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MEAT SCIENCE AND MUSCLE BIOLOGY |
* Department of Animal Sciences and Industry, Kansas State University, Manhattan 66506-0201;
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Department of Statistics, Kansas State University, Manhattan 66506;
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Department of Animal Science, Oklahoma State University, Stillwater 74078;
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Department of Animal Science, Texas Tech University, Lubbock 79409;
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# Department of Animal Science, University of Illinois, Champaign 61801;
and
|| Consultant, 1525 E. Kay Street, Derby, KS 63037; and
¶ Intervet/Schering-Plough Animal Health, Desoto, KS 66018
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Abstract |
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 Top Abstract INTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Key Words: β-adrenergic agonist • display color • high oxygen and carbon monoxide modified atmosphere packaging • Holstein beef • overwrap packaging • zilpaterol hydrochloride
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INTRODUCTION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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; Bass et al., 2006; Dikeman, 2007; Quinn et al., 2008). Feeding ractopamine slightly improved beef color (Dikeman, 2007). Quinn et al. (2008) found no differences for meat color from controls and ractopamine-fed heifers. Zilpaterol hydrochloride (ZH) fed 30 or 50 d improved color life of beef steaks (Strydom et al., 2000). Avendaño-Reyes et al. (2006) reported similar L* values for cattle fed ZH, ractopamine, or no β-agonist on d 1 and 14; however, control steaks at d 5 had reduced L* values compared with steaks from either β-agonist treatment. Faustman and Cassens (1991) noted slower discoloration of meat from beef cattle vs. beef from Holsteins. Little research is available comparing color attributes of steaks in various packaging systems from Holstein steers, which are about 8% of US fed-beef slaughter (Schaefer, 2005).
Centralized processing uses modified atmosphere packaging (MAP) to extend color life (Sørheim et al., 1999; Jayasingh et al., 2001; Kropf, 2004; Seyfert et al., 2004; Eilert, 2005). High oxygen MAP (HO-MAP) has elevated oxygen partial pressures that delay metmyoglobin formation compared with other MAP atmospheres (Jeyamkondan et al., 2000). But, meat in HO-MAP is very susceptible to lipid oxidation (Kropf, 2004; John et al., 2005). Antioxidants in HO-MAP slows flavor deterioration (Mancini et al., 2005), and use of low-oxygen MAP (CO-MAP) containing carbon monoxide results in steaks with a red color and little oxidation (Sørheim et al., 1999; Jayasingh et al., 2001; Mancini and Hunt, 2005; Cornforth and Hunt, 2008).
To examine the hypothesis that feeding time of ZH does not affect meat color, this study evaluated the color and color stability of calf-fed Holstein semimembranosus (SM) steaks (nonenhanced and enhanced) from cattle fed ZH for 0, 20, 30, or 40 d when packaged in 3 packaging systems, traditional PVC overwrap, and HO-MAP and CO-MAP.
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MATERIALS AND METHODS |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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Animals and Diets
Sixty calf-fed Holstein steers were selected randomly for muscle retrieval from a group (n > 2,300) that had been fed a feedlot diet in a commercial feed yard in California. Diets containing 7.56 g/t of ZH (100% DM basis, Intervet/Schering-Plough Animal Health, DeSoto, KS) were fed for 0, 20, 30 or 40 d (ZH0, ZH20, ZH30, and ZH40, respectively) and withdrawn 3 d before slaughter. On arrival at the feed yard, steers were implanted on d 0 with Revalor-IS (Intervet/Schering-Plough Animal Health); cattle were previously implanted with Synovex-S (200 mg of progesterone and 20 mg of estradiol benzoate; Fort Dodge Animal Health, Overland Park, KS) 120 d before the Revalor-IS implant.
