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Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 5/10/2010 Publication Date: 6/20/2010 Citation: King, D.A., Shackelford, S.D., Wheeler, T.L. 2010. Prediction of Pork Longissimus Lean Color Stability Using VIS/NIR [abstract]. Proceedings Reciprocal Meat Conference. 63:61. Interpretive Summary: Technical Abstract: Insufficient case-life is a costly problem facing pork processors. To assess Visible and Near-Infrared (VIS/NIR) spectroscopy as a technology to sort pork loins according to lean color stability, center-cut pork loins (n = 1208) were selected from the boning lines of four large-scale pork processors. VIS/NIR spectra (350 to 1050 nm) were collected on each loin immediately after boning and approximately 1 h after boning on the ventral portion of the longissimus exposed by rib removal. At 14 d postmortem, a 2.5-cm chop from each loin was placed in simulated retail display. Instrumental color variables [CIE L*, a*, b*, and overall color change (delta E)] were determined on d 0, 1, 7, 11, and 14 of display. Loins were blocked according to processing plant and observed d 14 delta E into calibration and prediction data sets. Principal component analysis of color variables collected on d 0 and 14 identified a principal component (PC1) explaining 66% of the variance, which was strongly associated with color change. Partial-least squares regression was used on the calibration dataset to develop models using VIS/NIR spectra to predict scores for PC1 which was validated on the prediction dataset. The prediction model explained 45 and 40% of the variation in observed PC1 values in the calibration and prediction datasets, respectively. Within each dataset, loins with predicted PC1 values less than 0 were classified as having stable lean color, while those with values greater than 0 were considered to have labile lean color. In the prediction dataset, chops predicted to have labile lean color had higher (P < 0.05) L* values, regardless of display day (60.6 vs. 57.1, respectively). Regardless of stability class, L* decreased (P < 0.05) between d 0 and 7 (59.1 vs. 58.4) and then increased (P < 0.05) between d 11 and 14 (58.5 and 59.6, respectively). Redness was similar (P > 0.05) between chops classified as stable and those classified as labile on d 0 (18.3 and 18.4, respectively) and d 1 (18.9 vs. 18.6) of display, but stable chops had higher (P < 0.05) a* values on d 7 (17.4 vs. 15.8), 11 (16.8 vs. 14.3), and 14 (15.6 vs. 12.7) of display. Labile chops had higher (P < 0.05) b* values than the labile chops on d 0 (21.7 vs. 20.1, respectively) and 1 (22.2 vs. 21.0), but the stability classifications did not differ on d 7 (21.4 vs. 21.0), 11 (21.2 vs. 21.0), and 14 (21.2 vs. 20.9). Overall color change increased (P < 0.05) as display progressed, though this increase was much more extensive in chops predicted to be labile. Stability classes did not differ in delta E on d 1 (P > 0.05; 1.6 and 1.7 for labile and stable classes, respectively). However, d 7 delta E was greater (P < 0.05) in the labile chops (3.4) than in the stable chops (2.6). The differences in delta E between chops predicted to be labile and those predicted to be stable had increased by d 11 (4.8 and 3.2, respectively; P <0.05) and 14 (6.2 and 3.8, respectively; P < 0.05). Differences between color stability groups in the calibration dataset were remarkably consistent with those reported for the prediction dataset. These data indicate that VIS/NIR spectroscopy is an effective technology to segregate pork loins with regard to color stability. |
