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ANIMAL PRODUCTS |
Animal Science Department, Iowa State University, Ames 50011
Abstract
The objective of this study was to examine the effect of early postmortem protein oxidation on the color and tenderness of beef steaks. To obtain a range of oxidation levels, the longissimus lumborum muscles (LM) from both strip loins of 20 steers fed either a finishing diet with vitamin E (1,000 IU per steer daily, minimum of 126 d [VITE]; n = 10 steers) or fed the same finishing diet without vitamin E (CON; n = 10 steers) were used. Within 24 h after slaughter, the LM muscle from each carcass was cut into 2.54-cm-thick steaks and individually vacuum packaged. Steaks from each steer were assigned to a nonirradiated group or an irradiated group. Steaks were irradiated within 26 h postmortem, and were aged at 4°C for 0, 1, 3, 7, and 14 d after irradiation. Steaks from each diet/irradiation/aging time treatment were used to determine color, shear force, and degree of protein oxidation (carbonyl content). Steaks from steers fed the VITE diet had higher (P < 0.01) 
-tocopherol contents than steaks from steers fed the CON diet. Immediately following irradiation, steaks that had been irradiated had lower (P < 0.05) L* values regardless of diet. Irradiated steaks, regardless of diet, had lower a* (P < 0.05) and b* (P < 0.01) values than nonirradiated steaks at all aging times. Carbonyl concentration was higher (P < 0.05) in proteins from irradiated steaks compared to nonirradiated steaks at 0, 1, 3, and 7 d postirradiation. Immunoblot analysis showed that vitamin E supplementation decreased the number and extent of oxidized sarcoplasmic proteins. Protein carbonyl content was positively correlated with Warner-Bratzler shear force values. These results indicate that increased oxidation of muscle proteins early postmortem could have negative effects on fresh meat color and tenderness.
Key Words: Beef • Irradiation • Oxidation • Protein • Quality • Tenderness
Introduction
Metabolic and other processes occurring in muscle tissue give rise to formation of reactive oxygen species and other oxidative compounds. These oxidative species include hydroxyl radicals, peroxyl radicals, superoxide anions, hydrogen peroxide, and nitric oxide (Butterfield et al., 1998
; Burton and Traber, 1990). Reactive oxygen species can interact with both lipids and proteins. In postmortem muscle tissue, when proteins are targeted by reactive oxygen species, the result of this interaction is often carbonyl formation and decreased sulfhydryl content of the protein (Hoffman and Hamm, 1978; Martinaud et al., 1997; Xiong, 2000). These modifications can significantly alter the properties of meat proteins and may ultimately influence the quality of meat products (Xiong, 2000).
Several processes influence oxidation of fresh meat. High levels of vitamin E in muscle results in meat with decreased rate of lipid oxidation, delayed metmyoglobin formation (Arnold et al., 1992, 1993; Liu et al., 1996), and increased rate of tenderization (Harris et al., 2001). Irradiation, while a powerful food safety tool, has been implicated in accelerating oxidation and producing free radicals, thereby changing the oxidative potential of meat products (Jo and Ahn, 2000; Nam and Ahn, 2003). Irradiation can influence the color of fresh meat (Nanke et al., 1998), yet reports of its effects on tenderness have been mixed (Heath et al., 1990; Yoon, 2003). However, few studies have been performed on early postmortem product. A recent report has shown that low-dose irradiation of chicken breasts within 24 h of slaughter resulted in product with significantly higher shear force values than nonirradiated controls (Yoon, 2003).
Currently, little is known about the effects of protein oxidation during the first 24 to 48 h after exsanguination on beef quality. Therefore, the objective of this study was to examine the impact of early postmortem protein oxidation on the color and tenderness of beef steaks.
