2. Materials andmethods
2.1. Beef fabrication
Beef inside rounds (USDA Select grade; 48 h post-mortem; IMPS #
168) from eight carcasses (n = 8) were obtained from a commercial
packing plant. In order to effectively simulate the commercial beef retail
marketing conditions in the United States, the carcasses utilized in this
study were from cattle of unknown backgrounds. The vacuumpackaged
cuts were transported on ice to the USDA-inspected meat
laboratory at University of Kentucky. External fat and adjacent muscles
were excised to separate the semimembranosus muscles. Each
semimembranosus muscle (n = 8) was then fabricated into ten 2.54-
cm ISM and OSM steaks. One steak assigned for proteome profiling
and determining myoglobin concentration was vacuum packaged and
frozen immediately at −80 °C until further analysis. The remaining
nine steakswere individually placed on Styrofoamtrays and aerobically
overwrapped with oxygen-permeable polyvinyl chloride film (15,500–
16,275 cm3/m2/24 h oxygen transmission rate at 23 °C). Individually
packaged steaks were assigned randomly for 0, 2, and 4 days of refrigerated
retail display (2 °C) under constant, cool white fluorescent lighting
(1300 lx). For each time point, three steaks were utilized for evaluation
of instrumental color and biochemical traits.