Characteristics of Pork Muscles Cooked to Varying End-Point Temperatures.

M. biceps femoris (BF), m. semimembranosus (SM) and m. semitendinosus (ST) from fresh pork ham were evaluated for characteristics of quality after cooking to an internal endpoint temperature of 62 °C or 73 °C. Fresh ham muscles from the left side (N = 68) were cut into 2.54 cm thick chops and allocated to cooking loss, Warner-Bratzler shear force (WBSF), pH and instrumental cooked color analysis. Cooking losses were greater (p < 0.0001) for SM and chops cooked to an internal temperature of 73 °C (p < 0.0001), whereas WBSF did not differ (p = 0.2509) among the three muscles, but was greater (p < 0.0001) in chops cooked to 73 °C. Fresh muscle's pH was greater (p < 0.05) in ST than BF or SM. Lastly, the interactive effect (p < 0.05) of muscle × endpoint temperature for ST chops cooked to 73 °C was lighter (L*), but, when cooked to 62 °C, they were more red (a*), more yellow (b*) and incurred less color change from red to brown than BF or SM. The current results suggest it is plausible for BF, SM and ST to be considered for alternative uses instead of traditional value-added manufacturing.

Identification of Breed Differences in Known and New Fescue Toxicosis Associated Phenotypes in Charolais-and Hereford-Sired Crossbred Beef Cows.

Beef cattle phenotypes are affected by the consumption of toxic fescue. Toxic fescue's impact is dependent on heat stress and breed composition, with genetic variability for robustness to toxin exposure believed to exist within and across breeds. The study objective was to characterize the effect of fescue toxicosis across breeds for known and novel heat and fescue stress-associated phenotypes. One-hundred crossbred fall-calving Charolais- and Hereford-sired cows of parities 1-3 were allocated to graze either toxic fescue (n = 50), non-toxic fescue (n = 25), or a rotation between toxic and non-toxic fescue (n = 25) for 156 days. Phenotypes impacted by breed (genetics) included hair coat score (p < 0.0001), hair reduction/shedding rate (p < 0.05), rectal temperature (RT) (p < 0.0001), vaginal temperature (p < 0.05), serum phosphorus concentration (p < 0.02) and respiration rate (RR) (p < 0.003). Cows on toxic fescue experienced reduced hair shedding efficacy (p < 0.0001), higher vaginal temperatures (p < 0.0001), increased systolic blood pressure (p < 0.04), increased RR (p < 0.0001) and reduced average daily gain (p < 0.0001), compared to cows grazing non-toxic fescue. Calves born from cows with higher RT during the last third of gestation had higher RT at weaning (p < 0.02), indicating potential physiological effects of in utero heat stress. The study indicates that beef cows exhibit variable responses to toxic fescue within and across breeds which may impact future calf phenotypes.

Cooked color of precooked ground beef patties manufactured with mature bull trimmings.

Lean (80%) ground beef was formulated with 0, 25, 50, 75, or 100% mature bull trimmings, formed into patties, cooked to 71 °C in an air-impingement oven, and stored at -20 °C until reheating to 71 °C either in a microwave oven or on a gas-fired chargrill. Instrumental color of raw patties was not (P ≥ .080) affected by levels of bull trim. After initial cooking, internal cooked redness values were not affected (P ≥ .202) by the proportion of bull trim; however, the internal reheated patty redness increased (greater a* values and lesser HA; P ≤ .001) with increasing proportions of bull trimmings. Formulating ground beef with high levels (>50%) of mature, bull trimmings had minimal effects on raw ground beef color, but patties formulated with the highest proportions of bull trimmings appeared undercooked even after cooking twice to 71 °C.

Application of tension to prerigor goat carcasses to improve cooked meat tenderness.

In two separate experiments, carcasses of intact Kiko × Boer male kids were assigned randomly to tension treatments applied 30 min postmortem: 1) suspended by the Achilles tendon (AT); 2) suspended from the pelvic bone with front and hind legs tied together (TS); or 3) suspended by the Achilles tendon, and the fore- and hindsaddle were separated at the 12th/13th thoracic intervertebral disk, external fat, accessory muscles and epimysium surrounding the longissimus muscle (LM) were cut (TC), and a 2.3-kg weight attached to the neck (TC + W). Warner-Bratzler shear force values for the LM were reduced (P < 0.05) 24.4 to 35.9 N in TS carcasses compared to AT carcasses, and WBSF values of SM from TS carcasses were 25.0 and 20.3 N less (P < 0.05) than those for AT and TC + W carcasses, respectively. Results indicated that cooked goat meat tenderness, particularly the LM and SM, may be improved greatly by suspending goat carcasses by the pelvic bone.

