The effects of the rigor state and freezing of cod prior to salting on the mass transfer during production and the quality of heavily cured cod have been investigated. Pre-rigor salting lead to a larger reduction in weight, a higher water loss and a lower uptake of NaCl than in fish salted post-rigor and in fish salted after frozen storage. The cause of this is believed to be the simultaneous influx of NaCl and rigor contractions in the fish muscle. In order to reduce the loss of proteins from the raw material and to increase the instrumental lightness values (L*) of the salt ripened product, the fish should be salted in pre-rigor state.However, if the primary focus is on the weight yield, the fish should be salted post-rigor after chilling or freezing pre-or post-rigor. Freezing and thawing of cod prior to salting post-rigor increased the firmness of the salt cured product compared to chilled fish salted post-rigor.

The quality of heavily salted cod was investigated as influenced by adjusted levels of calcium, magnesium and pH in the salt. The investigation was carried out as a multivariate study consisting of two separate 2 3 full factorial designs. The chemical composition, waterholding capacity, weight and protein yields, colour and firmness were used as quality indicators or responses to the salt mixtures tested. The pH of the salt was positively correlated with the muscle pH of the cured fillet. The pH of the muscle correlated negatively with the relative protein content, the lightness values and the sensory firmness of the cured muscle. The protein yield after the salt curing was also negatively correlated with the muscle pH. Calcium ions increased both the lightness and firmness and magnesium ions increased the lightness of the cured fillet.2

Yellow/brown discoloration of the muscle surface was investigated in downgraded heavily salted cod fillets from a processing plant. The results showed that discolored areas were relatively evenly distributed on the muscle surface and that lipid oxidation correlated with the copper and not the iron content, in the muscle. A model system for studying lipid oxidation and yellow discoloration of salted cod muscle was established and used for investigating the effect of including transition metals in the process. The model system confirms that copper is particularly pro‐oxidative. Of the redox states, the reduced form of copper was most potent. It appears that copper concentrates in the muscle during the brining. The results also indicate that copper induced lipid oxidation was increased by low pH of the fish muscle postmortem. The model system seems well suited for detailed studies of the salting process and may be useful for developing methods which can inhibit lipid oxidation in salted products.

Flavor characterization and quality of salt-cured and desalted cod (Gadus morhua) products was studied using sensory analysis and gas chromatography techniques. The products were produced in Iceland using two different processing methods (filleting and splitting) and three different salting procedures, i.e., the old single-step kench salting or a multistep procedure, and presalting (injection and brine salting or only brine salting), which was followed by kench salting. The main difference observed was between fillets and split fish, where the split fish was darker and had stronger flavor characteristics. Comparison of different salting procedures showed that the use of presalting improved the appearance of the salted products, which can be described as increased lightness and reduced yellowness of the products. In the same products, the intensity of curing flavors was milder, as described by sensory analysis and key aroma compounds. Derivatives from lipid and protein degradation contribute to the characteristic flavor of the salted products.

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