Assessment of the quality of refrigerated and frozen pork by multivariate exploratory techniques

Pork loin and leg were evaluated 24 h after slaughter and during refrigerated (5 °C) and frozen storage for microbial counts, pH, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS) and bioactive amines. Spermine was the prevalent amine in fresh pork loin and leg, followed by spermidine and agmatine. During refrigerated storage, pH, TVB-N, mesophilic and psychrotrophic counts increased and no changes (p < 0.05) were observed on polyamines; however putrescine, cadaverine and histamine were produced and accumulated throughout storage. Principal Component Analysis (PCA) and Hierarchical Cluster Analysis (HCA) for all parameters indicated a shelf life of 8 days for both cuts, which was also coherent with safety regarding histamine levels. During frozen storage, there was no change on amines and pH, TVB-N decreased, and TBARS increased. None biogenic amine was produced. PCA and HCA were not able to classify frozen pork based on the analyzed parameters; however, a shelf life of 90 days was suggested for the frozen cuts based on lipid oxidation.