Coffee Drying and Processing Method Influence Quality of Arabica Coffee Varieties (Coffea arabica L.) at Gomma I and Limmu Kossa, Southwest Ethiopia

Abstract

Solar tunnel drying and semiwash processing methods are popular among coffee growers in southwestern Ethiopia. However, the effect of these processing methods on coffee quality has not been studied in detail. The objective of this study was to evaluate the effect of processing and drying methods on the quality of coffee varieties at Gomma-I and Limmu Kossa areas in the 2016/2017 growing season. Two processing methods (fully washed and semiwashed) and three drying methods (solar tunnel, artificial, and natural sun) were compared using three coffee varieties (741, 7440, and 74110) to test their effect on coffee quality. Coffee beans processed by semiwash method and dried by solar tunnel produced nondefective (primary and secondary) coffee beans compared with others at both locations. Similarly, coffee beans processed by semiwashed method recorded the highest mean value for shape and make and body than wet processing method. Best coffee bean color, greenish color, was produced from coffee beans processed by the fully washed processing method. All coffee varieties processed by semiwashed method produced medium pointed acidity, the second most acceptable grade value for coffee quality for all drying methods. Coffee beans processed by the fully washed method produced more flavor than semiwash processing method. Coffee beans dried by sun and solar tunnel drying methods also produced better flavor than artificial drier. In general, all coffee varieties processed by semiwash method and dried by natural sun and solar tunnel method produced higher preliminary total quality and total specialty coffee value, graded under specialty grade Q1. Hence, coffee growers in the study area can use semiwash processing method and solar tunnel dryer as an alternative/complementary processing method since they produce better or equivalent quality product with full wash and natural sun drying method.

Effect of different drying airflows and harvest periods on the quality of specialty coffee (Coffea arabica L.)

“…This farm produces specialty coffee, and all process parameters are controlled until parchment coffee is obtained. Coffee beans were manually collected as mature fruits (17)(18)(19)(20)(21)(22). Ripe coffee beans were subjected to wet fermentation for 15 hours, followed by drying for 7 -10 days in greenhouse-type experimental rooms, where temperature, relative humidity and aeration were controlled.…”

“…Drying is one of the post-harvest steps with the most significant influence on coffee quality 19,20 . The coffee drying process reduces the bean's moisture content and prevents the microbial action responsible for spoilage during storage 21 . The drying process of green coffee beans may be accompanied by changes in the physical, chemical, and organoleptic properties of heat-sensitive components 20 .…”

“…Thus, the quality of the beverage could be defined while controlling the drying process 22 . The need for lower production costs and mitigating environmental damage has led to the development and research new drying techniques 21 .…”

Thermophysical properties of parchment coffee: New Colombian varieties

“…That is why the drying process should occur as soon as possible, and it must be duly controlled until the final moisture content is reached. Leading to one issue that the coffee growers face when drying their product since the harvest peaks might overlap with the rainy seasons (García et al, 2014); therefore, the drying process during this time is rather complicated, especially since they tend to sun‐dry the coffee (Firdissa et al, 2022) and the temperature inside the drying facilities highly fluctuate.…”

Analysis of Caffeine and Antioxidant Content of Ethiopian Coffee Varieties from Different Growing Areas

“…The genetic component and cultivation and processing practices significantly impact the physical characteristics and cup quality of coffee [10]. Recent research has shown that the yield, quality, and chemical makeup of Ethiopian coffees are also influenced by the cultivation region [11], environmental factors [12], harvest time [13], and postharvest processing techniques [14,15].…”