Effect of Antioxidant Application Methods on the Color, Lipid Oxidation, and Volatiles of Irradiated Ground Beef

ABSTRACT:  Four antioxidant treatments (none, 0.05% ascorbic acid, 0.01%α-tocopherol + 0.01% sesamol, and 0.05% ascorbic acid + 0.01%α-tocopherol + 0.01% sesamol) were applied to ground beef using either mixing or spraying method. The meat samples were placed on Styrofoam trays, irradiated at 0 or 2.5 kGy, and then stored for 7 d at 4 °C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined at 0, 3, and 7 d of storage. Irradiation increased lipid oxidation of ground beef with control and ascorbic acid treatments after 3 d of storage. α-Tocopherol + sesamol and ascorbic acid +α-tocopherol + sesamol treatments were effective in slowing down lipid oxidation in ground beef during storage regardless of application methods, but mixing was better than the spraying method. Irradiation lowered L *-value and a *-value of ground beef. Storage had no effect on lightness but redness decreased with storage. Ascorbic acid was the most effective in maintaining redness of ground beef followed by ascorbic acid +α-tocopherol + sesamol. Irradiation and storage reduced the b *-value of ground beef. Irradiation lowered ORP of ground beef regardless of antioxidants application methods, but ORP was lower in beef with mixing than spraying method. Beef sprayed with antioxidants produced more hydrocarbons and alcohols than the mixing application, but ascorbic acid +α-tocopherol + sesamol treatment was effective in reducing the amount of volatiles produced by irradiation. Therefore, mixing was better than the spraying method in preventing lipid oxidation and maintaining color of irradiated ground beef.     

Effects of aging time and natural antioxidants on the color, lipid oxidation and volatiles of irradiated ground beef

Beef rounds aged for one, two, or three weeks after slaughtering were ground added with 0.05% ascorbic acid+0.01% α-tocopherol or 0.05% ascorbic acid+0.01% α-tocopherol+0.01% sesamol, placed on Styrofoam trays and wrapped with oxygen-permeable plastic film, and treated with electron beam irradiation at 0 or 2.5kGy. The meat samples were displayed under fluorescent light for 7d at 4°C. Color, lipid oxidation, volatile analysis, oxidation-reduction potential (ORP) and carbon monoxide (CO) production were determined at 0, 3, and 7d of storage. Irradiation increased lipid oxidation of ground beef regardless of their aging time and storage period. As aging time increased lipid oxidation increased. Adding sesamol increased the effectiveness of ascorbate and tocopherol combination in reducing lipid oxidation especially as aging and storage time increased. The redness of beef were decreased by irradiation and adding ascorbic acid and α-tocopherol before irradiation was effective in maintaining the redness of irradiated ground beef over the storage period. The combination of ascorbic acid+α-tocopherol to ground beef was more effective in reducing ORP than adding sesamol. Irradiation increased CO production from all ground beef regardless of aging time or additives treatments. Volatile sulfur compounds produced by irradiation at Day 0 disappeared over the storage period. Alcohol greatly increased in all nonirradiated beef, but volatiles aldehydes only in irradiated control beef. Antioxidant treatments were effective in reducing aldehydes in ground beef during storage.     

Effects of Ascorbic Acid and Antioxidants on the Color of Irradiated Ground Beef

Irradiation significantly decreased the redness of ground beef (P < 0.05), and the visible color of beef changed from a bright red to a green/brown, depending on the age of meat. Addition of ascorbic acid (0.1%, wt/ wt) in ground beef prior to irradiation prevented color changes in irradiated beef, and the effect of ascorbic acid became greater as the age of meat or storage time after irradiation increased. Ground beef with added ascorbic acid had significantly lower oxidation‐reduction potential than the control (P < 0.05), and the low oxidation‐reduction potential of meat helped maintain the heme pigments in reduced form. Sesamol +α‐tocopherol had no effect in stabilizing color of irradiated beef.     

