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Thirty-eight steers and thirty heifers (14 to 17 months of age, from F(1) Hereford × Brahman cows bred to Angus or Hereford bulls), were either forage-fed for 123 days on millet-bermudagrass pasture or grain-fed for 90 days on a high-concentrate diet and were then commercially slaughtered. Warm carcass weights ranged from 167·8 kg to 324·3 kg. At 24 h post mortem, Texas Agricultural Experiment Station personnel (1) assigned scores or took measurements on each carcass for all factors used in yield grading and quality grading, (2) measured the length of hind leg (HL) and carcass length (CL) and (3) assigned a score for carcass muscling (MS) and, as appropriate, made an adjusted longissimus muscle area (ALA) evaluation. The 9th-10th-11th rib section from one side of each carcass was physically separated into longissimus muscle, fat, 'other soft tissue' and bone and ether extract determinations of the longissimus muscle and 'other soft tissue' components were made and used to adjust the yields of each of these components to a fat-free basis. Muscle to bone ratios ranged from 2·38 to 4·37. With both age and carcass weight held constant, diet, breed and sex explained only 35·8% of the variation in muscle to bone ratio. The best simple correlation with muscle to bone ratio was ALA/CL (r = ·59). Other measures significantly correlated with muscle to bone ratio included ALA (r = 0·55), MS (r = 0·50) and carcass weight (r = 0·49). Multiple regression analyses identified a three-variable subset comprised of ALA, carcass weight and CL which was related (P < 0·01) to muscle to bone ratio R(2) = 0·41). Data suggest that muscle to bone ratios differ widely among beef carcasses of similar genetic-management history and that there are carcass measures useful for predicting muscle to bone ratio., (Copyright © 1982. Published by Elsevier Ltd.)

Fifteen carcasses, 10 from steers and 5 from cows, were used for the present study. Five steer carcasses (group A) were electrically stimulated as intact, unsplit carcasses. The left sides of 5 steer carcasses (group B) and of 5 cow carcasses (group C) were electrically stimulated; the right sides of the same 5 steer carcasses (group D) and of the same 5 cow carcasses (group E) were used as controls and were not electrically stimulated. Electrically stimulated carcasses and sides (groups A and B) had brighter, more youthful colored lean, less "heat-ring" and produced more tender and more palatable rib steaks than did control sides (group D). Electrical stimulation did not (P > .05) affect ultimate pH or sarcomere length in steers or cows. Light and electron micrographs revealed increased (P < .05) structural damage (more severe contracture bands) in steer or cow muscles from electrically stimulated sides than in muscles from control sides; however, structural damage was not (P >.05) increased when intact steer carcasses were electrically stimulated and compared to unstimulated sides. Troponin-T was reduced in SDS gels of muscle from electrically stimulated, as compared to control, sides of cow carcasses (group C versus group E); no differences in percentage of protein subunits were observed between electrically stimulated and control sides of steer carcasses (group B versus group D). Electrical stimulation can be done on intact carcasses or sides of young beef to improve USDA lean maturity and lean color scores, to reduce "heat-ring" incidence and to improve tenderness.

A model system was developed to study attachment to and possibly detachment of bacteria from pork skin and thin-surface slices of beef and lamb carcasses. The technique involves embedding pork skin and beef and lamb surfaces in solidified wax with the skin surface exposed. After exposure of the skin or carcass surface to bacterial suspensions and subsequent manipulations, the sample is removed aseptically from the wax and subjected to agar plate counting methods. A direct relationship existed between bacterial counts of the skin or carcass surface and concentration of bacterial cells in the attachment medium. Much of the bacterial attachment occurred during the first minute of immersion in the attachment medium, although in some instances continued attachment occurred over a 30-min period. Gram-negative motile bacteria showed greater attachment than did gram-positive non-motile species. Temperature and pH of the attachment medium had little effect on the extent of bacterial attachment.

Beef top round roasts weighing approximately 2.3 lb. each were cooked from the thawed and frozen states in a countertop microwave oven (115v; 2,450 mHz) at the cooking power levels of "high" (553 watts) and "simmer" (237 watts) and also in a conventional oven at 163 degrees C (325 degrees F). Cooking times, energy consumption, cooking losses, and palatability of cooked products were compared. In general, no notable advantages were found in cooking at microwave "simmer" vs. "high".

Yersinia enterocolirica -like isolates from meats produced, black colonies on eight of nine lots of bismuth sulfite agar. Differences were observed in size and black metallic sheen of colonies on different lots of this medium. In addition, inhibition of Pseudomonas spp, differed among lots.

