Effect of Modified Lysozyme on the Microflora and Sensory Attributes of Ground Pork

Abstract

The effects of lysozyme monomer and thermochemically modified lysozyme on the microflora and sensory attributes of heated and unheated ground pork were investigated in this study. The dimer and trimer fractions of the modified lysozyme were 36.1 and 33.5%, respectively. The modified lysozyme exhibited higher hydrophobicity (40,600 U/mg of protein) and lower enzymatic activity (1,020 U/mg of protein) than the hydrophobicity (890 U/mg of protein) and activity (17,950 U/mg of protein) of the lysozyme monomer. Portions of ground pork (150 g) without lysozyme or supplemented with 5 mg/g lysozyme or modified lysozyme and either not heated or heated at 60°C for 10 min were stored at 4 ± 1°C and sampled at various times between 1 and 144 h. Meat color was not affected by either additive. After storage for 72 h, the mean odor score for meat supplemented with modified lysozyme and heated decreased from 5.0 at 1 h to 4.1, while the scores for all the other preparations were ≤3.2. After 144 h, the counts of Pseudomonas and Enterobacteriaceae in meat that was supplemented with modified lysozyme and not heated were, respectively, 1.1 and 0.9 log less than in the controls, and the numbers in such meat that was heated were, respectively, 1.2 and 2.4 log less than the numbers in the controls. The counts in meat supplemented with lysozyme and the controls were comparable. Heat treatment increased the bacteriostatic effect of modified lysozyme on gram-negative bacteria.