During slaughter in a commercial federally inspected facility, carcasses were electrically stimulated (45 V) 30 min postmortem to improve bleeding and to accelerate glycolysis, which could cause the deep portion of the SM to become more pale (Sammel et al., 2002). The current, wave type, time, and pulse duration of the commercial low voltage electrical stimulation were not able to be determined, but all carcasses were stimulated so all treatment combinations would be equally affected. Carcasses were chilled at 0 ± 2°C in a bone-to-bone configuration. Carcasses (n = 60, 360 to 484 kg, A-maturity) were selected randomly on d 1 postmortem, and 15 inside rounds (NAMP #168; NAMP, 2007) from each ZH feeding duration were removed from 1 side of each carcass, vacuum packaged, and commercially shipped refrigerated (1 to 3°C) to the Kansas State University Meat Laboratory.
Processing of Subprimals
On d 9 postmortem, subprimals were trimmed to remove the adductor muscle and excess fat, leaving the SM. The anterior portion (7.62 cm thick) of each SM was removed, re-vacuum packaged (barrier bag 620, Sealed Air Corp., Duncan, SC), and stored in the dark at 2°C until d 21 postmortem to simulate distribution. The remaining SM was vacuum packaged and stored in the dark at 2°C until d 10 postmortem; then it was enhanced and fabricated into steaks for PVC packaging and display.
Enhancement and Steak Fabrication
Randomly selected larger SM muscle portions (15 sets, each composed of 1 muscle portion from each feeding group, n = 60 total subprimal pieces) were removed from the package, weighed and passed once through a multiple-needle injector (model N30, Wolftec Inc., Werther, Germany). Each SM was injected to a 10% pump with a solution containing 0.3% sodium chloride, 0.35% phosphate (Brifisol 85 Instant, BK Giulini Corp., Simi Valley, CA), and 0.05% rosemary extract (NatureGuard Rosemary Extract, Newly Weds Foods Co./NORAC, Edmonton, Alberta, Canada). After a 10-min post-pump drain period, each SM was reweighed to determine the percentage pump calculated as [(pumped and drained cut weight – unpumped cut weight) ÷ unpumped cut weight] x 100. The cut surface of the SM was removed (faced) before it was fabricated into five 2.54-cm-thick steaks; 3 were assigned to a HO-MAP system (80% O2, 20% CO2) for 0, 3, or 5 d of retail display; and 2 were allotted to a CO-MAP system (69.6% N2, 30% CO2, and 0.4% CO) for 0 or 9 d of retail display. All MAP steaks were placed with the fresh-cut surface up in 24.5 cm x 14.3 cm x 5.0 cm rigid polypropylene trays (CS1178, Cryovac Sealed Air Corp., Duncan, SC) containing absorbent pads (Dri-Loc Soaker Pads, AC-50, Cryovac Sealed Air Corp.), covered with oxygen-barrier film (lid 550, 1.0 mils; less than 20.0 oxygen transmission mL per 24 h/m2 at 4.4°C with 100% relative humidity (RH), and moisture vapor transmission less than 0.1 g per 24 h/645.2 cm2 at 4.4°C and 100% RH, Cryovac Sealed Air Corp.), and packaged (Ross Jr. S-3180, Ross, Midland, VA). The HO-MAP and CO-MAP packages were boxed and placed into dark storage for 4 and 11 d, respectively, before being put into simulated retail display at postmortem d 14 and 21, respectively. For LoOx packaged steaks, 2 activated oxygen scavengers (model TLC, 9 g and 320 mL capacity; ActiveTech, Pactiv, Chicago, IL) were included in each package. Postpackaging O2 was less than 0.11%.
The smaller SM portion (7.62-cm unenhanced portion) was unpackaged 21 d postmortem. The cut surface was removed (faced) and two 2.54-cm-thick steaks were cut and placed cut surface up on a tray diaper in either a 22S or 4S foam trays (Cryovac Sealed Air). Steaks were overwrapped with a polyvinyl chloride (PVC) oxygen permeable film (MAPAC-M film, 23,250 mL per m2/24 h, 72 gauge, Resinite Packaging Films, Borden Inc., North Andover, MA) and assigned to 0 or 3 d of retail display. All PVC steaks were placed into simulated retail display upon completion of fabrication and packaging on d 21.
pH
Muscle pH was measured on d 0 and 3 for PVC-packaged steaks and on d 0, 3, and 5 or d 0 and 9 for HO-MAP- or CO-MAP-packaged steaks, respectively, by inserting the tip of a previously calibrated probe (MPI pH probe, glass electrode, Meat Probes Inc., Topeka, KS) twice into the deep SM (DSM) and 3 times into the superficial SM (SSM). Measurements within muscle area (DSM or SSM) were averaged for the final pH.
