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Determination of Nitrogen Factors for Pangasius and Alaska Pollack - FA0115

This project will determine nitrogen factors for Pangasius and Alaska pollack, two important commercial fish used in the UK, which are imported already prepared outside of UK and Europe. Nitrogen factors are analytical factors used to measure meat and fish content (i.e. the amount of meat or fish used) in compound products, and added water in raw meat and fish, and their products. They are used by both enforcement labs (public analysts) to check (QUID) labelling claims on meat and fish content, and by industry to check their raw materials. The use of nitrogen factors to calculate the fish content of coated fish products has also been accepted at an international level in Codex Alimentarius.
Unprocessed whole fish will be sourced and analysed for nitrogen, ash, moisture and fat content. Nitrogen factors are calculated based on the average nitrogen content of the fish (in gN/100g fish). These baseline nitrogen factors can be used by industry to ensure their raw materials are according to the required specifications. Also, commercial fillets of Pangasius, and fish blocks (the raw material used for most breaded fish products) of Alaska pollack, prepared under good manufacturing and hygienic practice, will also be analysed to compare with unprocessed whole fish, and set nitrogen factors for frozen Pangasius fillets and frozen Alaska pollack fillet/mince blocks prepared under the same or similar practices for both UK and global trade.
75 samples of whole Pangasius fish will be obtained directly from Vietnam. These samples will be obtained in 2 lots of roughly 37 taken 6 months apart.
75 samples of commercial Pangasius fillets will be obtained from a processor using good manufacturing practices in Vietnam, and where the process has been inspected and approved. These will be obtained in two lots of 37 samples taken 6 months apart.
75 samples of whole Alaska pollack will be obtained from the main fishing grounds. The samples will be taken in two lots of 37 in the two main seasons of Alaska pollack in March and September.
75 samples of frozen Alaska pollack fillet blocks, and 75 frozen mince blocks will be obtained from fish caught in the two main seasons March and September, and processed in a factory approved and inspected for good manufacturing practices.
Samples of whole fish will be filleted without water, homogenised and the 200g frozen samples distributed. Commercial fillets and blocks will be sampled, homogenised, frozen and 200g samples distributed.
All 250 samples will be divided randomly between the three labs – Youngs Seafood, LGC and WYAS, and analysed for moisture, nitrogen, ash and fat in duplicate. The total must add up to 100%. The duplicates should agree and a standards reference material analysed in duplicate with each batch of analyses.
The analytical results will be analysed statistically to see if there are significant differences in season. Similarly a large number of analyses conducted on the raw materials by Youngs Seafood over many years, and obtained from the same processors will be analysed statistically to see if there are significant differences in season. The results will be combined if the data is compatible and average factors and standard deviation calculated for the different samples of Pangasius and Alaska pollack.
The results will be approved by the AMC-Nitrogen factors Sub-Committee and published in a peer reviewed journal.
Project Documents
• FRP - Final Report : Final Report FA0115 evid4   (1073k)
• FRP - Final Report : Final REPORT FOR FA0115 Dec 13   (629k)
• ANX - Annex : Annexes 1 and 2 FA0115 Report   (234k)
Time-Scale and Cost
From: 2012

To: 2013

Cost: £60,500
Contractor / Funded Organisations
Royal Society of Chemistry
Food manufacturing industry