Effect of growing conditions and postharvest processing on arabica coffee bean physical quality features and defects.

The individual and interaction effects of elevation, production system (PS), shade and postharvest processing (PHP) on the ratio of dry beans to red cherries and the green bean physical quality features and defects of arabica coffee in southwestern Ethiopia were evaluated. The results showed that, with increasing elevation, the proportions of the total defected beans and large beans decreased while that of medium beans increased. Moreover, the proportion of secondary defects, 1000 seed weight and bean volume were higher for lowland and midland coffees than for highland coffee, but bean density was higher for highland than for lowland and midland coffees. The proportion of the total defected beans was also higher for modern plantation coffee in lowland than for modern plantation and semi-plantation coffees in midland and highland, but the 1000 seed weight was lower for semi-plantation coffee in highland than for modern plantation coffee in lowland and midland. The ratio of primary and secondary defects respectively was higher for dry- and wet-processed coffee in lowland than for dry- and wet-processed coffees in midland and highland. But, the ratio of small beans was lower for wet-processed coffee in lowland than for dry-processed coffee across elevations. The ratio of dry beans to red cherries and the 100 beans volume were higher for wet-processed modern plantation and semi-plantation coffees in midland than for dry-processed coffees of both production systems across elevations. However, the ratio of large beans was higher (1) for wet-processed modern plantation coffee in lowland than for dry- and wet-processed coffees of both production systems across elevations, and (2) for coffee that was grown without shade and wet-processed in lowland than for other coffees. Bean density was higher for dry-processed modern plantation and semi-plantation coffee in midland and highland, respectively than for other coffees across elevations. Overall, these results underlined the primary effects of elevation and PS, and the complex interaction effects between PHP and PS or shade on the ratio of dry beans to red cherries and the physical features and defects of green arabica coffee beans.

Trend, instability and decomposition analysis of coffee production in Ethiopia (1993-2019).

Measuring the trends of growth and variability in agricultural production is important to understand how outputs change over time. Ethiopia is the largest producer of coffee in Africa and the fifth in the world. Despite the abundant opportunities and continuous efforts made to enhance its production, it is often said that the productivity of Ethiopian coffee remains far below its potential. Yet, empirical data on the status of coffee production over time in Ethiopia is scant. We, thus, analyzed the trend, instability, and decomposition of coffee production in Ethiopia for three periods, i.e., the entire period (1993-2019), the pre-Agricultural Growth Program period (1993-2010), and the Agricultural Growth Program period (2011-2019). In all three periods, harvested area and production showed an increasing trend while productivity showed a cyclical decreasing trend. The compound growth rates of harvested area (8.14%) and production (6.68%) in the 1993-2019 period were positive and significant at 1% level, whereas that of productivity (-0.45%) was not significant. Similarly, the compound growth rates of harvested area and production during pre-AGP (6.02 and 6.06%) and AGP (6.43 and 3.57%) were positive, but only significant during AGP, and that of productivity in both pre-AGP and AGP (0.19 and -1.6%) were not significant. Productivity was, however, more stable than harvested area and production during the entire and pre-AGP periods, while harvested area and production were more stable in AGP than in the other two periods. Besides, the harvested area effect on production differentials was substantial in all three periods, while productivity and productivity-harvested area interaction effects declined production during the entire and AGP periods. Overall, the results demonstrate that to enhance and sustain coffee production in Ethiopia, using improved varieties and agronomic practices can be a better option than expanding the cultivation area since land is scarce and fixed in supply.

Differentiating the geographical origin of Ethiopian coffee using XRF- and ICP-based multi-element and stable isotope profiling.

To test the potential of different analytical tools to determine the geographical origin of Ethiopian coffee, 103 green arabica coffee samples from four coffee regions in Ethiopia were subjected to multi-elements and δ13C, δ15N and δ18O determinations. Multi-elements were determined by using inductively coupled plasma (ICP)- and X-ray fluorescence spectrometry (XRF)-based techniques, and δ13C, δ15N and δ18O were determined by using elemental analyzer-isotope ratio mass spectrometry. Using linear discriminant analysis, XRF-based multi-elements with and without δ13C appeared to be most effective in discriminating the geographical origin of coffee, giving higher classification accuracy (89 and 86%, respectively) than ICP-based multi-elements with and without stable isotopes (80%, each). These results demonstrate the potential of XRF-based multi-element profiling as a relatively fast and low-cost tool to trace the geographical origin of Ethiopian coffee. All together this study offers the proof of concept for a promising method that, upon standardization, could be used for coffee provenance authentication and fraud detection.

Effect of altitude on biochemical composition and quality of green arabica coffee beans can be affected by shade and postharvest processing method.

Although various studies have assessed altitude, shade and postharvest processing effects on biochemical content and quality of coffee beans, data on their interactions are scarce. The individual and interactive effects of these factors on the caffeine, chlorogenic acids (CGA) and sucrose contents as well as physical and sensory qualities of green coffee beans from large plantations in southwestern Ethiopia were evaluated. Caffeine and CGA contents decreased with increasing altitude; they respectively declined 0.12 and 1.23gkg-1 100m-1. Sucrose content increased with altitude; however, the altitude effect was significant for wet-processed beans (3.02gkg-1 100m-1), but not for dry-processed beans (0.36g kg-1 100m-1). Similarly, sucrose content increased with altitude with much stronger effect for coffee grown without shade (2.11gkg-1 100m-1) compared to coffee grown under shade (0.93gkg-1 100m-1). Acidity increased with altitude when coffee was grown under shade (0.22 points 100m-1), but no significant altitude effect was observed on coffee grown without shade. Beans grown without shade showed a higher physical quality score for dry (37.2) than for wet processing (29.1). These results generally underline the complex interaction effects between altitude and shade or postharvest processing on biochemical composition and quality of green arabica coffee beans.