Morphological, physiological, and biochemical characteristics are presented for yellow-pigmented and non-pigmented psychrotrophic, gram-positive, catalase-positive, pleomorphic rods from vacuum-packaged wholesale cuts of beef. These isolates were essentially species of Corynebacterium and Microbacterium thermosphactum .

Performance, carcass and palatability characteristics of Longhorn steers were compared with those of cattle currently popular in the United States-Hereford, Angus, Brahman, Holstein, two-breed crossbred (British beef breed crosses) and three-breed crossbred (1 4 dairy , 1 4 British beef and 1 2 European beef ) steers. Steers were fed roughage, then a growing diet (42 days), then a high energy (89% concentrate) diet (153 to 179 days by breed group) and slaughtered, individually, at USDA Choice finish or, failing that, after 186 days on the finishing diet. Data suggest that Longhorns, compared with types of cattle currently used: (1) are less desirable in physical appearance; (2) gain weight less rapidly, reaching the desired finish and slaughter weight as older animals; (3) convert feed to liveweight less efficiently; (4) deposit less subcutaneous fat, more internal fat, but essentially the same amount of intramuscular fat; (5) are as muscular (longissimus muscle area, estimated percentage of carcass muscle, muscle to bone ratio, muscle to fat ratio); (6) are as desirable in USDA quality grade and yield grade and (7) produce beef that is a palatable., (Copyright © 1982. Published by Elsevier Ltd.)

Incubation of bovine muscle at 37°C promoted a more drastic proteolytic change in myofibrillar proteins, as determined from sodium dodecyl sulphate polyacrylamide gels of isolated myofibrils, than incubation at 4°C. Degradation of myosin and troponin-T were the most noticeable changes at 37°C. Loss of α-actinin was observed in the 4°C incubated muscle. Ground bovine muscle incubated at pH 5·4 and 7 revealed that alterations in myosin and troponin-T were the most noticeable changes at ph 5·4 while troponin-T and α-actinin were altered at pH7. More troponin-T degradation occurred at pH 5·4 and 37°C than at pH7 and 4°C (similar to the degradation of myosin), indicating that troponin-T degradation in post-mortem muscle may be an indicator of overall myofibrillar proteolysis and not responsible for post-mortem tenderisation per se. Myosin degradation in the ground samples incubated at pH 5·4 and in whole samples incubated at 37°C was compared with the digestion of myofibrillar myosin by papain. Both pyrophosphate and Guba-Straub extracts of the 37°C and pH 5·4 treated samples confirmed that myosin degradation did occur to a much greater extent at this temperature and pH than at 4°C and pH7, and, in addition, at pH 5·4 frequent cleavage occurred near the papain sensitive site of myosin., (Copyright © 1983. Published by Elsevier Ltd.)

Wholesale cuts of lamb (loins, legs) were packaged in polyvinyl chloride (PVC) film and in two other types of packages with oxygen transmission rates (cc/100 in 2 /24 h) of 0.41-0.75 and 2.28 respectively, Psychrotrophic counts were low (2 × 10-1.1 × 10 3 per in 2 ) intially and after storage for 21 days increased to 10 3 -1.6 × 10 5 per in 2 ) Initially Corynebacterium species and Microbacterium thermosphactum were dominant. Upon refrigerated storage for 21 days, Lactobacillus , Pseudomonas , and Moraxella-Acinetobacter sp. became more significant. Among the Corynebacterium sp., buff-colored isolates, consisting of long, gram-positive pleomorphic rods in palisades were dominant.

Use of a NaOCl rinse did not consistently affect (P >.05) weight losses or visual scores for appearance of beef cuts and quarters shipped from Seattle, Washington to Anchorage, Alaska. Wrapping of beef with PVC film greatly enhanced (P < .05) overall appearance of beef but also increased (P < .05, six of 24 comparisons) microbial counts and increased (P < .05, 12 of 23 comparisons) extent of visual microbial damage. Microbial counts did not increase (P > .05) on PVC film-wrapped beef shipped in modified atmosphere (60% CO 2 , 25%O 2 , 15%N 2 ) vans. Surface discoloration was minimized and overall appearance was enhanced (P < .05) for hindquarters as a result of the combined (additive) effects of NaOCl rinsing, PVC film wrapping, and shipment in a van with modified atmosphere.

