicação em 31 de março e aceito em 8 de agosto de 2005.

The fingerprints of the volatile compounds of 21 commercial Brazilian coffee samples submitted to different industrial processing i.e. decaffeinated or different roasting degrees (traditional and dark) were studied. The volatiles were collected by headspace solid phase microextraction (HS-SPME) and analyzed by GC-FID and GC-MS. The chromatographic data matrices (fingerprints) obtained were explored by the principal component analysis (PCA) and partial least squares - discriminative analysis (PLS-DA). Initially the chromatographic profiles were aligned by the algorithm correlation optimized warping (COW). The PCA showed the discrimination of the decaffeinated coffees from the others with both the SPME fibres used. This separation probably occurred due to the loss of some volatile precursors during the decaffeination process, such as sucrose. For both the fibres tested, PDMS/DVB and CX / PDMS SPME, the PLS-DA models correctly classified 100% of the samples according to their roasting degree: (medium and dark), the main differences being the concentrations of some of the volatile compounds such as 2-methyl furan, 2-methylbutanal, 2,3-pentanedione, pyrazine, 2-carboxyaldehyde pyrrole, furfural and 2-furanmethanol.