Microbiological and sensory characteristics of beef loin steaks: Role of subcutaneous fat

Beef loin steaks with the subcutaneous fat attached, without subcutaneous fat and the subcutaneous fat that was removed from steaks were packaged and stored at 4°C ± 1°C in polyvinyl chloride (PVC) film for 0–6 days and in high-oxygen barrier (HOB) film for 0–28 days. Aerobic plate counts (APCs) of subcutaneous fat of intact steaks and of subcutaneous fat that was packaged and stored separately in PVC and HOB films were greater (P < 0·05) than those of comparable lean samples. The APCs of lean of steaks without subcutaneous fat that were packaged and stored in HOB film were lower (P < 0·05) than those of the lean of intact steaks. APCs of the lean of these two types of steaks packaged and stored in PVC film did not differ (P > 0·05). Mean surface discoloration and mean overall appearance scores of intact steaks packaged and stored in HOB film were greater than those of steaks packaged and stored without subcutaneous fat; differences were significant (P < 0·05) after 21 and 14 days, respectively. This difference in surface discoloration was attributed to metmyoglobin formation due to possibly higher levels of oxygen remaining in the packages of steaks without subcutaneous fat than in packages containing steaks with the fat attached.     

Microbiological and sensory characteristics of pork loin chops: Role of intramuscular fat

Pork loin chops of High, Intermediate and Low intramuscular fat were trimmed free of subcutaneous fat and then packaged and stored in polyvinyl chloride (PVC) film for 0-6 days or in high oxygen barrier (HOB) film for 0-28 days at 4°C ± 1°C. In general, marbling group had no (P > 0·05) effect on the aerobic plate count (APC) and did not result in major differences in the distribution of types in the microflora of pork loin chops. During storage, Pseudomonas spp. became dominant in the microflora of PVC-wrapped chops while Lactobacillus spp. became dominant in the microflora of chops stored in HOB film. Of the sensory characteristics examined, mean surface discoloration and mean overall appearance scores of chops of Low intramuscular fat stored in HOB film were usually lower (P < 0·05) than those of chops of Intermediate and High intramuscular fat. In contrast, marbling group usually had no significant effect on mean surface discoloration and mean overall appearance scores of chops packaged in PVC film.     

Microbiological and sensory characteristics of pork loin chops: Role of subcutaneous fat

Pork loin chops with the subcutaneous fat attached, without subcutaneous fat and the subcutaneous fat that was removed from chops were packaged and stored at 4°C±1°C in polyvinyl chloride (PVC) film for 0-6 days or in high-oxygen barrier (HOB) film for 0-28 days. Aerobic plate counts (APCs) of lean and fat of intact chops packaged and stored in either PVC or HOB film did not differ (P>0·05) in most comparisons. The APCs of subcutaneous fat portions that were packaged and stored separately in HOB film often were higher than those of comparable fat samples of intact chops. There was no consistent pattern of differences in the microflora of lean and fat samples. Differences in mean scores for surface discoloration, off odor and overall appearance of intact chops and chops without subcutaneous fat usually were either not significant (P>0·05) or inconsistent. Lean color scores of chops with or without subcutaneous fat did not differ except that chops with the subcutaneous fat removed were rated higher than intact chops during the early periods of storage. Fat color of subcutaneous fat packaged and stored separately in HOB film was often rated higher (slightly whiter) than that of comparable fat of intact chops.     

RELATIONSHIP OF USDA QUALITY GRADES TO PALATABILITY OF COOKED BEEF1

Prime carcasses produced loin and round steaks that were more palatable (P < 0.05) than were those from carcasses of Choice through Canner (7 grades) in 85.7% of comparisons and from carcasses of Choice through Standard (3 grades) in 69.0% of comparisons; comparable percentages were 71.4% (6 grades) and 42.9% (2 grades) for Choice and 74.3% (5 grades) and 35.7% (1 grade) for Good. Among Prime through Standard carcasses, grade predicted flavor, tenderness and overall palatability of loin steaks with 30 to 38% accuracy, but could explain no more than 8% of the variation in panel ratings/shear force values of round steaks.     

Potential role of Proteus-Providencia-Morganella species in quality deterioration of beef

Proteeae Isolation Medium of Hawkey et al. (1986) was effective for isolation and enumeration of Proteus-Providencia-Morganella spp. from beef and beef products. On this medium colonies were brown, surrounded by a zone of clearing. In an examination of retail beef samples packaged and stored in polyvinyl chloride (PVC) film, 5% contained these bacteria in a concentration of 10¹–10² cells per gram or cm². Isolates from retail beef samples included P. vulgaris, P. alcalifaciens, P. rettgeri, and M. morganii. None of the retail samples packaged and stored in high oxygen barrier (HOB) film contained detectable Proteus-Providencia-Morganella spp. Steaks inoculated with Proteus-Providencia-Morganella spp. and packaged and stored at 4°C in PVC film (15 days) or in HOB film (42 days) usually had a reduced count of Proteus-Providencia-Morganella spp. during storage. Slight increases in counts occurred on steaks inculated with P. vulgaris and P. rettgeri and stored at 4°C for 15 days in PVC film.     

