Table 1 provides the pertinent parameters affecting the performance of groundnut decorticator.

A bulk quantity of the pods of each of the three groundnut varieties used in this study were obtained from ICRISAT farms in Alupe, western Kenya. The pods were cleaned using the cyclone separator to remove dust and other unwanted materials. The varieties were referred to as ICGV 12991, ICGV 90704, and ICGV 99568. 100 pods from each variety were randomly selected and put in the bowls. For each pod, the axial dimensions of length, major diameter and minor diameter were measured using the vernier callipers reading to 0.05 mm and readings recorded. 1000 pod weight was determined by physically counting 1000 pods and then weighing in the electronic balance. Weight measurement was replicated three times and average weight compared. For determination of angle of repose, a pod was placed on the 70 mm by 70 mm metal sheet and one side of the sheet metal lifted until the pod just rolled down. The angle of the tilt was then measured using angle protractor and recorded. This was repeated for 10 pods and the average determined for each of the varieties. The bulk density of the pods was determined using the AOAC (1980) recommended method. This involved filling 1000 cm³ plastic container with the pods and then weighing the pods. The

Table 1. Pertinent parameters affecting efficiency of groundnut decorticators.

bulk density was calculated by dividing the weight by the volume. The pods were conditioned using the method of [10]. This involved soaking of the pods in clean water for a period of 48 h. At the end of soaking, the pods were spread out in thin layer to dry in natural air for about 8 h. The pods were then sealed in marked polythene bags and stored in that condition for a further 24 h. This enabled a stable and uniform moisture content of the pods to be achieved. The moisture content of the kernels was determined using electrical moisture meter. In this method, 100 g of nuts were placed in the moisture meter and moisture content read. Variation of moisture content was achieved through drying of the pods in the tray drier. Measurements of the moisture content using the moisture meter were taken at intervals of 5 minutes during the first two readings and intervals of 10 minutes for the other three readings. All the readings were recorded and mean and standard deviations determined.

Figure 1 shows the shelling unit of the wooden beater decorticator. The overall dimensions of the rod beater decorticator are: length of 800 mm, width of 250 mm and height of 940 mm. The shelling unit consists principally of a rotating cylinder and a stationary concave sieve. The cylinder is 190 mm in diameter and 200 mm in length. Twelve shelling metal bars each of 10 mm diameter and 200 mm long are mounted uniformly on the cylinder surface and parallel to its axis.

Figure 2 shows the wooden beater decorticator. The decorticator is powered manually and operates in the same manner as rod beater decorticator except that the impact, shear and compressive forces and tangential force are provided by wooded bars. The overall dimensions of the decorticator are: length of 745 mm, width of 270 mm and height of 1250 mm. A description of two essential units of the decorticator: the shelling and clean ing units are given in the following sections. The shelling