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Beef (LD muscle) sarcomere length measured by laser diffraction or phase contrast microscopy. Is there a difference?
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Abstracts
66 Effects of antimicrobials on shelf life characteristics of ground beef S. Belanger, A. Stelzleni, Department of Animal and Dairy Science, University of Georgia, Athens, United States
Objectives: The control of shiga toxin-producing E scherichia coli is of major concern for non-intact beef products such as ground beef. As novel antimicrobials are developed to reduce these pathogens, it is critical to understand their impact on meat quality. Thus, the objective of this research was to evaluate the effects of pathogen interventions on quality characteristics of ground beef. Materials and methods: Beef trim (85/15) was produced from whole boneless chuck rolls to ensure known source and packaging date. Beef trim was treated with 4.5% lactic acid (LA), 200 ppm peroxyacetic acid (PAA), 50 ppm electrolyzed oxidizing water (EO), or 2.0% levulinic acid plus 0.2% sodium dodecyl sulfate (LVA–SDS) compared to an untreated control (CON). Beef trim from all chucks were combined so treatment was not confounded by source. Fifteen kilograms of trim per treatment were individually placed on the spray cabinet conveyor (360 degree 6 nozzle sprayer, 275 kPa) for treatment application. The beef trim was ground through a 12.7-mm plate followed by a 6.4-mm plate. After grinding, patties (150 ± 2 g; 13 mm thick) were produced (Patty-O-Matic Protégé). Approximately 100 patties were made per treatment, 30 patties were randomly selected and assigned to a retail display for 0, 1, 2, 3, 4, or 5 d. An additional 5 patties were individually vacuum packaged and frozen for Kramer shear force analysis. Retail display patties were individually packaged in Styrofoam trays and wrapped with polyvinyl chloride film. Patties were placed in a coffin style retail display case at 3 ± 2 °C under 24 h florescent warm white lighting at 1851 (ix). On their respective day patties were collected for psychotropic bacteria, pH, purge, and lipid oxidation analysis. Objective and subjective color was measured daily on d 5 patties. This was replicated three times. Data was analyzed by PROC MIXED (SAS Inc.). If a treatment by day interaction occurred, the model was reanalyzed by day. Sample within treatment by replication was considered the random term. Comparisons were considered significant at α ≤ 0.05. Results: Psychotropic bacteria counts increased as time on display increased for all treatments (P b 0.05). After d 5 of display LA inhibited the growth of psychotropic bacteria compared to all other treatments (P b 0.05). Percent purge increased as time on display increased and LA had a greater percent purge compared to all other treatments (P b 0.05). After d 1 of shelf life PAA lipid oxidation was lower than EO and LA (P b 0.05) and similar to CON (P N 0.05). For a* and hue, redness decreased for all treatments as time on display increased and PAA retained greater redness after d 5 compared to all other treatments (P b 0.05). Delta E increased as time on display increased and the reflectance ratio of 630 nm/580 nm decreased over time for all treatments (P N 0.05). Initial color revealed that as time on display increased all treatments became darker red (P N 0.05). After d 2 of display the discoloration of LA and LVA–SDS maintained a lighter color compared to all other treatments (P b 0.05). After d 4, CON, LA, and LVA–SDS had a lower percent discoloration and after d 5 LA and PAA had less discoloration compared to all other treatments (P b 0.05). Kramer shear was similar for all treatments (P N 0.05). Conclusion: The use of EO and LVA–SDS would maintain an acceptable color for ground beef. Overall, EO and LVA–SDS can be used without negatively affecting quality compared to industry standards.
