AbstractSeveral quality criteria were determined in beef derived from animals of two age groups classified by dentition: those with four permanent incisors (55 head), and those with five or more permanent incisors (50 head), corresponding to chronological ages of up to 2.5 years and three years or more, respectively. The 105 animals were processed into beef in three local slaughtherhouses. From each left-carcass, samples from the Longissimus dorsi lumborum (LDL), Semimembranosus (SM) and Semitendinosus (ST) were obtained and analyzed for tenderness (Warner-Braztler Shear Force; WBS) and intramuscular fat as crude and cooked beef, and for contents of water and protein in crude condition, at the laboratory of Food Science and Technology, Mayagüez Campus of UPR. A similar number of crude samples were analyzed for contents of intramuscular fat and cholesterol at the laboratory of Meat Technology of the University of Florida in Gainesville. Animal age did not affect (P > 0.05) contents of water, protein or cholesterol, nor the WBS value. Intramuscular fat content of younger animals was lower (P less than 0.05) than that of the older group in crude beef analyzed at Mayagüez (1.89 vs. 2.73%) and Florida (2.60 vs. 3.48%), and in cooked beef analyzed in Mayagüez (2.98 vs. 4.56%), respectively. The general means of protein and cholesterol content were 20.38% and 56.41 mg/100 g (wet basis), the latter being lower than that found in the literature (70 to 75 mg/100 g). This difference is ascribed mainly to the common local practice of basing bovine feeding on grazing tropical grasses. Muscle did not affect (P > 0.05) the contents of protein and intramuscular fat in crude and cooked samples analyzed at Mayagüez, and of cholesterol (LD vs. SM) in crude beef samples analyzed at Florida. Intramuscular fat was higher (P less than 0.05) in crude samples from Longissimus analyzed at Florida. In addition, of the three muscles tested, Longissimus yielded crude beef with higher (P less than 0.05) intramuscular fat content (Florida samples) and of greatest tenderness (WBS 1.53 kg/1.27 cm). It is concluded that beef produced in Puerto Rico can be classified as moderately tender and low in intramuscular fat and cholesterol, thus constituting a healthy and appetizing source of nutrients for the consuming public.
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