The relationship of muscle fibre size to tenderness of beef.

Steaks were removed from loins of beef carcasses at 1, 3, 6 or 14 days post mortem for fragmentation index (MFI), Warner-Bratzler Shear Force (SF) and sensory panel tenderness evaluation. Also, after 1 day of storage, samples were removed for histological observations. Greatest improvement in tenderness, SF and MFI occurred within the first 6 days of storage. Sensory panel tenderness was correlated (P < 0·01) with SF and MFI. Average muscle fibre size was correlated (P < 0·01) with tenderness and SF at days 1 and 3, but not at days 6 and 14. Evidently, muscle fibre size is important to tenderness prior to post-mortem storage of meat and proteolysis, but becomes less of a factor in tenderness after 6 days of storage.

Carcass, muscle and meat characteristics of lean and obese pigs.

Six pigs obtained from a lean selected strain and six pigs obtained from an obese selected strain were slaughtered at about 110 kg live-animal weight. Carcasses were evaluated; hams were dissected into bone, skin, fat and lean, and loin samples were obtained for fiber type characteristics, percentage of fat and moisture, collagen analysis, sensory characteristics, textural properties and objective color analysis. Carcasses from lean pigs were longer, had less backfat and larger longissimus muscle cross-sectional areas than carcasses obtained from obese pigs. Hams from lean pigs had less fat, more bone and more lean than hams from carcasses of obese pigs. The percentages and cross-sectional areas of red and white muscle fibers of the longissimus muscle from lean and obese pigs were not different. However, lean pigs had intermediate fibers that were only 79% as large (P less than .10) as intermediate muscle fibers from obese pigs. Intermediate fibers represented only 7 and 10% of total fiber area, whereas white fibers represented 84 and 79% of total fiber area in longissimus muscle of lean and obese pigs, respectively. Overall, lean pigs tended to possess fewer fibers (-16%) per unit of area than obese pigs, indicating that total muscle fiber hypertrophy was partially responsible for the increased longissimus muscle area of the lean strain. Sensory properties of longissimus meat samples from lean and obese strains were not different. However, the shear force requirement of the longissimus samples from the lean strain were slightly, but significantly (P less than .10), higher than those from the obese strain. No differences were observed in meat color.

Effect of subcutaneous fat and high temperature conditioning on bovine meat tenderness.

Effects of subcutaneous fat cover and high temperature conditioning on tenderness of meat were studied using 16 steer carcasses. Longissimus subcutaneous fat cover was completely removed from eight carcasses and the right and left sides were stored at either 0°C or 26°C. After 6 h at 26°C, the sides were transferred to the 0°C room; and after 24 h, all sides were transferred to a 1°C room for the duration of the experiment. Cold temperature and removal of fat cover reduced (P < 0·05) the longissimus muscle temperature at 6, 9 and 12 h post-mortem. The pH of the longissimus muscle was lower (P < 0·05) as the result of high temperature conditioning and fat cover 6, 9 and 12 h post-mortem. Consequently, conditions existed which would have been expected to promote cold shortening, yet high temperature conditioning and fat cover had no consistent effects on myofibrillar fragmentation index, sarcomere length or shear values.

Growth and carcass traits of heifers as affected by hormonal treatment.

Seventy-seven heifers weighing about 200 kg were assigned randomly to intact control (C), ovariectomized (OVX) immunized against estradiol (BSA-E), BSA-E + trenbolone acetate (BSA-E + TBA), TBA or ovx + TBA groups. The objective of the study was to determine the effects of ovariectomy, immunoneutralization of estradiol and trenbolone acetate treatment on growth rate and carcass merit. Heifers were fed a corn-corn silage diet and were slaughtered when treatment groups attained live-animal weights of 433 kg. Observations of rate of growth, efficiency of feed conversion, characteristics of carcasses and characteristics of organoleptic properties of the cooked meat were made. Average daily gains (ADG) were similar in the control and OVX groups and tended to be less than in other treatment groups (P less than .36). Although not statistically significant, the observed mean for the BSA-E + TBA treatment suggests improved ADG and TDN per unit of gain, indicating a possible immunization X TBA interaction. Data also suggested that heifers implanted with TBA had increased ADG and efficiencies of gain. Possibly, immunoneutralization of endogenous estradiol can improve ADG as compared with control and OVX groups. Treatments had no effect on color or texture of lean muscle at the 12th rib interface. The OVX + TBA group had less (P less than .01) 12th rib fat cover than other groups and lower percent fat in the rib than C. The BSA-E + TBA and TBA groups also possessed larger (P less than .02) longissimus muscle areas than the control group. Observations of juiciness, tenderness and flavor were similar among all treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors associated with tenderness in young beef.

