Coffee is the world’s favorite beverage and the second most traded commodity worldwide after oil in the international market both in terms of volume and value[1]. Ethiopia is the center of origin for Arabica coffee which is produced throughout the country in four major production systems, namely forest coffee, semi-forest coffee, garden coffee, and plantation coffee production systems[2]. The quality of coffee is strongly influenced by environmental factors including altitude, daily temperature fluctuations, amount, and distribution of rainfall as well as the physical and chemical properties of soil [3]. Drying is an essential process in the preservation of agricultural products. In Ethiopia, smallholder coffee producers dry their coffee using the natural sun. This method of drying, however, has many limitations, including variability in drying duration, high labor demand, and dependence on weather conditions. Agricultural food products can dry more quickly to a safe moisture content and maintain a higher quality when they are dried in regulated temperature and humidity environments [4].
The moisture content of the coffee beans plays an important part in determining the coffee storage stability against deterioration[5]. It also has a great influence in threshing, separation, cleaning and grading operations. [6] Noted that the moisture dependent characteristics of physical properties have effect on the adjustment and performance of agricultural product processing machines. They further noted that the optimum performance of machines could be achieved at a specific range of moisture contents. It has been reported that the knowledge of physical properties and their dependence on the moisture content are useful for the design and development of methods and equipment [7]; [8].
One of the most important physical attributes taken into account during the separation and cleaning of agricultural grains is their geometric characteristics, such as size and form. Agricultural seeds are believed to be spheres or ellipses in theoretical calculations due to their uneven forms [9]; [10]. Size and shape have a role in determining coffee bean quality [11]. When designing the handling system, grading, and hulling, physical characteristics including size, angle of repose, crushing strength, and bulk density are crucial [12].
Physical attributes of agricultural food products are crucial parameters for determination of proper standards of design of grading, conveying, processing, and packaging systems [13]. Data on physical properties are important in the design of a specific machine or analysis of the behavior of products in order to perform various post-harvest operations [14]. Therefore, the engineering physical qualities of the bean should be researched in order to optimize the design of equipment for enhanced post-harvest handling and processing of various released coffee cultivars in diverse drying techniques. Food engineers who study various aspects of the coffee bean can also benefit from this information. On the other hand, no scientific research has been done on the same technical qualities of these recently released coffee varieties when dried in a lath house.