脂肪含量对雪花牛排在高氧气调包装贮藏期间肉色稳定性的影响

为探究雪花牛排在高氧气调包装贮藏期间的肉色稳定性,该实验选用两种不同脂肪含量(A1和A3等级)的雪花牛排,进行高氧气调包装(80％O2+20％CO2).在每个时间点(0、5和10 d),测定其各个指标的变化.结果表明,随着贮藏时间的延长两种等级的牛排脂质氧化程度均逐渐增大,肌红蛋白还原力逐渐减弱,使高铁肌红蛋白比例显著...     

Physical, Sensory and Microbiological Characteristics of Lamb Retail Cuts Vacuum Packaged in High Oxygen-Barrier Film

Lamb chops and steaks from fresh (F) or vacuum packaged (VP) racks, loins and legs were packaged in polyvinyl chloride (PVC) film or vacuum packaged in high oxygen-barrier (HOB) film. Use of previously vacuum packaged (PVP) cuts did not affect overall appearance of rib or loin chops during subsequent retail display but HOB film-packaged leg steaks from PVP cuts had lower overall appearance scores than did leg steaks from F cuts. Prior VP storage negatively affected flavor desirability and odor at the conclusion of retail display (4 days in PVC or 10 or 15 days in HOB film). Pseudomonas spp. were a dominant part of the microflora of PVC-wrapped chops while L. cellobiosus was a dominant part of the microflora of HOB-wrapped chops.     

Storage and display characteristics of electrically stimulated, hot-boned and nonstimulated, cold-boned beef

One side, randomly selected from each of 33 carcasses from forage-fed steers, was electrically stimulated within 30 min of exsanguination and hot-bonded (ESHB). Opposite sides were not electrically stimulated and were cold-boned (NESCB) following a 24 h chill (0°C). From 17 ESHB sides, portions of the longissimus dorsi (LD) and semimembranosus (SM) muscles were removed and immediately vacuum packaged. LD and SM muscles were removed from the remaining 16 ESHB sides, wrapped in polyvinyl chloride film, chilled (0°C) for 22 h and then vacuum packaged. LD and SM muscles from NESCB sides (n = 33) were removed and the vacuum packed at 24 h post mortem. Whole muscle characteristics were evaluated initially and after storage periods of 7, 14 or 21 days and steaks were displayesd for 5 years thereafter. Neither hot versus cold-boning nor storage for 21 days affected retail display characteristics of LD and SM steaks (P > 0·05). As retail display time increased, retail lean color, fat color and overall appearance scores decreased.     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Display Color of Unfrozen Vacuum Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), and hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM), vacuum packaged steaks. HB muscles frequently were visually brighter purplish-red than other treatments. Compared to ESHB, ES LD was not different, but ES SM was duller purplish-red in color. Reflectance indicators of reduced myoglobin and metmyoglobin were essentially the same across treatments in both muscles. Vacuum packaged fresh beef steaks from all treatments were acceptable in color at 0, 3, 7, and 14 days of display. Vacuum packaging appears suitable for steaks from any of these carcass treatments but is especially useful for steaks from hot boned cuts.     

Centralized Packaging of Beef Loin Steaks with Different Oxygen-Barrier Films: Physical and Sensory Characteristics

Vacuum packaged beef strip loins (n = 72) were stored (2 ° 1°C) for either 0, 12 or 24 days before fabrication; steaks were packaged and displayed (2°C or 7°C) up to 6 days in oxygen-permeable film or up to 30 days in vacuum packages (medium or high oxygen-barrier film). Steaks displayed at 2°C, rather than 7°C, tended to have higher overall appearance scores especially when steaks were from 12 or 24 day subprimals. Overall palatability of vacuum packaged steaks was unacceptable after 10–15 days of display. Vacuum packaged steaks can be displayed for 10 days if: (1) steaks are from relatively fresh subprimals, (2) steaks are vacuum packaged with high oxygen-barrier film, and (3) steaks are displayed at 2°C. Although visual scores for vacuum packaged steaks were acceptable for 20–30 days, off-odors and off-flavors were limiting factors in determining shelf-life.     

