Effects of high-pressure processing on cooked color and eating qualities of dark-cutting beef

High meat pH leads to an undercooked or an abnormal pink appearance in fully-cooked product. High-pressure processing (HPP) promotes protein denaturation. The objective was to evaluate the effects of HPP on cooked steak color and sensory attributes of dark-cutting beef. USDA Choice (mean pH = 5.5) and dark-cutting (mean pH = 6.3) strip loin sections were vacuum packaged and treated with 0 (no HPP), 300, 450, and 600 MPa of pressure for 90 s using chilled water. Steaks were randomly assigned to measure external cooked color, Warner- Bratzler shear force, and trained sensory panel. Applying 300 MPa of pressure improved ( P \u3c 0.05) redness of raw dark-cutting steaks compared with control. HPP treatments did not influence ( P \u3e 0.05) a∗ and chroma of the external cooked steak color. HPP treatments also did not affect ( P \u3e 0.05) initial juiciness, sustained juiciness, beef flavor intensity, or overall acceptability. However, 600 MPa made dark-cutting steaks tougher and lighter ( P \u3c 0.05) in appearance than all other treatments. In conclusion, low (300 MPa) and moderate (450 MPa) pressure levels improved raw steak redness without affecting the eating qualities of dark-cutting cooked steaks. HPP did not minimize the undercooked appearance commonly associated with high-pH beef

Metabolite Profile Differences between Beef Longissimus and Psoas Muscles during Display

The objective of this research was to compare metabolite profiles between beef and muscles during display. Beef short loins were collected 3 d postmortem ( = 10). Steaks were cut from each (LL) and (PM) muscle and displayed under retail conditions for 7 d. Surface color, biochemical properties, and metabolites were analyzed during storage. PM decreased in redness ( < 0.05) by d 3 of display compared with LL. There were differences in metabolite concentrations ( < 0.05) between each muscle type at each time point. Sugars, amino acids, tricarboxylic acid cycle intermediates, and glycolytic substrates were detected in both muscles. Glycolytic metabolites such as pyruvic acid, glucose–6–phosphate, and fructose were greater ( < 0.05) in LL than PM at all display times. On d 0, the intensity of pyruvic acid in LL and PM were 142 and 42, respectively. Citric acid and succinic acid were lower on d 0, but were greater ( < 0.05) in LL compared with PM by d 7 of display. Carnitine was lower ( < 0.05) in LL than PM at all display times. On d 7, carnitine level in LL was 4.1 while in PM was 13,500. The results suggest that in addition to muscle-specific differences in mitochondrial and enzyme activities, inherent metabolite differences also may contribute to muscle color stability

Species-Specificity in Myoglobin Oxygenation and Reduction Potential Properties

The objective was to compare oxygenation and reduction potential properties of bovine and porcine myoglobins in-vitro. Cyclic voltammetry and homology-based myoglobin modeling were used to determine the species-specific effects on myoglobin reduction potential and oxygenation properties at pH 5.6, 6.4, and 7.4. At all pHs, porcine myoglobin had greater (P = 0.04) oxygen affinity than bovine myoglobin. For both species, oxygen affinity was higher at pH 6.4 > pH 7.4 > 5.6 (P = 0.0002). Myoglobin reduction potential for both species was affected by pH (P < 0.0001). The redox potentials became more negative as pH increased, indicating a proton-coupled electron transfer. There were no differences (P = 0.51) between species in reduction potential properties of heme. Homology-based myoglobin modeling indicated that the porcine myoglobin has a shorter distance between the distal histidine and heme than does bovine myoglobin. The variation in amino acid composition between bovine and porcine myoglobin could be partially responsible for differences in oxygen affinity

Use of High-Pressure Processing to Improve the Redness of Dark-Cutting Beef

The objective was to evaluate the effects of high-pressure processing (HPP) levels on retail color of dark-cutting beef. Eight USDA Choice (mean pH = 5.5; normal-pH beef) and 12 dark-cutting (mean pH = 6.3) strip loins were obtained from a commercial packing plant within 2 d of harvest. Dark-cutting loins were cut into equal sections, vacuum packaged, and randomly assigned to 0 (no HPP), 300, 450, and 600 MPa of pressure for 90 s using chilled water. Following 48 h of dark storage at 2°C, dark-cutting loin sections were cut into 1.9-cm-thick steaks, placed in Styrofoam trays overwrapped in polyvinyl chloride (PVC) film, and placed in a simulated retail display for 8 d. The surface color readings were measured every 24 h using a HunterLab MiniScan XE Plus spectrophotometer, whereas a trained color panel (n = 6) evaluated discoloration, paleness, and lean color on steaks. Lipid oxidation was evaluated on day 0, 4, and 8 of retail display, and structural changes were determined using light microscopy on day 0 of display. There was a significant HPP level × day of retail display interaction for all instrumental color measurements. Throughout the retail display, L* values of 450 and 600 MPa applied steaks were greater (P \u3c 0.05) than 300 MPa and controls. There was a significant pressure level × day of retail display interaction when panelists evaluated lean color and discoloration. Steaks treated at 300 MPa exhibited brighter red color and lower (P = 0.0023) thiobarbituric acid reactive substance values than other pressure levels and normal-pH control steaks. Light microscopy analysis indicated that HPP increased space between muscle structures. In conclusion, low (300 MPa) and moderate (450 MPa) pressure levels can improve redness of dark-cutting steaks