Materials and Methods
Animals
Twenty beef steers of similar age and genetics were used in this study. To obtain a range of oxidative conditions, 10 steers were group fed a normal finishing diet (CON), whereas another 10 steers were group fed the same finishing diet that included 1,000 IU per head per day of vitamin E (VITE; Roche Vitamins, Inc., Parsippany, NJ) for at least the last 126 d before slaughter. The CON diet contained the following ingredients (DM basis): dry rolled corn (59%), chopped grass hay (8%), cane molasses (0.40%), wet corn gluten feed (30%), urea (0.15%), ground limestone (1.40%), trace mineral premix (0.024%; premix contained 13.2% Ca++, 0.10% Co, 1.5% Cu++, 10.0% Fe++, 0.44% Fe+++, 0.2% I, 8% Mn++, 5.0% S, and 12.0% Zn), salt (NaCl; 0.30%), Rumensin premix (0.0195%; Rumensin premix provided 34.4 mg of monensin sodium/kg feed on a DM basis), and vitamin A premix (0.08% on a dry matter basis; vitamin A premix provided 3,084 IU of vitamin A activity per kilogram of feed on a DM basis). Steers were approximately 9 mo old and weighed an average of 396 kg at the start of the feeding trial. Steers were weighed at 28-d intervals during the feeding trial to calculate ADG. Steers were slaughtered at an average weight of 634 kg using approved humane procedures at Iowa State University Meat Laboratory. At each slaughter time, four steers (two from each dietary treatment), were slaughtered, and the carcasses were conventionally chilled at -5°C for 24 h.
At 2, 4, 6, 8, and 24 h postmortem, temperature was measured using an Electrotherm digital probe (model No. TM99A; Cooper Instrument Corp, Middlefield, CT), and pH measurements were taken using a glass body insertion electrode (pH-Star S, SFK Technologies, Herlev, Denmark). Measurements were taken in the longissimus thoracis at the 12th rib on both sides of the carcass.
Collection of Steaks
Strip loins were removed from both sides of each carcass between 21 to 24 h postexsanguination, and 2.54-cm-thick longissimus lumborum (LM) steaks were cut from each strip loin and immediately vacuum packaged. All LM steaks (10 steaks/strip loin) from one loin from each carcass were assigned as a nonirradiated control, whereas all LM steaks from opposite-side strip loin of each carcass were assigned to be irradiated. Two adjacent steaks from each strip loin were assigned to an aging period of 0, 1, 3, 7, or 14 d postirradiation (1, 2, 4, 8, or 15 d postmortem) at 4°C. One steak from each aging period was designated for color, carbonyl, and sulfhydryl analysis, and one steak was designated for Warner-Bratzler shear force determination. In order to determine whether dietary treatment increased the vitamin E content of the steaks prior to irradiation, an additional steak was taken from each carcass at the posterior end of the strip loin, vacuum-packaged, frozen at -20°C, and sent to the University of Wisconsin Soil and Plant Analysis Laboratory (Madison, WI) for analysis of -tocopherol content. -Tocopherol content was determined according to the procedures of Liu et al. (1996).
Irradiation of Steaks
Irradiation was conducted at the Linear Accelerator Facility (LAF) in the Iowa State University Meat Laboratory. At 24 to 26 h postexsanguination, vacuum-packaged steaks from one side of each animal were irradiated (average dose = 6.4 kGy). Steaks from the opposite-side strip loins were not irradiated but were held at the same temperature (approximately 20°C) for the same length of time (approximately 10 min) as were the irradiated steaks. Samples were irradiated by a CIRCE IIIR Electron Beam irradiator (Thomson-CSF Linac, St. Aubin, France) with an energy level of 10 MeV, a power level of 10 kW, and a conveyor speed of 0.223 m/min. After irradiation, all steaks (irradiated and nonirradiated) were held at 4°C for 0, 1, 3, 7, or 14 d postirradiation (1, 2, 4, 8, and 15 d postmortem). At the completion of each aging period, steaks designated for Warner-Bratzler shear force were frozen until subsequent analysis. Steaks designated for laboratory analysis were used immediately for color measurements and biochemical analysis.
Warner-Bratzler Shear Force
All procedures were done in accordance to AMSA (1995) guidelines. Frozen 2.54-cm-thick steaks were thawed at 2°C and used for Warner-Bratzler shear force (WBSF) determination. Steaks were broiled in an electric broiler (General Electric, Model 6850; Chicago Heights, IL.) 15 cm away from the heat source. Steaks were broiled to an internal temperature of 30°C and then turned and broiled to a final temperature of 70°C. Temperature was monitored using an Electrotherm digital probe (model No. TM99A; Cooper Instrument Corp.) Steaks were covered with Saran wrap and allowed to chill overnight at 4°C. Steaks were equilibrated to room temperature (approximately 1 to 2 h), and six 1-cm-diameter cores were removed parallel to the muscle fibers. Each core was sheared perpendicular to the fiber direction using a TA XT2 Texture Analyzer with a 5-kg load cell (Texture Technologies Corp., Scarsdale, NY). All tests were performed using the Warner-Bratzler probe and guillotine set (TA-7B USDA, Texture Technologies, Corp.). The probe was lowered 30 mm from the point of resistance, and the penetration speed was 3.3 mm/s. All data were collected using Texture Expert software Version 1.22 (Texture Technologies, Corp.).