One hundred and twenty-two crossbred steers of varying percentages of Bos Indicus and Bos Taurus breeding were slaughtered to determine the relationship of carcass and meat characteristics to tenderness. Carcasses were graded and longissimus dorsi muscle samples were evaluated for fibre type characteristics, sensory and shear force determination, sarcomere length, intramuscular fat content, collagen content and solubility and fragmentation index. Sarcomere length and collagen content and solubility were not significantly related to shear force values or sensory tenderness ratings. The fragmentation index was highly correlated to sensory tenderness ratings (r = -0·60) and shear force values (r = 0·53) indicating that variation in tenderness is associated with myofibrillar protein degradation. A four variable regression equation that included fragmentation index, lean colour, marbling and per cent red fibres accounted for 56% of the variation in sensory tenderness. Fragmentation index directly accounted for 30% of the variation in sensory tenderness in the four variable equation.

The effects of rate change in body weight on tissue development and meat quality of youthful bulls.

Forty-eight Angus bulls about 13 mo of age were used to study the effects of rate of change in live weight on muscle fiber, collagen and sensory characteristics of meat. Bulls were fed a finishing diet before treatment, and assigned to three treatments: negative, zero or positive weight gain for 30 or 60 d prior to slaughter. Treatments were imposed by adjusting feed intake. Seventy-two hours after slaughter, carcasses were observed for quality and yield grade characteristics and longissimus muscle samples were obtained for fiber type, collagen and sensory characterization. Carcass lean at the 12th rib interface became darker in color (P less than .01), softer (P less than .05), coarser textured (P less than .01) and more physiologically mature (P less than .01) when bulls were fed an additional 30 d. Increases in average daily gain improved lean texture (P less than .05), but had insignificant effects on lean color. Marbling scores and percentages of kidney and pelvic fat increased (P less than .01) with length of time fed. Quantities of carcass fat were reduced by reducing daily weight gains through restricting dietary intake. Neither length of time fed nor rate of change in live weight affected (P greater than .05) muscle fiber characteristics. Increased age of bulls tended (P greater than .05) to be associated with an increase in red muscle-fiber quantity. Length of time fed or rate of change in live weight did not affect collagen characteristics or tenderness of meat.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary and sinoaortic baroreceptors and volume expansion in the monkey.

Experiments were performed to determine the effect of combined cardiopulmonary and and sinoaortic baroreceptor denervation on the renal responses of the anesthetized nonhuman primate to acute intravascular volume expansion. Adult male Macaca fascicularis monkeys underwent chronic bilateral thoracic sympathectomy (middle cervical ganglion--T6) or sham surgery performed in two stages. After a 1-3 week recovery period, each animal was anesthetized with sodium pentobarbital and subjected to cervical vagotomy--sinoaortic denervation or further sham denervation. Estimated blood volume was then acutely expanded 20% with 6% dextran in isotonic saline. Control renal excretory function did not differ between the two groups, and both groups had similar increases in urine flow, sodium excretion, osmolar clearance, free water clearance and renal plasma flow after volume expansion. The patterns of the responses showed some group differences in that the increases in renal excretion after volume-loading had an earlier onset in the denervated animals. These results demonstrate that combined ablation of thoracic sympathetic, vagal and sinoaortic neural pathways does not compromise the ability of the nonhuman primate to increase salt and water excretion when blood volume is acutely expanded. Therefore, these neural mechanisms are not necessary for eliciting the renal responses to this hypervolemic stimulus in this species during the anesthetized state.

