Quality Changes on Cod Fish (_Gadus morhua_) during Desalting Process and Subsequent High-Pressure Pasteurization  
[PERSON]  
1 Associated Laboratory for Green Chemistry-Network of Chemistry and Technology (LAQV-REQUIMTE), Chemistry Department, University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal; 1 [EMAIL_ADDRESS] (L.G.F. ); [EMAIL_ADDRESS] (M.J.M. ); [EMAIL_ADDRESS] (J.D. ); [EMAIL_ADDRESS] (C.A.P. ); [EMAIL_ADDRESS] (I.D.) 2 Department of Applied Technologies and Sciences, School of Agriculture, Polytechnic Institute of Beja, 7800-295 Beja, Portugal 2
of the cod muscle is usually reduced from approximately 82 to about 54%, and the salt content increases from 0.2% to 20% [4; 5]. After salting and drying, the cod is ready to be commercialized. However, before its consumption, the product must be desalted in tap water at room temperature or under refrigeration, due to the high salt content of the salted cod. This process usually takes between 1 and 3 days, depending on the cod size, the amount of salt, and the desalting conditions [6], showing a final water content of 80-85% and a salt content of 1-3% [7]. This fact, along with the considerable lifestyle changes observed in the last few decades, caused an increase in the demand for easy processes to prepare ready-to-eat products. The adjustment of several industries to those consumers' requirements resulted in the production of different cod products, such as frozen desalted cod, which has a relatively long shelf life (several months, being necessary to thaw before consumption), and refrigerated desalted cod. The commercialization of cod fish as a refrigerated product has many drawbacks, mostly due to its very short shelf life, between 1 and 5 days, which is caused by the favorable conditions for bacterial growth that cause its spoilage [8]. On the other hand, important changes take place in the textural, histological, and biochemical properties during desalting. The protein/cod matrix is rehydrated, and an improvement of the cod texture occurs [9], which is related to the increase in its muscle firmness [10]. The decrease in salt leads to water absorption by proteins, and consequently increases the water holding capacity [11]. Some enzymes play an important role in the post-mortem changes and degradation processes of fish, but in what concerns salted cod fish, as far as the authors are aware, there are no published data about the presence of enzymatic activity during the desalting processes. High-pressure processing (HPP) can be an option to limit microbial growth and extend the shelf life of desalted cod. HPP, in a range of 400 to 600 MPa, is now commonly applied to extend the shelf life of food products by inactivating a variety of pathogenic and spoilage vegetative bacteria, yeasts, moulds, and viruses, with minimal impact on organoleptic properties [12]. HPP emerges as a promising solution to extend the shelf life and enhance the safety of desalted/soaked cod. There are some studies issuing the efficacy of HPP in combination with various packaging techniques. [PERSON] and [PERSON] (2021) [13] explored different packaging solutions, revealing that HPP alone or combined with a modified atmosphere or a CO\({}_{2}\) emitter could extend the shelf life of rehydrated cod by at least 49 days. Also, [PERSON] et al. (2023) [14] focused on sustainable packaging solutions, highlighting the use of new recyclable multilayer plastic films in conjunction with HPP. The results indicate that these innovative packaging materials, when combined with HPP, can maintain high hygienic standards, and prolong the shelf life. Collectively, these findings emphasize the importance of HPP in modernizing fish processing methods, promoting sustainability, and meeting stringent quality standards in the food industry. Therefore, the aim of the present work was to study the evolution of some quality parameters of desalted cod during the desalting process at two different temperatures (4 and 20 \({}^{\circ}\)C).