Phospholipid and Myoglobin Concentrations in Ground Bovine Extensor, Semitendinosus, and Gastrocnemius

A possible quantitative relationship between phospholipid and extractable myoglobin, or between their rates of change during the heating of beef was investigated. Three muscles--extensor, semitendinosus, and gastrocnemius--were chosen for study at three heating end points--55°, 66°, and 77°C.

The investigated relationship was not shown statistically across the muscles or age categories represented by the samples used. The effects of several variables on the muscle components studied were analyzed individually.

Extractable myoglobin decreased as internal end point temperature increased. Increasing end point temperature also resulted in increased phospholipid concentration, dry weight basis, and total lipid, wet weight basis. Neither myoglobin nor phospholipid concentrations differed significantly among muscles. Total lipid, on the wet and the dry weight basis, was significantly influenced by muscle type. Animal age did not appear to affect myoglobin concentration. Muscles from the older animal appeared to have a greater total lipid and a lower phospholipid content than those from the younger animal.

Phospholipids were fractionated into classes and analyzed for lecithin, cephalin, and sphingomyelin. Heat treatment, muscle, or animal did not affect phospholipid fractions.