[show abstract][hide abstract] ABSTRACT: Ground beef with 10%, 15%, or 20% fat were added with none, 0.05% ascorbic acid + 0.01%alpha-tocopherol, or 0.05% ascorbic acid + 0.01%alpha-tocopherol + 0.01% sesamol, and irradiated at 0 or 2.5 kGy. The meat samples were displayed under fluorescent light for 14 d at 4 degrees C. Color, lipid oxidation, volatiles, oxidation-reduction potential (ORP), and carbon monoxide (CO) production were determined during storage. Irradiation increased lipid oxidation and total volatiles of ground beef regardless of fat contents. Ascorbic acid + alpha-tocopherol + sesamol treatment was the most effective in reducing lipid oxidation during storage. The production of ethanol in nonirradiated ground beef increased dramatically after 7 d of storage due to microbial growth. Total aldehydes and hexanal increased drastically in irradiated control over the storage period, but hexanal increased the most by irradiation. L*-values was decreased by irradiation, but increased in all meat regardless of fat contents as storage period increased. Irradiation reduced the redness, but fat contents had no effect on the a*-value of ground beef. Sesamol lowered, but ascorbic acid + alpha-tocopherol maintained the redness of irradiated beef up to 2 wk of storage. The yellowness of meat was significantly decreased by irradiation. The reducing power of ascorbic acid + alpha-tocopherol lasted for 3 d, after which ORP values increased. Irradiation increased CO production regardless of fat content in ground beef. In conclusion, up to 20% fat had no effect on the quality change of irradiated ground beef if ascorbic acid + alpha-tocopherol was added.
Journal of Food Science 09/2009; 74(6):C432-40. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: Four antioxidant treatments (none, 0.05% ascorbic acid, 0.01%alpha-tocopherol + 0.01% sesamol, and 0.05% ascorbic acid + 0.01%alpha-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 degrees 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. alpha-Tocopherol + sesamol and ascorbic acid +alpha-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 +alpha-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 +alpha-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.
Journal of Food Science 02/2009; 74(1):C25-32. · 1.78 Impact Factor
[show abstract][hide abstract] ABSTRACT: The objective of this study was to determine the effect of antimicrobials on the survival and proliferation of Listeria monocytogenes in turkey breast rolls following electron-beam irradiation. Six antimicrobial additive treatments that include no preservatives (control), 0.1% potassium benzoate (PB), 2% sodium lactate (SL), 0.1% potassium benzoate plus 2% sodium lactate (PB + SL), 2% sodium lactate plus 0.1% sodium diacetate (SL + SDA), and 0.1% potassium benzoate, 2% sodium lactate, and 0.1% sodium diacetate (PB + SL + SDA) were used. Sliced turkey breast rolls were artificially inoculated with approximately 10(6) cfu/cm(2) of 5-strain L. monocytogenes cocktails, then vacuum-packaged and irradiated at 0, 1.0, 1.5, 2.0, or 2.5 kGy. The radiation dose (kGy) that results in 90% reduction of viable cells for breast rolls, D(10) value, with various additive treatments ranged from 0.56 to 0.58 kGy. Adding PB (0.1%) or SL (2%) in turkey rolls failed to prevent L. monocytogenes from growing during refrigerated storage. In turkey rolls added with 2 (PB + SL or SL + SDA) or 3 (PB + SL + SDA) antimicrobial combinations had 2 or 3 wk of lag phases before L. monocytogenes growth, respectively. Irradiating turkey rolls, which were added with PB + SL or SL + SDA, at 1.0 kGy was effective in suppressing the growth of L. monocytogenes for about 6 wk when stored at 4 degrees C. No growth of L. monocytogenes after irradiation occurred during 42 d of storage for 2.0 kGy irradiated breast rolls formulated with 0.1% PB + 2% SL, 2% SL + 0.1% SDA or 0.1% PB + 2% SL + 0.1% SDA, and 1.0 kGy irradiated turkey breast with 0.1% PB + 2% SL + 0.1% SDA. Sensory panelists found that low-dose irradiation (1.0 kGy) had no effect on the sensory characteristics of ready-to-eat turkey breast rolls. Including SL + SDA had slightly negative effect for nonirradiated turkey breast rolls, but the sensory characteristics of 1.0 kGy irradiated turkey roll containing SL + SDA was not significantly different from the others receiving 1.0 kGy irradiation. For microbial safety, PB + SL and SL + SDA antimicrobial treatments combined with 1.0 kGy or 2.0 kGy irradiation are a promising technology.
