Characterization of smoked salmon by infrared spectroscopy

Smoked salmon results from the salting of the fillets, followed by smoking. Salting and smoking methods may vary depending on different recipes specific to each manufacturer and can cause variability in the composition of the end product.The aim of this work was to try to classify a posteriori two processes of production of smoked salmon by simple analyzes of near and medium infrared spectroscopy.The experiment was carried out on 6 salmons. For each salmon, 1 filet was salted and smoked according to the process A, the other filet was salted and smoked according to process B. Processes from industrial production are confidential.Samples were taken and analyzed both in near infrared spectroscopy (Foss NIRSystems model 6500) and in medium infrared microspctroscopy (IN10 Mx Thermo Scientific). The spectra were pre-processed and the multivariate analyzes implemented using the software "The Unscrambler".Principal component analyzes (PCAs) reveal spectral signatures (NIRS and MIR) which are characteristic of each process and therefore allow to discriminate at posteriori the samples from each process (A and B).This experiment demonstrates the power of infrared spectroscopy methods to characterize smoked salmon fillets and identified their technological itinerary

Effect of salting process on the histological structure of salmon flesh

Atlantic Salmon , Salmo Salar, is composed of approximately 70% water, 19% protein, 10% lipid and 1% small nutrients (vitamins, glycogen, pigments ...). Smoked salmon comes from the processing of fresh salmon: the fillets are removed from the fish, salted and then smoked. Salting can be carried out with dry salt or by brine injection. The objective of the study was to compare the evolution of the cell structure and ultrastructure of the salmon muscle subjected to salting with dry salt and salting by brine injection.The experiment was carried out on 6 salmons. For each salmon, 1 fillet was salted with dry salt and the other fillet was additionally injected with brine. The fillets were smoked at low temperature (20-22 ° C). Samples were taken for histological analyzes (cryofixation, preparation of 10 μm thick histological sections, staining and observation by optical microscopy) and ultrastructural analyzes (chemical fixation, dehydration, resin inclusion, ultrathin sections, staining and observation by electron microscopy).The results show a decrease in the size of the extracellular spaces after injection of brine, which is probably related to a swelling of the muscle cells that accumulate water. Dry salt salting, on the other hand, shows no difference in the extracellular size compared to the unsalted muscle.The salting substantially degrades the ultrastructure of the muscle with in particular a significant solubilization of the Z-lines. Salting by injection of brine leads to swelling of the myofibrils and almost complete solubilization of the Z lines