Analyses of the microbial safety and physicochemical characteristics of beef loin treated with high-pressure

This study aimed to evaluate the effects of high-pressure processing (HPP) on microbial safety and physicochemical quality of raw beef intended for use in raw pet food, with particular emphasis on microbial inactivation and physicochemical characteristics changes during refrigerated storage. Beef samples were treated at pressures of 0.1, 100, 300, and 500 MPa for 5-15 min and stored at refrigerated conditions for up to 2 weeks. Microvial populations, including Salmonella Typhimurium, Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus, were enumerated during storage. Physicochemical properties, including proximate composition, pH, color, water-holding capacity, shear force, thiobarbituric acid reactive substances (TBARS), and volatile basic nitrogen (VBN), were also analyzed. Microbial counts decreased with increasing pressure and holding time. The 500 MPa for 15 min treatment reduced S. Typhimurium to below the detection limit (< 1 log CFU/g) throughout storage, while other pathogens showed substantial reductions with limited regrowth. HPP did not affect proximate composition of pH; however, higher pressures increased lightness, yellowness, shear force, WHC, and TBARS, while redness decreased. VBN levels decreased with increasing pressure but increased during storage. HPP effectively enhanced microbial safety of raw beef while inducing pressure and time-dependent physicochemical changes associated with muscle protein denaturation, myoglobin oxidation, and enzyme inactivation. These results support HPP as a promising intervention for improving the safety of raw pet food, although quality changes should be considered in process optimization.