Premature browning (PMB) describes cooked beef that may appear done before reaching 71 °C. Ground beef from paired Longissimus lumborum (LL) and Psoas major (PM) muscles was formed into patties. Patties were cooked immediately, and after 48 and 96 h storage at 4 °C. Total reducing activity (TRA) and external color were measured immediately prior to cooking. Patties were cooked to internal end point temperatures of 60, 66, 71 or 77 °C and internal cooked color (L(*), a(*) and b(*) values) was measured. Raw PM patties had greater L(*) values and lesser a(*) values than those from LL (P<0.05). For LL and PM, raw a(*) and b(*) values decreased with storage from 0 h to 96 h (P<0.05). At 0 and 48 h storage, cooked patties prepared from PM had greater a(*) values than those prepared from LL at all internal endpoint temperatures (P<0.05). Internal cooked a(*) values of patties from PM decreased with storage of raw patties, whereas it was stable for LL patties (P<0.05).