Measuring citrate synthase activity as an enzymatic approach to the differentiation of chilled and frozen/thawed meat.

Citrate synthase belongs between mitochondrial enzymes which are released from the meat tissue after cell membrane damage caused by ice crystal formation. The presence of this enzyme can indicate a previous freezing process. In this study, we determined citrate synthase activity for chilled and frozen/thawed meats (chicken, pork, beef, and salmon). As an additional factor, we examined a potential connection between microbial spoilage and increased enzyme activity. UV spectrophotometry was used for the evaluation of the citrate synthase activity. The effect of microbial spoilage on the enzyme activity was established through microbial analysis, which was carried out for two weeks for chilled and five months for frozen/thawed meats. The citrate synthase activity in the frozen/thawed samples was significantly higher than in the chilled samples. Dependence of microbial contamination and the increased activity of the citrate synthase was not observed. Our results suggest that there could be designed specific limits of citrate synthase activity for the resolution of chilled and frozen/thawed meats.