Investigating the ice crystal morphology in frozen cooked rice based on size, fractal dimension and ANN modeling

Cooked rice was frozen in an air blast freezer at freezing temperatures of −5, −10, −15, −30 and −45 °C and stored at −5, −10, −15, −30 and −45 °C for up to 90 days. Cross-sectional images were captured using a fluorescence staining method, and then the equivalent diameters and perimeters of ice crystals were determined. The size and fractal dimensions were affected by the relationship between the freezing and storage temperatures. Artificial neural network analysis revealed that the behavior of response surface curves of both sizes and fractal dimensions were similar. The models demonstrated that the storage temperature of −25 °C for 90 days was required for maintaining the size and morphology of ice crystal immediately after freezing at −25 °C. These models would be effective tools for identifying the optimum operating conditions of frozen cooked rice based on the relationship between the ice crystal size and morphology.