No survivors of Yersinia enterocolitica were detected in beef roasts inoculated at levels as high as 3.1-3.8 × 10 6 viable cells per g when the final internal temperature in the center was 60 to 62 C. At 51 C some Y. enterocolitica survived. Extensive destruction of Y. enterocolitica occurred on beef during frozen storage. Counts of surviving organisms were greater on tryptic soy agar than on bismuth sulfite agar plates. Growth of Y. enterocolitica in brain heart infusion was better at pH 7 and 8 than at 6 or 9. Little or no growth occurred at pH 5.

Seventy-five steers (9 to 12 months of age) of Angus (n = 25), Brahman (n = 25) and Brahman × Angus (n = 25) breed-types of known history were fed a high-energy diet and five steers from each breed-type were slaughtered after 0, 56, 112, 168 and 224 days on test. At seven days post mortem, the left side of each carcass was fabricated and eight major primals or subprimals were obtained. Steaks were removed from the shoulder clod, strip loin, tenderloin, top sirloin, knuckle, top round, bottom round and eye of round for Warner-Bratzler shear (WBS) determinations and from the strip loin and bottom round for sensory panel evaluations. Steaks from Angus and Brahman × Angus steers were generally more tender than steaks from Brahman steers. Tenderness of steaks from steers of the three breed-types responded to time-on-feed differently: (a) steaks from Brahman steers improved (P < 0·05) in tenderness with increasing time-on-feed for all muscles except the M. psoas major (tenderloin); (b) with the exception of the M. longissimus muscle (strip loin), the tenderness of steaks from Angus steers did not change (P > 0·05) as time-on-feed increased and (c) for the Brahman × Angus steers, five of the ten muscles studied improved (P < 0·05) in tenderness with increasing time-on-feed. 'Acceptable' tenderness (WBS values of less than 4·5 kg) for most of the muscles was achieved at feeding periods from 112 to 224 days for Brahman, from 0 to 56 days for Angus and from 56 to 168 days for Brahman × Angus., (Copyright © 1985. Published by Elsevier Ltd.)

Forty-five steers (9-12 months of age) of Angus (n =15), Brahman (n = 15) and Brahman × Angus (n = 15) breed-types were fed a high-energy diet and then slaughtered after 0, 112 or 224 days of feeding. At 7 days post mortem, the M. longissimus and M. biceps femoris were removed from the left side of each carcass and steaks were obtained for determination of sensory panel ratings, Warner-Bratzler shear force, sarcomere length, collagen content and collagen solubility. Tenderness ratings of steaks from the M. longissimus and M. biceps femoris from Angus were generally higher than ratings for steaks from Brahman or Brahman × Angus steers. Steaks from Brahman × Angus received higher tenderness ratings than steaks from Brahman steers in only a few comparisons. The three breed-types of cattle responded to time-on-feed differently; Brahman cattle needed to have been fed longer than Angus cattle to produce equally tender beef. With increased time-on-feed, M. longissimus tenderness increased for all breed-types, but M. biceps femoris tenderness was not related to time-on-feed. Few significant differences were observed among breed-types and among time-on-feed periods for collagen content or collagen solubility. Tenderness differences were closely correlated with the contractile state of the muscle which, in turn, was associated with weight, subcutaneous fat thickness and temperature decline of the carcass., (Copyright © 1985. Published by Elsevier Ltd.)

A section of longissimus muscle was excised from six steers within 1 h post mortem. Half of the muscle section from each animal was held at 37°C (HT) and the other half was maintained at 1°C (C). Samples were collected from each muscle section in each treatment at 12 and 24 h to study the effect of conditioning temperature and incubation time on collagen properties by comparing the per cent soluble collagen and the relative distribution of collagen components. More of each collagen component (α(1), α(2), β(11) and β(12)) was present on SDS gels of samples incubated for 24 h versus 12 h. Although the collagen solubility did not increase to a great extent in the HT conditioned samples when compared with C samples, the HT treatment increased the effect of post-mortem ageing (i.e. more collagen molecules were solubilised and entered the gel during electrophoresis). Each collagen component, expressed as a percentage of total collagen, remained relatively constant when comparing different temperatures or post-mortem times. This indicates that the increase in collagen components being absorbed on the gels of 24 h post-mortem samples is mainly caused by an increase in the release of total collagen from the connective tissue matrix and not by the specific release of any one component. It was also found that some breakage of collagen crosslinks occurred during high temperature conditioning. No change in type III collagen of intramuscular connective tissue was found in this study., (Copyright © 1982. Published by Elsevier Ltd.)

