Adipose tissue and cholesterol metabolism.

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.

Cholesterol Content of Raw and Cooked Beef Longissimus Muscles with Different Degrees of Marbling

Two hundred fifty-six British and Continental crossbred yearling steers (329 kg initially) were fed to study the effect of time on feed on live performance, carcass characteristics, tissue composition, and steak tenderness. Steers were divided into four slaughter groups and fed for either 105, 119, 133, or 147 d. Daily gains (carcass weight-adjusted basis) increased in a quadratic manner (P < .05; maximum at 119 d), whereas feed intake tended to increase linearly (P < .08) as cattle were fed longer. Feed conversion (carcass weight-adjusted basis) for steers fed 119 d was superior to that of steers fed for 147 d. Carcass weight, s.c. fat thickness, kidney, pelvic, and heart fat, overall carcass maturity, and yield grade increased linearly (P < .01) with time on feed. Marbling score and the percentage of cattle grading U.S. Choice increased (linearly; P < .01) with time on feed but at a decreasing rate (quadratic; P < .05). Cholesterol and total lipid concentrations in longissimus muscle increased linearly (P < .01) as time on feed increased, whereas the percentage of protein and moisture tended to decrease linearly (P < .10 and P < .01). Tenderness of ribeye steaks tended to increase linearly (P < .07) with time on feed, primarily due to a linear decrease (P < .03) in the percentage of steaks considered tough (shear force above 4.50 kg). Performance and carcass characteristics indicate that a feedlot finishing period of 119 to 133 d is ideal for British Continental crossbred yearling steers (329 kg).

Effect of time on feed on performance of feedlot steers, carcass characteristics, and tenderness and composition of longissimus muscles

Cholesterol content of foods.

SUMMARY— During an 8-week storage period of bovine muscle at −4°C, the total extractable protein content dropped from 91 to 51%. This decline, accompanied by a decrease in water-binding capacity of muscle, was primarily caused by the insolubilization of both sarcoplasmic proteins and actomyosin. The increase in the free fatty acid content from about 1.6 to 9.1% over the 8-week period may be attributed to phospholipid hydrolysis. The TBA number rose progressively throughout the entire storage period while the peroxide value increased to a maximum in 2 weeks of storage and then decreased to a constant value of 7.

Chemical deterioration of frozen bovine muscle at -4°C.

SUMMARY

—A method was perfected for the precise, accurate measurement of total and free cholesterol in lipid extracts of raw beef and pork muscle and meat products. The average total cholesterol content of beef and pork muscles was estimated to be 58 and 65 mg % (mg per 100 g), respectively. Both beef and pork muscles had an average cholesterol ester concentration of about 6% of the total cholesterol. Regression equations indicated that the total cholesterol content of muscle increased very slightly as the percent lipid value rose. Extramuscular adipose fat from beef and pork carcassess had total cholesterol values between about 43 and 68 mg %. Total cholesterol was estimated for some meat products. During the broiling of ground chuck samples, up to 15% of the total cholesterol in raw meat was lost in the cook drip.

O. Fennema

Papers

Free and Esterified Cholesterol Content of Animal Muscles and Meat Products