Metmyoglobin Reducing Ability Research Articles

Improvement of Color and Oxidative Stabilities in Nellore Bull Dark Meat in High-Oxygen Package by Lactate and Rosemary Oil Extract

This study aimed to improve the color and oxidative stabilities of dark Nellore bull steaks with greater-than-normal ultimate pH (pHu) by the injection (8% raw wet weight basis) of a solution with L-lactate (2.5%), phosphate (0.3%) and rosemary extract (0.06%), with further packaging in high oxygen atmosphere (HiOx MAP). Longissimus lumborum muscles from pasture-fed Nellore bulls were divided into three pHu ranges: normal (<5.80), intermediate (5.81-6.19), and high (≥6.2). Muscles were then halved, with sections were randomly assigned to non-enhanced (C, n = 6/pHu range) or injected (E, n = 6/pHu range) groups, at 72 h postmortem. Each section was cut into 2 cm-slices, which were HiOx-packed and then stored for 5 days (dark) and displayed for 9 days (fluorescent lighting) at 2 °C. Higher pHu steaks exhibited greater a*, b*, h*, C* and surface oxymyoglobin and lower surface deoxymyoglobin and oxygen consumption compared to those of normal pHu between days 0 and 5 (p < 0.05). Over the time, normal-pHu muscles showed oxidative protection (lower TBARS and greater metmyoglobin reducing ability values, p < 0.05) in enhanced-steaks. Therefore, enhancement and HiOx MAP seem to produce greater-than-normal pHu Nellore bull steaks with a preferable color and quality, even after display time.

Metabolomics and bioinformatic analyses to determine the effects of oxygen exposure within longissimus lumborum steak on beef discoloration.

Meat discoloration starts from the interior and spreads to oxymyoglobin layer on the surface. The effects of oxygen exposure within a steak on the metabolome have not been evaluated. Therefore, the objective of this study was to evaluate the impact of oxygen exposure on the metabolome of the longissimus lumborum muscle. Six United States Department of Agriculture (USDA) Low Choice beef strip loins were sliced into steaks (1.91-cm) and packaged in polyvinyl chloride overwrap trays for 3 or 6 d of retail display. The oxygen exposed (OE) surface was the display surface during retail, and the non-oxygen exposed (NOE) surface was the intact interior muscle. The instrumental color was evaluated using a HunterLab MiniScan spectrophotometer. To analyze the NOE surface on days 3 and 6, steaks were sliced parallel to the OE surface to expose the NOE surface. Metmyoglobin reducing ability (MRA) was determined by nitrite-induced metmyoglobin reduction. A gas chromatography-mass spectrometry was used to identify metabolites. The a* values of steaks decreased (P < 0.05) with display time. MRA was greater (P < 0.05) in the NOE surface compared with the OE surface on days 3 and 6. The KEGG pathway analysis indicated the tricarboxylic acid (TCA) cycle, pentose and glucuronate interconversions, phenylalanine, tyrosine, and tryptophan metabolism were influenced by the oxygen exposure. The decrease in abundance of succinate from days 0 to 6 during retail display aligned with a decline in redness during display. Furthermore, citric acid and gluconic acid were indicated as important metabolites affected by oxygen exposure and retail display based on the variable importance in the projection in the PLS-DA plot. Citric acid was lower in the NOE surface than the OE surface on day 6 of retail display, which could relate to the formation of succinate for extended oxidative stability. Greater alpha-tocopherol (P < 0.05) in the NOE surface supported less oxidative changes compared to the OE surface during retail display. These results indicate the presence of oxygen can influence metabolite profile and promote migration of the metmyoglobin layer from interior to surface.

