Fast and non-destructive indicators were evaluated as tools to measure the technological quality of Arabica and Robusta coffee. Accordingly, considering the roasting intensity in highly valuable commercial samples, volume, mass, apparent density, moisture, total ash, ash insoluble in hydrochloric acid, and ether extract were characterized. The chromatic parameters L*, C*, Hº were measured using illuminants D65 and C. It was found that in roasted coffee beans, the parameters L*, C*, Hº, and coordinate b* had an antagonist interaction due to an increase in the roasting intensity, whereas after milling, only L* and Hº decreased progressively. Considering that the parameters L* and Hº followed similar patterns using both illuminants, D65 and C, it can be concluded that they are appropriate to evaluate coffee colour changes during roasting, enabling a relationship with coffee quality.
Roasted coffee samples of the two major trade species (Coffea arabica and C. canephora) were studied to identify sensory descriptors that might be used to determine blends production and evaluation, following the expectations of consumers. Coffee beans were roasted at 220 + 10 °C, for 7, 9, and 11 min, and the sensory profiles of the beverages were assessed. From descriptive analysis the eigenvalues allowed the identification of two principal components (PCs), being the variance between samples 68.9% and 21.1%. In the first PC the characteristic odor, astringency, body, bitter flavor, burned aroma, and residual, typical, and burned tastes prevailed. The correlation coefficient between the second PC and citric acid flavor and aroma reached 0.96 and 0.78, respectively. It was concluded that in beverages of these species, the descriptors of both components can be separated according to bean roasting time. Considering roasting time, the overall quality was also rated.
The chemical parameters pH, soluble solids, caffeine, trigonelline, total chlorogenic acids, total caffeoylquinic acids, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, total dicaffeoylquinic acids, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, total feruloylquinic acids, 3-Oferuloylquinic acid, and 5-O-feruloylquinic acid were measured in Arabica (C. arabica)and Robusta (C. canephora) green coffees in order to determine discrimination parameters. In general, Robusta green coffee showed higher values for pH, soluble solids, caffeine, total caffeoylquinic acids, total dicaffeoylquinic acid, and total feruloylquinic acid, but the content of soluble solids was not significantly different in both species of green coffee. Through application of a multivariate analysis, it was concluded that these chemicals form three clusters, being the group of caffeine, trigonelline, 3-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, 3-O-feruloylquinic acid, 5-O-feruloylquinic acid, 3,4-O-dicaffeoylquinic acid, 3,5-Odicaffeoylquinic acid, and 4,5-O-dicaffeoylquinic acid highly discriminating for Arabica and Robusta green coffees.
This work aims to achieve fast and non-destructive indicators that enable the definition of the quality of green coffee from Coffea arabica and C. canephora, respectively Arabica and Robusta, in high commercial samples (which displayed, respectively, medium sieve between 17.4 and 19.2, trade homogeneity of 94.3% and 97.0%, mass of 1000 beans with values of 213.16 g and 151.36 g, apparent densities of green coffee not significantly different, showing values of 0.629 and 0.630 g cm-3 and moisture ranging between 9.056 and 9.243%). Being these samples within the established range of the international market, and ensuring good storage conditions, the chromatic parameters L* (lightness), C* (chroma) and Hº (tone or hue angle) of these samples were assessed using illuminants D65 and C. It was concluded that through the application of colour parameters the quality of green coffee can be assessed. Yet, as coordinate a* (contribution of red or green) strongly affects tone of the green coffee, the illuminant type used in the measurement must be defined and/or combined in order to accurately characterize product quality.
Arabica and Robusta coffee beans were roasted at 220 ± 10°C for 7, 9 and 11 min to identify chemical descriptors in the beverages. The pH of the beverages showed the lowest value in the medium roasting level. In each degree of browning, the soluble solids content remained slightly higher in Arabica drinks. The contents of caffeine did not vary, but trigonelline decreased with burning up intensity. Chlorogenic acids also decreased with increasing roasting time. The 5-O-caffeoylquinic acid prevailed in Arabica and Robusta beverages, but the isomers of dicaffeoylquinic and feruolilquínic acids remained higher in Robusta. It was concluded that trigonelline and total caffeoylquinic, fatty dicaffeoylquinic and fatty feruolilquínic acids detached the beverages according to roasting intensity. Caffeine and pH allowed drinks separation between both species. Soluble solids take apart Arabica and Robusta drinks in each degree of roasting. All the individual groups of chlorogenic acids also explained 90% of the variance among samples.
To attain chemical descriptors responsible for sensory characteristics linked to the botanical origin of five Brazilian coffee genotypes, a chemical survey was carried out. Highest and lowest amounts of caffeine were found in Apoatã and Obatã. Coffea dewevrei showed the lowest contents of 5-CQA and 3-CQA. 3,5-diCQA was higher for Apoatã and minimum values were detected in Icatu. Apoatã showed the highest contents of 3,4-diCQA and 4,5-diCQA, Catuaí, Icatu and Obatã revealed lower values of 4,5-diCQA. Among hydroxycinnamic acids ferulic acid prevailed in all genotypes, with lower values in Icatu and Obatã. 3,4-DCA remained significantly higher in Apoatã, C. dewevrei and Catuaí. Caffeic acid and p-coumaric acid did not vary significantly. It was concluded that Apoatã was most adequate for the decaffeinated industry; Catuaí, Icatu and Obatã were identified as producers of good beverages. Apoatã and C. dewevrei seemed to share closer parental origins to Coffea canephora cv. Robusta, whereas Icatu, Obatã and Catuaí showed higher similarities to Coffea arabica.
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