Investigation of muscle-specific beef color stability at different ultimate pHs.

OBJECTIVE: This study was aimed to investigate the muscle-specific beef color stability at normal and high ultimate pHs. METHODS: The impact of muscle (Longissimus lumborum [LL] vs psoas major [PM]) and pH (normal ultimate pH [Np] vs high pH dark cutting beef [Hp]) on color stability, indicated by basic color traits, metmyoglobin reducing activity (MRA) and oxygen consumption (OC), as well as the lipid oxidation, were determined over 7 days of display at 4°C. RESULTS: Hp-LL had the highest pH (6.92), followed by Hp-PM (6.01), Np-PM (5.76), and Np-LL (5.52). Hp-LL had increased (p<0.05) a*, chroma and % oxymyoglobin during display. Hp-LL also had the highest metmyoglobin (MMb) reducing activity and OC among all the samples, thus, the greatest color stability, although very dark throughout storage, with lowest values for lightness (L*) and yellowness (b*). Np-LL also exhibited relatively high color stability, as a result of its lower % MMb and OC and higher MRA than psoas muscle samples. The 0.2 unit difference of the pH between Hp and Np psoas muscle, resulted in the difference of the color intensity, not the color stability. Interestingly, high pH psoas muscle (Hp-PM) did not have better color stability than Np-PM, and in fact had lower color stability than even Np-LL. The similar level of OC and lipid oxidation cannot explain the difference in color stability between Hp-PM and Np-LL. CONCLUSION: The Hp does not always show better color stability compared with Np beef, which depends on the muscle type. The balance of MRA and OC is important to keep the color in great intensity and stability in the meantime.

The effect of succinate on color stability of Bos indicus bull meat: pH-dependent effects during the 14-day aging period.

Bos taurus indicus bulls are very susceptible to pre-slaughter stress, which directly impacts the decline in muscle pH, leading to darker meat. The aim was to investigate the effect of succinate and atmosphere on the color stability of Nellore (Bos taurus indicus) Longissimus lumborum steaks classified by ultimate pH (pHu): normal pHu (5.40 ≤ pHu ≤ 5.79) and high pHu (pHu ≥ 5.80). The experimental treatment systems were: (i) vacuum packaging without succinate injection, (ii) HiOx-MAP (80 % O2 + 20 % CO2), and (iii) HiOx-MAP (80 % O2 + 20 % CO2) enhanced with sodium succinate injection (pH 5.4). Steaks from all treatment systems were stored at 4 °C for 14 days and tested for instrumental color, myoglobin content, oxygen consumption (OC), metmyoglobin-reducing activity (MRA), lipid oxidation, and microbiological analysis. High and normal pHu vacuum-packaged steaks exhibited greater color stability due to higher MRA. High and normal pHu steaks packaged with HiOx-MAP or HiOx-MAP enhanced with succinate showed improved color due to lower deoxymyoglobin content (%DMb) and OC up to the eighth day of storage. Still, succinate injection promoted increased (P < 0.05) lipid oxidation in normal pHu steaks and reduced MRA after 14 days. These findings emphasize the intricate interplay between pHu and packaging systems on Bos taurus indicus meat quality. Further research in this area could contribute to a better understanding of meat color abnormalities and provide insights into potential meat preservation and enhancement strategies.

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.

The retail color characteristics of vacuum-packaged beef m. longissimus lumborum following long-term superchilled storage.

This study investigated whether beef m. longissimus lumborum (LL) can be merchandised under retail conditions, following long-term superchilled storage (-1 °C). At 24 h post-mortem, the LL from left side of beef carcasses (n = 5) were fabricated into vacuum packaged beef thick-cuts, and then stored for 0, 2, 4, 8, 12, 16, or 20 weeks under superchilled conditions (-1 °C). Following storage, beef cuts were fabricated into steaks and aerobically displayed (0- 4 °C) for 5 days. Instrumental color, percentage of myoglobin redox forms, metmyoglobin reducing activity, oxygen consumption, and lipid oxidation were evaluated. After 4 weeks, the steaks had the highest a*, b* and chroma values between 1 and 3 days of display. Longer superchilled storage resulted in a rapid increase in discoloration and lipid oxidation which were observed in samples during display. Specifically, the a* values of steaks superchilled for 16 and 20 weeks approached the unacceptability threshold (a* ≥ 14.5) after 3 days of display.

Production system influences color stability and lipid oxidation in gluteus medius muscle.