Prevention of Transient Discoloration of Beef

Oxygen absorbent technology in conjunction with controlled atmosphere packaging(CAP) was used to prevent transient discoloration in master‐packaged beef steaks. Two types of commercial O₂ scavengers were used in the study. The master packs were stored at 1± 0.5 °C. The steaks from master packs were presented in a display‐case for visual evaluation. Reflectance spectra from each steak‐surface were obtained to estimate metmyoglobin content. Steaks packaged without O₂ scavengers showed more discoloration, and had significantly higher proportions of metmyoglobin when compared to steaks with O₂ scavengers, after most storage intervals (p < 0.05). Prevention of metmyoglobin formation was influenced by the number but not the type of O₂ scavenger employed (p > 0.05). Keywords: oxygen scavengers, centralized meat operations, transient discoloration     

Consumer responses for tenderness and overall impression can be predicted by visible and near-infrared spectroscopy,Meullenet–Owens razor shear,and Warner–Bratzler shear force

Beef ribeye rolls (n = 40) from Select, low Choice, top (upper 2/3) Choice, and Prime quality grade carcasses were used to determine the relationship of visible and near-infrared spectroscopy (VNIR) reflectance, Warner–Bratzler shear force (WBSF), and Meullenet–Owens razor shear (MORS) with consumer responses for tenderness and overall impression. Steaks (2.54 cm) were cut and assigned to either 14 or 28 d aging (n = 4/aging period). Reflectance in the VNIR spectrum was measured 1 d from the box-date no less than 30 min after cutting, and prior to aging. The steak used for VNIR measurement was designated for WBSF and MORS measurement, whereas three adjacent steaks were cooked for evaluation by a consumer panel (n = 240 members). Steaks from the Select-grade ribeye rolls had the greatest (P = 0.06) WBSF values and lower (P < 0.05) overall impression scores than those from top Choice and Prime quality grades. Consumer panelists evaluated steaks aged 28 d as more tender (P < 0.05) than those aged 14 d. The relationship of mechanical tenderness measurements were higher with consumer panel responses for tenderness than with overall impression, and those relationships were stronger for the Select grade than for quality grades with higher degrees of marbling. The 2nd derivatives of VNIR measurements were more successful at predicting consumer panel responses of tenderness and overall impression than WBSF and MORS; thus, VNIR methodology was less invasive and more predictive than other, more traditional tenderness measurements.     

Singular and combined effects of electrical stimulation, post-mortem ageing and blade tenderisation on the palatability attributes of beef from young bulls

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.     

CONSUMER EVALUATION OF THE PALATABILITY OF USDA SELECT,USDA CHOICE AND CERTIFIED ANGUS BEEF STRIP LOIN STEAKS FROM RETAIL MARKETS IN LUBBOCK,TEXAS, U.S.A.

ABSTRACT

Select, Choice and Certified Angus Beef (CAB) strip loin steaks were sold in Lubbock, TX to determine consumer acceptability. A home survey was attached to each package of steaks (return = 191 steak evaluations). Consumers did not detect differences in tenderness or flavor, but rated CAB steaks juicier (P < 0.05) than Select or Choice. However, 68% of CAB consumers rated steaks as extremely or very tender, but less than half rated Choice and Select steaks the same way. Consumer tenderness and flavor scores for Select steaks were more variable, but consumer satisfaction and tenderness acceptability did not differ (P > 0.05) between grades. Trained sensory panelists rated CAB steaks higher (P < 0.05) than Choice or Select for all palatability traits except flavor intensity. Shear force decreased (P < 0.05) by quality grade as CAB steaks sheared with the least resistance. These results showed marbling influenced objective palatability measures and decreased the variation in both objective and consumer measures of palatability.

PRACTICAL APPLICATIONS

Quality grades were established to predict beef palatability, but marbling can be an unreliable predictor of tenderness. Branded beef programs, such as Certified Angus Beef (CAB), have been developed to distinguish higher palatability products and provide more consistent products for consumers. Consumers can distinguish between levels beef tenderness and are willing to pay a premium for tender beef. Moreover, consumers find product consistency is moderately important when purchasing fresh beef. Therefore, the purpose of this study was to determine consumer acceptability based on in‐home evaluations of strip loin steaks from United States Department of Agriculture Select and Choice grades and CAB purchased from a retail supermarket environment.

     

Effects of Beef Carcass Electrical Stimulation and Hot Boning on Muscle Display Color of Polyvinylchloride Packaged Steaks

Ninety-six beef sides from 48 carcasses were used to determine the effects of control (C, chilled 48 hr at 5°C), electrical stimulation (ES, 45 min postmortem, 400 volts for 2 min, pulsed), hot boning (HB, 2 hr postmortem), and combination (ESHB) treatments on muscle color of longissimus (LD) and semimembranosus (SM) steaks packaged in polyvinylchloride film. LD from HB was mostly visually darker, had less oxymyoglobin, and more metmyoglobin than other treatments as was the SM, but SM had fewer differences between HB and ESHB. ES and ESHB muscles were visually similar, suggesting ES minimized the darkening effect of HB. Regardless of treatment, muscle color was acceptable at 0, 1, 3 and 5 days of display.     