Retail Display
Under continuous fluorescent lighting (2,153 lx, 3,000°K, color rendering index = 85, bulb model F32T8/ADV830/Alto, Philips, Bloomfield, NJ), all steaks were displayed at 2 ± 1.3°C in open-topped cases with 12-h defrost cycles (unit model DMF8, Tyler Refrigeration Corp., Niles, MI). Display cases were completely filled with one layer of packages that were rotated daily to minimize effects of package location in the case. Case temperature was monitored during display by using temperature loggers (RD-TEMP-XT, Omega Engineering Inc., Stamford, CT).
Visual Color
Trained color panelists (n = 6 to 8) who passed the Farnsworth-Munsell 100-hue test (Macbeth, Newsburgh, NY) evaluated each steak region (DSM and SSM) while packaged and in the display case for initial color on d 0, display color, and discoloration (AMSA, 1991). Display color and discoloration scores were recorded on d 1, 2, and 3 for steaks packaged in PVC, whereas steaks packaged in HO-MAP and CO-MAP were evaluated daily for 5 and 9 d, respectively. The initial color scale used across all packaging treatments was 1 = purplish pink or red or reddish tan of vacuum packages; 2 = bleached, pale red; 3 = slightly cherry red; 4 = moderately light cherry red; 5 = cherry red; 6 = slightly dark red; 7 = moderately dark red; 8 = dark red; and 9 = very dark red. Panelists scored each region to half-point increments.
The display color scale for evaluating color stability, also rated to the nearest half-point, was 1 = very bright red or very bright pinkish red; 2 = bright red or bright pinkish red; 3 = dull red or dull pinkish red; 4 = slightly dark red or slightly dark pinkish red; 5 = moderately dark red or moderately dark pinkish red; 6 = dark red to dark reddish tan or dark pinkish red to dark pinkish tan; 7 = tannish red or tannish pink; and 8 = tan to brown. A score of 5.5 was considered by the panelist as borderline acceptable.
The discoloration scale indicated, to the nearest whole point, the percentage of surface discoloration due to metmyoglobin formation. The scale used was 1 = none (0%); 2 = slight discoloration (1 to 19%); 3 = small discoloration (20 to 39%); 4 = modest discoloration (40 to 59%); 5 = moderate discoloration (60 to 79%); 6 = extensive discoloration (80 to 99%); and 7 = total discoloration (100%). Daily scores from each panelist for initial color, display color, and discoloration were averaged before statistical analysis.
Instrumental Color
Steaks not used for visual display color also were displayed and were evaluated (2 to 3°C) on the displayed surface for instrumental color on d 0 (after packaging) and 3 (packaged, end of display) for steaks overwrapped with PVC; on 0 (before packaging), 3 (unpackaged, mid-display), and 5 d (unpackaged, end of display) for HO-MAP, and on 0 (before packaging) and 9 d (unpackaged, end of display) for CO-MAP by using a calibrated HunterLab MiniScan XE Plus Spectrophotometer (45/0 LAV, 2.54-cm diameter aperture, 10° standard observer, Illuminant A, Hunter Associates Laboratory Inc., Reston, VA). The (International Commission on Illumination) L* (lightness), a* (redness), and b* (yellowness) values were recorded and used to calculate hue angle (tan–1 b*/a*) and saturation index (a*2 + b*2)1/2. Three scans were averaged for the SSM, 2 for the DSM.
Odor and Gas Concentrations
Carbon dioxide, oxygen, and carbon monoxide head space gas concentrations in MAP were determined by using a Tri-Gas MAP Headspace Analyzer (model 900121, sampling rate = 5 mL/sec, resolution = CO: 0.001%, CO2: 0.01%, O2: 0.01%, Bridge Analyzers Inc., Alameda, CA) at 0, 3, and 5 d of visual display for HO-MAP or 0 and 9 d for CO-MAP.