Twenty-five carcasses from each of three breedtypes (Brahman, Angus and Brahman × Angus) were physically separated into fat, lean and bone. Several muscles from the round and the femur were used to derive equations to predict carcass composition and muscle-to-bone ratio. The femur (as a percentage of the carcass) was shown to predict percentage carcass bone with 90% accuracy. All of the muscles studied were highly related to total carcass lean but the percentage of carcass as M. biceps femoris was the best single muscle indicator of carcass lean of the muscles studied. More variation in carcass lean could be accounted for by a multiple regression equation, involving all four muscles studied, than by any single muscle. M. biceps femoris-to-femur ratio was found to predict carcass muscle-to-bone ratio with a high degree of accuracy. The USDA yield grades were found to be reliable indicators of carcass composition. A two-variable equation involving adjusted fat thickness and biceps femoris accounted for 88·6% of the variation (RSD = 1/·64) in percentage of carcass as separable lean., (Copyright © 1985. Published by Elsevier Ltd.)

Thirty Santa Gertrudis bulls (approximately 15-18 months old) were slaughtered, dressed and split into siides. The right side of each carcass was electrically stimulated (ES) with seventeen impulses (1·8s impulse duration; 1·8s interval between impulses) of 550 V (AC) and 5 A while the left side served as a non-stimulated control (not-ES). At 24h post morten, USDA quality and yield grade data were obtained from each side. On the second day post mortem, all sides were fabricated and strip loins, top sirloin butts and ribeyes were obtained from each side for post-mortem ageing and blade tenderisation studies. Steaks were removed after a post-mortem ageing period of 4 or 18 days and before (not-BT) or after blade tenderisation (BT) for sensory panel evaluations or shear force determinations. ES sides had more youthful lean maturity (P < 0·0001), higher marbling (P < 0.·002), higher USDA quality grades (P < 0·0.0001) and finer-textured lean (P < 0·002) than did not-stimulated (not-ES) sides. ES significantly improved (P < 0·05) palatability traits in two of twenty-four comparisons; BT significantly improved palatability traits in twelve of twenty-four comparisons and 18-day post-mortem ageing significantly improved palatability traits in seven of twelve comparisons. No significant reductions (P < 0·05) in shear force values were observed for steaks from ES versus not-ES sides while significant reductions (P < 0·05) were observed for steaks from BT versus non-BT cuts (four of six comparisons) and for steaks from cuts aged for 18 versus 4 days (ten of twelve comparisons). BT and 18-day post-mortem ageing were more effective for increasing palatability or for decreasing shear force requirements than was ES; however, ES greatly improved lean colour of meat from bulls., (Copyright © 1982. Published by Elsevier Ltd.)

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 CO 2 , increased and the percentage of O 2 , 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.

Boneless pork roasts were vacuum-packaged; one group remained in vacuum-packages (controls), other vacuum-packages were injected with one of six gas mixtures: (a) 100% O 2 , (b) 20% CO 2 + 80% N 2 , (c) 50% CO 2 + 50% O 2 . (d) 20% CO 2 + 80% O 2 , (e) 25% CO 2 + 25% O 2 + 50% N 2 , or (f) 51% CO 2 + 30% O 2 + 18% N 2 + 1% CO. Roasts were stored from 0-35 days at 1-3 C and chops from each treatment were observed under retail conditions for 5 days. Differences, both in psychrotrophic and lactobacillus counts, between roasts stored in modified gas atmospheres and those stored in vacuum-packages were rarely statistically significant. Psychrotrophic counts of pork chops from roasts stored for 21-35 days in modified gas atmospheres were somewhat higher than those prepared from comparable vacuum-packaged roasts. However, few of these differences were statistically significant. The initial microbial flora of the roasts consisted of Pseudomonas and Lactobacillus spp. Pseudomonas spp. remained a significant part of the microflora of roasts stored in 100% O 2 , whereas lactic acid bacteria ( Lactobacillus and Leuconostoc spp.) predominated on roasts after 1 week in all other atmospheres.

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.

Pseudomonas putrefaciens and lactobacillus counts of inoculated pork skin obtained with the maceration method usually were higher than were those obtained with the rinse method. Scalding and dehairing and shaving caused extensive destruction of the test organisms when placed on the skin before these slaughter-dressing steps. Smaller decreases in count occurred during singeing and washing and during evisceration and washing. Increases in S value (log count by maceration method minus log count by rinse method) for P. putrefaciens and a Lactobacillus sp. after freezing-thawing of inoculated pork skin may be related to a higher death rate of bacteria in the water film than for those entrapped in skin crevices. P. putrefaciens and the Lactobacillus sp. that were attached to pork skin exhibited greater heat resistance than did those bacteria which were not attached to skin. During storage of inoculated pork skin, S values of P. putrefaciens and the Lactobacillus sp. increased; this increase probably reflects increased strength of attachment of bacteria to the skin. Scanning electron microscopy of inoculated pork skin showed the formation of extracellular structures which may play a role in attachment of bacteria to skin or meat surfaces.