Color stability and tenderness variations within the gluteus medius from beef top sirloin butts.

Beef top sirloin butts (n=48) from USDA quality grade (QG; upper 2/3 US Choice vs. US Select) and yield grade categories (YG; 1 and 2 vs. 4 and 5) were aged 14 days, GM steaks were cut, with 2 steaks removed from the anterior (ANT), middle (MID) and posterior (POST) sections of the GM. One steak from each section was cut into lateral (LAT), central (CENT) and medial (MED) portions, packaged aerobically, and displayed for 7 days, whereas the second steaks were cooked to 71°C for WBSF. Top Choice-steaks were redder and more yellow (P<0.05) than Select steaks during display. Cooking losses were greatest (P<0.05) in the MED, and least (P<0.05) in the CENT, portions of GM steaks. Neither QG nor YG category affected WBSF, but differences within the GM were found for (P<0.05) WBSF. Results of this experiment indicate tenderness and color stability gradients exist within the GM.

Noni puree (Morinda citrifolia) mixed in beef patties enhanced color stability.

Ground beef, mixed with 0, 2, 4, and 6% Noni puree, was formed into 150-g patties, aerobically packaged, and displayed in retail for 5d. After 2 and 3d, patties with higher concentrations of Noni were perceived as redder and less discolored (P<0.05) by visual panelists. Noni patties were found to have greater (P<0.05) a* values than controls, even though all patties became less red during display. After 3 and 5d of retail display, patties with higher concentrations of Noni puree also had lower TBARS (were less oxidized; P<0.05). In fresh taste panels, panelists perceived the patties to have less beef flavor and greater incidence of off-flavors (P<0.05) as Noni puree concentration increased. The potential of Noni puree to improve the color stability and shelf life of fresh ground beef is very promising, but the flavors produced by the addition of Noni in ground beef may be detrimental to its use.

Compositional and instrumental firmness variations within fresh pork bellies.

Fresh pork bellies (n=24) were cut into 15 sections to measure the intra-belly variation in compositional and mechanical firmness characteristics. Length and width of each belly was measured before the belly was divided into 3 rows (D = dorsal; C = central; and V = ventral) and 5 columns (labeled 1, 2, 3, 4, and 5 from cranial to caudal), resulting in 15 belly sections of equal dimensions. The belly section with the greatest compression value was D-1, whereas the lowest compression value was found in the V-4 section (column×row, P<0.001). Conversely, the greatest and least puncture values were observed in the C-2 and V-5 locations, respectively (column×row, P=0.016). The D-3 section had the lowest proportion of lean and the greatest proportion of fat, but the greatest lean and lowest fat percentages were found in the V-1 and C-4 sections, respectively (column×row, P<0.001). The greatest proportions of saturated fatty acids (SFA) were found in the V-4 and V-5, and the lowest proportions of SFA were in D-1 (column×row, P<0.001). Moreover, C-4 and V-1 had the greatest percentages of monounsaturated fatty acids (MUFA), whereas the lowest MUFA content was observed in D-1, D-2, and D-3 (column×row, P<0.001). The D row (columns 1, 2, 3, and 5) also had the greatest proportion of polyunsaturated fatty acids (PUFA), but the lowest proportions of PUFA were located in C-4, V-4, and V-5 (column×row, P<0.001). Consequently, the iodine value was greatest in D-1 and lowest in V-4, V-5, and C-5 (column×row, P<0.001). It is apparent from these results that there is an obvious fatty acid composition gradient within bellies, which results in considerable intra-belly variation in composition and firmness.

The effects of feeding broiler litter on microbial contamination of beef carcasses.

Two experiments were conducted to test the effects of feeding broiler litter, either directly in the diet or indirectly through pasture-fertilization, to beef cattle on the incidence of Salmonella typhimurium (S) and Escherichia coli O157:H7 (EC) contamination of carcasses and ground beef. In Experiment 1, beef cows (n = 32) were allotted either ad libitum access to grass hay or a formulated diet (80% deep-stacked broiler litter and 20% corn). In Experiment 2, beef cows (n = 32) were assigned to graze on pastures fertilized with a commercial fertilizer or fresh broiler litter. Cows in Experiment 1 were harvested following a 56-d feeding period; whereas, cows in Experiment 2 were harvested after 5, 10, 20, and 40 d of grazing pastures. All samples of muscle, purge, and ground beef were culture-negative for S and EC, suggesting that beef cattle may consume properly handled deep-stacked broiler litter, or pastures fertilized with fresh litter, without increasing the likelihood of carcass/meat contamination with S and (or) EC.