Effects of postmortem aging and hydrodynamic pressure processing of pork loin quality

The objective of this study was to determine the influence of hydrodynamic pressure processing (HDP) and aging on the overall quality and protein characteristics of pork loins. Boneless pork loins (n = 12) were split into anterior and posterior halves and were assigned to control and HDP treatments. Following treatment on day 0, each half was divided into two portions (0 and 7 days aging). Samples were removed for the determination of Warner-Bratzler shear force (WBSF), centrifugal moisture loss (CML), gravitational drip loss (DL), color, protein solubility and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of whole muscle protein extracts. WBSF decreased with HDP (P < 0.05) and aging treatments (P < 0.0001). CML decreased (P < 0.0001) with aging. Controls exhibited slightly less DL after 1 day than HDP samples, but the increase in DL between 1 and 7 days was similar for control and HDP samples. Treatment effects on L*, a* and b* measurements were minimal. Myofibrillar and total protein solubility were higher (P < 0.01) in HDP samples compared with controls at day 0 but not at day 7. Sarcoplasmic protein solubility decreased (P < 0.05) with aging. SDS-PAGE analysis of muscle proteins demonstrated a strong aging effect and only minor HDP differences. With aging, bands corresponding to 30-33 and 135 kDa increased (P < 0.0001), while bands corresponding to 38 and 95 kDa decreased (P < 0.05) in intensity (relative to the actin band). The 60 kDa band intensity increased (P < 0.05) with both aging and HDP treatments. Thus, data from this study suggest that HDP enhances aging tenderization in pork loins through the physical disruption of the muscle ultrastructure while having little detrimental effect on other parameters of pork quality. This study demonstrates that hydrodynamic pressure processing is an effective postharvest technology for enhancing aging tenderization in pork loins through the physical disruption of the muscle ultrastructure with minimal impacts on other pork quality parameters such as water-holding capacity and color.