228 Metabolite Differences between the Oxygen-Exposed and non-Oxygen Exposed Surfaces of the Longissimus Lumborum Muscle

Abstract The effects of oxygen exposure on the metabolites present in beef longissimus lumborum have not been evaluated. Therefore, the objective of this study was to evaluate the impact of oxygen exposure on the color attributes and metabolites present in longissimus lumborum muscle. USDA Low Choice beef strip loins were sliced into steaks (1.91 cm) and packaged in polyvinyl chloride overwrap trays for 3 or 6 days of retail display. The oxygen exposed (OE) surface was considered the display surface during retail, and the non-oxygen exposed (NOE) surface was the intact interior muscle. Instrumental color was evaluated using a HunterLab Miniscan EZ spectrophotometer. To analyze the NOE surface on day 3 and 6, steaks were sliced parallel to the OE surface to expose the NOE surface. Metmyoglobin reducing ability (MRA) was determined by submerging samples in nitrite to induce metmyoglobin reduction. A gas chromatography-mass spectrometry was used to identify metabolites. The least square means were determined using the GLIMMIX procedure of SAS with significance at a P &amp;lt; 0.05. Metabolites were analyzed using the MetaboAnalyst 5.0. Redness (a* values) of steaks decreased (P &amp;lt; 0.05) with greater display time. MRA was greater (P &amp;lt; 0.05) in the NOE surface compared with the OE surface on days 3 and 6. Upregulation of glucose-1-phosphate and down regulation of gluconic acid, ribose, sedoheptulose-7-phosphate in the NOE surface on day 0 compared with NOE on day 6 indicates a shift from glycolysis to the pentose phosphate pathway. On day 6 of display, the OE surface was upregulated in xanthine and gluconic acid, indicating an increase in purine and pentose phosphate metabolisms, while there was a down regulation of mannitol and malic acid compared with the NOE surface. These results indicate the presence of oxygen can influence metabolite profile and negatively influence MRA and color.

Spectro 1-A Potential Spectrophotometer for Measuring Color and Myoglobin Forms in Beef.

The objective of this study was to compare the Color Muse Spectro 1 sensor to the HunterLab MiniScan XE Plus spectrophotometer for evaluating beef color. Color coordinates (lightness (L*), redness (a*), yellowness (b*), chroma (C*), and hue (h*)), myoglobin redox forms (metmyoglobin (MMb), deoxymyoglobin (DMb), and oxymyoglobin (OMb)), and metmyoglobin reducing ability (MRA) were measured on beef steaks over a 5-days storage period. The results indicated that L*, b*, C*, MMb%, OMb%, and MRA% values obtained with Spectro 1 were comparable to those of MiniScan. However, Spectro 1 values for a* were overestimated compared to MiniScan (p < 0.05), whereas those for h* and DMb% were underestimated (p < 0.05). Regardless, Spectro 1 had the capability to detect changes in color coordinates, myoglobin forms, and MRA throughout the storage period. Bland–Altman plots demonstrated that L*, b*, and C* are interchangeable between the two instruments, but it was not the case for a*, h*, myoglobin forms, and MRA. Color coordinates measured by Spectro 1 exhibited excellent stability over time, evidenced by the low total color difference (ΔE*ab) values. Collectively, these findings indicate that Spectro 1 is a potential alternative spectrophotometer for studying meat color and myoglobin redox forms.

53 Oxygen Exposure Effects on the Biochemical Attributes oflongissimus Lumborum Muscle During Retail Display

Abstract Limited studies have compared the effects of oxygen within a steak on biochemical properties. The objective was to evaluate the effects of oxygen exposure on the biochemical attributes of longissimus lumborum muscle. Steaks were (1.91 cm) sliced from USDA Low Choice beef strip loins (n = 7), packaged in polyvinyl chloride overwrap trays, and randomly assigned to day 3 or day 6 in retail display. During display, instrumental color was evaluated daily using a HunterLab MiniScan spectrophotometer. The display surface was considered as oxygen exposed (OE), while the interior of the steak was denoted as not exposed to oxygen (NOE). NOE was obtained by slicing the steak in half parallel to the previously OE surface. The NOE pieces were evaluated for bloom, while NOE and OE surfaces were used oxygen consumption (OC) and metmyoglobin reducing ability (MRA). Nitrite-induced metmyoglobin reduction was used to measure MRA, while changes in deoxymyoglobin level with vacuum were used as an indicator of OC. The data were analyzed using the GLIMMIX Procedure of SAS (n = 7 replications) and considered significance at P &amp;lt; 0.05. With increased display time, the a* values (redness) decreased (P &amp;lt; 0.05) for instrumental color. NOE steak surface had greater (P &amp;lt; 0.05) MRA compared with OE surfaces. Oxygen exposure affected the OC of the steaks, with the OE surfaces having lower (P &amp;lt; 0.05) OC compared to NOE surfaces on day 6 of display. The exposure of oxygen to the muscle resulted in a decrease in activity, paralleling in decline in retail color and color stability. In conclusion, the presence of oxygen can result in negative impacts on the shelf life of steaks; however, the non-exposed interior of muscle remains more biochemically active.

