Crust pore characteristics and their development during frying of French-fries

• Crust pore sizes and microstructure vs frying time are determined in French-fries.
• Methods include dynamic wicking (DW) and scanning electron microscopy (SEM).
• Two different pore scales are observed by SEM and no obvious pore interconnection.
• DW determines smaller pore sizes and shows interconnected pore network.
• Pores issue from tissue disruption, water evaporation within cells and shrinkage.

This work determines pore characteristics of the French-fry crust and their development at two time intervals during frying. dynamic wicking (DW) and scanning electron microscopy (SEM) are used for that reason. DW is used to determine the effective mean pore radius of the crust. SEM is used to observe the microstructural characteristics of the crust interior and surface. The shapes and sizes of openings/pores in the crust and surface and cell sizes in the crust and core are determined by analysis of the SEM images. Except from new to the literature data on pore sizes in French-fry crusts the above observations provide insight on phenomena occurring in the crust during frying. In addition, the behavior of the interconnected crust porous network during capillary penetration is assessed by DW. Finally, an approximate rate of frying oil uptake in the crust region is estimated considering a capillary penetration theory for oil uptake.