Effects of different post mortem chilling technologies on chilled pork color and quality classification

The objectives of this article were to study on effects of the conventional chilling method(45 min post mortem, (3±0.5)℃, 0.4 m/s, air chilling for 24 h) and the two-stage rapid chilling method(35 min post mortem, -20℃, 2 m/s, air chilling for 1.5 h; (3±0.5)℃, 0.4 m/s, air chilling for 22.5 h) on chilled pork color and quality grading. pH value, temperatures, instrumental color features (L^*, a^*, b^*) and sensory color scores of chilled pork were measured to determine the correlations among them and make quality grading. The results showed that for the conventional chilling method, T_45min was correlated(p＜0.01) with pH_45min(-0.37), L^*(0.45) and color score(-0.39) and color score was most significantly correlated(p＜0.01) with L^*(-0.80); the percentage of PSE pork was 18.6% and those of RFN pork and DFD pork were 80.4% and 1.0%, respectively. For the two-stage rapid chilling method, temperatures of chilled pork at the early post mortem time were significantly reduced(p＜0.05) and pH values dropped slowly; the percentage of PSE pork was reduced to 12.0% and that of RFN pork was increased to 87.0%, that of DFD pork was still 1.0%. The results indicated the two-stage rapid chilling method could improve chilled pork color, thus improve pork quality.