Effects of quality grade and intramuscular location on beef semitendinosus muscle fiber characteristics, NADH content, and color stability.

The objective of this study was to determine the impact of quality grade and steak location on color stability of semitendinosus (ST) steaks during a 9-d refrigerated study. Twenty-one ST muscles (12 Choice and 9 Select) were purchased from a commercial beef packing plant and fabricated into twelve 2.54-cm thick steaks per muscle. Steaks 1, 6, and 12 were designated for immunohistochemistry while remaining steak locations of proximal (steaks 2 to 4), middle (5 to 8), and distal (9 to 11) were randomly assigned to 0, 4, or 9 d of simulated retail display. Surface color attributes of day-9 steaks were recorded daily by a visual color panel and spectrophotometer. On days 0, 4, and 9 of display, steaks were analyzed for metmyoglobin reducing ability (MRA) and oxygen consumption (OC). Grade × day of display (DOD) interactions were detected for L*, a*, surface oxymyoglobin (OMb) and metmyoglobin (MMb) percentages, and visual panel surface redness and discoloration scores (P ≤ 0.02); however, no Grade × DOD interactions were observed for MRA or OC (P > 0.17). There were location main effect (LOC) × DOD interactions for L*, a*, surface MMb, visual panel surface redness and discoloration, and MRA (P ≤ 0.02). Distal steaks had lower L* values compared with the other locations (P < 0.01), which coincided with steaks being rated visually darker red (P < 0.01). Proximal steaks had greater a* values and had less surface discoloration than middle steaks (P < 0.05), which had an increased percentage of surface MMb (P ≤ 0.04). Distal and proximal steaks had increased MRA compared with middle steaks on days 0 and 4 (P < 0.05), and distal steaks had greater OC than the other locations throughout display (P < 0.01). There were fewer type I fibers at the proximal end with a greater percentage located at the middle and distal ends, and an increased percentage of type IIX fibers at the middle and proximal locations (P ≤ 0.01). Less type IIA fibers were detected at the middle LOC compared with the other two locations (P < 0.10). Larger type I, IIA, and IIX fibers were located at the proximal and middle locations compared with the distal LOC (P < 0.01). ST color and color-stability characteristics were influenced by DOD and LOC, which may partially be explained by differences in fiber types among locations.

PSXIV-2 Late-Breaking: The effect of nicotinamide riboside on pork loin chop color stability – a pilot study

