Evaluation of beef strip loin steaks of varying marbling scores and maturity levels fed a high energy corn-based concentrate diet prior to harvest
The purpose of this study was to compare palatability traits of beef strip loin steaks of varying marbling scores from young steers and mature fed cull cows fed a high-energy corn based ration for at least 120 d prior to harvest. Strip loins (n = g150) were selected to equally represent ten treatments. Treatments included USDA marbling scores of Slightly Abundant and greater (SLAB+), Modest and Moderate (MT/MD), Small (SM), Slight (SL), and Traces and Practically Devoid (TR/PD) from young “A” maturity carcasses (Y) and mature (C or greater maturity) carcasses (M). Subprimals were aged 21 d under vacuum at 2 to 4°C. Following aging, all strip loins were fabricated into 2.5 cm-thick steaks, frozen, and stored at -20oC. Steaks were thawed for 24 h at 2 to 4oC and were cooked on a gas radiant broiler grill to a medium degree of doneness (71°C) monitored by a digital thermometer in the geometric center of each sample. Consumers (n = 120) were served one sample from each treatment in a random order. Trained and Consumer sensory panels evaluated each steak for tenderness, juiciness, flavor identity, flavor liking, and overall liking on a 10 cm, verbally anchored line-scale. Acceptability of tenderness, juiciness, flavor liking, and overall liking were also rated. For trained panels, 15 panels were conducted consisting of seven trained panelists in a dark room under red lights. Panelists were trained during three different sessions by being fed varying quality and maturity grades. Each sample was evaluated for initial juiciness, sustained juiciness, initial tenderness, sustained tenderness, beef flavor, and flavor intensity on a 10 cm, verbally anchored line-scale (0 = extremely dry/tough/unbeef-like; 100 = extremely juicy/tender/beef-like). The samples rated the highest (P < 0.05) for overall liking were Y-SLAB+ and Y-MT/MD. For tenderness, juiciness, and flavor, Y-SLAB+ ranked highest (P < 0.05) compared to all other treatments. For all palatability traits, M-TR/PD ranked the lowest (P < 0.05) in each category. Both maturity levels for SLAB+ and MT/MD samples had highest (P < 0.05) tenderness ratings than all other treatments. Both M-SLAB+ and M-MT/MD were rated higher (P < 0.05) than Y-SM for tenderness, flavor liking, and overall liking. Both Y-SM and M-SM rated (P < 0.05) the same for tenderness and overall liking. Within each marbling score, young fed cattle rated higher or equal to (P < 0.05) mature cattle for tenderness, juiciness, and overall liking. The percentage of acceptability for tenderness, juiciness, and overall liking was highest for Y-SLAB+ (P < 0.05). The percentage of juiciness, flavor, and overall liking acceptability was higher (P < 0.05) for M-SLAB+ and M-MT/MD samples than Y-SM. For trained panels, samples from Y-SLAB+ rated highest (P < 0.05) for initial juiciness, sustained juiciness, initial tenderness, sustained tenderness, beef flavor, and flavor intensity. Also, M-TR/PD rated lowest (P < 0.05) in initial juiciness, initial tenderness, sustained tenderness, beef flavor, and flavor intensity. The meat from young cattle rated higher (P < 0.05) for both initial tenderness and sustained tenderness when compared to mature cattle with the same marbling score. For all marbling scores, except SM, young cattle resulted in a higher quality eating experience than mature cattle. However, M-SLAB+ and M-MT/MD were rated higher than Y-SM for all palatability traits, indicating cull cows fed a high concentrate diet prior to harvest with Modest or higher marbling from mature corn fed cull cows may produce a similar eating quality to young cattle with lower marbling scores.