Effects of Ascorbic Acid and Antioxidants on the Lipid Oxidation and Volatiles of Irradiated Ground Beef

Beef loins, aged for different lengths of time post slaughter, were treated with ionizing radiation. Irradiated ground beef produced volatile sulfur compounds (S‐volatiles) responsible for the unique irradiation odor and accelerated lipid oxidation. The quality changes by irradiation became greater as aging and storage time increased. During aerobic storage, the S‐volatiles disappeared whereas volatile aldehydes drastically increased in irradiated beef. Addition of ascorbic acid at 0.1% (wt/wt) or sesamol +α‐tocopherol at each 0.01% level to ground beef before irradiation effectively reduced lipid oxidation and S‐volatiles. As storage time increased, however, the antioxidant effect of sesamol + tocopherol in irradiated ground beef was superior to that of ascorbic acid.     

Color, Oxidation-Reduction Potential, and Gas Production of Irradiated Meats from Different Animal Species

ABSTRACT: Turkey breasts, pork loins, and beef loins were aerobically or vacuum-packaged and electron beamirradiated at 3 kGy. Irradiation increased the redness of turkey breast regardless of packaging or storage. Irradiation drastically decreased the redness of aerobically packaged beef loin. Irradiated meats produced higher amounts of CO and CH₄ than nonirradiated. The oxidation-reduction potential (ORP) of meats decreased after irradiation, but increased during the storage. Little differences in CO and ORP values among the irradiated meats from different species were detected. This indicated that CO and ORP were not the only factors involved in the color changes of beef loin by irradiation.     

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.     

Effect of electron-beam irradiation before and after cooking on the chemical properties of beef, pork, and chicken

Ground beef, pork, and chicken thigh meats were irradiated at 0 or 5.0kGy before and after cooking and then stored at -40°C in oxygen permeable bags. The pH, lipid oxidation, volatiles, and carbon monoxide production of the meat were determined at 0 and 6months of storage. The pH values of raw meats from different animal species were different (5.36-6.25) and were significantly increased by cooking, irradiation, and storage (p<0.05). Irradiation had no effect on the TBARS values of ground beef and pork, but significantly increased the TBARS of chicken thigh meat. Cooking, whether it was done before or after irradiation, caused significant increase in TBARS and was most significant in chicken and pork. The numbers of volatiles analyzed by GC/MS were higher in irradiated meats than the non-irradiated ones regardless of meat source. Sulfur-containing compounds were newly produced or increased by irradiation, but dimethyl disulfide and dimethyl trisulfide were not detected in the non-irradiated meats regardless of cooking treatment. Irradiation time, whether done before or after cooking, had little effect on the TBARS, volatiles, and carbon monoxide production in the meat.     

Carbon monoxide-heme pigment is responsible for the pink color in irradiated raw turkey breast meat

Turkey breast muscles were aerobically or vacuum packaged, irradiated at 0, 2.5, or 5.0 kGy using a Linear Accelerator (electron beam), and stored at 4°C. The CIE color values, reflectance scan, oxidation-reduction potential (ORP), production of gaseous compounds, and lipid oxidation of samples were determined at 0, 1, and 2 weeks of storage. Absorption spectra of sample drips were determined at 1 week of storage. Irradiation increased the a-value of both aerobically and vacuum-packaged turkey breast, but vacuum-packaged meat had stronger intensity than the aerobically packaged. The increased redness in vacuum-packaged meat was stable during the 2 weeks of storage. The production of CO in meat, which can bind to myoglobin as a sixth ligand, was proportional to irradiation dose. The ORP was decreased by irradiation, but was increased during storage. The ORP and lipid oxidation values were lower in vacuum-packaged than those in aerobically packaged turkey breast. Therefore, increased a-values in irradiated turkey breast should be caused by the decreased ORP and heme pigment-CO ligand formation. The absorption spectra of meat drip also showed that the peak wavelengths of irradiated turkey breast were similar to that of the CO-myoglobin.     

Fat content and ascorbic acid infusion influence microbial and physicochemical qualities of electron beam irradiated beef patties

The effects of fat content and post-slaughter ascorbic acid (AA) infusion on microbial and physicochemical qualities of beef patties processed by electron beam irradiation were investigated in a 4 °C storage trial. Beef muscles from AA-infused or control animals were ground and mixed with tallow to achieve a final fat content of 4%, 17% and 30%, respectively. Beef patties were irradiated at 5 and 10 kGy with a linear electron beam accelerator. Non-irradiated and non-infused ground beef patties served as a control. The addition of fat significantly (p<0.05) increased aerobic, total coliform, E. coli, and psychrotrophic bacteria counts in beef patties during storage. Irradiation at both dosages exerted a pasteurization effect on psychrotrophic bacteria for up to 7 days of storage. No viable aerobic, total coliform, or E. coli bacteria were detected in any irradiated beef patties during storage. Physicochemical changes caused by lipid oxidation and surface discoloration of beef patties were significantly (p<0.05) increased by both the addition of fat and irradiation processing. Beef patties made from AA-infused animals did not alter bacterial counts. Instead, post-slaughter infusion of AA exerted a pro-oxidant effect in the beef patties that led to a significant (p<0.0.5) increase in lipid oxidation and surface discoloration of stored patties.     

