Application of colour parameters for assessing the quality of Arabica and<br>Robusta green coffee

Abstract

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.

Can Elevated Air [CO2] Conditions Mitigate the Predicted Warming Impact on the Quality of Coffee Bean?

“…At control temperature, the apparent density values were close to those of field collected beans of C. arabica cultivars that show values between 0.63 and 0.68 g mL -1 ( Molin et al, 2008 ; Bicho et al, 2014 ), although the mass of 100 beans ( Table 1 ) was lower than the usual range (ca. 15–20 g) under sun or shade cultivation ( Ricci et al, 2006 ; Bicho et al, 2014 ). Temperature has driven most of the observed changes regarding the bean yield, mass, and increasing apparent density, whereas elevated [CO 2 ] per se did not alter these traits.…”

“…Determination of color attributes of whole bean was performed globally following Bicho et al (2014) . Briefly, color parameters, lightness ( L ∗ ), and chromaticity (coordinates a ∗ and b ∗ ) were obtained with a Minolta CR 300 colourimeter (Minolta Corp., Ramsey, NJ, United States) coupled with a glass container for solid samples (CR-A504).…”

Perspectives on the potential impacts of climate changes on coffee plant and bean quality

“…The moisture content in marketable green coffee bean should not exceed 12.5%, otherwise the beans will be easily attacked by fungi, allowing the accumulation of ochratoxin A to prohibited levels (Bicho et al, 2014;Coste, 1992).…”

“…The coffee bean becomes light brown and, their volume increases, and aroma formation begins. At 180-200°C, with the disruption of the endosperm, bean cracking occurs, bluish smoke and aroma appears, and caramelization develops (Bicho et al, 2014). In fact, it is known that the chemical reactions responsible for the aroma and flavor of roasted coffee are triggered at such temperatures.…”

“…The Maillard and Strecker reactions, involving carbohydrates (reducing sugar), proteins, and other compounds, promote the synthesis of, low-and high-molecular-weight compounds, e.g., melanoidins, which are simultaneously degraded and produced (Farah, 2012). Depending on the roasting intensity (in temperature and duration of the high temperature exposure), it follows that roasted coffee can show a brownish colour, yellower in lighter roasts, becoming reddish brown in medium roasting and dark brown in intense roasting (Bicho et al, 2014).…”