Effects of Different Processing Methods of Coffee Arabica on Colour, Acrylamide, Caffeine, Chlorogenic Acid, and Polyphenol Content

Abstract

An effect of a processing method (dry and wet) and a degree of roasting (light, medium, and dark) of 15 coffee (Coffea arabica) samples on the content of caffeine, chlorogenic acid (CQA), total polyphenols (TPP), acrylamide (AA), and on the colour parameters L*, a*, and b* was evaluated. Neither processing nor roasting affected caffeine content (p > 0.05). The degree of roasting accounted for 46% and 72% of explained variability of the CQA content and AA content, respectively (p < 0.05). AA content was in the range from 250 (wet-processed, light-roasted samples) to 305 µg·kg−1 (wet-processed, dark-roasted coffees), but the dark roasting only tended (p > 0.05) to increase AA content. Wet-processed, dry-roasted coffee had higher (p < 0.05) TPP content (48.5 mg·g−1) than its dry-processed, dry-roasted counterpart (42.5 mg·g−1); the method of processing accounted for 70% of explained variability of TPP. Both the method of processing and the degree of roasting affected the L*, a*, and b* values (p < 0.01), but the lower values (p < 0.05) of these parameters in the dark-roasted samples were found only within the wet processing. A negative correlation between the AA content and lightness (L*) was established (r = −0.39, p < 0.05). It was concluded that from the consumers’ viewpoint, the results of the present study indicate relatively small differences in quality parameters of coffee irrespective of the method of processing or degree of roasting.

Physicochemical and Sensory Properties of Arabica Coffee Beans of Arara cv. Dried Using Different Methods

“…Murkovic and Derler [ 54 ] noted that sugar levels are positively associated with better coffee quality and tend to undergo changes during drying. These compounds play a crucial role in the chemical reactions that occur during coffee roasting, such as the Maillard reaction, which leads to the formation of compounds responsible for the beverage’s characteristic color, aroma, and flavor [ 8 ]. The sugar levels found in this investigation were generally higher when compared to other studies, indicating that these sugars contributed to the classification of the coffee as “Special” as determined via a sensory analysis.…”

“…After drying, the moisture content of the coffee is reduced to an adequate range of 11 to 12% (w.b.) [ 7 , 8 ].…”

“…Here, the beans are periodically stirred to maintain uniform drying. Modifications to this method aim for improved results, and some configurations include a forced ventilation system with heated air and a suspended patio setup [ 8 ]. In most fixed-bed dryers, air flows from the lower layer to the surface of the grain mass.…”

Chemical and Biological Characterization of Green and Processed Coffee Beans from Coffea arabica Varieties

“…In Typica variety coffee beans from plants grown in two different places, the caffeine content in light roasting was 4.19 mg/g and 5.01 mg/g; when the level of roasting was increased to a dark level, the content presented an increase (5.18 mg/g and 6.12 mg/g), a similar effect that was reflected in this study [ 21 ]. Other studies on C. arabica have not reported variations in its content at different levels of roasting (11.9–13 mg/g), even using temperatures between 194 and 217 °C, showing a thermostable behavior of caffeine [ 23 ].…”

Comparative Metabolome Profiles and Antioxidant Potential of Four Coffea arabica L. Varieties Differing in Fruit Color

“…Finally, coffee also contains volatile and carbohydrate compounds such as saccharides and alcohols, stilbene, and vitamins [57,60,62]. Among the vitamins, L-ascorbic acid had higher accumulation in either RF or YF than PF (Table S4B,E).…”