The effects of sex condition, genotype and diet on bovine muscle fiber characteristics.

The effects of sex condition, breed type and dietary energy level on muscle fiber characteristics were examined at various ages and related to carcass characteristics and meat palatability. Cattle fed a low-energy diet had a significantly higher percentage of red muscle fibers, larger white muscle fiber areas and a greater percentage area of red muscle fibers than cattle fed a high-energy diet. A significant sex × breed within slaughter group interaction existed, which was complicated due to differences within breeds and sexes at different points of physiological maturity. Separate correlation coefficients for bulls and steers are shown that suggest strong directional interactions between carcass characteristics and meat quality, and muscle fiber characteristics.

The effect of sex condition and growth implants on bovine muscle fiber characteristics.

Steers, bulls and bulls implanted with Synovex-S or Ralgro were slaughtered at 12 and 16 months of age. With increasing animal age, the percentage of intermediate fibers decreased while the percentage of white fibers increased. The area of all fibers increased with increasing age. Bulls had a higher percentage of red fibers, larger red and intermediate fibers and a higher percentage area of red and intermediate fibers compared with steers. Implanted bulls were generally intermediate to intact bulls and steers in muscle fiber type characteristics. Carcass fat measurements and tenderness ratings were positively correlated to the percentage of white muscle fibers and negatively correlated to the percentage of intermediate fibers. Carcass characteristics and sensory properties of meat are discussed in relation to muscle fiber characteristics.

Vacuum-Packaged Trimmings as a Source for Ground Beef Patties: Changes During One Year of Frozen Storage.

Vacuum-packaged beef trimmings were stored for four time periods of 0, 1, 2 and 3 wk (4 lots) at 5°C. After the storage period, the four lots of trimmings were evaluated for chemical, microbial and sensory properties. Each lot was then made into beef patties. Two lots of patties (0 and t wk of storage at 5°C) were further stored at -18°C for 0, 3, 6, 9 and 12 months and used to determine sensory properties. The two lots prepared from trimmings stored for 2 and 3 wk were evaluated for chemical properties at 0, 6, 9 and 12 months of -18°C frozen storage. Patties prepared from vacuum-packaged beef trimmings stored for 2 and 3 wk had significantly lower sensory ratings as compared to ratings for patties made from trimmings stored for 0 or 1 wk. Microbial counts indicated that bacterial action could be more important than oxidative rancidity as the cause for these changes. Increased length of frozen storage time did not markedly affect sensory properties.

Vacuum Packaging Versus Modified Atmosphere Packaging of Lamb Loins.

Lamb loins were allocated (30 loins/treatment) to three packaging treatments: (a) vacuum-packaged, (b) vacuum-packaged followed immediately by injection of a 20% CO2:80% N2 atmosphere, and (c) vacuum-packaged followed immediately by injection of a 40% CO2:60% N2 atmosphere. Loins in each packaging treatment were then assigned (6 loins/period) to one of five storage periods--0, 7, 14, 21 or 28 d. During storage, the CO2 concentration increased in vacuum packages (initial vs. 21 d) and decreased in modified atmosphere packages (initial vs. 7 or 28 d); O2 concentration was higher in vacuum packages than in modified atmosphere packages at every storage period. Vacuum packaging was superior to modified atmosphere packaging for maintaining desirable appearance of wholesale loins, particularly if the atmosphere contained a high CO2 concentration. Appearance of retail chops was not substantively affected by the method used to package (vacuum vs. modified atmosphere) the wholesale loin from which they originated. Palatability of cooked chops was not affected by packaging method in 28 or 30 comparisons among product from loins that had been stored for 0 to 28 d before organoleptic testing.

Physical and Sensory Properties of Restructured Beef Steaks Formulated with Various Flake Sizes and Mixing Times.

