Oil absorption during frying of frozen parfried potatoes

A tracer method was used to assess the uptake of oil by commercial frozen parfried potatoes fried (180 degrees C, 150 s) in colza oil (CO) involving a short post-frying immersion in hot coconut fat (CF), CO and CF were determined directly in the crust by differential scanning calorimetry (crystallization temperature and enthalpy -42.7 degrees C/50 J/g and 10 degrees C/71 J/g, respectively). Oil uptake by the crust during frying in CO or CF was similar (average 25.3%). Potato samples transferred immediately after frying in CO to the CF bath had most of the CO absorbed replaced by CF after a 10 s post-frying, meaning that CO was readily accessible in the crust structure. Samples fried in CO and cooled for up to 60 s before transfer to hot CF showed only partial replacement of CO. Oil wetting the surface of the sample at the end of frying was estimated as 70 to 80% of the total oil uptake. Formation of the crust (frying time > 1 min) was required for oil to migrate into intercellular spaces that are dynamically formed during frying and thus accessible to CF and solvents.