Beef and pork longissimus dorsi and semimembranosus muscles and chicken breast and thigh muscles were excised 24 hr postmortem from carcasses of marketweight grain-finished feedlot beef cattle, marketweight hogs on a typical finishing diet, and broilers on a commercial grain diet. Muscle samples were immediately ground and formed into patties and stored raw or after cooking, at 4ЊC (cooked) or Ϫ20ЊC (raw and cooked). TBA values (on sample weight basis) of frozen raw samples were higher for beef and pork than for chicken, as was heme iron content. However, TBA values of cooked samples were highest for chicken thigh muscles, which contained the most polyunsaturated fatty acids, at all storage temperatures.

The effect of adding propyl gallate (PG) and ethylenediaminetetraacetic acid (EDTA) in the distillation 2-thiobarbituric acid (TBA) test of fish and meat samples was determined with the purpose of minimizing further oxidation of lipids during the test. Alsddeiermined was the effect of chilled blending on TBA values. The addition of PC and EDTA to the distillation mixture substantially lowered TBA values of catfish samples, while it did not show any significant effect on beef, pork, and chicken samples. Chilled blending also was effective for fish samples, although less effective than adding PG and EDTA in distillation; it did not have perceptible effect on meat samples. The addition of PG and EDTA in the blending process (the initial Step of the test) was most effective for both fish and meat samples. The differences in the results between fish and meat samples have been discussed in terms of general differences in fatty acid composition of fish and meat. Finally, the addition of PC and EDTA in the blending process is recommended in the distillation TBA test of fish and meat, particularly of fish, to minimize further lipid oxidation occurring during the test.

The relationships of marbling level (eight levels from "Moderately Abundant" to "Practically Devoid") and cooking to cholesterol content of beef longissimus muscle steaks were studied. Only raw steaks with "Practically Devoid" marbling contained significantly less cholesterol (wet basis) than did raw steaks with any of the other seven marbling scores. However, steaks cooked to an internal temperature of 60' or 75°C showed no significant differences in cholesterol content among any of the eight marbling groups. The cholesterol content of cooked steaks was 22-48% higher than that of raw steaks when cooked to 60°C and 38-65% higher when cooked to 75°C; cooking reduced the weight of each steak, thereby increasing the cholesterol content of the steak expressed as a percentage of the cooked weight.

No abstract

Muscles of beef, pork and chicken purchased in two seasons were analyzed for lipid oxidation potential, concentrations of total pigments, myoglobin and nonheme iron, and microsomal enzymic lipid peroxidation activity. To determine lipid oxidation potential, thiobarbituric acid (TBA) assays with antioxidant protection were conducted on raw and cooked comminuted muscles stored at 4°C. TBA values of raw chicken muscles (white and dark) and pork muscles were low and changed little during 2–6 days of storage, whereas the values of raw beef muscles were higher and increased progressively. However, TBA values of cooked muscles of all three species increased during 2–4 days of storage with no marked differences among the species. Total pigment and mycglobin concentrations best explained the differences in TBA values of stored, raw muscles among the three species.