Computational fluid dynamics (CFD) modelling and experimental validation of thermal processing of canned fruit salad in glass jar Matteo Cordioli a , Massimiliano Rinaldi a , Gabriele Copelli b , Paolo Casoli b , Davide Barbanti a,⇑ a Department of Food Science, University of Parma, Parco Area delle Scienze 47/A, 43124 Parma, Italy b Department of Industrial Engineering, University of Parma, Parco Area delle Scienze 181/A, 43124 Parma, Italy article info Article history: Received 5 March 2014 Received in revised form 29 October 2014 Accepted 2 November 2014 Available online 15 November 2014 Keywords: CFD Thermal processing Canned fruit salad Natural convection Conduction abstract In this paper the heat transfer of a fruit salad during the pasteurization treatment was investigated. The objective of the paper was to develop and validate a computational fluid dynamics (CFD) model for pre- dicting the temperature profiles during the thermal processing of this sample. Samples of a commercial fruit salad, composed of five different fruits with different shapes, sizes and thermal properties, sub- merged in water/sugar syrup, were submitted to thermal treatments in a pilot plant and temperature profiles at different locations were experimentally recorded. Results showed that the slowest heating point (SHP) was positioned at 19–20% of the can height: fruit closest to the SHP such as pear presented the lowest F value. Moreover, F values resulted to be influenced by the distance from the jar bottom as function of natural convection motion of the syrup. CFD model simulations data were then successfully validated against the experimental ones: results, expressed as RMSE, showed a good fitting between cal- culated and experimental data, both for syrup (mean RMSE 1.47 °C) and fruit pieces (mean RMSE 1.63 °C). In addition, F values calculated from both experimental and simulated temperatures resulted very similar with only little differences. In conclusion, the proposed approach and mathematical model can thus be usefully applied for the simulation and prediction of thermal processes of canned fruit salad for process design and optimization. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction In the food industry, a great number of fruits and vegetables are packaged in cans or jars, filled with an appropriate sugar syrup or brine, and thermally processed in order to increase their shelf life through the inactivation of both spoilage microorganisms and enzymes (Kiziktas et al., 2010). Heat transfer mechanisms in canned food are conduction for solid and high viscosity liquid foods, natural convection for low viscosity liquid foods, convection plus conduction for liquid foods with solid particles and convection followed by conduction for liquid foods containing starch or viscosity modifiers (Chen and Ramaswamy, 2007). Moreover, it is widely known that quality as well as nutritional characteristics of foods can be dramatically reduced by the thermal stabilisation processes. Hence, time and temperature combination during the heating and the cooling cycles must be properly assessed to guarantee both effectiveness (inactivation of microor- ganisms and enzymes) and efficiency (retention of sensory and nutritional characteristics as well as limiting of costs). As a conse- quence, the thermal process must be properly designed by study- ing the thermal properties of foods and the mechanism of heat transfer during the treatment. These purposes are normally achieved by a relevant number of experimental trials with an increase in costs and time consumption thus reducing the possibil- ity to have fast, efficient and in-depth results (Sun, 2007). In order to overcome these limits, in the last years, process design in the food industry has been increasingly carried out by using numerical solutions of process governing equations, model- ling and calculation methods (Weng, 2005). Among these, computational fluid dynamics (CFD), has found widespread application in many areas of food processing such as spray drying, baking, sterilization, heat exchangers design, chilling, mixing, fermentation and in the agri-food industry (Sun, 2007). CFD is a simulation tool which uses powerful computers and applied mathematics to model fluid flow situations for the predic- tion of heat, mass, momentum transfer and optimal design in industrial processes (Anandharamakrishnan, 2011; Chhanwal et al., 2012; Kuriakose and Anandharamakrishnan, 2010; Xia and Sun, 2002). Several works deal with CFD simulations of canned foods: Kumar et al. (1990) simulated the natural convection in http://dx.doi.org/10.1016/j.jfoodeng.2014.11.003 0260-8774/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +39 521 905706. E-mail address: davide.barbanti@unipr.it (D. Barbanti). Journal of Food Engineering 150 (2015) 62–69 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng