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Background: Limited knowledge is currently available on the effects of modified atmospheric packaging (MAP) on the metabolite profiles of cooked beef. The objective was to evaluate the impact of packaging on the cooked color and cooked metabolite profile of normal-pH (normal bright-red color) and atypical-dark-cutting beef (inherently slightly dark-colored) longissimus lumborum muscle. Methods: Normal-pH (pH 5.56) and atypical dark-cutting (pH 5.63) loins (n = 6) were procured from a commercial meat processor. Steaks were randomly assigned to one of three different packaging methods: vacuum packaging, carbon monoxide (CO-MAP), and high oxygen (HiOx-MAP). Following 5 d of retail display, steaks were cooked to 71 °C on a clamshell-style grill, and samples were collected for untargeted metabolites using gas-chromatography mass spectrometry. Results: Raw atypical dark-cutting steaks were less red (p < 0.05) than raw normal-pH steaks. However, there were no differences in internal cooked color between normal-pH and atypical dark-cutting steaks. Steaks packaged in HiOx-MAP steaks had a lower (p < 0.05) cooked redness than vacuum and CO-MAP steaks. A total of 129 metabolite features were identified in the study. Serine and tryptophan were over-abundant in cooked atypical dark-cutting beef compared to raw atypical samples. Citric acid levels were greater in HiOx-MAP packaged beef compared with VP both in normal and atypical dark-cutting beef after cooking, while no differentially abundant metabolites were shared between vacuum and CO-MAP steaks after cooking. Discussion: A slight increase in pH did not influence metabolite profiles in different packaging. However, there were packaging effects within normal and atypical dark-cutting beef. Conclusions: This study suggests that packaging conditions change metabolite profiles, which can influence cooked metabolites. Therefore, the metabolomics approach can be used to better understand cooked color defects such as premature browning. [ABSTRACT FROM AUTHOR]

Meat color is an important sensory property influencing purchasing decisions and the value of the product during grading. Any deviation from a bright red color, especially in beef, leads to economic losses. Darkcutting beef is a color deviation in which beef fails to have a bright red color. The dark-cutting condition has a worldwide occurrence. The dark-cutting condition in the US results in $210 million annually. The current talk will focus on recent advances in basic and applied research in dark-cutting beef color. The proteomics and metabolomics research showed that glycolytic proteins and metabolites are less abundant in dark-cutting beef than normal-pH beef. Interestingly, dark-cutting beef has greater mitochondrial protein content than normal-pH beef. Although the mechanistic basis for increased mitochondrial content is unclear, we speculate that higher energy demand pre-slaughter contributes to increased mitochondrial biogenesis. This metabolic alteration plays a critical role in detriments of substrate metabolism in dark-cutting beef muscles, contributing to aberrant postmortem pH decline. In recent research, we compared metabolomic and lipidomic profiles using different shades of dark-cutting beef, such as mild, moderate, and severe, demonstrating that metabolite and lipid profiles vary significantly between normal and severe dark-cutting samples. However, there were not many differences between mild and moderate. Applied research to improve dark-cutting beef has utilized various post-harvest practices such as modified atmospheric packaging, enhancement, nitrite-embedded film, and high-pressure processing. The use of modified atmospheric packaging and antioxidant enhancement reversed the dark color of steaks. Recently, we have demonstrated that high-pressure processing (HPP) of strip loin steaks can reverse dark color when packaged in PVC overwrap. Dark-cutting steaks processed with 300 MPa (megapascal pressure) for 90 sec using chilled water (6 to 10 °C) immediately improved redness and had similar redness as USDA Choice steak on d 3 of retail storage. In addition, dark-cutters maintained a brighter red color than normal-pH USDA Choice during retail display (hence, less loss due to meat discoloration). The trained panelists also noticed no taste, flavor, or tenderness differences between USDAChoice and dark-cutters applied with 300 MPa. The application of HPP allows aerobic overwrap polyvinyl chloride (PVC) packaging with no use of modified atmosphere packaging (MAP) trays. In summary, understanding the fundamental basis helps to elucidate the etiology of dark-cutting beef occurrence, while applied research helps to improve the value of dark-cutting beef. [ABSTRACT FROM AUTHOR]

A dark red to coffee bean color present within the ribeye between the 12th and 13th rib of a beef carcass at the time of grading is the hallmarking characteristic of dark-cutting (DC) beef. However, the degree of darkness within the ribeye can vary. Limited studies have evaluated DC beef of varying visual severity throughout aging and retail display. Therefore, the objective was to evaluate the impact of varying degrees of dark-cutting severity on the bloom and retail color of beef longissimus lumborum subjected to 0, 21, or 39 d of aging. Beef strip loins (IMPS #180; n = 8/ treatment) were collected from commercial beef processors based on the visual degree of SC at the time of grading. Strip loins represented one-half dark, twothirds dark, full dark, and a normal, cherry-red colored control. At 48 to 60 h postmortem, loins were fabricated by slicing two 2.54 cm steaks from the anterior end of each loin for retail display (unaged) or biochemical analysis. The remaining portion of the strip loin was segmented into two sections and assigned to 21 or 39 d of wet aging. Following aging, one 2.54 cm steak from the anterior end of each loin was cut for retail display. All steaks designated for retail display were placed into Styrofoam trays and overwrapped with polyvinyl chloride film and placed into retail display following aging. Bloom, metmyoglobin reducing activity, and pH were evaluated for biochemical analysis. Color measurements were taken each day of display using a HunterLab MiniScan EZ spectrophotometer. The data were analyzed using the Glimmix procedure of SAS. One-half and normal steaks had a lower (P < 0.05) initial pH than two-thirds and full steaks. Unaged full steaks had greater (P < 0.05) metmyoglobin reducing activity than unaged normal and half steaks. Steaks aged for 21 and 39 d were more (P < 0.05) red initially following bloom than unaged steaks. Full and two-thirds steaks aged for 0 d had a decreased (P < 0.05) a* value on d 0 of display than normal and half steaks aged for 0 d. Similarly, following 21 and 39 d of aging full and two-thirds dark steaks had a lower (P < 0.05) a* value and were less red in color than normal and half steaks on the initial day of retail display. By d 4 of display, normal and one-half steaks aged for 21 d had a greater (P < 0.05) a* value than two-thirds steaks aged for 21 d. When aged for 39 d, all treatments were similar (P < 0.05) in redness by the end of display. Results from this study indicate that the visual severity of dark-cutting can impact color throughout aging and retail display. [ABSTRACT FROM AUTHOR]

Dark-cutting beef is hallmarked by a dark red to almost purple color present within the interface of the ribeye between the 12th and 13th rib of the beef carcass. Yet, the shade or degree of darkness present within the ribeye can vary widely and have a substantial impact on the color and biochemical traits of the steaks. However, limited studies have compared color characteristics of different degrees of dark-cutting during retail display. Therefore, the objective of this study was to evaluate the impact of the visual degree of dark cutting at the time of grading on the retail color and color stability attributes of beef longissimus lumborum steaks. Beef strip loins (IMPS #180) were collected from two different Midwestern beef processors over the course of two collections. Strip loins (n = 8/treatment) were identified based on the degree of dark-cutting present within the ribeye to represent one-half dark, two-thirds dark, full dark, and a control of USDA Choice. At 48 to 60 h postmortem, loins were fabricated from the anterior end into 2.54 cm steaks and randomly assigned to retail display or d 0 lab analysis. Steaks designated for retail display were placed into Styrofoam trays and overwrapped with polyvinyl chloride film, and placed into retail display in coffin style display cases under continuous lighting for 5 d. Steaks designated for d 0 analysis were evaluated for pH, bloom, oxygen consumption, and metmyoglobin reducing activity. All color measurements were taken using a HunterLab MiniScan EZ spectrophotometer. The data were analyzed using the PROC GLIMMIX procedure of SAS at an a < 0.05. Two-thirds and full dark-cutter steaks had a greater (P < 0.05) pH than half and normal steaks on d 0. Moreover, full dark-cutter steaks had a decreased (P < 0.05) bloomed L* value and were darker in color on d 0 than normal and half steaks. Full dark-cutter steaks had a greater (P < 0.05) oxygen consumption and metmyoglobin reducing activity on d 0 than normal and half steaks. Full and two-third steaks had a decreased (P < 0.05) a* value and were less red in color on d 0 of retail display than normal and half steaks. All degrees of dark-cutters had a reduced change in redness than USDA Choice steaks. These results indicate color stability activity can be dependent on the degree of dark-cutting, with full and two-thirds dark-cutters being similar in biochemical activity. [ABSTRACT FROM AUTHOR]