Combined effect of gamma irradiation,ascorbic acid,and edible coating on the improvement of microbial and biochemical characteristics of ground beef

This study was conducted to evaluate the combined effect of gamma irradiation and the incorporation of natural antimicrobial compounds in cross-linked films on the microbiological and biochemical characteristics of ground beef. Medium-fat (23% fat) ground beef patties were divided into three separate treatment groups: (i) control samples without additives, (ii) ground beef samples containing 0.5% (wt/wt) ascorbic acid, and (iii) ground beef samples containing 0.5% ascorbic acid and coated with a protein-based cross-linked film containing immobilized spice powders. Meat samples were irradiated at doses of 0, 1, 2, and 3 kGy and stored at 4 +/- 2 degrees C. Microbial growth (based on total aerobic plate counts [APCs] and total coliforms) was evaluated, as were the content of thiobarbituric acid-reactive substances (TBARS) and that of free sulfydryl groups. At the end of the storage period, Enterobacteriaceae, presumptive Staphylococcus aureus, presumptive Pseudomonas spp., Brochothrix thermosphacta, and lactic acid bacteria were enumerated. Regardless of the treatment group, irradiation significantly (P < or = 0.05) reduced the APCs. Irradiation doses of 1, 2, and 3 kGy produced immediate APC reductions of 2, 3, and 4 log units, respectively. An APC level of 6 log CFU/g was reached after 4, 7, and 10 days for samples irradiated at 1, 2, and 3 kGy, respectively. Lactic acid bacteria and B. thermosphacta were more resistant to irradiation than were Enterobacteriaceae and Pseudomonas. The TBARS and free sulfydryl contents were stabilized during postirradiation storage for samples containing ascorbic acid and coated with the protein-based cross-linked film containing immobilized spice powders.     

Formation of Trans Fatty Acids in Ground Beef and Frankfurters due to Irradiation

ABSTRACT:  This study was conducted to investigate possible formation of trans fatty acids due to irradiation of ground beef and frankfurters. Ground beef and frankfurter samples were irradiated at doses of 0, 1, and 5 kGy at 4 °C, and stored at 4 °C for 7 d (ground beef) or 3 mo (frankfurters). After irradiation and storage of the samples, trans fatty acids along with other fatty acids were analyzed using a modification of AOAC method 996.01. The results showed that 1 kGy irradiation did not induce any change in trans fatty acid content. However, 5 kGy irradiation caused a small but statistically significant ( P < 0.01) increase in the dominant trans fatty acid, C18:1 trans , which increased from 3.99% (of total fatty acid) for the nonirradiated ground beef to 4.05% for the 5 kGy sample, and from 1.21% for the nonirradiated frankfurter to 1.28% for the 5 kGy sample. Irradiation had no apparent effect on C16:1 and C18:2 trans fatty acids. In addition, irradiation slightly decreased the relative amount of poly-unsaturated fatty acid of ground beef and frankfurters, particularly after storage. Compared to variations in trans fatty acid content and fatty acid composition occurring naturally in meat and meat products, the changes due to irradiation were negligible.     

Addition of Antioxidant to Improve Quality and Sensory Characteristics of Irradiated Pork Patties

The effects of added antioxidants on the oxidative quality changes of irradiated pork patties were studied. Lipid oxidation (TBARS) was not a concern, even in aerobically packaged irradiated pork patties when antioxidants were added. Irradiation produced sulfur compounds, such as dimethyl sulfide and dimethyl disulfide, responsible for irradiation off‐odor. The addition of gallate + tocopherol or sesamol + tocopherol was effective in reducing the sulfur volatiles, but had no effect on the redness of irradiated raw pork patties. Aerobic packaging was highly effective in reducing sulfur volatiles and off‐odor from irradiated meat during storage. Antioxidants had little effect on the sensory characteristics and consumer acceptance of irradiated pork, and consumers did not consider the red color of irradiated raw pork as a quality defect.     