Odor scores were subjectively measured on d 9 CO-MAP steaks immediately after the packages were opened by 2 individuals familiar with typical off-odors of meat products. The following scale was used: 1 = no off odor, 2 = slight off odor, 3 = small off odor, 4 = moderate off odor, and 5 = extreme off odor; values greater than 2 were considered unacceptable.
Design and Statistical Analysis
The experimental design was a split plot; the whole plot experimental unit was a Holstein steer to which feeding treatments were randomly assigned. The subplot experimental units were steaks to which day of retail display was randomly assigned. Visual and instrumental color traits were repeat measures taken on each muscle area (DSM and SSM). All packaging treatments were analyzed separately. Through use of the MIXED procedure (SAS Institute Inc., Cary, NC), subsets of least squares means were subjected to pair-wise comparisons by using Fisher’s LSD procedure at the P < 0.05 level of significance, depending on which main effects and interactions were significant. Diet, muscle area, and day were the main effects tested. Interactions tested were diet x display day, diet x muscle area, muscle area x day, and diet x day x muscle area. When appropriate to simplify mean comparisons, we compared means for 1) the 2 display times for each muscle area x diet combination, 2) the 2 muscle areas for each diet x display time combination, and 3) the 4 diets for each display time x muscle area combination.
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RESULTS AND DISCUSSION |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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pH.
A significant difference in pH occurred for the main effect of diet (Table 1). Steaks from calf-fed Holsteins fed ZH40 had greater (P < 0.05) pH values (5.48) than steaks from ZH20 and ZH30 (5.44 and 5.43, respectively) dietary treatments. Our pH values were comparable with those of Moloney et al. (1994), who reported pH values between 5.47 and 5.51 for Friesian steers fed various levels of the β-agonist L-644,969. However, no differences (P > 0.05) occurred in pH values of loin (5.41) and sirloin (5.43) from Holstein and beef steers (Faustman and Cassens, 1991). In our study, no differences (P > 0.05) in pH were noted for the DSM (5.45) and SSM (5.46) portions.
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reported that longissimus lumborum and gluteus medius steaks from crossbred beef steers fed ZH for 50 d tended to have less metmyoglobin formation than ZH0- or ZH30-supplemented cattle. By the end of display, all steaks reached modest (40 to 59%) to moderate (60 to 79%) discoloration levels. Faustman and Cassens (1991) found a greater (P < 0.05) percentage of metmyoglobin formation for Holstein LM steaks than for crossbred beef steer steaks daily through 6 d of display.
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also reported no difference (P > 0.05) in lightness (L* values) of longissimus lumborum steaks from bulls fed ZH or no β-agonist. Moloney et al. (1994) reported greater (P < 0.05) hue angle values after display 2 d for LM steaks from Friesian steers fed L-644,969.
Steaks from all dietary regimens were a more vivid red color (P < 0.05, greater a* values and saturation indices) on display d 0 than d 3 (Table 1). No differences (P > 0.05) in redness or saturation index values due to ZH feeding duration were noted for steaks on display d 0 or 3. In contrast, Strydom et al. (2007) noted greater (P < 0.05) chroma (saturation index) values for LM steaks from ZH-supplemented cattle compared with control steaks.
On display d 0, steaks from the ZH40 group were more yellow (P < 0.05, greater b* value) than steaks from ZH0- or ZH20-fed Holsteins. There were no differences (P > 0.05) in b* values for dietary treatment by display d 3. Steaks from all diet regimens were less yellow (P < 0.05, lesser b* values) on display d 3 than at d 0.
HO-MAP
pH and Percentage Pump.
No differences (P > 0.05) due to ZH feeding duration occurred for pH values, which ranged from 5.76 to 5.79 (Table 3). The diet x muscle area interaction was not significant; however, pH values for the DSM were numerically greater (P > 0.05) than for the SSM across all diet treatments (Table 4). Our pH values for Holstein steaks were greater than those reported by Moloney et al. (1994) and Dunne et al. (2004), probably because of phosphate in the enhancement solution (Seyfert et al., 2005). The percentage pumps in our study averaged 9.9% and were not different across dietary treatments.