Color Measurements
Color was measured after each aging period (0, 1, 3, 7, and 14 d after irradiation). Fresh steaks were removed from the vacuum packages and allowed to bloom for 15 min at 4°C. A Hunter Lab Mini Scan XE Plus (Hunter Associates Laboratories, Inc., Reston, VA) was used for measurement of L*, a*, and b* values. Illuminate D65 was used, and the instrument had a 10° observer and a port diameter of 25 mm. Three readings per steak were taken and averaged for statistical analysis.
Sarcoplasmic Protein Extraction
Sarcoplasmic proteins were extracted according to Shackelford et al. (1994) with modifications. At 0, 1, 3, 7, and 14 d postirradiation, 10 g of finely diced fresh meat were homogenized in 3 vol of ice-cold extraction buffer (10 mM EDTA, 2 µM E-64, 100 mg/L trypsin inhibitor, and 2 mM phenylmethylsulfonylfluoride [PMSF], 100 mM Tris•HCl, pH 8.3) using a polytron PT 3100 (Kinmetaica AG, Littau, Switzerland) set at 22,000 rpm. Samples were centrifuged (27,000 x g) for 30 min at 4°C. The supernatants were filtered through cheesecloth and sample volume was recorded. Protein concentration of each sample was determined using a Bradford assay (BioRad Protein Assay Kit; BioRad Laboratories, Hercules, CA; Bradford, 1976). The pellet fraction was used immediately for purification of myofibrils.
Myofibril Purification
Four grams of pellet from each sarcoplasmic protein extraction were weighed and homogenized in 10 vol of standard salt solution (100 mM KCl, 2 mM MgCl2, 1 mM EGTA, 1 mM NaN3, 20 mM K2HPO4, pH 7.0). Myofibrils were further purified by differential centrifugation (Huff-Lonergan et al., 1995), and protein concentration was determined using the Biuret method as modified by Robson et al. (1968).
Measurement of Protein Oxidation
Carbonyl Assay.
Samples from each fraction (sarcoplasmic and myofibrillar) were diluted to 6 mg/mL using 1 mM EDTA, 50 mM NaHPO4 (pH 7.4). Carbonyl content of both the sarcoplasmic proteins and highly purified myofibrils was assayed by reactivity with 2,4-dinitrophenylhydrazine (DNPH; Reznick and Packer, 1994). The carbonyl content was expressed as nanomoles of DNPH fixed per milligram of protein using an absorption coefficient of 21,000 M-1cm-1.
Sarcoplasmic Protein Gel Sample Preparation for Immunodetection of Carbonyls.
Both DNPH-derivatized and their control samples from the carbonyl assay described previously were vortexed, and duplicate 200-µL aliquots were removed and placed in microcentrifuge tubes for sample preparation. Samples were concentrated by addition of an equal volume of ice-cold acetone, vortexed, and centrifuged at 21,000 x g for 10 min at 4°C. Supernatants were discarded, and the pellet was dissolved in 50 µL of 8 M urea and 40 mM Tris•HCl (pH 6.8). Samples were vortexed and heated at 37°C for 10 min to ensure solubilization. Protein concentrations of the samples were determined using a Bradford protein assay kit (Bio-Rad Laboratories) as previously described. Samples were mixed with 25% (vol/vol) gel-loading buffer (20% [vol/vol] glycerol, 0.2% [wt/vol] bromophenol blue, 0.75% [vol/vol], 148 mM Tris•HCl, pH 6.8.) Samples were then frozen at -80°C until SDS-PAGE and immunoblotting.
Myofibrillar Protein Gel Sample Preparation for Immunodetection of Carbonyls.
