73 Awardee Talk: Recent updates in dark-cutting beef color research

Abstract 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. Dark-cutting 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 USDA-Choice 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.