Abstract
Coffee is one of the most important agricultural commodities. The objective of this study was to simultaneously determination the biochemical constituents (caffeine, chlorogenic and nicotinic acids) and correlation with organoleptic cup quality of commonly grown coffee Arabica varieties in contrasting altitude of Southwest Ethiopia. A rapid and validated HPLC Diode Array Detector method was used for the simultaneous determination of targeted analytse in green and roasted coffee beans. The moisture content and pH were recorded from 10.13±0.04 to 12.49±0.08 and 5.36±0.04 to 5.81±0.04 respectively. The results of the chemical analysis showed that caffeine content in green coffee varieties was ranged from 12.34±0.08 mg/g (high altitude) to 19.89±0.28 mg/g (low altitude), chlorogenic content was also recorded 27.17±0.38 mg/g (high altitude) to 39.18±0.24 mg/g (low altitude) and nicotinic acid was ranged from 7.13±0.52 mg/g (low altitude) to 10.16±0.75 mg/g (high altitude). The caffeine content in roasted coffee varieties was ranged from 13.93±0.29 (high altitude) to 20.88±0.14 mg/g (low altitude) and chlorogenic content was recorded 8.56±0.02 (high altitude) to 16.21±0.10 mg/g (low altitude) and nicotinic acid ranged from 8.76 ±0.11 mg/g (high altitude) to 6.34±0.031 mg/g (low altitude). A highly significant decrement was observed in chlorogenic acid content after roasting, as altitude increases the caffeine and chlorogenic acid decreased. In contrary, nicotinic acid increase as altitude increase in green coffee varieties. As can be concluded from the result, as altitude increases caffeine and chlorogenic acid decreases but nicotinic acid increase. The caffeine content in green beans was lower as compared to roasted beans; significant degradation of chlorogenic acid was observed after roasting beans of the same variety. There was a significant interaction between altitude and coffee varieties on chemical constituents of coffee. These chemical contents could be used for coffee discriminators of coffee varieties and different altitudes. A highly significant correlation was also observed between biochemical contents and cup quality evaluation with altitude. Keywords: key word Altitude, Coffee, Varieties’ DOI : 10.7176/FSQM/93-03 Publication date: January 31 st 2020
Highlights
Coffee (Coffea L.) is the world’s favorite beverage and the second-most traded commodity after oil (Davis, 2012).The coffee bean is obtained from the fruit of the coffee plant, a small evergreen shrub belonging to the genus Coffea, family Rubiaceae (Davis et al, 2006).Only two species namely arabica (Coffea arabica L.) and robusta (CoffeacanephoraPierre) are under commercial cultivation (Lashermes et al, 1999; Anthony et al, 2002).The value of coffee for producers' country about $ 14 billion annual income generator and more than 18 countries, including Ethiopia, export coffee product to more than 165 countries providing a livelihood for an estimate of 100 million people around the world (ICO, 2001)
The result of chemical constituents was chlorogenic acid in coffee variety 7454 on contains lower (27.17±0.38 mg/g), in high altitude compared to mid-altitude (33.85±2.26 mg/g) and (39.18 ± 0.24 mg/g) in low altitude green beans
The caffeine content of roasted beans coffee varieties 7454 higher (20.88±0.14 mg/g) in low altitude compared to mid-altitude (17.72±1.46 mg/g) and high altitude (16.92±1.38 mg/g)
Summary
Coffee (Coffea L.) is the world’s favorite beverage and the second-most traded commodity after oil (Davis, 2012).The coffee bean is obtained from the fruit of the coffee plant, a small evergreen shrub belonging to the genus Coffea, family Rubiaceae (Davis et al, 2006).Only two species namely arabica (Coffea arabica L.) and robusta (CoffeacanephoraPierre) are under commercial cultivation (Lashermes et al, 1999; Anthony et al, 2002).The value of coffee for producers' country about $ 14 billion annual income generator and more than 18 countries, including Ethiopia, export coffee product to more than 165 countries providing a livelihood for an estimate of 100 million people around the world (ICO, 2001). Coffee is one of the major sources of export in the Ethiopian economy as it contributes 25-30% of Ethiopia's total export earnings (Abu Tefera, 2015).Beverage quality often referred to as drinking quality or liquor quality, is an important attribute of coffee (Muschler, 2001; Agwanda et al, 2003) and acts as a yardstick for price determination (Agwanda et al, 2003).Coffee beverage quality is based on the characterization of a large number of factors including taste and aroma These factors are related to the biochemical content of roasted beans. A thousand compounds, appearing during roasting, are involved in coffee beverage quality These compounds rise from a smaller number of biochemical compounds present in green beans. Beverage quality assessment is done organoleptically by trained coffee tasters (Van der Vossen, 1985; Agwanda, 1999) and Kathurima et al, 2010) recommended this method as sufficiently reliable for use as a basis of selection in quality improvement programs
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