Frankfurters (9.07-kg batches) were conventionally made in which three replications of the following treatment combinations were used (a) curing ingredients: 0 or 50 ppm of sodium nitrite, 75 ppm of sodium nitrite-25 ppm of sodium nitrate, or 50 ppm of sodium nitrite-25 ppm of sodium nitrate, (b) seasoning: dry soluble or equivalent ground spice, (c) cooked product temperatures of 65.5 or 76.6 C and (d) radiation processing levels of either 0, 0.8 or 3.2 megarads. Regardless of curing ingredient combinations or levels of irradiation, lowering internal cooked product temperatures (65.5 vs. 76.6 C) improved internal color, off-odor, off-flavor, moistness and overall desirability scores of frankfurters. Use of a dry soluble seasoning in comparison to an equivalent natural ground spice seasoning had no effect on sensory, chemical or palatability traits of irradiated frankfurters. Although not significant, frankfurters made without nitrite (0-NO 2) compared to those made with 75 NO 2 -25 NO 3, had greater process shrinkage values and were significantly less desirable in visual color, off-flavor and overall palatability. External and internal color scores of frankfurters made with NO 2 and NO 3 combinations were less intensely pink, with an increase in irradiation from 0 to 0.8 to 3.2 megarads. Sensory traits (off-flavor, off-odor, texture and overall palatability) were less desirable in those frankfurters irradiated at 3.2 megarads as compared to those irradiated at 0.8 megarads. Both levels of irradiation produced less desirable frankfurters than the non-irradiated controls (0 megarads). Improvements in sensory properties of irradiated frankfurters may be accomplished by use of at least 50 ppm of NO 2 and cooking to a final internal product temperature of 65.5 C.

Beef, pork and lamb loins were vacuum-packaged as subprimal cuts (controls), reformed subprimal cuts and as retail cuts (steaks or chops). Subprimal cuts, reformed subprimal cuts and one group of retail cuts remained vacuum-packaged. Other groups of retail cuts were injected with atmospheres of either 20% CO 2 + 80% N 2 or 40% CO 2 + 60% N 2 . Cuts were randomly assigned to storage periods of 0-21 days at 2 ± 1 C. At weekly intervals, steaks or chops were removed from each treatment and examined after storage for 5 days under retail display conditions. Psychrotrophic bacterial counts and lactobacilli counts of steaks and chops stored in CO 2 -N 2 atmospheres usually were lower, though not often statistically significant, than those of comparable vacuum-packaged steaks, chops or loins. Psychrotrophic counts of steaks and pork chops, initially held in CO 2 ,-N 2 atmospheres and then subjected to retail display, usually were lower than those of comparable steaks and chops that had been vacuum-packaged (without added CO 2 -N 2 ) or prepared from vacuum-packaged loins.

One hundred and ninety-six boneless pork roasts were vacuum-packaged. Twenty-eight roasts remained vacuum-packaged to serve as controls. The remaining packages were divided into six groups of 28 packages each and injected with one of six gas mixtures: (a) 100% O 2 , (b) 20% CO 2 + 80% N 2 , (c) 50% CO 2 + 50% O 2 , (d) 20% CO 2 + 80% O 2 , (e) 25% CO 2 + 25% O 2 + 50% N 2 or (f) 51% CO 2 + 30% O 2 + 18% N 2 + 1% CO. Five packages from each packaging treatment were removed from storage after 7, 14, 21, 28 or 35 days. Data collection included gas composition of the intact packages and off-odor, surface discoloration, overall appearance, retail caselife and palatability of cuts. The most prevalent gas in vacuum packages was CO 2 with weight percentages of 62-88% during the 35-day storage period. Packages initially injected with an atmosphere containing 100% O 2 showed a gradual decrease in O 2 and an increase in CO 2 with increased storage. Roasts stored in O 2 -containing atmospheres for 14 and/or 21 days had a higher incidence of off-odor and chops from such roasts had lower overall appearance ratings after 1 day of retail display and lower flavor and overall palatability ratings than comparable vacuum packaged meats. These differences were significant only for roasts stored in modified atmospheres containing high concentrations of O 2 and only after extended periods of storage. Data suggest that a modified gas atmosphere of 20% CO 2 + 80% N 2 is a suitable alternative to vacuum-packaging.