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Initial Color. Steaks across all diet regimens were moderately light cherry red on d 0 of display (Table 3). The DSM of steaks for all diet treatments had decreased (P > 0.05) initial color scores compared with the SSM (Table 4).
Display Color. No differences (P > 0.05) occurred in display color scores for ZH treatment until the end of display (Figure 3). On d 5, steaks from the ZH20 feeding duration were darker (P < 0.05) than steaks from other feeding durations. Steaks from all dietary regimens were an unacceptable tannish-red color at the end of display. Although no interaction between diet regimen and muscle area occurred, the DSM of steaks from all diets had decreased average (P > 0.05) display color scores (lighter pale red) than the SSM (Table 4).
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). However, that study did not examine effects of various feeding durations. Behrends et al. (2003), John et al. (2005), and Seyfert et al. (2005) all reported decreasing a* values for MAP beef steaks during simulated display. In our study, diet x muscle area interactions were significant for a*, b*, and saturation indices (Table 4). The SSM of control steaks was redder (P < 0.05) than the DSM; steaks from the ZH20, ZH30, and ZH40 treatments were not different (P > 0.05) in redness of the DSM and SSM. Control steaks had a redder (P < 0.05) SSM portion than the SSM of steaks from ZH diet regimens. No differences (P > 0.05) in DSM a* values occurred across ZH feeding durations. The DSM of Holstein steaks from ZH treatments was more yellow (P < 0.05) than the SSM. No differences (P > 0.05) were noted in DSM b* values across diet treatments; however, the SSM of control steaks was more yellow (P < 0.05) than the SSM of ZH20, ZH30, or ZH40 steaks.
Saturation indices were not different (P > 0.05) for the DSM and SSM of control and ZH20 steaks, but the DSM was more vivid (P < 0.05) than the SSM of both ZH30 and ZH40 steaks. The DSM portion of steaks from the control and ZH40 was more vivid (P < 0.05) than the DSM of ZH20 steaks. The SSM of steaks from control cattle was more vivid (P < 0.05) than the SSM of steaks from other ZH treatments. Moloney et al. (1994) found a significant linear effect for saturation indices of LM steaks from Friesian steers fed the β-agonist L-644,969 on display d 2, 3, and 6, whereas steaks from dairy cattle fed no β-agonist were more vivid (P < 0.05, greater saturation indices) than steaks from cattle supplemented with L-644,969. Overall, the instrumental color data from the present study agree with display scores of the panelists.
CO-MAP
pH.
No differences (P > 0.05) in pH values of Holstein steaks occurred for diet regimen (Table 5) or the interaction of diet x muscle area (Table 6). Moloney et al. (1994) reported no differences in ultimate pH values (5.47 and 5.51) of the SM muscle from Friesian steers fed different doses of L-644,969. Our greater pH values may be due to the use of an alkaline phosphate in the enhancement solution (Seyfert et al., 2005).
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Odor Scores. Off-odor scores were not different (P > 0.05) across diet regimens (Table 5). All steaks had an acceptable odor after display d 9.
Initial Color.
Steaks from all diet regimens could be characterized as typical, moderately light cherry red initial color (Table 5). The DSM had numerically less (P > 0.05) initial color scores than the SSM for all diet treatments (Table 6). The tendency for a lighter red color in the DSM is likely due to differences in carcass chilling (Sammel et al., 2002) and not ZH feeding duration.
Display Color. Table 7 contains the display color means for the diet x muscle area x display day interaction. For the DSM, no differences (P > 0.05) occurred in display color scores for ZH feeding duration on display d 1 to 5, d 7, and d 9. At the beginning of display, the DSM portion of ZH20 and ZH40 steaks was lighter red (P < 0.05, decreased display color scores) than the DSM of control steaks. The DSM of ZH20 and ZH30 steaks (d 6) and the ZH20 DSM (d 8) were lighter red (P < 0.05) than the DSM of control steaks.
