Detection of frozen-thawed beef, pork and chicken meat

Thawed meat is usually of lower quality and less expensive than chilled meat, which some dishonest people may exploit by fraudulently marketing it as chilled. This study focused on methods for detecting and distinguishing frozen meat from chilled meat. The activity of the enzyme aconitase in the eluate was determined, and the mineral cations (Na+, K+, Mg2+) as well as the concentrations of organic acids (acetic, citric, and lactic) were analysed in chilled and thawed meat stored for 7, 14, and 150 days at -18 °C. After 150 days of storage, aconitase activity increased from 47.2 ± 7.2 U.L-1 to 395.3 ± 59.2 U.L-1 in pork, from 45.8 ± 11.5 U.L-1 to 133.3 ± 31.8 U.L-1 in beef, and from 17.2 ± 8.6 U.L-1 to 143.6 ± 41.5 U.L-1 in chicken. The mineral content decreased during storage in meat samples, especially Na+ and K+ cations (P < 0.05). The results for organic acids were less conclusive. Principal component analysis (PCA) of the data confirmed a clear separation between chilled and thawed meat for all species, with a high variability of nearly 72%.