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Improving food labelling - Government Chemist announces new research findings

14 Sep 2011
Tags:  Food

LGC announces publication of landmark research papers to support improved testing of food label claims

We know oily fish is good for us, but when a food label claims, for example, that the product ‘contains 30% salmon’, who verifies this claim and how? Scientists working with LGC have completed two research studies into the test that is used to verify label claims and their findings. This research sheds interesting new light on how to calculate the amount of salmon and other high value flesh foods in compound food products.

Pre-packed, named fish or meat products must be labelled with the amount of named fish or meat present calculated as a percentage of the final weight of the product. This is known as quantitative ingredient declaration or QUID. Manufacturers label their packaged products according to recipe and mass balance data. Their QUID claims are then subject to spot checks by Public Analyst laboratories, for example, who carry out official sampling tests using a process that involves analysing nitrogen and other parameters, as well as calculating the ‘apparent total meat (or fish) content’.

Public Analysts use an approach known as the Stubbs & More procedure, following work by George Stubbs and Andrew More in the then Laboratory of the Government Chemist (now LGC) at the beginning of the 20th century .  The procedure uses a comparison of the species-specific nitrogen content of a sample with the known species’ nitrogen content, termed the ‘nitrogen factor’.

Scientists on behalf of the Government Chemist, which is a statutory role at LGC, recently carried out two major studies on the nitrogen factors in the Stubbs & More procedure:

  • A critical review of the scientific literature and
  • A complete reappraisal of the nitrogen factors for farmed salmon.

The literature review pinpointed all the validated databases for nitrogen factors for meat, poultry and fish and highlighted that more work is needed to continue to provide protection for consumers and to create a level playing field for industry. For example, new data is required on farmed fish as opposed to wild fish as well as on new Asian-farmed commercial species such as pangasius and tilapia. The latter species are being introduced as novel whitefish fillets into the UK and European markets in large quantities and at very competitive prices.

Cost-effective methods of gathering the necessary data were also recommended in the paper for industry to develop modern nitrogen factors in collaboration with regulators and other interested parties. To access the review see ‘Nitrogen factors as a proxy for the quantitative estimation of high value flesh foods in compound products, a review and recommendations for future work‘, D. Thorburn Burns, M Walker, S. Elahi and P. Colwell, Anal. Methods, 2011, 3, 1929,  DOI: 10.1039/c1ay05214d.

The Government Chemist also led the way with the complete modernisation of the nitrogen factor dataset for farmed Atlantic salmon. Prior to this, the only nitrogen factor for Atlantic salmon Salmo salar was for wild rather than farmed salmon; moreover it was based on limited data as long ago as 1973. Based on forensically controlled sampling and over 2,000 separate analyses, the new study recommended statistically valid factors for farmed salmon and the ingredient known as salmon frame mince, collected from the flesh remaining on the salmon ‘frames’ after removal of fillets. The comprehensive paper describing how the study was carried out, the calculations involved, the life cycle of the salmon and the recommended new nitrogen factors is freely available from the open access Journal of the Association of Public Analysts (online) at: and includes for the first time in such studies a full set of data in machine readable form.

Michael Walker, who coordinated publication of the studies on behalf of the Government Chemist said: “With increasing costs any temptation to cut corners with high value foods would hit consumers, particularly the least advantaged, and responsible traders. These studies provide solid data to enable QUID claims for fish and meat to be assessed and any irregularities followed up by in-factory inspection.”

- Ends -

Notes to editors

  1. G. Stubbs and A. More, (1919), “The estimation of the approximate quantity of meat in sausages and meat pastes”, Analyst, 44, 125-127.
  2. Great Britain, Food Safety Act 1990, Elizabeth II Chapter 16, London: The Stationery Office.
  3. Regulation (EC) No 178/2002 of the European Parliament and of the Council of 28 January 2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety. OJ L 31, 1.2.2002, 1-24
  4. Directive 2000/13/EC of the European Parliament and of the Council of 20 March 2000 on the approximation of the laws of the Member States relating to the labelling, presentation and advertising of foodstuffs, OJ L 109, 6.5.2000, 29-42; implemented in GB by The Food Labelling Regulations 1996 as amended.