OBJECTIVE: We aimed to evaluate the color and oxidative stability of beef gluteus medius (GM) from cattle raised in organic and non-organic production systems. METHODS: The GM samples (n = 10) were obtained from organic (ORG; n = 5) or non-organic (NORG; n = 5) beef samples, sliced into 2.54-cm steaks, packaged in aerobic conditions, and stored for nine days at 4°C. ORG and NORG steaks were compared regarding myoglobin concentration, pH, instrumental color, delta E (ΔE), metmyoglobin reducing activity (MRA), and lipid oxidation on days 0, 5, and 9. RESULTS: Feeding system did not influence (p>0.05) the myoglobin concentration. ORG steaks exhibited greater (p<0.05) meat pH, yellowness, and MRA, whereas NORG steaks exhibited greater (p<0.05) redness, chroma, R630/580, delta E, and lipid oxidation. ORG and NORG steaks exhibited similar (p>0.05) lightness and hue angle. During storage, ORG and NORG exhibited an increase in muscle pH, hue angle, and lipid oxidation; and a decrease (p<0.05) in redness, yellowness, chroma, and color stability (R630/580). Both samples exhibited a stable (p>0.05) pattern for lightness and MRA. CONCLUSION: Therefore, the production system can affect beef color and lipid stability during storage.

Changes in color, myoglobin, and lipid oxidation in beef patties treated by dielectric barrier discharge cold plasma during storage.

The objective of this work was to investigate the changes in color, metmyoglobin reducing activity (MRA), and lipid oxidation (TBARS) and their relationships in beef patties treated by dielectric barrier discharge cold plasma (DBD-CP) at different voltages and frequencies during storage at 4 °C. DBD-CP treatment, including treatment voltages and frequencies, caused the decrease of a⁎ value and MRA (P < 0.05), promoted the accumulation of metmyoglobin (P < 0.05), and significantly increased TBARS values (P < 0.05). It was the first time revealed that the effect of treatment voltage on the quality of beef patty was greater than that of frequency. In addition, there were significant and strong positive correlations between a⁎ value and MRA and negative correlations between a⁎ value, metmyoglobin (MMb)% and TBARS. Taken together, Data demonstrated that DBD-CP treatment can significantly affect meat redness, Mb contents, MRA, and lipid oxidation in ground beef during storage, and accelerate discoloration and lipid oxidation of meat.

Carbon Chain Length of Lipid Oxidation Products Influence Lactate Dehydrogenase and NADH-Dependent Metmyoglobin Reductase Activity.

The biochemical basis of lower metmyoglobin reducing activity (MRA) in high-oxygen modified atmospheric packaged (HiOx-MAP) beef than those in vacuum and polyvinyl chloride (PVC) packaging is not clear. To explore this, the effects of lipid oxidation products with varying carbon chain length on lactate dehydrogenase (LDH) and NADH-dependent metmyoglobin reductase activity were evaluated. Surface color, MRA, and lipid oxidation of beef longissimus lumborum steaks (n = 10) were measured during 6-day display. Further, two enzymes, LDH and NADH-dependent metmyoglobin reductase (n = 5), critical for MRA were incubated with or without (control) lipid oxidation products of varying carbon chain length: malondialdehyde (3-carbon), hexenal (6-carbon), and 4-hydroxynonenal (9-carbon). Steaks in HiOx-MAP had greater (P < 0.05) redness than vacuum and PVC, but had lower (P < 0.05) MRA and greater (P < 0.05) lipid oxidation on day 6. LDH and NADH-dependent metmyoglobin reductase activities were differentially influenced by lipid oxidation products (P < 0.05). The results indicate that the difference in reactivity of various lipid oxidation products on LDH (HNE > MDA = hexenal) and NADH-dependent metmyoglobin reductase (HNE = MDA > hexenal) activity could be responsible for lower MRA in HiOx-MAP.

Effects of Muscle-Specific Oxidative Stress on Cytochrome c Release and Oxidation-Reduction Potential Properties.

Mitochondria play a significant role in beef color. However, the role of oxidative stress in cytochrome c release and mitochondrial degradation is not clear. The objective was to determine the effects of display time on cytochrome c content and oxidation-reduction potential (ORP) of beef longissimus lumborum (LL) and psoas major (PM) muscles. PM discolored by day 3 compared with LL. On day 0, mitochondrial content and mitochondrial oxygen consumption were greater in PM than LL. However, mitochondrial content and oxygen consumption were lower (P < 0.05) in PM than LL by day 7. Conversely, cytochrome c content in sarcoplasm was greater on days 3 and 7 for PM than LL. There were no significant differences in ORP for LL during display, but ORP increased for PM on day 3 when compared with day 0. The results suggest that muscle-specific oxidative stress can affect cytochrome c release and ORP changes.

Effects of Metmyoglobin Reducing Activity and Thermal Stability of NADH-Dependent Reductase and Lactate Dehydrogenase on Premature Browning in Ground Beef.

Premature browning is a condition wherein ground beef exhibits a well-done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH-dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in-vitro. Beef patties (lean: fat = 85:15) were packaged in high-oxygen modified atmosphere (HiOX-MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH-dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX-MAP counterparts. Thermal stability of OxyMb, NADH-dependent reductase, and LDH were different and pH-dependent. LDH was able to generate NADH at 84 °C; whereas NADH-dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.

