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Detecting the mislabelling of thawed meat as fresh meat has been an analytical challenge for many years.  The most established technique, based on measuring the HADH enzyme (see FAN method explainers) is not perfect.

This paper (purchase requires) reports the development of an assay based on a different biochemical marker enzyme for the detection of previously-frozen pork The authors proposed mitochondrial citrate synthase (CS) as a candidate biomarker enzyme, and developed an ELISA to measure CS and test their hypothesis.

For the development of sandwich ELISA, polyclonal antibodies (pAb) against CS were produced in two different laboratory animals (rabbits and guinea pigs). A sandwich ELISA was optimized by utilizing rabbit anti-CS pAb as capture and guinea pig anti-CS pAb as detection antibody,  The limit of detection (LOD) and limit of quantification (LOQ) of the sandwich ELISA were calculated to be 3.71 ng/ml and 11.24 ng/ml, respectively. The sandwich ELISA was having 100.78 ± 1.66 % of accuracy, and the assay was found to be having good repeatability as well as reproducibility. The assay showed a good storage stability up to 12 weeks of storage at refrigeration temperature (4 ± 1 °C).

The authors report that there was a statistically significant difference between results from fresh/chilled and frozen/thawed pork meat.

Photo by patrick le on Unsplash

One of the simplest frauds to perpetrate for frozen seafood, particularly small items such as prawns, is to bulk up the declared weight by including the weight of some, or all, of the ice glaze.  A glaze is essential for product quality.  In most jurisdictions, including the US, EU and UK, the declared net weight on the pack must exclude the weight of any added glaze. 

The US FDA have just released results from 28 imports of frozen seafood tested between 2022 and 2024.  They found that 10 of the 28 were violative for short weighing.  The % of short weighing ranged from 2.4 – 9.9% of the declared pack weight.  These samples were not randomised – they includes some samples taken as the result of complaints, as well as the FDA’s surveillance samples which are targeted on a risk basis.  Samples were in retail packs, and were collected at port of entry.  Further details, including countries of origin, can be found here.

Photo by AM FL on Unsplash