Abstract The objective of this pilot study was to examine the effect of oral supplementation of nicotinamide riboside chloride (NR) on pork loin chop color stability. Seven days prior to the beginning of the experiment, 10 finishing barrows (initial BW 111.9±1.6 kg) were assigned to individual pens that allowed ad libitum access to food and water. Barrows were randomly assigned to 1 of 2 NR treatments, 0 or 30 mg/kg daily of NR (ChromaDex, Irvine, CA) mixed in Karo syrup and administered by oral gavage. Barrows were administered their assigned treatment for 10 d, after which they were harvested under USDA inspection. Twenty-four hours postmortem, whole-boneless loins were fabricated, vacuum packaged, and aged for 10 d. Loins were cut into 3 chops immediately posterior to the spinalis dorsi, with chop 1 being used for day-0 metmyoglobin reducing ability (MRA) analysis, chop 2 being used for day-4 MRA and oxygen consumption rate (OCR) analyses, and chop 3 for 8-day objective/subjective color evaluation and MRA and OCR analyses. There were no Treatment × Day interactions for all objective and subjective color measurements (P &amp;gt; 0.77). Day of display affected all measures consistent with the discoloration of meat (P &amp;lt; 0.02), except L* value which was not affected (P = 0.14). Objective measures indicated NR chops had greater a*, greater surface oxymyoglobin, and less surface metmyoglobin formation over the 8-day display period (P &amp;lt; 0.01). Panelists indicated NR chops had less discoloration form over the entire 8-day display period (P &amp;lt; 0.01), but treatment did not affect OCR and MRA (P &amp;gt; 0.19). Feeding NR at the end of the finishing period may enhance visual pork loin chop color during simulated retail display; however, a larger study is needed to confirm this finding.

Mitochondrial functionality and beef colour: A review of recent research

The bright-red colour of meat that consumers prefer depends on the depth of oxygen diffusion into the tissue and myoglobin oxygenation. Interestingly, both processes are influenced by mitochondrial activity in postmortem muscle. The transition of muscle metabolism from aerobic to anaerobic pathways affects various cellular processes including mitochondrial functionality. Numerous studies report that even with compromised structure, mitochondria continue to influence postmortem beef colour via oxygen consumption and metmyoglobin reducing activity. Hence, an in-depth understanding of the pre- and post-harvest factors affecting mitochondrial functionality can significantly enhance existing knowledge of meat colour and colour stability. Several comprehensive reviews have discussed the biochemical factors affecting meat colour, but there are only a few that have sections on the impact of mitochondria on beef colour. Furthermore, advancement of high-throughput techniques such as metabolomics and proteomics has enabled researchers to elucidate metabolite and protein changes related to mitochondria. Therefore, the objective of this review is to provide an overview on the role of mitochondria in beef colour, with a focus on recent advances in mitochondrial research, oxygen consumption, and metmyoglobin reducing ability. Keywords: Myoglobin, metmyoglobin reducing activity, meat colour, metabolomics, oxygen consumption, proteomics

Effects of aldehyde products of lipid oxidation on the color stability and metmyoglobin reducing ability of bovine Longissimus muscle.

Lipid oxidation and metmyoglobin (MMb) reduction are popular issues in meat color research. This study evaluated the effects of aldehyde products, particularly 4-hydroxy-2-nonenal (HNE) and hexenal, of lipid oxidation on the oxymyoglobin stability, mitochondrial membrane permeability, MMb reduction ability, electron transport chain-mediated MMb reduction, and nicotinamide adenine dinucleotide reduced form (NADH)-dependent MMb reductase activity of bovine Longissimus muscle. The results indicated that HNE and hexenal accelerate the oxidation rate of oxymyoglobin, significantly increase the permeability of the mitochondrial membrane, and inhibit electron transport chain-mediated MMb reduction. However, HNE and hexenal were found to exert no effect on the activity of NADH-dependent MMb reductase. Thus, the aldehyde products of lipid oxidation could damage the microstructure of mitochondria and inhibit mitochondria-mediated MMb reduction, which is disadvantageous in terms of the color stability of fresh bovine Longissimus muscle.

Effect of Intramuscular Fiber Type Variation on Beef Semitendinosus Steak Metmyoglobin Accumulation during Retail Display