Restructured cow beef steaks were made using six different flake size formulations: (a) coarse, (b) medium, (c) fine, (d) coarse + medium, (e) medium + fine and (f) coarse + fine meat flakes. Each formulation was mixed for 0, 5, 10 or 15 min, pressed into "logs", frozen and cut into steaks. Steaks were evaluated for physical appearance, fat and moisture content, cooking properties, texture and sensory attributes. Steaks made from the coarse flakes had large fat particles and therefore received lower (P<0.05) ratings for physical appearance. Restructured steaks made from the fine particles were more tender (P<0.05) and received significantly higher (P<0.05) textural desirability and overall palatability ratings than restructured steaks made from coarse particles. A mixing time of 5 min resulted in higher scores (P<0.05) for juiciness and tenderness as compared to restructured steaks made from meat mixed for 15 min. Mixing time had no significant effect on cooking losses or binding strength.

Physical and Sensory Properties of Chicken Patties Made with Various Levels of Fat and Skin.

Chicken patties were prepared from spent fowl meat and contained either 0, 10, 20 or 30% added skin and fat. One-half of each of these treatments was coated with a calcium alginate film while the other half served as controls. Percentages of fat, moisture, cooking loss and shrinkage, as well as textural properties and sensory attributes, were determined for patties from each formulation/coating treatment. Patties containing 30% added skin and fat lost more moisture during cooking than the all-meat patties. In addition, patties containing 20 or 30% added skin and fat received lower texture desirability ratings as compared to the all-meat patties. No significant differences were observed in juiciness, flavor desirability or overall palatability due to the level of added skin and fat. Chicken patties coated with a calcium alginate film were rated as being significantly more juicy and palatable then patties without a calcium alginate coating.

Effect of Added Wheat Gluten and Mixing Time on Physical and Sensory Properties of Spent Fowl Restructured Steaks.

Spent fowl meat (50 % dark/50% white meat) was flaked and formulated to include: (a) no added wheat gluten (control), (b) 1 % wheat gluten and (c) 2% wheat gluten. Each formulation was mixed for 5 min, half was removed and the remainder was mixed an additional 10 min. After mixing, each formulation was pressed into logs, frozen and cut into steaks. Steaks were evaluated for fat and moisture content, cooking loss, textural properties and sensory attributes. Neither addition of wheat gluten nor mixing time had any significant effect on moisture and fat content or total cooking losses. Texture desirability ratings showed a preference for the firmer steaks made with added gluten and mixed for 15 min. These steaks were also rated as being more juicy. Addition of 2% wheat gluten adversely affected flavor desirability.

Precooking and Flake Size Effects on Spent Fowl Restructured Steaks.

Four formulations of spent fowl muscle, each made to contain 40% dark muscle and 60% white muscle, were prepared as follows: (a) raw meat, large flake size; (b) raw meat, small flake size; (c) precooked meat, large flake size and (d) precooked meat, small flake size. Each formulation was mixed with 0.3% NaCl, 0.25% Na tripolyphosphate and 0.25% hydrolyzed vegetable protein for 10 min, pressed into logs under 400 psi, frozen and cut into steaks. Steaks were evaluated for moisture and fat content, cooking properties, texture and sensory attributes. Restructured steaks made from precooked chicken muscle had lower initial moisture contents and lost less moisture during cooking than restructured steaks made from raw meat. Flake size had no significant effect on cooking losses; however, the smaller flake sizes contributed to a more tender product. Steaks made from the raw chicken meat were of a more acceptable flavor. Restructured steaks made from raw flakes were significantly more desirable in texture and overall palatability and were more tender and juicy than restructured steaks made from precooked chicken.

Effect of Feeding Regimen and Vacuum-Packaged Storage on Sensory and Physical Properties of Beef Steaks.

The longissimus, semitendinosus and semimembranosus muscles from 12 grain-fed and 12 forage-fed cattle were vacuum packaged, stored for either 7 or 21 d and retail packaged and displayed. Primal and retail cut appearance traits and sensory attributes were evaluated. Longissimus steaks had a more yellow fat color after 5 d of display (P<0.05) and semitendinosus had a more intense flavor (P<0.05) when taken from forage-fed cattle. Generally, there were only a few minor differences in sensory properties due to feeding regimen. Primal and retail cut appearance traits (primarily muscle color and percentage surface discoloration) of all three muscles were significantly affected by the length of storage; however, storage period affected sensory properties on only the longissimus and semitendinosus muscles.

