A coupled photogrammetric–finite element method approach to model irregular shape product freezing: Mozzarella cheese case

The freezing process can be industrially performed to extend shelf life and to improve exportability of Italian high-moisture Mozzarella cheese. This cheese is usually characterized by a non-regular spheroidal shape that may be responsible for local differences of temperature on the surface and that can influence the overall freezing time. In this work, Mozzarella freezing was modelled by coupling the finite element method and a photogrammetric procedure that permitted to reconstruct the three-dimensional domain of the product. Computational models were validated by performing experimental trials, and results were accurate (root mean square error<1.47°C). With the photogrammetric technique it was possible to estimate volume, surface area, shape and size of the cheeses, and to study temperature–surface distribution that was found to be non-homogeneous. Freezing models highlighted that the surface area-to-volume ratio of the product, that ranged between 1.09 and 1.15cm−1, is one of the most critical parameters that define the freezing time of the cheese. A geometrical approximation of the cheese based on the surface area-to-volume ratio, showed good accuracy in terms of freezing times. These models can be valuable for Mozzarella cheese freezing optimization and design, to recover efficiency and to improve quality.