Control myofibrils and DNPH-derivatized myofibrils were diluted with an equal volume of 12% sodium dodecyl sulfate (SDS) to a final concentration of 6% SDS. A Lowry assay (DC Protein Assay Kit, BioRad Laboratories) was used to determine protein concentration (Lowry et al., 1951). Carbonyl groups were derivatized for immunodetection using the Oxyblot Protein Oxidation Kit (Intergen, Purchase, NY) according to kit instructions. After derivatization was complete, samples were mixed with gel-loading buffer (0.002% bromophenol blue [wt/vol], 2% SDS [wt/vol], 180 mM 2-mercaptoethanol, 10% glycerol [vol/vol], and 62.5 mM Tris•HCl, pH 6.8). Samples were stored at -80°C until SDS-PAGE and immunoblotting.
Immunodetection of Oxidized Proteins.
Derivatized and control myofibril and sarcoplasmic samples were run on 10 cm (wide) x 12 cm (tall) x 1.5 mm (thick) 12% discontinuous polyacrylamide gels (Huff-Lonergan et al., 1996). After electrophoresis, samples were transferred onto Poly Screen polyvinylidene difluoride (PVDF) transfer membrane (NEN Life Science Products, Inc., Boston, MA). Transfer was done for 90 min at a constant 90 V in a TE-22 transfer tank (Amersham Biosciences, Piscataway, NJ) at refrigerated temperatures in 25 mM Tris, 192 mM glycine, and 15% methanol (vol/vol). Membranes were then blocked in PBS-Tween (80 mM disodium hydrogen orthophosphate, anhydrous, 20 mM sodium dihydrogen orthophosphate, 100 mM sodium chloride, and 0.1% polyoxyethylene sorbitan monolaurate [Tween-20]) containing 1% BSA (Pierce, Rockford, IL). After blocking, membranes were placed in primary antibody (polyclonal rabbit anti-DNP antibody S7150-4 Oxyblot Protein Oxidation Kit; Intergen) diluted 1:150 in PBS-Tween, 1% BSA (vol/vol), and incubated overnight at 4°C. Membranes were then washed three times (10 min/wash) using PBS-Tween at room temperature before incubation with the secondary antibody diluted 1:300 in PBS-Tween 1% BSA (vol/vol) (goat anti-rabbit HRP; catalog No. S7150-5; Oxyblot Protein Oxidation Kit; Intergen) for 2 h at room temperature. Membranes were washed three times (10 min/wash), using PBS-Tween, and the detection of bound secondary antibodies was done using ECLPlus kit (Amersham Pharmacia Biotech) according to the manufacturer’s instructions. Chemiluminescence was detected using a 16-bit charge-coupled device camera (FluorChem8800; Alpha Innotech Corporation, San Leandro, CA) and FluorChem IS-800 software (Alpha Innotech Corporation).
Statistical Analysis
Data were analyzed using PROC GLM (SAS Version 8.01; SAS Inst, Inc., Cary NC) as a split-plot design with steer as the experimental unit. The whole plot was vitamin E treatment (0 vs. 1,000 IU of vitamin E), and the split plot was irradiation treatment (0 or 6.4 kGy). Specific comparisons were made within aging period. Each slaughter date served as a replication. Replication x vitamin E was the whole-plot error term and the replication x vitamin E x irradiation interaction was the split-plot error term. Pearson correlation coefficients were calculated to determine the linear relationship between carbonyl content of the sarcoplasmic or myofibrillar proteins and WBSF values. Statistical significance (P < 0.05) was determined using Fisher’s "r to z" transformation.
Results and Discussion
Carcass Data and Vitamin E Concentrations
There were no differences (P > 0.05) in ADG between the steers fed the control diet or those fed the diet containing 1,000 IU of vitamin E per steer daily. The ADG for the steers in the study was 1.78 kg/d on feed (data not shown). All of the carcasses were of A-maturity and supranutritional vitamin E supplementation did not affect (P > 0.05) any carcass characteristics measured (Table 1). Steers fed the diet containing a supranutritional level of vitamin E had higher (P < 0.01) amounts of -tocopherol in the LM (Table 1). These results are similar to those previously reported by Arnold et al. (1992), Liu et al. (1996), and Harris et al. (2001).
