Use of hydrogen peroxide and carbonate/bicarbonate buffer for soaking of bacalao (salted cod)

Dry-salted cod (Gadus morhua) rehydration assisted by pulsed electric fields: modelling of mass transfer kinetics

BACKGROUND

Dry-salted cod (Gadus morhua) must be rehydrated before consumption and this step can take up to 5 days. Desalting of cod on an industrial scale poses many problems, mainly related to the long processing times and the quality of the final product. For this reason, many researchers have focused on finding new desalting methods to improve mass transfer. The application of pulsed electric fields (PEF) has been proposed as an alternative method for improving mass transfer in many food processes. However, there is no previous literature on the use of PEF to improve animal tissue rehydration. Therefore, the present study aimed to investigate the influence of two PEF pre-treatments [PEF (1) 500 V cm^-1 and PEF (2) 1000 V cm^-1 ] on mass transport kinetics during the rehydration process of salted cod. The rehydration process was carried out under static conditions for 6 days, immersing dry-salted cod samples in tap water (5 ± 0.5 °C).

RESULTS

The results show that the use of PEF technology increases the rate of the rehydration process of dry-salted cod and influences the redistribution of salt. In general, the samples pre-treated with PEF showed higher weight gain and lower salt loss than the control samples during the rehydration process.

CONCLUSION

The application of PEF prior to rehydration of salted cod samples could be of interest to the food industry as a result of a higher process yield (higher weight gain) and the possibility to reduce the water renewal because less NaCl is lost in the wastewater. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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

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 Z(NaCl) = Y(NaCl) 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.

Quality changes during cod (Gadus morhua) desalting at different temperatures

BACKGROUND

To advise consumers and manufacturers regarding decreasing the time needed to desalt salted cod (a time-consuming process), there is a need to develop knowledge about quality changes at different desalting temperatures. The objective of this work was to evaluate the physico-chemical, microbiological and sensory quality changes and their causes during cod desalting at 5, 10 and 15 °C, using a cod/water ratio of 1:9 without water changes. The influence of slices with different thickness and different desalting times was also evaluated.

RESULTS

Desalting promoted a decrease in the levels of total volatile basic nitrogen, thiobarbituric acid reactive substances and free amino acids nitrogen (FAA-N). The highest FAA-N values were found in 'thicker' samples desalted at 15 °C due to the higher proteolytic bacteria number observed in these samples, which activity compensated the leaching of soluble components to the desalting solution. The water uptake and the salt leaching out of the muscle found during the processes created conditions for the bacterial growth, contributing to the spoilage at 15 °C. Based on fresh odour and 'off'-flavours results, 'thicker' samples desalted at 15 °C after 72 h were close to spoilage and on microbial levels were spoiled.

CONCLUSION

In order to extend the shelf life and safety of cod desalted products, desalting at temperatures above 10 °C is not advisable. © 2014 Society of Chemical Industry.