ObjectivesThe objective of this study was to examine effects of steak location (LOC) on muscle fiber type distribution and metmyoglobin accumulation of Semitendinosus (ST) steaks.Materials and MethodsTwenty ST muscles (IMPS 171C) from a commercial abattoir were wet aged for 22 d. Progressing from the proximal to distal end, each ST was fabricated into twelve 2.54-cm thick steaks. Steaks 1 through 4 were designated proximal (PROX), 5 through 8 were designated middle (MID), and 9 through 12 were designated distal (DIST), with steaks 1, 6, and 12 utilized for fiber type analysis. Remaining steaks within each location were randomly assigned to 0, 4, or 9 d of simulated retail display under fluorescent light. Day-0 and -4 steaks were utilized for metmyoglobin reducing ability (MRA) analysis. Day-9 steaks were subjected to daily objective and subjective steak surface metmyoglobin analyses, and day-9 MRA analysis.ResultsThere were Location × Day interactions (P < 0.01) for surface metmyoglobin percentage and visual panel percent discoloration scores. On d 0 of display, PROX steaks had less surface metmyoglobin than the other locations (P < 0.01), which were not different (P = 0.51). On d 1, MID steaks had more metmyoglobin than the other locations (P < 0.04), and DIST steaks had more (P < 0.01) metmyoglobin than PROX steaks. From d 2 to 6, MID steaks had more metmyoglobin than steaks from other locations (P < 0.01), which did not differ (P > 0.17). On d 7 of display, MID steaks tended to have more metmyoglobin than steaks from other locations (P < 0.09), which did not differ (P = 0.65). On d 8 and 9, MID steaks had more metmyoglobin than PROX steaks (P < 0.02), and DIST steaks did not differ from the two locations (P > 0.15). No differences in panel percent discoloration scores were found between muscle locations on d 0 (P = 1.00); however from d 1 to 5, MID steaks had more discoloration than PROX and DIST steaks (P < 0.04), which did not differ (P > 0.12). From d 6 to 8, MID steaks had more discoloration than PROX steaks (P < 0.05), and steaks from both locations did not differ from DIST steaks (P > 0.16). On d 9, PROX steaks had less discoloration than MID and DIST steaks (P < 0.03), which did not differ (P = 0.72). At d 0 and 4 of display, PROX and DIST steaks had greater reducing ability than MID steaks (P < 0.01), but were not different (P = 0.33) from one another. At d 9 of display, all locations possessed the same MRA (P > 0.51).Location affected percentage of all 3 fiber types (P < 0.01). There were less type I fibers in PROX steaks than the other 2 locations (P < 0.01), and MID steaks tended to have more (P = 0.10) than DIST steaks. Proximal steaks had more (P < 0.01) type IIA fibers than the MID location, and tended to have more (P = 0.07) than DIST steaks. The DIST steaks tended to have more (P = 0.08) type IIA fibers than MID steaks. Steaks from PROX and MID locations did not differ (P = 0.72) in type IIX fiber percentage, but did possess more type IIX fibers than the DIST steaks (P < 0.01).ConclusionThroughout most of display, ST MID steaks accumulated more surface metmyoglobin than PROX and DIST steaks, which was also detected by a visual panel. Steaks from the MID location possessed less MRA compared to the other 2 locations on d 0 and 4 of display. Differences in MRA and discoloration may be due to the MID location possessing less type IIA fibers.

Light Source Influences Color Stability and Lipid Oxidation in Steaks from Low Color Stability Beef Triceps brachii Muscle

AbstractColor of retail fresh meat is one of the most important quality attributes affecting purchasing decisions for consumers. The objective of this study was to evaluate the impact of different light sources on surface color and lipid oxidation during retail display of fresh steaks from beef Triceps brachii (TB), a muscle with low color and lipid oxidative stabilities. Steaks (n = 12) from 20 TB muscles were overwrapped with oxygen-permeable polyvinyl chloride, and assigned to one of three lighting treatments, i.e., high UV fluorescent (HFLO), low UV fluorescent (FLO), and light emitting diode (LED), in temperature-controlled deli cases. Steaks were removed on retail display d 1, 3, 5, and 7 for evaluating instrumental color (L*, a*, and b* values), surface myoglobin redox forms, metmyoglobin reducing ability, and lipid oxidation. Surface redness (a* values) of TB steaks decreased (P &lt; 0.05) during retail display. Light source influenced a* values, with HFLO-displayed steaks having higher (P &lt; 0.05) a* values than steaks exposed to both FLO and LED light sources. Oxymyoglobin levels were higher (P &lt; 0.05) for TB steaks displayed under HFLO lights than those displayed under FLO (on d 3 and 7) or LED (on d 5 and 7) lights. Steaks displayed under HFLO lights had lower (P &lt; 0.05) metmyoglobin levels than those exposed to both FLO and LED lights on d 5 and 7. Lipid oxidation increased over retail display time, and on d 7 of retail display, steaks exposed to HFLO had less (P &lt; 0.05) lipid oxidation than those displayed in FLO or LED. The results of the present study indicated that color stability and lipid oxidation in TB steaks during retail display are impacted by light source. The HFLO lighting may help to minimize surface discoloration and lipid oxidation in low color stability beef muscles.