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Display color scores for the DSM across all diet regimens and ZH20, ZH30, and ZH40 SSM increased (P < 0.05) from display d 0 to 3 before decreasing (P < 0.05) on d 4 and increasing (P < 0.05) again to the end of display (d 9). The SSM portion from control Holsteins increased (P < 0.05) from display d 0 to 9.
The DSM portion was acceptable for the entire display period, whereas the SSM area from all feeding durations was borderline unacceptable by display d 9. For crossbred beef steaks packaged in CO-MAP, the DSM was also lighter (P < 0.05) than the SSM on display d 0 to 4. Improved color stability of the DSM may be due to the inclusion of CO in CO-MAP that increases shelf life of that muscle portion (Hunt et al., 2004).
Discoloration.
Discoloration scores were different (P < 0.05) by diet regimen and display day (Figure 5). Steaks from all dietary regimens were more discolored (P < 0.05) on d 2 and 3 from the beginning of display before decreasing (P < 0.05) discoloration scores occurred on d 4. Steaks from the ZH0, ZH20, and ZH30 diet groups were slightly more discolored (P < 0.05) by the end of display than on d 4. Discoloration scores for ZH40 were not different (P > 0.05) on d 4 through d 9 of display. Steaks from all feeding durations were less than 20% discolored during the entire 9 d of display; thus, the slight increase in metmyoglobin would not likely be of practical importance. Inclusion of CO in the gas blend possibly served to inhibit myoglobin oxidation during longer shelf life periods (Cornforth and Hunt, 2008).
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Instrumental Color. No significant interaction (Tables 5 and 6) or diet main effect differences occurred for L* or hue angle values. Steaks were darker (P < 0.05) on d 9 than on d 0 of display (Table 5).
The DSM of steaks from ZH0, ZH30, and ZH40 feeding durations were a more (P < 0.05) vivid red color than the SSM portion (Table 6). No differences (P > 0.05) in a* values or saturation indices occurred between the DSM and SSM of the ZH20 treatment. Within the SSM, ZH30 and ZH40 steaks were a less (P < 0.05) vivid red than the SSM of control and ZH20 steaks. The DSM of control steaks was redder (P < 0.05) than the DSM of ZH20 and ZH40 treatments. The DSM of steaks from all feeding regimens was more yellow (P < 0.05) than the SSM, with the DSM of control steaks being more yellow (P < 0.05) than its ZH20 counterpart. For the SSM, control steaks had greater (P < 0.05) b* values than ZH30 steaks. Saturation indices were also greater (P < 0.05) for the DSM portion of control steaks compared with the same muscle area from the ZH20 and ZH30 feeding groups. These instrumental values are indicative of a bright red color and thus support panelist visual scores for display color and discoloration.
In conclusion, our data clearly indicate that steaks from Holstein steers fed ZH20 or ZH30 will have a normal pH and equal to or a slight advantage in display color stability when packaged in a traditional PVC overwrap system compared with steaks from nonsupplemented cattle. Feeding ZH40 causes minor detrimental effects on PVC display color and discoloration scores. Feeding duration of ZH produced few significant positive or negative differences for instrumental color traits of SM steaks for either MAP system. All ZH feeding durations for steaks packaged in CO-MAP resulted in improved display color compared with control steaks and could be the packaging system of choice for color stability for beef from ZH-fed animals.
More notable than ZH diet differences was the variation in color development and stability of the DSM and SSM muscle areas. The DSM had more desirable initial and display color scores at the beginning of simulated display; however, it became dark and discolored more rapidly after only 1 to 2 display days. Compared with traditional packaging methods, HO-MAP and CO-MAP improved display and instrumental color differences between the DSM and SSM. Both muscle portions of Holstein steaks were the brightest red and least discolored at the end of display in CO-MAP. Use of CO-MAP for SM steaks will minimize differences in color between the DSM and SSM.
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Footnotes |
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2 The authors acknowledge Tyson Foods (Springdale, AR) for their support of this research.
3 Corresponding author: hhunt{at}ksu.edu
Received for publication January 28, 2009. Accepted for publication July 15, 2009.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMATERIALS AND METHODSRESULTS AND DISCUSSIONLITERATURE CITED |
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| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
