Relationships between Ultimate pH and Microbial, Chemical, and Physical Characteristics of Vacuum-Packaged Pork Loins

• Published in: Journal of food science 2008-04, Vol.73 (3), p.M104-M110
• Main Authors: Knox, B.L, van Laack, R.L.J.M, Davidson, P.M
• Format: Article
• Language: English
• Subjects: Animals; Bacteria; Bacteria, Aerobic - growth & development; Biological and medical sciences; Chemical compounds; Colony Count, Microbial; Consumer Behavior; Consumer Product Safety; drip loss; Enterobacteriaceae; Enterobacteriaceae - growth & development; food contamination; Food industries; Food Microbiology; Food Packaging - methods; Food Preservation - methods; Food science; Fundamental and applied biological sciences. Psychology; General aspects; Genetics; Glucose; Glucose - analysis; Handling, storage, packaging, transport; Humans; Hydrogen-Ion Concentration; Impact analysis; lactic acid; Lactic Acid - analysis; lactic acid bacteria; Lactobacillus - growth & development; Lipid Peroxidation; Meat - microbiology; Meat - standards; Meat and meat product industries; meat composition; microbial contamination; microbiology; oxidation; physical properties; plate count; Pork; psychrotrophic bacteria; Quality Control; rancidity; shelf life; Swine; Taste; Temperature; Thiobarbituric Acid Reactive Substances - analysis; Time Factors; Vacuum; vacuum packaging
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1750-3841.2008.00667.x

This study evaluated the effect of ultimate pH (pHu) of pork on shelf life based upon microbial growth, drip loss, and oxidative rancidity (2-thiobarbituric acid [TBA] procedure) in vacuum-packaged loins stored at 4 °C. Glucose and lactate concentrations of the pork loins were also measured. Thirty-six pork loins (pH = 5.56 to 6.57) were collected at a commercial slaughter facility 1-d postslaughter. All pigs were from the same genetic line. Loins were grouped by pH (group: pH range): A: 5.55 to 5.70, B: 5.71 to 5.85, C: 5.86 to 6.00, D: 6.01 to 6.15, and E: > 6.16. They were analyzed at days 0, 6, 14, 24, and 34. For aerobic plate counts, groups A and B were significantly lower than C through E, while psychrotrophic or Enterobacteriaceae counts of groups A and A through C were significantly lower than groups B through E and D and E, respectively. Lactic acid bacteria counts were not significantly influenced by pHu. Group A had higher glucose concentrations than groups C through E and higher lactate concentrations than groups D through E on most sampling days. Group A had a higher TBA value than group E at days 0 and 34. Group A displayed greater drip loss than groups D and E at day 6 and groups B through D on days 24 and 34. Based on the microbial and drip loss results, a pork loin pHu of 5.8 to 5.9 appears to be optimum to provide a vacuum-packaged shelf life of at least 24 d with minimum drip loss.