67 Beef (LD muscle) sarcomere length measured by laser diffraction or phase contrast microscopy. Is there a difference? A.P. Bernardo, G. Vilella, C. Battaglia, P.E. de Felicio, S.B. Pflanzer, Department of Food Technology, State University of Campinas, Campinas, Brazil
Objectives: Variations in the myofibrillar protein structure can have significant effects on tenderness. Muscle sarcomere length (SL) has been exhaustively evaluated in experiments to determine whether tenderness was affected by cold shortening. Two methods are very much cited in the literature for measuring SL, laser diffraction and phase contrast microscopy. However, there are only a few scientific works that present a comparison between measurements obtained with these methods, being difficult to explain some low values obtained with laser diffraction in the absence of cold shortening. The purpose of this research was to compare the SL of Longissimus dorsi (LD) muscle, measured by the two methods. Materials and methods: Two experiments were carried out. Trial 1 — LD samples from F1 crossbreds (Angus × Nellore) 18 months old heifers (n = 7) and young bulls (n = 13). Trial 2 — LD samples from 24 to 36 months old Bos indicus (BI) bulls (n = 16). The LD muscle (12th rib), from both trials, was evaluated for ultimate pH (pHu), cooking loss (CL), Warner–Bratzler shear force (WBSF) and sarcomere length. The pHu and SL were measured on fresh samples 4 days post-mortem, while CL and WBSF were evaluated after 14 days of aging. For laser diffraction, samples were fixed in glutaraldehyde and small fiber bundles were passed through the helium–neon laser. For microscopy, myofibrillar extract was obtained by grinding and centrifugation to evaluate sarcomeres by phase contrast. The statistical analyses were performed separately for both trials, and the results expressed as mean ± SEM. Results: The results were: trial 1 — pH (5.53 ± 0.03), SL (2.05 ± 0.02 μm and 1.80 ± 0.03 μm, for SL by microscopy and laser, respectively), CL (23.25 ± 0.69) and WBSF (3.63 ± 0.11) were not affected by gender (P N 0.05). There was a positive correlation (r = 0.88; P b 0.001) from SL measured by microscopy and laser, while the correlation between SL and WBSF was not significant (P N 0.05). Regarding the regression procedures, a linear trend for SL measured by microscopy and laser (r2 = 0.78; SLlaser = 1.3165 ∗ SLmicroscopy − 0.9049) was found. In laser diffraction the SL ranged from 1.48 to 2.23 μm, while in microscopy the SL ranged from 1.81 to 2.32 μm. Trial 2 — the mean values for pH, WBSF and CL were 5.58 ± 0.03, 6.12 ± 0.39 and 23.52 ± 0.72, respectively. Different from trial 1, there was a significant (P b 0.001) negative correlation (r = −0.70) between WBSF and SL for both laser and microscopy methods in the BI samples. Correlation (r = 0.80; P b 0.001) and linear regression (r2 = 0.64; SLlaser = 1.2137 ∗ SLmicroscopy − 0.7608) between SL by laser and microscopy were found. In laser diffraction the SL ranged from 1.31 to 2.03 μm, while in microscopy the SL ranged from 1.80 to 2.17 μm. Conclusion: These data suggest that instrumental tenderness is correlated with sarcomere length regardless of the sarcomere length method, however the methods influenced the sarcomere length, and, generally, the diffraction method results in shorter sarcomere length values. Keywords: Beef tenderness, Cold shortening, Sarcomere length, Warner–Bratzler shear force.
Keywords: Antimicrobial, Ground beef, Quality. doi:10.1016/j.meatsci.2014.09.082
doi:10.1016/j.meatsci.2014.09.083
Abstracts
66 Effects of antimicrobials on shelf life characteristics of ground beef S. Belanger, A. Stelzleni, Department of Animal and Dairy Science, University of Georgia, Athens, United States
Objectives: The control of shiga toxin-producing E scherichia coli is of major concern for non-intact beef products such as ground beef. As novel antimicrobials are developed to reduce these pathogens, it is critical to understand their impact on meat quality. Thus, the objective of this research was to evaluate the effects of pathogen interventions on quality characteristics of ground beef. Materials and methods: Beef trim (85/15) was produced from whole boneless chuck rolls to ensure known source and packaging date. Beef trim was treated with 4.5% lactic acid (LA), 200 ppm peroxyacetic acid (PAA), 50 ppm electrolyzed oxidizing water (EO), or 2.0% levulinic acid plus 0.2% sodium dodecyl sulfate (LVA–SDS) compared to an untreated control (CON). Beef trim from all chucks were combined so treatment was not confounded by source. Fifteen kilograms of trim per treatment were individually placed on the spray cabinet conveyor (360 degree 6 nozzle sprayer, 275 kPa) for treatment application. The beef trim was ground through a 12.7-mm plate followed by a 6.4-mm plate. After grinding, patties (150 ± 2 g; 13 mm thick) were produced (Patty-O-Matic Protégé). Approximately 100 patties were made per treatment, 30 patties were randomly selected and assigned to a retail display for 0, 1, 2, 3, 4, or 5 d. An additional 5 patties were individually vacuum packaged and frozen for Kramer shear force analysis. Retail display patties were individually packaged in Styrofoam trays and wrapped with polyvinyl chloride film. Patties were placed in a coffin style retail display case at 3 ± 2 °C under 24 h florescent warm white lighting at 1851 (ix). On their respective day patties were collected for psychotropic bacteria, pH, purge, and lipid oxidation analysis. Objective and subjective color was measured daily on d 5 patties. This was replicated three times. Data was analyzed by PROC MIXED (SAS Inc.). If a treatment by day interaction occurred, the model was reanalyzed by day. Sample within treatment by replication was considered the random term. Comparisons were considered significant at α ≤ 0.05. Results: Psychotropic bacteria counts increased as time on display increased for all treatments (P b 0.05). After d 5 of display LA inhibited the growth of psychotropic bacteria compared to all other treatments (P b 0.05). Percent purge increased as time on display increased and LA had a greater percent purge compared to all other treatments (P b 0.05). After d 1 of shelf life PAA lipid oxidation was lower than EO and LA (P b 0.05) and similar to CON (P N 0.05). For a* and hue, redness decreased for all treatments as time on display increased and PAA retained greater redness after d 5 compared to all other treatments (P b 0.05). Delta E increased as time on display increased and the reflectance ratio of 630 nm/580 nm decreased over time for all treatments (P N 0.05). Initial color revealed that as time on display increased all treatments became darker red (P N 0.05). After d 2 of display the discoloration of LA and LVA–SDS maintained a lighter color compared to all other treatments (P b 0.05). After d 4, CON, LA, and LVA–SDS had a lower percent discoloration and after d 5 LA and PAA had less discoloration compared to all other treatments (P b 0.05). Kramer shear was similar for all treatments (P N 0.05). Conclusion: The use of EO and LVA–SDS would maintain an acceptable color for ground beef. Overall, EO and LVA–SDS can be used without negatively affecting quality compared to industry standards.
