The objective of this study was to evaluate the effects of marbling category and postmortem aging on the palatability of lamb loin chops as determined by U.S. consumers. Additionally, our secondary objective was to determine the relationship between marbling, flank streaking, intramuscular fat percentage (IMF), and the palatability traits of tenderness, juiciness, flavor liking, and overall liking.
Carcasses (n=180; 60/treatment) were selected at a commercial lamb processor in Greeley, Colo., with initial marbling score and flank streaking (200 = traces00, 300 = slight00, 400 = small00, 500 = modest00, 600 = moderate00, 700 = slightly abundant00) being determined within seconds of carcass ribbing because carcasses immediately (in less than one minute’s time) entered the fabrication room after ribbing. Full lamb loins (IMPS 232; 1 × 1in) representing the three targeted marbling levels [LOW, Medium (MED), HIGH] were obtained based on initial marbling score, vacuum packaged, shipped to Texas Tech University, and stored under refrigeration (2-4°C) until fabrication. On Day 21 postmortem, loins were removed from packaging, and marbling score was assessed following a 10-minute bloom period to ensure marbling was classified correctly during the initial plant assessment. Lamb loins had the following 21-day marbling score ranges: LOW = slight00- slight90, MED = small00- modest20, HIGH = modest50- slightly abundant40. Loins were fabricated, leaving only the longissimus muscle, then manually sliced into 2.5-cm thick chops. Chops were vacuum-packaged individually and either frozen immediately at minus-20ºC, or stored at 2ºC until 42 days postmortem, then frozen. After thawing for sensory testing, chops were cooked on a clamshell grill utilizing a time schedule with a 3-minute cook period to target medium degree of doneness (71°C) followed by a 45-second rest period before serving.