A combination of freeze-grinding and screening to separate flesh and bone in processed marine food waste (head and backbone offal of fish) was evaluated. Samples were dorsal muscle (flesh), spine (bone), and backbone offal of yellow-fin tuna. A hammer mill with a screen opening size of 5.00 mm was used for the freeze-grinding process. Flesh, bone, a mixture of both, and backbone offal were separately freeze-ground to measure variations in particle size. Flesh and bone were also separately subjected to batch grinding to measure changes in particle sizes over time. By passing the ground product through a sieve with an appropriate screen opening size, flesh and bone could be separated into small and large particles, respectively, Grinding temperature and time were found to be important operational parameters optimizing the efficiency of the separation method.