LAUSR

Salting is a technique used for preserving fish meat and allows obtaining added value products. The salting process provokes several structure modifications, which in turns cause changes in the fish texture. Thus, the objective of this study was to investigate the effect of three salting procedures (dry salting [DS], mixed salting [MS] and brining [BS]) on the rheology and structure of Merluccius hubbsi (Argentine hake). Rheological properties were evaluated using dynamic oscillatory and thermorheology tests, and the structure changes by scanning electron microscopy. DS samples showed the highest values of salt concentration referred to liquid phase (zNaCl ), while BS showed the lowest ones. In all cases, elastic (G') and loss (G″) modulus increased with salting time. G' values exceeded G″ values, indicating a predominant solid behavior. DS samples presented the greatest increase in rheological parameters (G', G″ and η*). Thermomechanical spectra allowed to identify an increase in denaturation temperature (Td) of proteins (myosin and actin) for DS and MS, and to a lesser extent for BS (Td = 46.7 ± 0.4°C, Td = 50.3 ± 0.8°C, Td = 58.8 ± 0.6°C and Td = 58.2 ± 0.9°C for fresh, BS, MS and DS, respectively). Ultrastructural images evidenced conformational changes on the myofibrillar proteins and the connective tissue (collagen). BS caused the least superficial damage to hake tissue. Based on the results, BS could be the method recommended for the industrial production of salted M. hubbsi. PRACTICAL APPLICATION: During salting of hake, variations in water and salt content have a significant effect on the myofibrillar and connective tissue proteins. The study of rheological properties and microstructure allows a better understanding of the conformational changes induced by the salting process. The least surface damage exhibited by brining fillets is consistent with the mass transfer mechanism that leads to the formation of a film on the muscle surface that dilutes the salt; for this reason, compared to dry and mixed salting, brining could be the method recommended for the industrial production of salted (>15% w/w) Merluccius hubbsi.