2.9. Sensory analysis
Steaks were thawed at 4 °C for 24 h and then modified broiled at 163 °C in a forced-air convection oven (DFG-102 CH3; G.S. Blodgett CO., Burlington, VT) to an internal core temperature of 62.8 or 71.1 °C for sensory evaluation. Panelists were trained according to AMSA (1995) guidelines that involved triangle screening tests; 6 to 8 training sessions by a panel leader; then statistical evaluation of panelists that were presented six samples with distinct tenderness, flavor, and juiciness differences replicated on 4 different days. Panelists with the highest F-ratios were used for panels. Panelists for this study had many hours of previous experience. All panel sessions were performed in an environmentally controlled (21±1 °C, 55±5% RH) booth-partitioned room with a mixture of adjustable red light (b107.64 lm) and green light (b107.64 lm). An orientation (“warm up”) sample was evaluated in the booths from an extra steak and the scores given by the panel leader were discussed with the panelists at one time before each session. Each steak was cut into 1.27×1.27×2.54 cm pieces and randomly identified with three-digit-codes. Trained panelists (n=6) evaluated palatability attributes on an eight-point scale for myofibrillar tenderness, juiciness, flavor, overall tenderness, and connective tissue amount (1=extremely tough, dry, bland, tough, and abundant; 8=extremely tender, juicy, intense, tender, and none, respectively) for each sample. Myofibrillar tenderness was evaluated after 4–6 chews, whereas connective tissue was evaluated as the residue left in the samples just before they would normally be swallowed. Each steak was represented by two pieces evaluated back to back and scores averaged. Six steaks representing both quality grades, both end-point temperatures, and all 3 aging methods were evaluated in each test session. Evaluating only six steaks per session required 18 sessions. Unsalted crackers and de-ionized water were presented to panelists between samples. Samples were presented to the panelists in a randomized order.