Mechanisms of Pink Color Formation in Irradiated Precooked Turkey Breast Meat

ABSTRACT: Precooked turkey breast meat was aerobically packaged or vacuum-packaged and irradiated at 0, 2.5, or 5.0 kGy. CIE color, reflectance, oxidation-reduction potential (ORP), gas production, and lipid oxidation were determined at 0, 7, and 14 d. Irradiation increased redness of vacuum-packaged meat, and the redness was distinct and stable under vacuum. Irradiation decreased ORP and produced carbon monoxide (CO). This indicated that the pink color was caused by the heme pigment-CO complex formation. The reflectance of meat and the absorption spectra of myoglobin solution supported the assumption that denatured CO-myoglobin is the pigment in irradiated precooked turkey breast.     

Influence of dietary conjugated linoleic acid on volatile profiles, color and lipid oxidation of irradiated raw chicken meat

Forty-eight, 27-week-old White Leghorn hens were fed a diet containing 0, 1.25, 2.5 or 5.0% conjugated linoleic acid (CLA) for 12 weeks. At the end of the 12-week feeding trial, hens were slaughtered, and boneless, skinless breast and leg meats were separated from carcasses. Meats were ground through 9 and 3-mm plates, and patties were prepared. Patties prepared from each dietary treatment were divided into two groups and either vacuum- or aerobic-packaged. Patties were irradiated at 0 or 3.0 kGy using a linear accelerator and stored at 4°C. Samples were analyzed for thiobarbituric acid reactive substances, volatile profiles, color and odor characteristics at 0 and 7 days of storage. Dietary CLA reduced the degree of lipid oxidation in raw chicken meat during storage. The content of hexanal and pentanal in raw chicken meat significantly decreased as dietary CLA level increased. Irradiation accelerated lipid oxidation in meat with aerobic packaging, but irradiation effect was not as significant as that of the packaging. Dietary CLA treatment improved the color stability of chicken patties. Color a*-value of irradiated raw chicken meat was higher than that of the nonirradiated meat. Dietary CLA decreased the content of polyunsaturated fatty acid and increased CLA in chicken muscles, which improved lipid and color stability and reduced volatile production in irradiated and nonirradiated raw chicken meat during storage.     

Combined effect of natural essential oils, modified atmosphere packaging, and gamma radiation on the microbial growth on ground beef

Selected Chinese cinnamon, Spanish oregano, and mustard essential oils (EOs) were used in combination with irradiation to evaluate their ability to eliminate pathogenic bacteria and extend the shelf life of medium-fat-content ground beef (23% fat). Shelf life was defined as the time when the total bacterial count reached 10(7) CFU/g. The shelf life of ground beef was determined for 28 days at 4 degrees C after treatment with EOs. The concentrations of EOs were predetermined such that sensory properties of cooked meat were maintained: 0.025% Spanish oregano, 0.025% Chinese cinnamon, and 0.075% mustard. Ground beef samples containing EOs were then packaged under air or a modified atmosphere and irradiated at 1.5 kGy. Ground beef samples (10 g) were taken during the storage period for enumeration of total mesophilic aerobic bacteria, Escherichia coli, Salmonella, total coliforms, lactic acid bacteria, and Pseudomonas. Mustard EO was the most efficient for reducing the total mesophilic aerobic bacteria and eliminating pathogenic bacteria. Irradiation alone completely inhibited the growth of total mesophilic aerobic and pathogenic bacteria. The combination of irradiation and EOs was better for reducing lactic acid bacteria (mustard and cinnamon EOs) and Pseudomonas (oregano and mustard EOs). The best combined treatment for extending the shelf life of ground beef for up to 28 days was EO plus irradiation (1.5 kGy) and modified atmosphere packaging.     

Color Characteristics of Irradiated Vacuum-Packaged Pork, Beef, and Turkey

Changes in color of irradiated meat were observed to be species-dependent. Irradiated pork and turkey became redder due to irradiation but irradiated beef a* values decreased and yellowness increased with dose and storage time. The extent of color change was irradiation dose-dependent and was not related to myoglobin concentration. Visual evaluation indicated pork and turkey increased in red ness whereas beef decreased in redness as dose levels increased. Reflectance spectra showed that irradiation induced an oxymyoglobin-like pigment in pork and that both oxymyoglobin and metmyoglobin developed in beef as a result of irradiation.     

