Detecting commercial fraud in Atlantic salmon (Salmo salar) using NMR spectroscopy
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One way to preserve food is to freeze it, and today, frozen food is cheaper than fresh food. Because of this difference in value, the food industry can see economic benefits in misleading the consumer by labelling frozen-thawed food as fresh, and thus increasing the profits.This is the type of food falsification that will be the first topic of this thesis (i)). The focus will be on fish, and particularly on Atlantic salmon (Salmo salar). Trichloroacetic acid extracts of salmon muscle were analysed using NMR spectroscopy. The statistical analysis of NMR data allowed to find the differences in metabolic profiles of fresh and frozen-thawed salmon. It is particularly in the content of aspartate that the difference is evident.Another way food is falsified is by adding other, often cheaper, ingredients to the finished food products, and not labelling it properly. This is the second type of food falsification that will be discussed in this thesis(ii)). Trichloroacetic acid extracts of mixes of salmon and cod were analysed using NMR spectroscopy. By using statistical analysis and developing a SIMCA model, the mixes were correctly identified. The pure samples were also correctly classified, confirming the validity of the model.The first developed protocol allows testing of an arbitrary sample of salmon, and deciding whether it has been frozen or not, regardless of how many days it s been since the time of slaughter. The second protocol allows testing of a potential mix of salmon and cod, and deciding whether it is pure salmon, pure cod or a mix. Both methods will be possible to use as tests of quality in the fish industry.