Comparison of the quality of hazelnuts shelled with modified conical sheller and stone sheller

Two crackers (a modified conical sheller, widely used in Spain, and a stone sheller, widely used in Turkey) with different sheller characteristics were evaluated in terms of undamaged kernels, damaged kernels, broken kernels, left-in-the-shell kernels, cracked nuts, unbroken nuts and total recyclable nuts. Trials were carried out in a commercial hazelnut processing plant, using the 1996 Akcakoca hazelnut crop, which had a 50% kernel ratio (weight percentage ratio of the kernel to that of the whole hazelnut). The modified conical sheller gave a significantly higher output of undamaged kernels (67.5%) than the stone sheller (61.5%) (P = 0.0001). Left-in-the-shell kernels, cracked nuts and total recyclable nuts were significantly lower in the modified conical cracker (about 6, 4.5 and 30%, respectively) compared with those produced by the stone sheller (about 8, 7 and 35%, respectively). The two shellers produced similar levels of damaged kernels (about 3%), broken kernels (about 1%), and unbroken nuts (about 20%). Correlation analysis suggested that a better level of quality (a low percentage of damaged kernels and high percentage of undamaged kernels) can be obtained at the expense of increased unbroken nuts and total recyclable nut percentages for both the modified conical sheller and the stone sheller. At smaller diameter ranges, it is also necessary to accept a higher level of left-in-the-shell kernels for the stone sheller to achieve a better quality of shelled hazelnut. (C) 1999 Silsoe Research Institute.