Effect of dietary zinc and ractopamine hydrochloride on pork chop muscle fiber type distribution, tenderness, and color characteristics1,2

A total of 320 finishing pigs (PIC 327 × 1050; initially 98 kg) were used to determine the effects of adding Zn to diets containing ractopamine HCl (RAC) on muscle fiber type distribution, fresh chop color, and cooked meat characteristics. Dietary treatments were fed for approximately 35 d and consisted of a corn-soybean meal-based negative control (CON), a positive control diet with 10 mg/kg of RAC (RAC+), and the RAC+ diet plus 75, 150, or 225 mg/kg added Zn from either ZnO or Availa-Zn. Loins randomly selected from each treatment (n = 20) were evaluated using contrasts: CON vs. RAC+, interaction of Zn level × source, Zn level linear and quadratic polynomials, and Zn source. There were no Zn source effects or Zn source × level interactions throughout the study (P > 0.10). Pigs fed RAC+ had increased (P < 0.02) percentage type IIX and a tendency for increased (P = 0.10) percent type IIB muscle fibers. Increasing added Zn decreased (linear, P = 0.01) percentage type IIA and tended to increase (P = 0.09) IIX muscle fibers. On d 1, 2, 3, 4, and 5 of display, pork chops from pigs fed the RAC+ treatment had greater (P < 0.03) L* values compared to the CON. On d 0 and 3 of display, increasing added Zn tended to decrease (quadratic, P = 0.10) L* values and decreased (quadratic, P < 0.03) L* values on d 1, 2, 4, and 5. Pigs fed RAC+ had decreased (P < 0.05) a* values on d 1 and 4 of display and tended to have decreased (P < 0.10) a* values on d 0 and 2 compared to CON pork chops. Pork chops from the RAC+ treatment had a tendency for increased (P < 0.08) oxymyoglobin percentage compared to CON pork chops on d 1, 2, 4, and 5. On d 0, as dietary Zn increased in RAC+ diets, there was a decrease (linear, P < 0.01) in the formation of pork chop surface oxymyoglobin percentage. Metmyoglobin reducing ability (MRA) of pork chops on d 5 was decreased in the RAC+ group. Chops from pigs fed added Zn had increased (quadratic, P < 0.03) MRA on d 3 and 5 of the display period. There was a trend for increased (linear, P = 0.07) cooking loss with increasing Zn in RAC diets and treatments did not affect tenderness as measured by Warner-Bratzler shear force (P > 0.07). In conclusion, RAC+ diets produced chops that were lighter and less red but maintained a greater percentage of surface oxymyoglobin throughout a 5-d simulated retail display. Ractopamine reduced MRA at the end of the display period, but supplementing Zn to RAC diets restored MRA to near CON treatment levels at the end of the display period.

Effects of the Programmed Nutrition Beef Program on meat quality characteristics1,2

