Roasting Process Optimization of Walnut Kernels for the Preparation of Walnut Cream Using Response Surface Methodology

Roasting has considerable effects on the quality of cream made of nuts. In this study, the roasting conditions of walnut kernels were optimized based on the stability parameters of the produced cream. Temperatures of 100-150°C for 10-30 minutes were used to roast walnut kernels. The amount of oil separation, peroxide, acidity and Thiobarbituric acid values of the cream, as well as color parameters were determined after three months of storage at 25°C. The results showed that the oil separation increased with temperature and time of roasting (from 4.16% at 100°C/10min to 7.85% at 150°C/30min). Peroxide, acidity and thiobarbituric acid values were significantly affected by temperature and time of roasting. In addition, it was shown that as the temperature increased, the redness and yellowness increased, but the lightness of the samples decreased. Finally, the temperature of 116°C for 12 minutes was chosen as the optimized roasting conditions for producing walnut cream.