Jun 26

Food safety and quality – how fresh is your fish?

fishThe moment a fish is caught it begins the natural process of decay, being broken down by enzymes (from the fish itself or bacteria naturally present).

Measuring the resulting chemicals produced gives a measure of the freshness, and thus the quality, of the fish.

Similarly, as LGC’s Michael Walker asks in a recent article for Food Science & Technology, mouldy food served in restaurants or shops is likely to be sent straight back with a complaint, but what happens if the mould isn’t spotted and is unwittingly ingested? There’s more at stake than an unappetising meal and a bad reputation for the restaurant.

Contamination of raw food material by toxic mould metabolites, known as mycotoxins, can cause vomiting and diarrhoea as well as cancer. Careful crop husbandry, timely harvesting and proper storage provide barriers to contamination and statistically valid sampling followed by chemical analysis acts to secure supply chain safety. Yet contamination can still occur.

Accurate analysis of these breakdown products is therefore essential. Measure too low and the produce will appear better quality than it is – potentially affecting shelf life. Measure too high and the fish (in this instance) may have to be discarded. In extremes, certain breakdown products can cause food poisoning, due to biogenic amines like histamine being formed.

The FSA reminds us that histamine, which can cause scombrotoxic fish poisoning, is produced when fish and fish products from the family that includes tuna, mackerel, and herring are not refrigerated correctly. Warmer temperatures allow bacteria to multiply and produce histamine at levels that can make people ill if it is eaten. Unfortunately, cooking the fish will not destroy histamine. Histamine in fish is controlled by Regulation (EU) No 1019/2013 of 23 October 2013 amending Annex I to Regulation (EC) No 2073/2005 as regards histamine in fishery products.

Not all toxins are controlled by Regulation 1881/2006 (though, in his article, Michael handily provides a list of those which are covered).

If you are charged with assessing accuracy of analysis in fish or meat, LGC’s Proficiency Testing team is giving you the opportunity to order test material 748 in our meat and fish scheme (QMAS).

Test material 748:

  • Quality parameters in fish

Target analytes:

  • Histamine
  • Total Volatile Nitrogen (TVN)
  • Trimethylamine (TMA)

Next available:

  • Round MT233
  • Despatch date 21 September 2015

If you would like to register for this test material, please click here, or if you would like further info, email us here.

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