Pork loins were vacuum-packaged; one group remained vacuum-packaged, other vacuum packages were injected with gas atmospheres of either 20% CO 2 + 80% N 2 or 40% CO 2 + 60% N 2 . Loins were stored for 7, 14, 21 and 28 days at 1-3 C. After each storage interval, chops were prepared from loins and subjected to 5 days of retail display. Psychrotrophic bacterial counts of lean and fat surfaces of loins stored in 40% CO 2 + 60% N 2 were frequently significantly lower than counts of comparable sites of vacuum-packaged loins. Lactobacillus counts of the subcutaneous fat cover of loins stored in CO 2 + N 2 were in most instances (7 of 8 comparisons) significantly higher than those of vacuum-packaged loins; this was true in only 2 of 8 comparisons for the lean surface. Psychrotrophic bacterial counts of chops prepared from loins subjected to the various storage treatments were seldom significantly different. During storage of pork loins, lactobacilli became a predominant part of the microflora and comprised more than 90% of the microflora after 21 days for loins stored in CO 2 + N 2 and after 28 days for vacuum-packaged loins. Pseudomonas spp. continued to persist to a greater degree in the vacuum-packaged loins than in the loins stored in CO 2 + N 2 .

Frankfurters were manufactured to contain certain combinations of curing ingredients (sodium nitrite, sodium nitrate and DL alpha-tocopherol). Some frankfurters were made to contain in the finished product 0% added moisture, others were made to contain 10% added moisture, some frankfurters were not irradiated (0-megarad), others were irradiated with either 0.8 or 3.2 megarads (Cobalt-60 radiation source). Use of DL, alpha-tocopherol (at a level of 206 ppm) was associated with greater processing shrinkage, more off-flavor and less overall palatability (P<0.05). The most desirable external and internal cured color and firmest texture was in frankfurters made with 50 ppm of NO 2 or with 100 ppm of NO 2 , irrespective of irradiation level. Use of irradiation (0.8 or 3.2 megarads) on frankfurters made without nitrite or nitrate did not improve visually determined cured color but did improve this color when determined spectrophotometrically; nevertheless, cured color of irradiated frankfurters made without use of nitrite or nitrate was not comparable to that of non-irradiated or irradiated frankfurters made with 100 ppm NO 2 . Irrespective of added moisture or curing ingredient combinations, significant differences (P<0.05) in palatability traits were associated with increasing irradiation levels (0, 0.8 or 3.2 megarads). Off-flavor increased, texture was less firm and overall palatability was less desirable as irradiation level increased. Low-dose irradiation (⩽1 megarad) may be feasible for enhancing the palatability traits of frankfurters containing lower levels of nitrite (lower than 156 ppm) but it appears that the correct irradiation level would be lower than the 0.8 megarad used in this study.

One hundred and ninety-six boneless beef roasts ( longissimus muscles) were vacuum packaged. Twenty-eight roasts remained vacuum packaged to serve as controls while the remaining packages were injected with one of six gas mixtures: (a) 100% O 2 , (b) 20% CO 2 + 80% N 2 , (c) 50% CO 2 + 50%O 2 , (d) 20% CO 2 + 80% O 2 , (e) 25% CO 2 + 25% O 2 +50% N 2 or(f) 51% CO 2 + 30% O 2 + 18% N 2 + 1% CO. Five cuts from each packaging treatment were stored in a 1-3-C cooler for 7, 14, 21, 28 or 35 days and subsequently evaluated for relative percentages of various gases in the intact packages, off-odor, surface discoloration. overall appearance, metmyoglobin percentages and palatability. Packages initially injected with modified gas atmospheres containing O 2 increased in relative percentages of CO 2 with advancing storage times. Roasts stored in modified atmospheres initially containing high levels of O 2 exhibited a greater incidence of off-odor, more surface discoloration, lower overall appearance ratings, shorter retail caselife and lower overall palatability ratings than vacuum-packaged roasts or roasts stored in an atmosphere initially containing 20% CO 2 + 80% N 2 .

