Meat quality variation in the robotic sorting of pork loins

A robot was used to make fiber-optic reflectance measurements from 400 to 700 nm in 10-nm increments at six sites, 10 cm apart, along the length of 48 pork loins. Meat quality was assessed in the longissimus dorsi near the thoracolumbar junction using 1) a bag-drip method for fluid loss, 2) a subjective evaluation of wetness, 3) a colorimeter measurement of paleness (CIE L), and 4) a subjective evaluation for Japanese pork color scores (JPCS). Sorting of the loins in the commercial plant from which they originated was correlated (P < .01) with fluid loss (r=.57), with wetness scores (r=-.57), with CIE L* (r=.71), and with JPCS (r=-.64). Laboratory measurements of pH at the site of meat quality assessment were correlated (P < .01) with fluid loss (r=-.61), with wetness scores (r=.65), with CIE L* (r=-.74), and with JPCS (r=.77). Average spectra obtained robotically were correlated (P < .01) with fluid loss (r=.56 at 670 nm, and R=.76 adding 560 and 540 nm), with wetness score (r=-.65 at 480 nm, and R=.75 adding 530 and 570 nm), with CIE L* (r=.76 at 480 nm, and R=.82 adding 690 and 520 nm), and with JPCS (r=-.70). In sorting loins that were all categorized as normal at the plant, mean reflectance data collected robotically were correlated with fluid loss, r=.42 (P > .05) at 700 nm and R=.58 (P > .05) adding 430 nm; with wetness score, r=.25 (P > .05); with CIE L*, r=.58 (P < .025) at 700 nm; and with JPCS, r=-.71 (P < .01) at 700 nm. Thus, as well as detecting obvious PSE loins, the robotic probe also had a limited capability to sort loins all categorized as normal at the plant.