Relationships Among Initial Color or Biochemical Traits and Final Discoloration in the Pork Longissimus Dorsi, Triceps Brachii, and Psoas Major

Abstract

The goal was to determine relationships between color or biochemical traits at the beginning of retail display (day 1) and final discoloration (day 5) in longissimus dorsi (LD), triceps brachii (TB), and psoas major (PM) and determine what combination of initial traits was most predictive of final discoloration in each muscle. Muscles from 20 pigs were aged in vacuum packages and fabricated to yield 3 chops per muscle. These 3 chops from the same muscle from a single pig were displayed together under constant lighting for up to 5 d. On day 1, all chops in a package were evaluated for visual dis-coloration, instrumental color, and myoglobin (Mb) forms. One chop on day 1 was evaluated for oxygen consumption (OC), metmyoglobin-reducing activity, and Mb content. Final visual discoloration and 630/580 nm ratio were evaluated on one chop from each muscle on day 5. Pearson correlation coefficients were compared between LD, TB, and PM using Fisher’s z test in SAS. Stepwise regression models were developed using the REG procedure. All initial traits were correlated to final visual discoloration and 630/580 nm ratio in TB and PM (|0.47|≤r≤|0.72|), except redness, day 1 630/580 nm ratio, OC, and Mb (P≥0.07). Final LD 630/580 nm ratio was correlated to initial lightness, redness, hue angle, deoxymyoglobin, and pH (|0.48|≤r≤|0.75|). Initial lightness and Mb (0.20≤partial R2≤0.21) were most predictive of final LD visual discoloration (R2=0.33). Yellowness was most predictive of 630/580 nm ratio for all muscles (0.32≤partial R2≤0.85). Correlations were generally stronger in TB and PM compared with LD but did not differ from each other (P≥0.17). In all muscles, color-stable chops were initially darker, were less yellow, and had lesser hue angles.