Role of postmortem bioenergetics in beef colour chemistry

Meat colour is one of the primary factors affecting the acceptability of retail meat cuts. Therefore, displaying the natural bright-red colour of meat is a major goal of the meat industry. Consumers frequently reject to retail meat cuts with discolouration even at low levels of surface browning and/or darkening, which in turn results in significant food waste and economic loss. Thus, understanding the factors that influence meat colour deviations such as discolouration or darkening is crucial in developing effective strategies to minimise the display colour-related quality issues. Numerous factors influence series of biochemical reactions of post-mortem muscles and the chemical state of myoglobin, which ultimately affects meat colour and colour stability. Recent studies have demonstrated the incidence of dark-cutting beef post-mortem can be attributed to the combination of lower glycolytic potential, less glycolytic metabolites, enzymes and dysregulated energy metabolism. This review will focus on the role of post-mortem bioenergetics and mitochondria dynamics that affect beef colour chemistry

National Beef Quality Audit–2016: assessment of cattle hide characteristics, offal condemnations, and carcass traits to determine the quality status of the market cow and bull beef industry

To continue the series that began in 1994, the National Beef Quality Audit (NBQA) – 2016 was conducted to quantify the quality status of the market cow and bull beef sector, as well as determine improvements made in the beef and dairy industry since 2007. The NBQA-2016 was conducted from March through December of 2016, and assessed hide-on carcasses (n = 5,278), chilled carcasses (n = 4,285), heads (n = 5,720), and offal items (n = 4,800) in 18 commercial processing facilities throughout the United States. Beef cattle were predominantly black-hided; 68.0% of beef cows and 67.2% of beef bulls possessed a black hide. Holstein was the predominant type of dairy animal observed. Just over half (56.0%) of the cattle surveyed had no mud contamination on the hide, and when mud was present, 34.1% of cattle only had small amounts. Harvest floor assessments found 44.6% of livers, 23.1% of lungs, 22.3% of hearts, 20.0% of viscera, 8.2% of heads, and 5.9% of tongues were condemned. Liver condemnations were most frequently due to abscess presence. In contrast, contamination was the primary reason for condemnation of all other offal items. Of the cow carcasses surveyed, 17.4% carried a fetus at the time of harvest. As expected, mean carcass weight and loin muscle area values observed for bulls were heavier and larger than cows. The marbling scores represented by cull animal carcasses were most frequently slight and traces amounts. Cow carcasses manifested a greater amount of marbling on average than bull carcasses. The predominant fat color score showed all carcasses surveyed had some level of yellow fat. Only 1.3% of carcasses exhibited signs of arthritic joints. Results of the NBQA-2016 indicate there are areas in which the beef and dairy industries have improved and areas that still need attention to prevent value loss in market cows and bulls

National Beef Tenderness Survey–2015: Palatability and Shear Force Assessments of Retail and Foodservice Beef

Beef retail steaks from establishments across 11 US cities and beef foodservice steaks from establishments in 6 US cities were evaluated using Warner-Bratzler shear (WBS) force and consumer sensory panels. The average post-fabrication aging time of steaks at retail establishments was 25.9 d with a range of 6 to 102 d, and those from foodservice establishments averaged 31.5 d with a range of 3 to 91 d. The retail steaks with the lowest WBS value ( < 0.05) was the boneless top loin, compared to the top round steaks, which had the higher ( < 0.05) average WBS value. For the foodservice sector, top loin and ribeye steaks had the lowest ( < 0.05) WBS values, whereas the top sirloin represented the highest ( < 0.05) WBS values. The top blade retail steaks received among the highest consumer ratings ( < 0.05), whereas the top round and bottom round steaks received among the lowest ( < 0.05) consumer ratings for overall liking, tenderness liking, tenderness level, flavor liking, and juiciness liking. For the foodservice sector, the ribeye and top loin steaks were rated higher ( < 0.05) than top sirloin steaks for all consumer rating categories. The WBS values and sensory ratings were comparable to previous surveys, indicating no substantial changes in tenderness. Additional emphasis in improving the tenderness of top and bottom round steaks is necessary to increase consumer acceptability of these cuts

National Beef Quality Audit–2016: assessment of cattle hide characteristics, offal condemnations, and carcass traits to determine the quality status of the market cow and bull beef industry

To continue the series that began in 1994, the National Beef Quality Audit (NBQA) – 2016 was conducted to quantify the quality status of the market cow and bull beef sector, as well as determine improvements made in the beef and dairy industry since 2007. The NBQA-2016 was conducted from March through December of 2016, and assessed hide-on carcasses (n = 5,278), chilled carcasses (n = 4,285), heads (n = 5,720), and offal items (n = 4,800) in 18 commercial processing facilities throughout the United States. Beef cattle were predominantly black-hided; 68.0% of beef cows and 67.2% of beef bulls possessed a black hide. Holstein was the predominant type of dairy animal observed. Just over half (56.0%) of the cattle surveyed had no mud contamination on the hide, and when mud was present, 34.1% of cattle only had small amounts. Harvest floor assessments found 44.6% of livers, 23.1% of lungs, 22.3% of hearts, 20.0% of viscera, 8.2% of heads, and 5.9% of tongues were condemned. Liver condemnations were most frequently due to abscess presence. In contrast, contamination was the primary reason for condemnation of all other offal items. Of the cow carcasses surveyed, 17.4% carried a fetus at the time of harvest. As expected, mean carcass weight and loin muscle area values observed for bulls were heavier and larger than cows. The marbling scores represented by cull animal carcasses were most frequently slight and traces amounts. Cow carcasses manifested a greater amount of marbling on average than bull carcasses. The predominant fat color score showed all carcasses surveyed had some level of yellow fat. Only 1.3% of carcasses exhibited signs of arthritic joints. Results of the NBQA-2016 indicate there are areas in which the beef and dairy industries have improved and areas that still need attention to prevent value loss in market cows and bulls