67 Beef (LD muscle) sarcomere length measured by laser diffraction or phase contrast microscopy. Is there a difference? A.P. Bernardo, G. Vilella, C. Battaglia, P.E. de Felicio, S.B. Pflanzer, Department of Food Technology, State University of Campinas, Campinas, Brazil
Objectives: Variations in the myofibrillar protein structure can have significant effects on tenderness. Muscle sarcomere length (SL) has been exhaustively evaluated in experiments to determine whether tenderness was affected by cold shortening. Two methods are very much cited in the literature for measuring SL, laser diffraction and phase contrast microscopy. However, there are only a few scientific works that present a comparison between measurements obtained with these methods, being difficult to explain some low values obtained with laser diffraction in the absence of cold shortening. The purpose of this research was to compare the SL of Longissimus dorsi (LD) muscle, measured by the two methods. Materials and methods: Two experiments were carried out. Trial 1 — LD samples from F1 crossbreds (Angus × Nellore) 18 months old heifers (n = 7) and young bulls (n = 13). Trial 2 — LD samples from 24 to 36 months old Bos indicus (BI) bulls (n = 16). The LD muscle (12th rib), from both trials, was evaluated for ultimate pH (pHu), cooking loss (CL), Warner–Bratzler shear force (WBSF) and sarcomere length. The pHu and SL were measured on fresh samples 4 days post-mortem, while CL and WBSF were evaluated after 14 days of aging. For laser diffraction, samples were fixed in glutaraldehyde and small fiber bundles were passed through the helium–neon laser. For microscopy, myofibrillar extract was obtained by grinding and centrifugation to evaluate sarcomeres by phase contrast. The statistical analyses were performed separately for both trials, and the results expressed as mean ± SEM. Results: The results were: trial 1 — pH (5.53 ± 0.03), SL (2.05 ± 0.02 μm and 1.80 ± 0.03 μm, for SL by microscopy and laser, respectively), CL (23.25 ± 0.69) and WBSF (3.63 ± 0.11) were not affected by gender (P N 0.05). There was a positive correlation (r = 0.88; P b 0.001) from SL measured by microscopy and laser, while the correlation between SL and WBSF was not significant (P N 0.05). Regarding the regression procedures, a linear trend for SL measured by microscopy and laser (r2 = 0.78; SLlaser = 1.3165 ∗ SLmicroscopy − 0.9049) was found. In laser diffraction the SL ranged from 1.48 to 2.23 μm, while in microscopy the SL ranged from 1.81 to 2.32 μm. Trial 2 — the mean values for pH, WBSF and CL were 5.58 ± 0.03, 6.12 ± 0.39 and 23.52 ± 0.72, respectively. Different from trial 1, there was a significant (P b 0.001) negative correlation (r = −0.70) between WBSF and SL for both laser and microscopy methods in the BI samples. Correlation (r = 0.80; P b 0.001) and linear regression (r2 = 0.64; SLlaser = 1.2137 ∗ SLmicroscopy − 0.7608) between SL by laser and microscopy were found. In laser diffraction the SL ranged from 1.31 to 2.03 μm, while in microscopy the SL ranged from 1.80 to 2.17 μm. Conclusion: These data suggest that instrumental tenderness is correlated with sarcomere length regardless of the sarcomere length method, however the methods influenced the sarcomere length, and, generally, the diffraction method results in shorter sarcomere length values. Keywords: Beef tenderness, Cold shortening, Sarcomere length, Warner–Bratzler shear force.
Keywords: Antimicrobial, Ground beef, Quality. doi:10.1016/j.meatsci.2014.09.082
doi:10.1016/j.meatsci.2014.09.083