Colour optimisation of ground pistachio during roasting

Main Article Content

R. Yeganeh


colour, pistachio nuts, roasting


In this research, ‘Ahmad Aghaei’ pistachio cultivar harvested from Iran in 2011 was supplied by the Pistachio Research Institute. The effect of roasting times (5, 10, 15, 20, 25 and 30 min) and temperatures (120, 130, 140, 150 and 160 °C) on the colour of pistachio nuts was investigated. Initially, the L value (lightness) decreased for all temperatures and then increased for 120 and 130 °C with increases in roasting temperature and time. Values of a (redness) and ?E (colour difference) for pistachio samples showed an increase while b decreased. Changes in L, a and b (yellowness) values of pistachio were used to develop and to validate a numerical dynamic model. The developed prediction models satisfactorily described the colour development as a function of roasting temperature and time for L, a, b and ?E of ground-state measurements. As a result of variance analysis, the effects of the roasting process on colour values of pistachios were found to be statistically significant. In addition, changes in colour values gave high R2 and the obtained nonlinear equations may be utilised to determine the optimum roasting degree based on time and temperature. A reverse approach for modelling is used in order to establish that it is possible to obtain the optimal condition directly from the experimental data modelling step.

Abstract 39 | PDF Downloads 30


Aktas, T. and Polat, R., 2007. Changes in the drying characteristics and water activity values of selected pistachio cultivars during hot air drying. Journal of Food Process Engineering 30: 607-624.
Arena, E., Campisi, S., Fallico, B. and Maccarone, E., 2007. Distribution of fatty acids and phytosterols as a criterion to discriminate geographic origin of pistachio seeds. Food Chemistry 104: 403-408.
Caglarirmak, N. and Batkan, A.C., 2005. Nutrients and biochemistry of nuts in different consumption types in Turkey. Journal of Food Processing and Preservation 29: 407-423.
Cammarn, S.R., Lange, T.J. and Beckett, G.D., 1990. Continuous fluidized-bed roasting. Chemical Engineering Progress 86: 40-46.
Davidson, V.J., Brown, R.B. and Landman, J.J., 1999. Fuzzy control system for peanut roasting. Journal of Food Engineering 41: 141-146.
Demir, A.D., Celayeta, J.M.F., Cronin, K. and Abodayeh, K., 2002. Modelling of the kinetics of color change in hazelnuts during air roasting. Journal of Food Engineering 55: 283-292.
Driscoll, R.H. and Madamba, P.S., 1994. Modelling the browning kinetics of garlic. Food Australia46: 66-71.
Fallico, B., Arena, E. and Zappalà, M., 2003. Roasting of hazelnuts. Role of oil in color development and hydroxymethylfurfural formation. Food Chemistry 81: 569-573.
Gezginc, Y. and Duman, A.D., 2004. The effect of pistachio processing techniques and storage conditions on quality. Gida 29: 373-378.
Hernández, J.A., Heyd, B. and Trystram, G., 2008. On-line assessment of brightness and surface kinetics during coffee roasting. Journal of Food Engineering 87: 314-322.
Kahyaoglu, T., 2008. Optimization of the pistachio nut roasting process using response surface methodology and gene expression programming. LWT - Food Science and Technology 41: 26-33.
Kahyaoglu, T. and Kaya, S., 2006a. Determination of optimum processing conditions for hot-air roasting of hulled sesame seeds using response surface methodology. Journal of the Science of Food and Agriculture 86: 1452-1459.
Kahyaoglu, T. and Kaya, S., 2006b. Modeling of moisture, color and texture changes in sesame seeds during the conventional roasting. Journal of Food Engineering 75: 167-177.
Koroglu, M., Okay, Y. and Koksal, A.I., 2000. The effect of salting and roasting process period on pistachio nut quality. Gida 25: 337-340.
Koshteh, K. and Urutyan, V., 2005. Global pistachio production and marketing challenges. Indian Journal of Economics and Business 4: 95-113.
Krysiak, W., 2006. Influence of roasting conditions on coloration of roasted cocoa beans. Journal of Food Engineering 77: 449-453.
Luh, B.S., Wong, W.S. and El-Shimi, N.E., 1982. Effect of processing on some chemical constituents of pistachio nuts. Journal of Food Quality5: 33-41.
Maskan, M. and Karatas, S., 1999. Storage stability of whole-split pistachio nuts (Pistachia vera L.) at various conditions. Food Chemistry 66: 227-233.
Midilli, A. and Kucuk, H., 2003. Energy and exergy analyses of solar drying process of pistachio. Energy 28: 539-556.
Moss, J.R. and Otten, L., 1989. A relationship between color development and moisture content during roasting of peanut. Canadian Institute of Food Science and Technology Journal 22: 34-39.
Özdemir, M. and Devres, O.Y., 1999. The thin layer drying characteristics of hazelnuts during roasting. Journal of Food Engineering 42: 225-233.
Özdemir, M. and Devres, O., 2000a. Analysis of color development during roasting of hazelnuts using response surface methodology. Journal of Food Engineering 45: 17-24.
Özdemir, M. and Devres, O., 2000b. Kinetics of color changes of hazelnuts during roasting. Journal of Food Engineering 44: 31-38.
Özdemir, M., Seyhan, F.G., Bakan, A.K., Ilter, S., Özay, G. and Devres, O., 2001. Analysis of internal browning of roasted hazelnuts. Food Chemistry 73: 191-196.
Pittia, P., Dalla Rosa, M. and Lerici, C.R., 2001. Textural changes of coffee beans as affected by roasting conditions. LWT-Food Science and Technology 34: 168-175.
Saklar, S., Katnas, S. and Ungan, S., 2001. Determination of optimum hazelnut roasting conditions. International Journal of Food Science & Technology 36: 271-281.
Simsek, A., 2007. The use of 3D-nonlinear regression analysis in mathematics modeling of color change in roasted hazelnuts. Journal of Food Engineering 78: 1361-1370.
Yeganeh, R. and Trystram, G., 2013. Intensification of pistachio by deep frying. Quality Assurance and Safety of Crops & Foods 5: 131-139.
Wall, M.M. and Gentry, T.S., 2007. Carbohydrate composition and color development during drying and roasting of macadamia nuts (Macadamia integrifolia). LWT - Food Science and Technology 40: 587-593.