Centralized Packaging of Beef Loin Steaks with Different Oxygen-Barrier Films: Microbiological Characteristics

Vacuum packaged beef strip loins (n = 72) were stored (2° 1°C) for either 0,12 or 24 days before fabrication; steaks were packaged and displayed (2°C or 7°C) up to 6 days in oxygen-permeable film or up to 30 days in vacuum packages (medium or high oxygen-barrier film). For steaks displayed in oxygen-permeable film, Pseudomonas spp. were a considerable (25–49%) or dominant (>50%) part of the microflora. The microflora of vacuum-packaged steaks from 0 day loins was dominated by a combination of hetero- and homofermentative Lactobacillus spp.; when vacuum-packaged steaks were from 12 and 24 day loins, the microflora was in most cases dominated by the heterofermentative Lactobacillus cellobiosus.     

Effect of Time-on-Feed on the Palatability of Rib Steaks from Steers and Heifers

Rib steaks from steers (n=326) and heifers (n=68) that were either grass-fed or fed high-concentrate diets for 30–230 days were used in palatability studies. Extending time-on-feed beyond 100 days (steers) or 90 days (heifers) provided little additional palatability assurance. Within time-on-feed strata from 100 through 230 days, few differences in palatability were found between rib steaks from carcasses of different USDA quality grades. The minimum marbling requirement for the U.S. Choice grade could be lowered with no appreciable loss in palatability if the stipulation was made that cattle had been fed a high-concentrate diet for at least 90 days.     

Effects of oestradiol-17β implantation on performance, carcass traits, meat sensory traits and endocrine aspects of bulls and steers

Twenty-eight Simmental bull calves were randomly allotted to one of three treatments at birth. Ten bulls (IB) and nine steers (IS), castrated within 3 days of birth, were implanted with oestradiol (E(2)). The remaining calves were non-implanted, control bulls (CB). Calves were implanted within 3 days of birth and at 200-day intervals until slaughter at 14·8 months of age and at a mean carcass weight of 381·6 kg. Blood samples were taken every 14 days from 9·8 through 14·8 months and serum was analyzed for E(2) and testosterone (T) levels. Carcasses were chilled in a 3 to 7°C cooler. Carcass data were obtained and aged longissimus dorsi steaks were evaluated by a trained sensory panel and a Warner-Bratzler shear (WBS) device. Scrotal circumferences were smaller (P < 0·0.5) for IB than for CB. Control bulls had heavier weaning weights (P < 0·05) than IB and higher (P < 0·05) feedlot gains than IS. Implanted steers required more (P < 0·05) feed/unit of gain than CB and IB. Implanting bulls with E(2) increased (P < 0·05) serum E(2) levels and tended (P < 0·10) to reduce T levels. Serum E(2) in IS and IB were drastically increased (P < 0·05) for 4 to 6 weeks following re-implantation during the feedlot phase, then sharply declined. Implanted steer carcasses had more youthful maturity scores than CB carcasses. The incidence of hear ring (dark, coarse, band formation) was greater (P < 0·05) for IB than for IS, probably because of the thinner fat cover (P < 0·05) on IB. Ribeye areas were smaller (P < 0·05) and yield grades were higher for IS than for CB. Testicle weights were not significantly different between IB and CB, although variability was greater for IB. Carcass masculinity was least (P < 0·05) for IS, and IB were less (P < 0·05) masculine than CB. The only difference in longissimus dorsi sensory traits was that steaks from IB were juicier than steaks from CB. Also, WBS values were lower (P < 0·05) for IS than for CB.     

Internal Premature Browning in Cooked Steaks from Enhanced Beef Round Muscles Packaged in High-oxygen and Ultra-low Oxygen Modified Atmospheres

ABSTRACT: Beef round muscles were injection-enhanced to 6%, packaged in high-oxygen (HiOx) or ultra-low oxygen (LoOx) modified atmospheres, stored 7 d and displayed 2 d (HiOx) or stored 16 d and displayed 1 d (LoOx) at 0 °C, and cooked to 71.1 °C. Raw internal color for steaks in HiOx was lighter, redder, more yellow and saturated, and had more oxymyoglobin and less deoxymyoglobin than steaks in LoOx ( P < 0.0001). Cooked internal color of steaks from HiOx appeared prematurely brown and was darker, less red, yellow, and saturated, and had more denatured myoglobin than steaks from LoOx ( P < 0.0001). This study presents conclusive evidence that modified-atmosphere packaging influences internal cooked color development of beef steaks.