Abstract
During coffee drying, different temperatures applied to the beans with varied humidity content levels can interfere in the membranes integrity, germination, organic acid and carbohydrate content resulting in coffees with distinct flavors. The quality control of the beans will be much more effective the earlier the alterations provoked in the postharvest are detected. This work has an objective to study alternative methods for the dehydration of the coffee beans using ultra-drying followed by slow drying and its impact on the sensorial quality, chemical composition and physiology. For that purpose, coffee lots were processed by the methods, dry (natural coffee) and wet (fully washed coffee); and sun-dried and machine-dried at a constant 60°C temperature and alternating 60/40°C. The sensory quality of the samples was assessed by the Specialty Coffee Association of America (SCAA) analysis protocol. The sugar, total titratable acidity and the phenolic compound content was also analyzed. The physiological alterations of the coffee beans were analyzed by germination tests, emergence speed index, electrical conductivity and potassium leaching. The temperature of the drying air significantly altered the sensorial quality of the coffee beans. The processing way associated to drying methods causes many physiological alterations with the highest damage observed in the natural coffees. For the first time, we are showing that drying with heated air at 60/40oC is promising for the fully washed coffee beans, which are more tolerant to dehydration than the natural coffee beans. Conversely, the natural coffee beans were much more sensitive to drying regardless the temperature, with very low performance in the physiological analyses. The drying at the constant 60oC temperature is inappropriate for the natural coffee as well as for the fully washed coffee beans. In addition, the physiological tests used were shown effective for the early evaluation of coffee beans quality. Key words: Coffea arabica L., processing, drying, sensory analysis, chemical composition, germination.
Highlights
INTRODUCTIONThe quality of coffee is determined mainly by the flavor and aroma formed during the roasting of the beans
The quality of coffee is determined mainly by the flavor and aroma formed during the roasting of the beans.Approximately 300 chemical compounds present in green coffee beans originate about 850 compounds after the roasting (Flament, 2001)
The objective of the present research was to assess the effects of different processing and drying methods on the physiological quality and chemical composition of coffee beans, analyzing their interrelation with the quality of the drink
Summary
The quality of coffee is determined mainly by the flavor and aroma formed during the roasting of the beans. Being dependent on the combination of genetic, environmental and technological factors (Bertrand et al., 2006; Farah et al, 2006) Other factors, such as postharvest procedures interfere in the coffee quality, especially processing and drying (Borém et al, 2008a, 2014; Saath et al, 2010, 2014; Taveira et al, 2012). That method is based on a quantitative descriptive analysis of the drink, conducted by a team of selected tasters and, making use of a non-structured scale from 6 to 10 points for the evaluation of the fragrance, aroma, flavor, aftertaste, acidity, body, balance, sweetness, absence of defects and drink uniformity, with evaluation of the global quality of the coffee according to the terminology presented by Lingle (2011). The objective of the present research was to assess the effects of different processing and drying methods on the physiological quality and chemical composition of coffee beans, analyzing their interrelation with the quality of the drink
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