Determination of the Best Drying Temperature of Hazelnut (Corylus avellana) after Six Months of Storage

Drying is one of the most important stages of hazelnut processing and its optimization improves the quality of the final product. The quality of hazelnut is dependent on chemical and organoleptic characteristics of fruit that is affected in the drying process. In present research, samples of Gerd cultivar of hazelnut (Corylus avellana) were dried in shelled and in-shell forms using a laboratory dryer in single-layered form, in three temperatures of 40, 50 and 60°C and 1 m/s air velocity, and  stored for six months. The time and energy required for drying and qualitative changes of hazelnut (oil content, protein content, acidity content and peroxide value of oil) were evaluated. The results showed that the hazelnuts dried under 60°C required the lowest time and energy for drying and the in-shell hazelnuts dried under this temperature (60°C) had the lowest acidity compared to other treatments. In addition, temperature had a significant effect on the qualitative traits of hazelnut. The results from taste tests showed that consumers prefer the shelled and in-shell hazelnuts dried in 50°C compared to other samples.  Based on the results, the 50°C is recommended temperature for drying hazelnuts.