Experimental study and numerical modeling of the freezing process of marine products

• Freezing times of crab meat packed in pouches and claws were measured and predicted.
• Mathematical models describe the industrial freezing of crab products.
• Freezing of foodstuffs with heterogeneous and irregular structure were modeled.
• Ice crystals sizes in the frozen tissue were determined by histological analysis.
• A correct design and control of the industrial crab freezing process was achieved.

An increasing interest in the exploitation of new Patagonian marine crabs was manifested by the industry, due to their commercial value as frozen products. In the present work the freezing of two products: crab meat in plastic pouches and crab claws was experimentally conducted and numerically modeled. Non linear, non-stationary heat conduction partial differential equations were solved to simulate the freezing of pouches, using a computational program in finite elements coded by the authors. The freezing of crab claws was simulated considering the irregular geometry of the system and two domains with different thermal properties (crab meat in contact with a calcareous layer) using Heaviside and Gaussian functions, to obtain a smoother specific heat curve. Heat transfer coefficients in the industrial tunnel freezer were determined from independent experiments. The influence of the freezing rate on the size of the ice crystals was determined by histological observations. Numerical models were satisfactorily validated by means of experimental time–temperature curves obtained at industrial scale in freezing tunnels. Tracking of the warmest point paths in each product was performed. These simulations are of great value for food process design and can help to optimize and control the freezing of new products.