Assessment of objective measures of beef steak juiciness and their relationships to sensory panel juiciness ratings

The objective of this study was to evaluate multiple instrumental measures of beef juiciness and determine their relationships with sensory panel juiciness ratings. Treatments were selected to maximize variation in juiciness and included 5 USDA quality grades (Prime, upper two-thirds Choice, lower one-third Choice, Select, and Standard) as well as 2 enhanced Select treatments (112 and 107% of the initial raw weight) and were prepared to 3 degrees of doneness (DOD; rare [66 degrees C], medium [71 degrees C], and well done [77 degrees C]). A total of 21 objective measures of raw samples were evaluated and included marbling level, CIE color values, pH, water activity, proximate composition, and multiple measures of water-holding capacity. Also, 17 objective measures were evaluated for cooked beef samples and included cooking loss, drip loss, and compression-based methods used to quantify expressible moisture. These measures were compared with results from a previous sensory study to evaluate the relationship between the various objective measures and sensory panel juiciness ratings. Differences (P < 0.05) were found among quality treatments for many of the measures evaluated, with the greatest differences occurring for many of the measures among samples cooked to different DOD. Of all the objective measures evaluated, protein percentage, cooking loss, and pressed juice percentage (PJP) were most closely associated (P < 0.05) with consumer juiciness ratings (r = -0.55, r = -0.51, and r = 0.45, respectively). Additionally, cooking loss and PJP were more closely associated (P < 0.05) with trained sensory panel initial and sustained juiciness ratings than all other measures evaluated. Regression analysis revealed that PJP explained (P < 0.05) 20, 48, and 45% of the variation in consumer, trained panel initial, and trained panel sustained juiciness scores, respectively. This was a greater percentage of the variation than slice shear force explained (P < 0.05) in trained sensory panel initial (39%) and sustained tenderness ratings (40%) and similar to the amount explained (26%) in consumer tenderness ratings. These results indicate PJP was a better predictor of sensory panel juiciness scores than all traits evaluated other than the cooking loss of steaks evaluated by sensory panelists. Pressed juice percentage explained a similar or greater amount of variation in sensory panel scores as slice shear force, indicating PJP as a potential industry standard for objective juiciness evaluation.