Impact of varying visual severities of dark-cutting beef on the biochemical color characteristics, retail color, and metabolome of longissimus lumborum steaks

Abstract

The objective was to evaluate the impact of varying visual severities of unaged dark-cutting beef on the retail color attributes and metabolite profile of beef longissimus lumborum steaks. Beef carcasses (n = 8/treatment) were selected at the time of grading from a commercial facility based on the visual degree of dark-cutting severity. Treatments included a bright cherry-red colored normal-pH control, shady, moderate, and moderately severe dark-cutting beef. Retail color, pH, bloom color, oxygen consumption, metmyoglobin reducing activity, lipid oxidation, and untargeted metabolomics analysis using gas chromatography mass-spectrometry were determined. pH and lightness (L* values) were normal-pH (5.51, 37.56), shady (5.90, 36.96), moderate (6.33, 35.38), and moderately severe (6.40, 32.65), respectively. Normal-pH beef had a lower (P < 0.05) metmyoglobin reducing activity than moderate and moderately severe dark-cutting beef. There were no differences (P > 0.05) in oxygen consumption between different shades of dark-cutters, but normal-pH had lower oxygen consumption (P < 0.05) than moderately severe. Metabolite profiling indicated downregulation of glucose, fructose-6-phosphate, and glucose-6-phosphate, while there was an upregulation of amino acid and lipid-based metabolites such as isoleucine, threonine, and glyceryl monopalmitate in all three dark-cutting severities compared with normal-pH beef. The abundance of succinic acid was lower in all shades of dark-cutting beef than in normal-pH beef. In the pairwise comparisons to normal-pH beef, there were 12, 21, and 43 metabolites significantly different for shady, moderate, and moderately severe, respectively. As dark-cutting severity increases, metabolites linked to energy metabolism change, including a decrease in glycolytic metabolites.