Effective Conversion of Metmyoglobin to Oxymyoglobin by Cysteine-Substituted Polyphenols.

Reaction products from the peroxidase-catalyzed oxidation of polyphenols in the presence of cysteine showed a potent activity for reducing metmyogolobin (MetMb) to bright-colored oxymyogolobin (MbO2). High-performance liquid chromatography (HPLC) purification of the reaction products from catechin, chlorogenic acid, dihydrocaffeic acid, hydroxytyrosol, nordihydroguaiaretic acid, and rosmarinic acid afforded corresponding S-cysteinyl compounds, the structures of which were determined by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). The isolated cysteinyl polyphenols showed a concentration-dependent reducing activity for MetMb to MbO2 for the initial 1 h. However, after 1 h, some of them decreased the amount of MbO2 produced. The effect of the number of cysteinyl sulfur substitutions in polyphenols on both MetMb reduction and MbO2 maintenance was examined using hydroxytyrosols with different numbers of cysteine substitutions; these hydroxytyrosols were synthesized from hydroxytyrosol and an N-acetylcysteine methyl ester. The hydroxytyrosol derivative substituted with two N-acetylcysteine esters exhibited the most effective reducing activity without any effect on MbO2.

Effects of natural antioxidants on colour stability, lipid oxidation and metmyoglobin reducing activity in raw beef patties.

BACKGROUND: Minced meats undergo oxidative changes and develop rancidity more quickly than intact muscle since grinding exposes more of the muscle surface to air and microbial contamination. Due to concerns about toxicological safety of synthetic antioxidants, recent studies have put more focus on natural antioxidant compounds derived from food components. METHODS: The effects of four natural antioxidants (vitamin E, carnosine, grape seed extract and tea catechins) on oxidative processes and metmyoglobin reducing activity in raw beef patties during refrigerated (4°C) storage were investigated and the results were compared with butylated hydroxyanisole treatment patties. The correlation of lipid oxidation, colour and metmyoglobin reducing activity of beef patties were also studied. RESULTS: Samples treated with carnosine had the highest redness values on the eighth day. Tea catechins, vitamin E and grape seed extract showed higher protective effect against lipid oxidation than carnosine. Metmyoglobin reducing activity increased greatly in all samples during the storage. Significant correlation between redness value and lipid oxidation was demonstrated, while a weak correlation between metmyoglobin reducing activity and any other parameters was shown.

Potential mechanisms of carbon monoxide and high oxygen packaging in maintaining color stability of different bovine muscles.

The objectives were to compare the effects of packaging methods on color stability, metmyoglobin-reducing-activity (MRA), total-reducing-activity and NADH concentration of different bovine muscles and to explore potential mechanisms in the enhanced color stability by carbon monoxide modified atmosphere packaging (CO-MAP, 0.4% CO/30% CO2/69.6% N2). Steaks from longissimus lumborum (LL), psoas major (PM) and longissimus thoracis (LT) packaged in CO-MAP, high-oxygen modified atmosphere packaging (HiOx-MAP, 80% O2/20% CO2) or vacuum packaging were stored for 0day, 4days, 9days, and 14days or stored for 9days then displayed in air for 0day, 1day, or 3days. The CO-MAP significantly increased red color stability of all muscles, and especially for PM. The PM and LT were more red than LL in CO-MAP, whereas PM had lowest redness in HiOx-MAP. The content of MetMb in CO-MAP was lower than in HiOx-MAP. Steaks in CO-MAP maintained a higher MRA compared with those in HiOx-MAP during storage. After opening packages, the red color of steaks in CO-MAP deteriorated more slowly compared with that of steaks in HiOx-MAP.

Influence of different production strategies on the stability of color, oxygen consumption and metmyoglobin reducing activity of meat from Ningxia Tan sheep.

Fifty male Ningxia Tan sheep were randomly divided into five groups (10 per group). Different feeding strategies were applied to each group for 120 days prior to slaughter. The sheep belong to five groups were pastured for 0 h (feedlot-fed), 2h, 4h, 8h, 12h per day on a natural grazing ground, respectively. M. semitendinosus muscle from Tan sheep was obtained after slaughter. Instrumental color, pH values, oxygen consumption rate, metmyoglobin reducing activity and relative metmyoglobin percentages were analyzed after 1, 3, 5, 7 and 9 days of refrigerated storage. Long-term daily grazing and herbage-based diet were conducive to maintain a lower oxygen consumption rate, higher metmyoglobin reducing activity and lower metmyoglobin accumulation. The combination of pasture-fed and feedlot-fed was conducive to weight gain, and at the same time, increased the color stability of the meat from Ningxia Tan sheep.