Raw-meat packaging and storage affect the color and odor of irradiated broiler breast fillets after cooking

Raw breast fillets were divided into two groups and either vacuum or aerobically packaged. The fillets in each group were subdivided equally into two groups and then irradiated at 0 or 3 kGy using a Linear Accelerator. After 0, 3 and 7 days of storage at 4?°C, fillets were cooked in an 85?°C water bath (cook-in-bag) to an internal temperature of 74?°C. Oxidation-reduction potential (ORP) of raw fillets was measured before cooking, and color and sensory characteristics were analyzed after cooking. Irradiation decreased the ORP of meat, but the potential in aerobically packaged fillets increased during storage. After cooking, color a*-value of irradiated fillets was higher than that of the non-irradiated. Irradiation of raw meat also changed color L* and b* values after cooking. Aerobic storage reduced the redness of cooked meat induced by irradiation. Irradiated raw broiler fillets stored for 0 day and 3 day under aerobic conditions before cooking produced a oxidized chicken-like odor. The odor, however, disappeared after 7 days of storage under aerobic conditions before cooking. For raw broiler samples stored under vacuum conditions, significant differences in color and odor between irradiated and non-irradiated fillets remained throughout the 7-day storage period after cooking. Irradiation had only a minor influence on lipid oxidation of raw breast fillets as indicated by low TBARS values. This study indicates that the effect of irradiation on color and odor of broiler breast fillets after cooking can be reduced significantly through shelf-display of raw fillets under aerobic conditions. Storage under vacuum conditions before cooking is not effective in reducing irradiation-induced changes in the color and odor of breast fillet after cooking.     

Addition of garlic or onion before irradiation on lipid oxidation, volatiles and sensory characteristics of cooked ground beef

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.     

Effect of Low‐Dose Electron Beam Irradiation on Quality of Ground Beef Patties and Raw,Intact Carcass Muscle Pieces

The objectives of this study were to determine the effects of a low‐dose (≤1 kGy), low‐penetration electron beam on the sensory qualities of (1) raw muscle pieces of beef and (2) cooked ground beef patties. Outside flat, inside round, brisket and sirloin muscle pieces were used as models to demonstrate the effect of irradiation on raw beef odor and color, as evaluated by a trained panel. Ground beef patties were also evaluated by a trained panel for tenderness, juiciness, beef flavor, and aroma at 10%, 20%, and 30% levels of fat, containing 0% (control), 10%, 20%, 50%, and 100% irradiated meat. With whole muscle pieces, the color of controls appeared more red (P < 0.05) than irradiated muscles, however, both control and treatments showed a gradual deterioration in color over 14 d aerobic storage at 4 °C. Off‐aroma intensity of both control and treatments increased with storage time, but by day 14, the treated muscles showed significantly (P < 0.05) less off‐aroma than the controls, presumably as a result of a lower microbial load. It was found that a 1 kGy absorbed dose had minimal effects on the sensory properties of intact beef muscle pieces. Irradiation did not have a significant effect (P > 0.05) on any of the sensory attributes of the patties. Low‐dose irradiation of beef trim to formulate ground beef appears to be a viable alternative processing approach that does not affect product quality.     

Antioxidant Properties of Far Infrared-treated Rice Hull Extract in Irradiated Raw and Cooked Turkey Breast

ABSTRACT: The antioxidant effect of far infrared-treated rice hull (FRH) extracts in irradiated turkey breast meat was compared with that of sesamol and rosemary oleoresin. The FRH extracts significantly decreased thiobarbituric acid-reactive substances values and volatile aldehydes (hexanal, pentanal, and propanal) and was effective in reducing the production of dimethyl disulfide responsible for irradiation off-odor in irradiated raw and cooked turkey meat during aerobic storage. The antioxidant activity of FRH extracts (0.1%, wt/wt) was as effective as that of rosemary oleoresin (0.1%). However, the addition of FRH extracts increased red and yellow color intensities and produced an off-odor characteristic to rice hull in raw and cooked meat.