Microstructure alterations in beef intramuscular connective tissue caused by hydrodynamic pressure processing.

Scanning electron microscopy (SEM) was utilized to evaluate microstructural changes in intramuscular connective tissue of beef semimembranosus muscle subjected to hydrodynamic pressure processing (HDP). Samples were HDP treated in a plastic container (HDP-PC) or a steel commercial unit (HDP-CU). Control and HDP samples were obtained immediately post-treatment and after 14days of aging for SEM and Warner-Bratzler shear force (WBSF) analysis. Immediately post-treatment, HDP treated samples exhibited lower (P<0.01) WBSF than did controls. After aging, HDP-PC samples had lower (P<0.01) WBSF than that of aged controls. SEM analysis indicated that HDP-PC treatment disrupted the integrity of the collagen fibril network of the endomysium in both the non-aged and aged samples. Aging effects on the intramuscular connective tissue were observed in the HDP-PC and control samples. Both WBSF and connective tissue changes were greater in the HDP-PC than in the HDP-CU treated samples. Data suggest that shockwave alterations to connective tissue contribute to the meat tenderization of HDP.

Recombinant bovine somatotropin (rbST) increases size and proportion of fast-glycolytic muscle fibers in semitendinosus muscle of creep-fed steers.

The objective of this study was to determine the effect of recombinant bovine somatotropin (rbST) on muscle fiber histology and histochemistry in creep-fed beef steers. Crossbred steer calves were assigned to one of two treatment groups: control (sham-injected; n = 12) or rbST-injected (0.09 mg x kg(-1) x d(-1); n = 12). Calves were injected every 14 d starting at d 28 of age until weaning at 205 d of age. Biopsies of the semitendinosus muscle were performed on d 100, and slaughter samples of semitendinosus muscle were collected for muscle fiber analyses on d 206. The rbST-treated calves had larger (P = 0.045) fast-twitch-glycolytic (FG) fibers [2,564 +/- 10 vs 2,351 +/- 11 microm2 cross-sectional area, respectively] than controls. No differences (P = 0.36) between rbST-treated and control steers in cross-sectional area were detected for slow-twitch-oxidative (SO) [1,192 +/- 20 vs 1,148 +/- 22 microm2, respectively] or fast-twitch-oxidative-glycolytic (FOG) fibers [1,484 +/- 35 vs 1,403 +/- 38 microm2, respectively]. The percentage distribution for FOG fibers was greater for control calves than for the rbST-treated calves (38.4 vs 34.9 +/- 0.1%, respectively; P = 0.014), whereas the percentage distribution for FG fibers was greater in the rbST-treated calves than for control calves (53.5 vs 48.4 +/- 0.2%, respectively; P = 0.03). The percentage distribution for SO fibers tended to be greater for the control calves than for the rbST-treated calves (13.1 vs 11.7 +/- 0.1%, respectively; P = 0.07). The percentage of FG fibers increased with age (45.4 vs 56.6 +/- 0.8%, respectively; P = 0.001), whereas the percentage distribution of SO (14.3 vs 10.5 +/- 0.5%, respectively) and FOG fibers (40.3 vs 32.9 +/- 0.7%, respectively) decreased (P = 0.001) from d 100 to d 206. The increased longissimus muscle area and dissectable lean tissue in rbST-treated calves are associated with a greater percentage of FG fibers, which possess larger cross-sectional areas than the other fibers.

Hot processing and grind size affect properties of cooked beef patties.

This study was conducted to further understand the role that hot processing and grind size exert on cooked beef patty tenderness and other properties. Low-fat (10%) hot-processed (HP) and cold-processed (CP) beef were ground either through a 0.32 or 0.40 cm plate. A 20% fat CP product was also manufactured through a 0.32 cm plate. HP patties had higher pH, shorter sarcomere lengths, higher tenderness scores (including greater number of smaller particles during chewing) lower shear force values, higher flavor scores, less well-done cooked color, longer cooking times and higher cooking yields than CP patties (p<0.01). The use of a 0.32 cm rather than a 0.40 cm plate improved tenderness properties, especially for HP patties. Other properties were not greatly influenced by grind size. Sensory evaluation and scanning imagery of patties suggested that the greater tenderness of hot processed patties may be due to the presence of smaller meat particles. Highly contracted muscle, providing resistance to grinding, could be responsible for the small meat particles.

The hydrodyne: a new process to improve beef tenderness.

The organoleptic trait most affecting consumer acceptance of beef is tenderness. The Hydrodyne process uses a small amount of explosive to generate a shock wave in water. The shock wave passes through (in fractions of a millisecond) objects in the water that are an acoustic match with water. Four beef muscles (longissimus, semimembranosus, biceps femoris, and semitendinosus) exposed to either 50, 75, or 100 g of explosives were significantly tenderized compared with controls. As much as a 72% reduction in shear force was observed for the longissimus muscle using 100 g of explosives. Reductions in shear force with magnitudes of 30 to 59% improvements were observed for the other three muscle types. Results suggest that tenderizing beef with the Hydrodyne process presents a potentially novel opportunity in the way the meat industry can tenderize meat.

Effect of sex class on nutrient content of meat from young goat.

The effect of sex class on proximate composition and cholesterol, vitamin, mineral, and fatty acid content was determined for carcass composite samples of cooked goat meat. Soft tissues (fat and lean) from dissection of one side of seven carcasses each for female, castrate, and intact male Florida native or F1 crosses of Florida natives with Nubian or Spanish goats were ground, formed into patties, and then broiled. Also, a leg slice was removed from the side not used for dissection, broiled, and then sampled for fatty acid determination. Broiled samples from female goats had lower (P = .04) moisture and higher (P = .03) fat and total calories than did samples from castrates and intact males. Sex class had no effect on cholesterol, vitamin, or mineral content of cooked goat meat. Broiled goat leg slices from intact males were lower (P = .005) in percentage of total saturated fatty acids and had a higher (P = .01) unsaturated to saturated fatty acid ratio than samples of broiled leg slices from females or castrates. Broiled goat meat had higher values for calcium, potassium, thiamin, and cholesterol than that reported in USDA Handbook 8 for cooked composite samples of beef or chicken. Also, broiled goat meat had lower total lipid, phosphorus, and vitamin B12 than composite values reported for beef. Other nutrients were similar to those reported for cooked composite samples of beef and chicken.

Occurrence of giant fibers in muscles from wild pigs native to the United States.

The semimembranosus (SM) and triceps brachii (TB) muscles from wild pigs native to Florida. USA, were evaluated for histological characteristics. All three fiber types were present in both muscles in varying proportions, reflecting differences between tonic and phasic functioning muscles. Typical fiber arrangements were observed with red fibers grouped in clumps and surrounded by white fibers. The triceps brachii muscle contained a greater percentage of ßR and αR fibers and possessed more giant fibers than the SM muscle which contained more αW fibers. The giant fibers observed resembled ßR or αR fibers. The presence of hypertrophied fibers in the muscles from these wild pigs suggests that the 'giant fiber syndrome' is an intrinsic susceptibility for muscle fiber enlargement in these animals and not necessarily associated with breeding for muscularity since the carcasses from these pigs contained very small muscles and very little fat.