Sixty feeder steers were assigned scores for frame size (small, medium or large) and muscle thickness (No. 1, No. 2 or No. 3), fed for 112 days and slaughtered. Grade data were collected for all 60 carcasses; 12 sides (four from each muscle thickness group) were fabricated into boneless, closely trimmed retail cuts and the 12 rounds from each of these sides were also physically separated into muscle, fat and bone. Marbling score and USDA quality grade varied inversely (P < 0·05) with frame size. Carcass quality grades were: 33·3% Choice; 67·7% Good and 0·0% Standard for small-framed cattle; 30·3% Choice, 42·4% Good and 27·3% Standard for medium-framed cattle and 5·5% Choice, 66·7% Good and 27·8% Standard for large-framed cattle. Analysis of variance showed significant (P < 0·05) differences among all muscle thickness groups in the longissimus muscle area and carcass weight but no difference in yield grade between the No. 1 and No. 3 muscle thickness groups; the larger mean longissimus muscle area of carcasses from steers in the No. 1 muscle thickness group was offset by their heavier carcass weight and their greater thickness of fat over the longissimus muscle. However, when analysis of covariance was used to hold fatness or fatness and frame size constant, the difference in yield grade between muscle thickness groups No. 1 and No. 3 was significant (P < 0·05). Also, carcasses from cattle assigned muscle thickness scores of No. 1, as feeders, had the highest (P < 0·05) muscle to bone ratio of the round (4·1 to 1) while carcasses from cattle assigned thickness scores of No. 3, as feeders, had the lowest (P < 0·05) muscle to bone ratio of the round (3·4 to 1)., (Copyright © 1982. Published by Elsevier Ltd.)

Wholesale pork loins were either vacuum-packaged, packaged in an atmosphere of 20% CO 2 + 80% N 2 or packaged in an atmosphere of 40% CO 2 + 60% N 2 . After storage, the primal cuts were evaluated visually for muscle color, fat cover appearance, off-odor, lean surface discoloration and overall appearance. Retail cuts fabricated from the wholesale loins were evaluated for surface discoloration and overall appearance during a 5-day retail display period or they were used for sensory panel evaluation. Few significant differences between packaging treatments were found during the storage period for traits evaluated on the primal cuts. Few significant differences between packaging treatments were observed for either retail display data or sensory panel evaluation.

Frankfurters of twelve treatment combinations were made using a conventional manufacturing procedure. Manufacturing treatments included formulations of either 60% pork/40% beef, 100% mechanically deboned chicken (MDC) or 100% mechanically deboned turkey (MDT); sodium nitrite levels of 0 or 50 ppm; and sodium acid pyrophosphate (SAPP) levels of 0 or 3,750 ppm. Finished frankfurters were either not irradiated or irradiated at temperatures of either -34.4 or -51.1°C and at a dose level of 0.8 or 3.2 Mrad. Addition of SAPP did not significantly affect external or internal color, off-flavor incidence or overall palatability of any of the frankfurters but significantly increased processing shrinkage for pork/beef and chicken franks, decreased frankfurter pH values for pork/beef and chicken franks and improved texture of pork/beef, chicken and turkey franks. Addition of 50 ppm nitrite, as compared to use of no nitrite, significantly decreased processing shrinkage of turkey franks, increased batter and frankfurter pH of pork/beef franks, increased consumer cooking loss of chicken franks but decreased consumer cooking loss of turkey franks, decreased off-flavor of pork/beef, chicken and turkey franks, and improved internal color of pork/beef, chicken and turkey franks. An irradiation temperature of -51.1°C as compared with -34.4°C, decreased off-flavor intensity and increased palatability of pork/beef franks but did not affect other properties of pork/beef franks or any of the properties of chicken or turkey franks. Franks irradiated with 0.8 Mrad differed (P<0.05) from those that were not irradiated in only 3 of 18 sensory traits (including overall palatability of pork/beef franks); franks irradiated with 3.2 Mrad differed (P<0.05) from those which were not irradiated in 8 of 18 sensory traits (including overall palatability of pork/beef, chicken and turkey franks).

Twenty-five steers of each of three breedtypes (Angus, Brahman and F(1) Brahman x Angus) were sorted by frame size and muscle thickness, assigned to groups (five steers of each breedtype) to be fed for 0, 56, 112, 168 or 224 days, slaughtered and compared for various carcass traits. Steers of each breedtype had similar dressing percentages. Carcasses from all three breedtypes merited similar USDA quality and yield grades; breedtypes differences in quality grade were slight. Differences were found in the fat deposition patterns exhibited by the three breedtypes. Brahman steers tended to deposit more of their total fat as subcutaneous fat early in the feeding period. Angus steers had more (P < 0·05) seam fat as a percentage of carcass weight at all five feeding periods and more (P < 0·05) kidney, pelvic and heart fat at two of the five feeding periods than Brahman steers. Brahman steers had a higher percentage of their separable lean in the muscles of the round than did steers of the other breedtypes., (Copyright © 1985. Published by Elsevier Ltd.)