The objective of this study was to examine the effects of alternative finishing strategies on beef steak color and cooked meat characteristics. Beef steers (n = 64 pens; 8 steers/pen) were allocated to a randomized complete block design with a 2 × 2 factorial treatment arrangement and initial body weight serving as the blocking factor. Factor 1 consisted of dietary treatment with cattle either being fed a conventional feedlot diet (CON) or a diet that included Programmed Nutrition Beef Program supplements. Cattle in the Programmed Nutrition (PN) treatments were fed in two-stages: 1) the basal diet with Programmed Nutrition Beef Receiver from d 1 to 20 and the basal diet with Programmed Nutrition Beef Finisher from d 21 to harvest. Factor 2 consisted of the inclusion (EGP+) or absence (EGP-) of an exogenous growth promoting program. Steers in the EGP+ treatments were implanted initially with Component E-S, reimplanted with Component TE-IS, and fed 400 mg · d(-1) · steer(-1) of ractopamine hydrochloride for the final 28 d before harvest. Steers were harvested on d 175 of feeding and 1 strip loin was removed from 2 carcasses selected at random from each pen for transport to Kansas State University. After 14 d of aging, loins were fabricated into 2.54-cm thick steaks for objective and trained sensory panel measurement of cooked meat characteristics and objective color measurements during 7 d retail display. There were no interactions (P > 0.10) between feeding strategy and exogenous growth promotants for all objective measures of color and cooked meat characteristics. Throughout the display period, PN steaks were darker (P = 0.02) than CON steaks, but surface percentages of oxymyoglobin and metmyoglobin and metmyoglobin reducing ability were unaffected by feeding strategy (P > 0.10). Loins and steaks from PN cattle possessed decreased moisture loss during aging and cooking (P < 0.01). Trained sensory panel evaluation of cooked meat revealed a dietary program × growth promotant interaction for myofibrillar tenderness, connective tissue amount, and overall tenderness (P = 0.01). Compared to the CON/EGP- and PN/EGP- treatments, steaks from the CON/EGP+ and PN/EGP+ treatments were evaluated by panelists as being less myofibrillar and overall tender (P < 0.05). The alternative feeding strategies presented in this study can favorably impact water-holding capacity without negatively compromising retail display discoloration.

Effects of dietary zinc level and ractopamine HCl on pork chop tenderness and shelf-life characteristics (2013)

A total of 320 finishing pigs (PIC 327 × 1050; initially 216 lb) were utilized to determine the effects of adding Zn to diets containing ractopamine HCl (RAC) on muscle fiber type distribution, fresh chop color, and cooked meat characteristics. Dietary treatments were fed for approximately 35 d and consisted of: a corn-soybean meal–based negative control (CON); a positive control diet with 10 ppm of RAC (RAC+); and the RAC+ diet plus 75, 150, or 225 ppm added Zn from either ZnO or Availa-Zn. Loins from 80 barrow and 80 gilt carcasses were evaluated. No Zn source effect or Zn source × level interactions we observed during the study (P > 0.10). Pigs fed the RAC+ had increased (P < 0.02) percentage type IIX and a tendency for increased percentage type IIB muscle fibers. Increasing added Zn decreased (linear, P = 0.01) percentage type IIA and tended to increase (P = 0.09) IIX muscle fibers. On d 1, 2, 3, 4, and 5 of display, pork chops from pigs fed the RAC+ treatment had greater (P < 0.03) L* values (lighter) compared with the CON. On d 0 and 3 of display, increasing added Zn tended to decrease (quadratic, P = 0.10) L* values and decreased (quadratic, P < 0.03) L* values on d 1, 2, 4, and 5. Pigs fed RAC+ had decreased (P < 0.05) a* values (less red) on d 1 and 4 of display and tended to have decreased (P < 0.10) a* values on d 0 and 2 compared with CON pork chops. RAC+ decreased (P < 0.001) metmyoglobin reducing ability (MRA) of pork chops on d 5. Chops from pigs fed added Zn had increased (quadratic, P < 0.03) MRA on d 3 and 5 of the display period. There was a trend for increased (linear, P = 0.07) cooking loss as added Zn increased in RAC diets. In conclusion, RAC+ diets produced chops that were lighter and less red but maintained a higher percentage of surface oxymyoglobin throughout a 5-d simulated retail display. RAC+ reduced MRA at the end of the display period, but supplementing Zn to RAC diets restored MRA to near CON treatment levels at the end of the display period.; Swine Day, Manhattan, KS, November 21, 2013