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: The effect of electron beam irradiation on the survival and growth of Listeria monocytogenes and natural microflora in oven-roasted turkey breast rolls and turkey hams was evaluated. Slices of turkey breast rolls and hams were inoculated with a 5-strain mixture of L. monocytogenes to achieve 10(6) to 10(7) cfu/cm2; vacuum-packaged; irradiated at 0 (control), 1.0, 1.5, 2.0, or 2.5 kGy; and stored at 4 degrees C for up to 28 d. Numbers of naturally occurring bacteria on sliced turkey hams and breast rolls were 2.72 and 6.22 log10 cfu/cm2, respectively. The values of the radiation dose that results in 90% reduction of viable L. monocytogenes in breast rolls and hams were 0.52 and 0.47 kGy, respectively. For breast rolls, the log10 reductions of L. monocytogenes after irradiation at 1.0 and 2.5 kGy were 1.5 and 4.7, respectively, whereas they were 2.0 and 5.5 for hams. The log10 reductions of aerobic plate count (APC) in breast rolls after 1.0 and 2.0 kGy of irradiation were 2.9 and 5.2, whereas that of hams was < 10 cfu/cm2 after 1.0 and 2.0 kGy of irradiation. In 2.0-kGy irradiated hams, L. monocytogenes grew to 4.82 log10 cfu/cm2 after 28 d of storage at 4 degrees C, whereas APC increased to 2.98 log10 cfu/cm2, respectively. In breast rolls after 14 d of storage, APC in 1.0-kGy irradiated samples increased to 7.53 log10 cfu/cm2, and APC increased to 2.63 and 4.68 log10 cfu/cm2 for 2.0-kGy irradiated breast rolls after 14 and 28 d of storage. However, during the storage of breast rolls, L. monocytogenes grew slowly or even stopped to grow in both nonirradiated and irradiated breast rolls due to the competitive inhibition of natural flora in breast rolls. This study showed that irradiation (1.0 to 2.5 kGy) effectively reduced the number of L. monocytogenes and natural flora. However, L. monocytogenes and natural flora that survived irradiation could multiply during the 28-d storage period at 4 degrees C. Thus, additional hurdles are needed to ensure the microbial safety after low-dose irradiation.
[show abstract][hide abstract] ABSTRACT: Irradiation is an effective technology in eliminating Listeria monocytogenes, but it induces quality changes in meat products at or above specific radiation doses. To minimize irradiation-induced quality changes, only low irradiation doses are recommended. However, low-dose irradiation provides a chance for some pathogens to survive and proliferate during prolonged storage. To solve this problem, antimicrobial ingredients [2% sodium lactate (SL), 0.1% sodium diacetate (SDA), 0.1% potassium benzoate (PB)] and low-dose irradiation were combined and tested for their effects on the growth of L. monocytogenes and meat quality. The log10 reductions of L. monocytogenes in hams following exposure to 1.0 to 2.5 kGy of irradiation ranged from 2.0 to 5.0. The D10 values were 0.52 kGy for control ham or ham with PB, SL, or PB + SL; 0.49 kGy for ham with SL+SDA; and 0.48 kGy for ham with PB + SL + SDA (PSS). Addition of SL + SDA or PB + SL in combination with 1.0 kGy of irradiation was effective in suppressing the growth of L. monocytogenes for about 6 wk when stored at 4 degrees C, whereas 2.0 kGy of irradiation was listeriostatic. Ham irradiated with 1 kGy in combination with PSS was listeriostatic throughout storage. SL increased firmness of turkey hams, and sensory panelists noted that the saltiness was a little higher in products containing SL, but its overall impact on quality was minimal. Amounts of benzene were detected in irradiated hams with PB, showing PB was not fit as an antimicrobial ingredient for irradiated foods. In conclusion, 2% SL and 0.1% SDA in combination with low-dose irradiation were effective in ensuring the safety of ready-to-eat meat products against L. monocytogenes.
[show abstract][hide abstract] ABSTRACT: Breast rolls with 6 antimicrobial additive treatments—no preservatives (control), 0.1% potassium benzoate (PB), 2% sodium lactate (SL), 0.1% potassium benzoate plus 2% sodium lactate (PB + SL), 2% sodium lactate plus 0.1% sodium diacetate (SL + SDA), and 0.1% potassum benzoate, 2% sodium lactate, and 0.1% sodium diacetate (PB + SL + SDA)—were prepared. Samples were irradiated at 0, 1.0, or 2.0 kGy, and then the quality characteristics of turkey rolls were analyzed. Adding 2% SL increased the hardness, springiness, cohesiveness, chewiness, and resilience of breast rolls. Addition of PB or SDA, and irradiation had no significant effect on texture. Adding 2% SL affected color values. The color a* and b* values of turkey rolls with 2% SL added were significantly lower than those of the control, and this difference was maintained after irradiation and during storage. No difference in color and texture was observed between turkey rolls added with SL and those added with SL + PB + SDA. Breast rolls containing antimicrobials had more lipid oxidation than control. Irradiation and storage slightly enhanced lipid oxidation, although the overall lipid oxidation was very low. Irradiation promoted the formation of dimethyl disulfide and dimethyl trisulfide. Adding PB in breast rolls greatly increased the formation of benzene during irradiation, whereas other antimicrobial additives had no significant effects on volatiles.