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). Temperature of the LM at 2 and 4 h postmortem was higher (P < 0.05) in LM from steers fed the vitamin E diet. However, the LM temperature did not differ (P > 0.05) between dietary treatments at later times (6, 8, or 24 h) postmortem (Table 1).
Color Analysis
Immediately after irradiation (d 0), instrumental color analysis showed that, within a diet group, irradiation resulted in lower (P < 0.05) L* values (Table 2). Nanke et al. (1998) reported similar values on vacuum-packaged beef strip loin steaks that were irradiated at specified doses. In the current study, saturation index and hue angle were calculated to determine the amount of discoloration incurred in the product (Little, 1975). Diet had no effect (P > 0.05) on saturation index or hue angle; however, saturation index was lower (P < 0.05) in the irradiated samples (CON/irradiated = 17.2, CON/nonirradiated = 26.0, VITE/irradiated = 16.5, VITE/ nonirradiated = 25.9; data not shown). Irradiated beef had greater (P < 0.05) hue angle irrespective of diet (CON/irradiated = 61.3, CON/ nonirradiated = 50.8, VITE/irradiated = 62.9, VITE/ nonirradiated = 50.9; data not shown). These results indicate that, shortly after processing, irradiation resulted in less intense color and greater discoloration of the steak surface regardless of diet.
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). However, after 14 d of storage, irradiated steaks from animals fed the control diet (CON/irradiated) were darker (lower L values; P < 0.05) than their nonirradiated counterparts (CON/nonirradiated). In addition, when comparing across diets, the irradiated steaks from steers fed the control diet (CON/irradiated) were also darker (lower L* values, P < 0.05) than the other treatment groups.
At all aging times, nonirradiated steaks had higher (P < 0.05) a* values (indicating a redder color) than irradiated steaks, which is consistent with the results of Nanke et al. (1998). Further analysis at 1, 3, and 14 d postirradiation revealed that irradiated steaks from steers in the vitamin E supplementation group were less red in color (P < 0.05) compared to irradiated steaks not supplemented with vitamin E (Table 2).
Analysis of b* values revealed irradiated steaks had lower (P < 0.01) b* values at all days postirradiation studied (Table 2). However, the addition of vitamin E to the finishing diet had no (P > 0.01) effect on b*. These results indicate that, after irradiation, the surfaces of steaks appeared less yellow in color compared to nonirradiated steaks. These results conflict with those reported by Nanke et al. (1998), who found no differences in b* values at irradiation doses up to 7.5 kGy.
Collectively, these results indicate that irradiation has an immediate negative influence on the color of fresh, vacuum-packaged beef steaks. It has been hypothesized that the primary reason for the color change noted in irradiated beef is due to oxidation of myoglobin. Incorporation of vitamin E into the product by including it in the diet of steers prior to slaughter does not provide sufficient protection against discoloration when the product is irradiated at moderate doses.
Protein Solubility and Oxidation
The amount of soluble protein that can be extracted from the meat can give an indication of the relative level of denaturation that may have occurred. In this study, solubility of the sarcoplasmic proteins (on a milligram of protein extracted per gram of tissue) was evaluated 0, 3, and 14 d after irradiation. Whereas there was no difference (P > 0.05) due to diet (VITE vs. CON), there was a difference (P < 0.05) due to irradiation (Figure 1). No difference (P > 0.05) was found when protein extractability was measured the day on which samples were irradiated (d 0); however, after 3 d of storage, the irradiated samples had less (P < 0.05) extractable protein. After 14 d of storage, the irradiated samples still tended to have less (P = 0.07) extractable protein than their nonirradiated counterparts (Figure 1), indicating that irradiation may influence the solubility of the sarcoplasmic protein.
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). Total carbonyl content was higher (P < 0.05) in myofibrillar proteins isolated from irradiated steaks than in myofibrillar proteins isolated from nonirradiated steaks at all time points (0, 1, 3, 7, and 14 d postirradiation; Figure 3). However, diet had no (P > 0.05) effect on total carbonyl content of either sarcoplasmic or myofibrillar protein.
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). Oxidative reactions involving the side chains of amino acids can lead to the formation of carbonyl groups. This conversion may ultimately result in a loss of catalytic activity and increased susceptibility to protein degradation (Stadtman, 1990) or protein aggregation and loss of solubility. Formation of carbonyls in meat can be caused by several oxidative treatments and has even been shown to occur in beef myofibrils during postmortem aging (Martinaud et al., 1997).
