Double freezing of cod fillets: Influence on sensory, physical and chemical attributes of battered and breaded fillet portions

Abstract

Fillet samples were processed on board a research vessel from cod (Gadus morhua) in different states of rigor mortis. In addition, headed and gutted fish in different states of rigor were frozen and, after ten days of frozen storage, the fish were thawed, processed into fillets and refrozen. During subsequent frozen storage at -24 degrees C of breaded and battered portions processed from the different fillet batches several quality attributes were tested using sensory, physical, and chemical methods. The measurements indicated differences in the quality attributes depending on refreezing and rigor states. Especially the sensory texture attributes gumminess and, with some restrictions, firmness were found to be suitable for distinguishing single frozen (SF) from double frozen (DF) samples. This finding was supported by the outcome of the measurement of penetration force where generally a significantly (p < 0.05) higher force was necessary to penetrate the DF compared to SF samples. DF samples were generally lighter (higher L*) than SF samples. The colour difference delta E between both sample types was at least very clear and therefore visible. However, no clear differences between SF and DF samples were found when evaluating the flavour attributes and using instrumental texture profile analysis for texture characterisation. Also, all chemical parameters measured did not allow to clearly distinguish between single and double frozen samples. Therefore, it can be stated that, at least when using cod as raw material for processing battered and breaded portions, the different methods for preparing the fillet blocks will, if at all, only affect the textural quality of the final products.

Liquid loss in thawed cod—Deconvoluting the effects of freezing‐rate, freezing cycles, frozen storage time, and thawing‐rate through a full factorial design

“…The fish is typically frozen on-board followed by a frozen storage period until thawing, processing, and refreezing before distribution. Some studies are available on this topic, and they all conclude that double freezing can bring about good product for lean fish (Maccallum, Laishley, Dyer, & Idler, 1966;Schubring, 2001Schubring, , 2002 and other fish species as well (Botta & Shaw, 1978;Schubring, 2010). This section mainly deals with the effects of the second freezing and the second thawing.…”

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“…Otherwise, this may lead to denaturation of the muscle proteins as well as structural damage of membranes, which can result in increased drip loss, loss of water holding capacity and textural changes (Duun and Rustad, 2007). Freeze-thaw cycle ruins the stability of muscle structure and cause prooxidant scattering and accumulation of lipid oxidation (Schubring, 2002).…”