Influence of temperature and fish thickness on the mass transfer kinetics during the cod (Gadus morhua) desalting process

• Published in: Journal of the Science of Food and Agriculture
• Main Authors: Oliveira H., Gonçalves A., Nunes M.L., Vaz-Pires P., Costa R.
• Other Authors: CIIMAR - Centro Interdisciplinar de Investigação Marinha e Ambiental
• Format: Article in Journal/Newspaper
• Language: English
• Published: John Wiley and Sons 2016
• Subjects: Gadus morhua
• Online Access: https://hdl.handle.net/10216/120403; https://doi.org/10.1002/jsfa.7657

BACKGROUND: The aim of this study was to analyse the influence of desalting temperature, fish thickness and desalting time on the mass transfer kinetics during the cod desalting process by physico-chemical analyses. RESULTS: Both water uptake and salt loss increased with increasing temperature (15 °C > 10 °C > 5 °C) up to 24 h in ‘thicker’ pieces. The equilibrium achievement was faster in ‘thinner’ pieces and also with increasing temperature. Longer desalting times at 10 °C can be a good practice to be used during cod desalting at an industrial scale in order to obtain commercial products with higher yields. The faster mass transfer during desalting of ‘thinner’ pieces appears to follow three periods as a result of diffusion of the components (water, NaCl, and soluble proteins) because of the concentration differences, and pressure gradients due to expansion/shrinkage of the protein matrix, which is dependent on the NaCl content. The refractive index can be used by industry as an indirect measurement to determine the moment at which the ‘thicker’ samples are near the ZNaCl = YNaCl equilibrium. CONCLUSION: Optimum combinations between the process variables analysed are essential in order to speed up the mass transfer kinetics during cod desalting at an industrial scale. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry The authors thank the Portuguese Foundation for Science and Technology (FCT) for the funding provided to H. Oliveira through a PhD grant (SFRH/BD/33394/2008) and also the support of FCT under the PEst-OE/AGR/UI4033/2011 project. The authors also would like to thank the group from ESAC chemical laboratory who provided valuable help whenever necessary.