Western Blotting of Oxidized Sarcoplasmic Proteins
Highly sensitive Western blotting of derivatized sarcoplasmic samples revealed the extent to which specific sarcoplasmic proteins were oxidized by the irradiation treatment and/or protected by supplementation with the antioxidant (vitamin E; Figure 4). Western blots showed that irradiation increased the number of oxidized proteins compared to steaks that were not irradiated, as indicated by the appearance of more bands (immunologically detectable DNP residues) in irradiated steaks (Figure 4). Differences due to diet were detected in sarcoplasmic proteins from irradiated steaks. Steaks from steers supplemented with vitamin E and irradiated at 24 h postmortem contained fewer oxidized sarcoplasmic proteins compared to steaks from steers not supplemented with vitamin E and irradiated. However, the differences in nonirradiated steaks were not as striking. Steaks that were not irradiated and were from steers supplemented with vitamin E had only slightly less total oxidized proteins than nonirradiated unsupplemented steaks (Figure 4). From these results, it is apparent that vitamin E supplementation may help to protect some sarcoplasmic proteins from becoming oxidized when the tissue is exposed to highly oxidizing conditions (like irradiation) early postmortem.
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). Unlike the sarcoplasmic proteins, however, there were no observable differences in carbonyl content between diets in the myofibrillar samples. This might be partially explained by the fact that vitamin E is lipid soluble and, therefore, can be concentrated in lipid bilayers or membranes (Burton and Traber, 1990). In general, it appears that vitamin E has a greater impact on sarcoplasmic proteins than myofibrillar proteins in this study.
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and 4). It is important to note that the carbonyl content of both the sarcoplasmic fraction and the highly purified myofibrils measured 1 d after irradiation (2 d postmortem) were correlated (P < 0.05) with the shear force after 14 d of aging (r = 0.424 and 0.530 for sarcoplasmic protein and myofibrillar protein, respectively). Thus, increased early postmortem protein oxidation (as measured by carbonyl content) in both the sarcoplasmic and myofibrillar fractions of the tissue is associated with increased shear force values at later times postmortem. It is possible that aggregation and denaturation of myofibrillar proteins, and/or inactivation of some proteolytic enzymes compromised the ability of beef to tenderize during aging.
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). Extensive oxidation of proteins may lead to denaturation and aggregation (Decker et al., 1993). Oxidation of one of the most abundant myofibrillar proteins, myosin, can cause the formation of large, insoluble aggregates (Xiong, 2000) that may be more resistant to degradation. In addition, the formation of carbonyl groups in some enzymes can result in a lack of catalytic activity (Stadtman, 1990). For example, histidine residues are among the many amino acids that are susceptible to carbonyl formation. Some proteases depend on a histidine residue in their active site for their activity. One of the enzyme systems thought to be responsible for postmortem protein degradation and early increases in tenderness is the calpain system. Hydrolysis of peptide bonds by calpains requires a transfer of electrons between the active site histidine and cysteine residues (Mehdi, 1991). Therefore, in order to function in postmortem muscle, the calpains (and other cysteine proteases) need to be maintained in a reduced form. If either of these processes (aggregation/denaturation of structural proteins or oxidation and inactivation of key enzymes) occurs in meat before tenderization is complete, it is possible that subsequent tenderization could be compromised. Because a significant amount of proteolysis does occur early postmortem (Melody et al., 2004), it is important to know whether oxidation of proteins occurring before aging is complete influences tenderness. Implications
Irradiation is a very useful tool to improve food safety; however, because of its potential to induce protein oxidation (as well as lipid oxidation), the effects of irradiation on fresh meat quality need continued study to ensure consumer acceptance. Results of this study indicate that early postmortem irradiation of fresh beef steaks increases oxidation of both sarcoplasmic and myofibrillar proteins. More importantly, increased protein oxidation during the first 24 h postmortem (as measured by carbonyl content) can substantially decrease beef tenderness even in steaks aged 14 d.
