The effects of ultrasonic-assisted curing versus static curing as a control on the quality parameters and gel properties of minced pork were studied. Ultrasonic-assisted curing was carried out with different ultrasonic power (180, 240 and 300 W) and times (30, 60 and 90 min). The results showed that the pH and cooking yield of minced meat were significantly increased after ultrasonic treatment compared with the control group (P < 0.05), the chloride content increased significantly (P < 0.05), and textural properties were significantly improved. The 240 W/60 min treatment group had the maximum hardness, springiness and chewiness, which were significantly better than those of the other treatment groups (P < 0.05). The L* value of minced meat subjected to ultrasonic treatment at 240 W for 60 min was significantly higher than that of the 30 and 90 min treatment groups (P < 0.05); with increasing ultrasonic time, the a* value first increased and then decreased. Ultrasonic-assisted curing reduced the juice loss and imparted good water- and oil-holding capacity to minced pork. Compared with the control group, the total juice and water loss of the 240 W/60 min treatment group were reduced by 48.34% and 58.21%, respectively, which had the best emulsion stability among all the experimental groups. Meanwhile, this treatment group had the lowest apparent viscosity and the strongest flow performance. In conclusion, ultrasonic-assisted curing could significantly improve the quality of minced meat, and the optimal process parameters were 240 W and 60 min for ultrasonic power and time, respectively.

In order to investigate the correlation between Pseudomonas fluorescens and Brochothrix thermosphacta and pork quality, in this study, the microbial load, pH, color (L*, a* and b* values), texture, total sugar content, total volatile basic nitrogen (TVB-N) value and thiobarbituric acid reactive substances (TBARS) value were determined and the microstructure of pork muscle fiber was observed by scanning electron microscopy during storage at 4 ℃. The results showed that the microbial load, pH, TVB-N content and TBARS value of pork increased with storage time, while the total sugar content, L* value, a* value, hardness and chewiness decreased. Microbial growth during the storage of meat caused changes in the structure of muscle fibers. The change in the physicochemical quality pork was correlated with the species and growth rate of microorganisms on it, and the spoilage capacity of B. thermosphacta was higher than that of P. fluorescens. The correlation analysis showed that the total bacterial count, pH, total sugar content, TVB-N content and TBARS value were closely related to storage time, among which the total bacterial count had the highest correlation with storage time and therefore could be used as an indicator for quality evaluation and shelf life prediction.