EFFECTS OF SCREEN APERTURE ON GROUNDNUT DECORTICATION

Abstract

The high rate of bruised and split kernels realized from most groundnut decorticators necessitated the need to develop a decorticator with optimum clean kernels recovery. The objective of this study was to determine the effects of screen aperture on decorticating three selected groundnut varieties commonly cultivated in Nigeria. The varieties were Samnut 10, 14 and 18. A modified groundnut decorticator was used as part of the study. A removable oblong-shaped screen replaced the fixed net-like iron bars in the modified decorticator. 50kg each of the selected groundnuts in-shell were graded into three grades (I, II and III) while screen apertures of 8, 10 and 12 mm were used for decorticating the groundnuts at 8 % (d.b) moisture level using three replications in a complete randomized design. The results were evaluated using ANOVA at P<0.05 while the significant difference were evaluated using NDMRT. The analysis of variance test showed that the variations in clean, bruised and split kernels of the decorticated groundnuts in-shell were significant at 5 % level of significance. Results obtained showed progressive increase of clean kernels recovered. It revealed that both Samnut 10 and 18 recorded the highest percentages of clean kernels of 79.62 and 77.80 %, respectively at 8 % moisture content and 12 mm screen aperture. However, when screen apertures were varied from 8 – 12 mm for grade III, the rate of clean kernels recovery decreased progressively from 94.68 % using 8 mm aperture to 31.61 % with 12 mm aperture. It was also evident from the results obtained that the smaller the difference between the screen aperture and the major diameter of the groundnut pods the better the quality of higher percentage of clean kernels obtained.