Footnotes
1 This journal paper of the Iowa Agric. and Home Econ. Exp. Stn., Project No. 3700, was supported by grants from the USDA National Research Initiative Competitive Grants Program (Project No. 2000-01705), and by the Hatch Act and State of Iowa funds. The authors acknowledge the technical assistance of M. Holtzbauer and the Iowa State University Linear Accelerator facility; A. Trenkle and R Berryman at the Iowa State University Beef Nutrition Farm; and the laboratory assistance of A. Asmus, A. Ostendorf, A. Yelden, and M. Van Utrecht. 
2 Correspondence: 2278 Kildee Hall (phone: 515-294-9125; fax: 515-294-9143; e-mail: elonerga{at}iastate.edu).
Received for publication June 4, 2003. Accepted for publication November 10, 2003.
Literature Cited
AMSA. 1995. Research guidelines for cookery, sensory evaluation and instrumental tenderness measurements of fresh meat. National Livestock and Meat Board. Chicago, IL.
Arnold, R. N., S. C. Arp, K. K. Scheller, S. N. Williams, and D. M. Schaefer. 1993. Tissue equilibration and subcellular distribution of vitamin E relative to myoglobin and lipid oxidation in displayed beef. J. Anim. Sci. 71:105–118.[Abstract]
Arnold, R. N., K. K. Scheller, S. C. Arp, S. N. Williams, D. R. Buege, and D. M. Schaefer. 1992. Effect of long- or short- term feeding of -tocopheryl acetate to Holstein and crossbred beef steers on performance, carcass characteristics, and beef color stability. J. Anim. Sci. 70:3055–3065.[Abstract]
Bradford, M. M. 1976. A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 72:248–254.[Medline]
Burton, G. W., and M. G. Traber. 1990. Vitamin E: Antioxidant activity, biokinetics, and bioavailability. Annu. Rev. Nutr. 10:357–382.[Medline]
Butterfield, D. A., T. Koppal, B. Howard, R. Subramaniam, N. Hall, K. Hensley, S. Yatin, K. Allen, M. Aksenov, M. Aksenova, and J. Carney. 1998. Structural and functional changes in proteins induced by free radical-mediated oxidative stress and protective action of the antioxidants N-tert-butyl--phenylnitrone and Vitamin E. Ann. N. Y. Acad. Sci. 854:448–462.
Decker, E. A., Y. L. Xiong, J. T. Calvert, A. D. Crum, and S. P. Blanchard. 1993. Chemical, physical and functional properties of oxidized turkey white muscle myofibrillar proteins. J. Agric. Food Chem. 41:186–189.
Harris, S. E., E. Huff-Lonergan, S. M. Lonergan, W. R. Jones, and D. Rankins. 2001. Antioxidant status affects color stability and tenderness of calcium chloride-injected beef. J. Anim. Sci. 79:666–677.
Heath, J. L., S. L. Owen, and S. Tesch. 1990. Effect of high energy electron irradiation of chicken meat on thiobarbituric acid values, odor, and cooked yield. Poult. Sci. 69:313–319.[Medline]
Hoffman, K., and R. Hamm. 1978. Sulfhydryl and disulfide groups in meats. Adv. Food Res. 24:1–111.[Medline]
Huff-Lonergan, E., F. C. Parrish, Jr., and R. M. Robson. 1995. Effects of postmortem aging time, animal age, and sex on the degradation of titin and nebulin in bovine longissimus muscle. J. Anim. Sci. 73:1064–1073.[Abstract]
Huff-Lonergan, E., T. Mitsuhashi, D. D. Beekman, F. C. Parrish, Jr., D. G. Olson, and R. M. Robson. 1996. Proteolysis of specific muscle structural proteins by µ-calpain at low pH and temperature is similar to degradation in postmortem bovine muscle. J. Anim. Sci. 74:993–1008.[Abstract]
Jo, C., and D. U. Ahn. 2000. Production of volatile compounds from irradiated oil emulsion containing amino acids or proteins. J. Food Sci. 65:612–616.
Little, A. C. 1975. Off on a tangent, a research note. J. Food Sci. 40:410–411.
Liu, Q., K. K. Scheller, S. C. Arp, D. M. Schaefer, and S. N. Williams. 1996. Titration of fresh meat color stability and malondialdehyde development with Holstein steers fed vitamin E supplemented diets. J. Anim. Sci. 74:117–121.[Abstract]
Lowry, O. H., N. J. Rosenbrough, A. L. Farr, and R. J. Randall. 1951. Protein measurement with the folin phenol reagent. J. Biol. Chem. 193:265–275.