Effect of Comminution Method and Pressure on Restructured Beef Steaks.

Restructured steaks were made using six methods of meat comminution: (a) sliced parallel, (b) sliced perpendicular to muscle fibers (2-mm thick slice), (c) flaked at -5 C, (d) flaked at -2.2 C, (e) flaked at 2.2 C and (f) ground through a 3.2-mm plate. Meat used was from cow inside rounds. After comminution, meat was stuffed into casings and pressed under pressure (200, 600 or 1,000 psi). The "logs" were then frozen, cut into steaks and evaluated for cooking characteristics and sensory attributes. Intact round steaks were used for controls. The amount of pressure used to form the restructured steaks had no effect (P>.05) on any of the cooking characteristics or sensory properties. Particle production method had no effect (P>.05) on cooking characteristics; however, tenderness, texture description and flavor desirability ratings were higher (P>.05) for flaked steaks as compared to the sliced or intact steaks.

Sensory Attributes of Precooked, Calcium Alginate-Coated Pork Patties.

Ground pork patties were prepared containing 37% fat and assigned to one of five treatments: (a) control; (b) precooked, no calcium alginate coating; (c) calcium alginate coated, no precooking; (d) calcium alginate coated before precooking and (e) calcium alginate coated after precooking. The calcium alginate coating significantly improved sensory attributes. Warmed-over flavor (WOF) was eliminated in precooked, alginate-coated patties as judged by sensory scores and TBA values. Coated patties with no precooking, and patties coated after precooking were found to be more desirable than control patties.

Appearance of Beef, Pork and Lamb Stored in Vacuum or Modified Gas Atmospheres.

Beef, pork and lamb loins were vacuum-packaged as subprimal cuts, vacuum-packaged as reformed subprimal cuts, vacuum-packaged as retail cuts or packaged in modified gas atmospheres as retail cuts. Cuts were stored and evaluated, after 0, 7, 14 or 21 days of storage, for surface discoloration and overall appearance. Gas analysis of the heads pace of packages was also obtained. In all vacuum packaging treatments, the percentage of CO2, increased and the percentage of O2, decreased with increased storage. The gas composition in modified gas atmosphere packages changed little during the 21-day study. Using systems and gas combinations involved in the present study, retail cuts of beef, pork and lamb could not be successfully precut, retail-packaged and stored for 7 to 21 days in vacuum or modified gas atmospheres. Vacuum-packaged retail cuts and retail cuts stored in modified gas atmospheres sustained extensive surface discoloration and were of unsatisfactory appearance, even after only 7 days of storage and 1 day of retail display. Conversely, storage of retail cuts as vacuum-packaged reformed subprimal cuts for 7 to 21 days decreased (P < .05) surface discoloration and improved (P < .05) overall appearance in comparison to retail cuts from loins stored as subprimals for comparable times in vacuum packages.

Blade Tenderization Effects on Cooking and Palatability Characteristics of Steaks from Bullock and Cow Carcasses.

Steaks (n = 240) from bullock and cow carcasses were studied to determine effects of blade tenderization on cooking and palatability characteristics. After two control (0×) steaks were removed, strip loins, inside rounds, outside rounds and top sirloin butts (all boneless) were blade-tenderized; additional steaks were removed after one (1×) and two (2×) passes through a blade tenderizer. Evaluations included cooking time, cooking loss, visual degree of doneness, Warner-Bratzler shear force and sensory panel evaluation for tenderness, amount of organoleptically detectable connective tissue, flavor, juiciness and overall palatability. Blade tenderization of bullock muscles resulted in steaks which required less time to cook, had decreased amounts of organoleptically detectable connective tissue and had increased tenderness, flavor and overall palatability ratings. Blade tenderization of cow muscles had little or no effect on cooking characteristics, tenderness, flavor, or overall palatability of muscles from the round but increased the tenderness, decreased the shear force value and amount of organoleptically detectable connective tissue, and increased the overall palatability of the longissimus dorsi muscle. Blade tenderization, though it will usually improve tenderness, will not improve the product enough to make beef of unsatisfactory quality comparable to that from high quality beef.