Effect of microwave treatment on oil contents, fatty acid compositions and mineral contents of hazelnut varieties

The oil content of both ‘raw’ and hazelnut kernels was significantly (p < 0.05) reduced as the microwave power increased from 180 W to 360 W. The contents of fatty acids flucuated for all varieties with microwave power, with a significant (p < 0.05) increment observed for ‘Sivri’ hazelnut at 180 and 720 W. The maximum linoleic acid contents for ‘Raw’, ‘Sivri’ and ‘Tombul’ hazelnuts were found as 11.87%, 12.61% and 17.68% for nuts roasted at 540 W, unroasted and those roasted at 720 W, respectively. It was observed that K (9735.1 mg/kg) and Mg (2343.7 mg/kg) contents of the investigated samples were found at the maximum levels in unroasted ‘Tombul’ hazelnut, while the highest P (2845.0 mg/kg) and S (1795.3 mg/ kg) contents are determined for hazelnut roasted at 720 W (p < 0.05). The highest Ca content in hazelnut kernel was also observed at 360 W with 2400.9 mg/kg. However, roasting process did not dramatically affect the mineral contents of samples.