Martinaud, A., Y. Mercier, P. Marinova, C. Tassy, P. Gatellier, and M. Renerre. 1997. Comparison of oxidative processes on myofibrillar proteins from beef during maturation and by different model oxidation systems. J. Agric. Food Chem. 45:2481–2487.
Mehdi, S. 1991. Cell-penetrating inhibitors of calpain. Trends Biochem. Sci. 16:150–153.[Medline]
Melody, J. L., S. M. Lonergan, L. J. Rowe, T. W. Huiatt, M. S. Mayes, and E. Huff-Lonergan. 2004. Early postmortem biochemical factors influence tenderness and water-holding capacity of three porcine muscles. J. Anim. Sci. (In press).
Nam, K. C., and D. U. Ahn. 2003. Use of antioxidants to reduce lipid oxidation and off-odor volatiles of irradiated pork homogenates and patties. Meat Sci. 63:1–8.
Nanke, K. E., J. G. Sebranek, and D. G. Olson. 1998. Color characteristics of irradiated vacuum-packaged pork, beef, and turkey. J. Food Sci. 63:1001–1006.
Reznick, A. Z., and L. Packer. 1994. Oxidative damage to proteins: Spectrophotometric method for carbonyl assay. Methods Enzymol. 233:357–363.[Medline]
Robson, R. M., D. E. Goll, and M. J. Temple. 1968. Determination of protein in "tris" buffer by the biuret reaction. Anal. Biochem. 24:339–341.[Medline]
Shackelford, S. D., M. Koohmaraie, L. V. Cundiff, K. E. Gregory, G. A. Rohrer, and J. W. Savell. 1994. Heritabilities and phenotypic and genetic correlations for bovine postrigor calpastatin activity, intramuscular fat content, Warner-Bratzler shear force, retail product yield, and growth rate. J. Anim. Sci. 72:857–863.[Abstract]
Stadtman, E. R. 1990. Metal ion-catalyzed oxidation of proteins: biochemical Mechanism and biological consequences. Free Radic. Biol. Med. 8:315–325.
Xiong, Y. L. 2000. Protein oxidation and implications for muscle food quality. Pages 85–111 in Antioxidants in Muscle Foods. E. A. Decker, C. Faustman, and C. J. Lopez-Bote, ed. Wiley, New York.
Yoon, K. S. 2003. Effect of gamma irradiation on the texture and microstructure of chicken breast meat. Meat Sci. 63:237–277.
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  K. M. Carnagey, E. J. Huff-Lonergan, A. Trenkle, A. E. Wertz-Lutz, R. L. Horst, and D. C. Beitz Use of 25-hydroxyvitamin D3 and vitamin E to improve tenderness of beef from the longissimus dorsi of heifers J Anim Sci, July 1, 2008; 86(7): 1649 - 1657. [Abstract] [Full Text] [PDF]
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 M.R. Ramirez and R. Cava Effect of Physico-chemical Characteristics of Raw Muscles from Three Iberian x Duroc Genotypes on Dry-cured Meat Products Quality Food Science and Technology International, December 1, 2007; 13(6): 485 - 495. [Abstract] [PDF]
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K. R. M. Carlin, E. Huff-Lonergan, L. J. Rowe, and S. M. Lonergan Effect of oxidation, pH, and ionic strength on calpastatin inhibition of {micro}- and m-calpain J Anim Sci, April 1, 2006; 84(4): 925 - 937. [Abstract] [Full Text] [PDF]
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M. Seyfert, M. C. Hunt, R. A. Mancini, K. A. Hachmeister, D. H. Kropf, J. A. Unruh, and T. M. Loughin Beef quadriceps hot boning and modified-atmosphere packaging influence properties of injection-enhanced beef round muscles J Anim Sci, March 1, 2005; 83(3): 686 - 693. [Abstract] [Full Text] [PDF]
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L. J. Rowe, K. R. Maddock, S. M. Lonergan, and E. Huff-Lonergan Oxidative environments decrease tenderization of beef steaks through inactivation of {micro}-calpain J Anim Sci, November 1, 2004; 82(11): 3254 - 3266. [Abstract] [Full Text] [PDF]
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