Effect of freeze–thaw cycles on physicochemical properties and color stability of beef semimembranosus muscle

The effects of freeze–thaw cycle on the physicochemical properties and color stability of beef semimembranosus muscle during cold storage were investigated. Meat was tested for effects on color (CIE L ⁎, a ⁎, b ⁎), myoglobin content (%), metmyoglobin reducing ability (MRA), thiobarbituric acid reactive substances (TBARS), heme pigment content (ppm), SDS-PAGE profile, and tissue microstructure. Fresh meat showed significantly ( p < 0.05) higher values of CIE a ⁎, CIE b ⁎, and oxymyoglobin content (%) compared to freeze–thawed meat during cold storage. However, metmyoglobin content (%) was higher in freeze–thawed meat than in fresh meat during 7 days of cold storage. There were no significant differences ( p > 0.05) in MRA among the treatments during cold storage. The TBARS value (0.387 mg/kg) of fresh meat was significantly ( p < 0.05) higher than those of freeze–thawed meats after 5 days of cold storage. These results suggest that the freeze–thaw process could accelerate the deterioration of meat color.

Contributions of Muscles of Various Color Stabilities to the Overall Color Stability of Ground Beef

Ground high (HCS), intermediate (ICS), and low color stability (LCS) cow muscles were used to investigate effects of blending muscles of different color stabilities on ground beef display color. Six formulations at 90% and 80% lean points combining HCS, ICS, and LCS muscles were: 50% HCS + 50% ICS; 50% HCS + 50% LCS; 50% ICS + 50% LCS; 33.3% HCS + 33.3% ICS + 33.3% LCS; 75% HCS + 25% LCS; and 25% HCS + 75% LCS. Patties were packaged in a high oxygen (80% O(2), 20% CO(2)) modified atmosphere, held in dark storage for 5 d, then displayed for 4 d. The 80% lean patties containing >or= 50% HCS had the brightest red initial visual color. During display 75% HCS + 25% LCS at both lean points had the most cherry-red display color. Patties containing a greater proportion of HCS had greater metmyoglobin reducing ability throughout display. HCS, ICS, and LCS muscle can be mixed without adverse color affects, provided LCS muscle is <or= 25%, and HCS muscle is >or= 50% of the blend.

Cow biological type affects ground beef colour stability

To determine the effects of cow biological type on colour stability of ground beef, M. semimembranosus from beef-type (BSM) and dairy-type (DSM) cows was obtained 5 d postmortem. Three blends (100% BSM, 50% BSM + 50% DSM, 100% DSM) were adjusted to 90% and 80% lean points using either young beef trim (YBT) or beef cow trim (BCT), then packaged in high oxygen (High-O 2; 80% O 2) modified atmosphere (MAP). The BSM + YBT patties had the brightest colour initially, but discoloured rapidly. Although DSM + BCT patties had the darkest colour initially, they discoloured least during display. Metmyoglobin reducing ability of ground DSM was up to fivefold greater than ground BSM, and TBARS values of BSM was twofold greater than DSM by the end of display (4 d). Though initially darker than beef cow lean, dairy cow lean has a longer display colour life and may be advantageous to retailers using High-O 2 MAP.

Improving color stability of beef top round (2001)

The beef inside round muscle, especially the deep portion, has poor color stability, a troublesome condition for the meat industry. We examined influences of pre-rigor temperature and pH decline on chemistry of the inside (deep) semimembranosus (ISM) and outside (surface) semimembranosus (OSM) in relation to initial color and stability. Cold-boned ISM had a slower chill rate; faster pH decline; more denatured protein; less metmyoglobin reducing ability, oxygen consumption, and water holding capacity; and a lighter, less stable color than the OSM. Cold-boned steaks were two-toned in color and discolored by day 3 of display. Hotboned ISM and OSM chilled at the same rate, had similar pH declines, similar chemical characteristics, and acceptable color traits up to day 5 of display. Techniques that chill the entire beef SM faster produced a more uniform stable color, extended the color life of the ISM, and minimized rework and discounting.