The heat-induced gel strength in suspensions of two types of plasma protein isolates and egg albumen were compared to investigate the use of bovine blood plasma in food systems as a replacement for egg albumen and other proteins. A viscosity index, based on a counter-flow back-extrusion model, was used to measure gel strength. The optimum pH for gel formation was 7.0 for phosphated and nonphosphated plasma protein suspensions and 9.0 for egg albumen. The protein gel strengths were compared at 8% protein concentrations and at their respective pH optima. The gel strength of heated bovine plasma protein suspensions was greater (P < .01) than that of egg albumen, indicating that blood plasma exhibited a binding ability superior to that of egg albumen. The addition of controlled low levels of sodium and calcium increased (P < .05) the binding ability of both plasma protein isolates, while egg albumen showed no changes (P > .05). Greater concentrations substantially decreased (P < .01) the gel strength in both types of heated plasma protein suspensions and egg albumen, revealing that all three protein types exhibited an ionic strength dependency.

Boneless beef roasts ( longissimus muscles) were vacuum-packaged and then the bags were injected with one of six gas mixtures: 100% O 2 , 20% CO 2 +80% N 2 , 50% CO 2 + 50% O 2 , 20% CO 2 +80% O 2 , 25% CO 2 + 25% O 2 +50% N 2 or 51% CO 2 + 30% O 2 + 18% N 2 + 1% CO. One group of roasts, vacuum-packaged without added gas served as controls. Roasts were stored for 0-35 days at 1-3 C. At five weekly intervals, steaks were removed from roasts in each treatment and examined after storage for 5 days under retail display conditions. Psychrotrophic plate counts of roasts stored in modified gas atmospheres were usually higher than those stored in conventional vacuum packages. Differences in lactobacillus counts between roasts stored in modified gas atmospheres and those stored in vacuum packages rarely were statistically significant. Counts of retail steaks prepared from roasts stored in various gas atmospheres were usually slightly higher than those prepared from comparable vacuum packaged roasts. In most instances these differences were not statistically significant. Initially, the microbial flora of vacuum-packaged beef roasts consisted primarily of Moraxella-Acinetobacter and Pseudomonas spp. Lactobacilli predominated on roasts at later storage intervals even on roasts stored in atmospheres initially containing 100% O 2 or 20% CO 2 + 80% O 2 . Pseudomonas spp. remained a substantial part of the microflora of roasts stored in high O 2 containing atmospheres.

The right sides of six beef carcasses were electrically stimulated, whereas the left sides were not so treated. Sections of longissimus and semimembranosus muscles were removed from electrically stimulated sides at 1 h postmortem (hot-boned) and from sides which were not electrically stimulated at 24 h postmortem (conventionally boned); these muscles were vacuum-packaged immediately after removal and aged for 2 weeks at 1 ± 1 C. After aging, steaks were removed and used for determinations of palatability, cooking loss, pH, sarcomere length and protein solubility. Further evaluation included purification and electrophoresis of myofibrillar proteins. Longissimus muscles from electrically stimulated, hot-boned beef had lower (P < .05) juiciness ratings than those from conventionally handled sides; semimembranosus muscles from electrically stimulated, hot-boned sides sustained lower (P < .05) weight losses during storage but higher (P < .05) cooking losses than muscles from conventionally handled sides. Hot-boning of electrically stimulated beef had no effect (P > .05) on tenderness, flavor desirability, pH, sarcomere length, amount of non-protein nitrogen or percentage of soluble myofibrillar proteins; slight alterations were noted in the electrophoretic banding patterns, on SDS gels, of myofibrillar proteins from electrically stimulated. hot-boned sides. Hot-boned beef was as palatable as conventionally handled beef if sides were electrically stimulated on the kill floor before hot-boning and if beef from both treatments was vacuum packaged and aged for 2 weeks at 1 ± 1 C.

Beef quarters were used in a study which had all combinations of the following treatments: 14 or 21 days storage, with or without PVC film wrapping, with or without NaOCl spraying and with nitrogen atmosphere or ambient air environments. In this study, best results for storing beef quarters 14 days were obtained by using PVC film (with or without NaOCl spraying); best results for storing beef quarters 21 days were obtained from PVC film wrapped (with or without NaOCl spraying) or unprotected quarters (with or without NaOCl spraying). Use of a nitrogen atmosphere did not consistently decrease bacterial counts and did not improve the physical appearance of quarters. Even the best system for protecting beef quarters during 21 days of storage did not result in beef that was desirable in appearance or condition at the conclusion of the storage trial.