Heat transfer finite element model of fresh fruit salad insulating packages in non-refrigerated conditions

The quality of many foods is significantly affected by temperature fluctuations that can occur during distribution and transport. Packaging materials can help to shield the product from temperature variation by increasing the heat transfer resistance. Thermal insulation power is influenced by several factors, such as material, geometry, and degree of contact between materials. To maintain the cool chain of fruit salad with syrup during the transportation (temperature less than 5 °C), thermal insulation effect of different packaging materials was investigated. A parametric analysis using a finite element model able to describe the heat transfer inside the containers, on varying packaging material (expanded polystyrene: EPS, and air), geometry, dimension, and boundary conditions, was developed and validated. Good agreement was obtained between numerical and experimental results (R2 up to 0.98). The effectiveness of the insulation configurations was evaluated by determining the time taken for the temperature to rise the critical value of 5 °C. Results showed that insulating performance of the air is better than EPS. This is realistic only taking into account insulation layer less than 0.013 m. From a practical point of view, an EPS packaging could result stronger compared to a packaging characterised by an insulating air layer. For the same EPS insulation thickness, product temperature exponentially decreases with the volumetric capacity (R2 = 0.99).