Quality changes of fresh and frozen protein solutions extracted from Atlantic cod (Gadus morhua) trim as affected by salt, cryoprotectants and storage time.

摘要

Fish protein solutions were extracted from cod (Gadus morhua) trim using thepH-shiftprocess. Fresh and frozen stability of cod protein solutions (CPS) [at 3% protein, pH 7.9, and different levels of salt, with/without cryoprotectants (sucrose, sorbitol and polyphosphate)]stored for different times and temperatures were studied. The results indicated that the fresh CPS was spoiled microbiologically after 3 days of storage at +2 degrees C. Viscosity (Brabander Unit) decreased in samples containing3 and 5% salt and increased in samples containing 10 and 15% salt after 2 days of storage at +2 degrees C. Viscosity of fresh samples containing 10 and 15% salt decreased with storage time. The expressible moisture and whiteness of fresh samples were not influenced by the storage time. Adding cryoprotectants to CPS containing 1.2, 3, 5, and 15% salt increased thewater holding capacity (WHC) and decreased theexpressible moisture. It also increased viscosity (BU) in samples containing 3 and 5% salt significantly after 14 weeks of storage at -24 degrees C. The cryoprotectants had no significant effect onimproving the whiteness of the samples. The storage time also increased the expressible moistureand decreased WHC in frozen samples. The most stable frozen samples were those with 5% salt and cryoprotectants followed by the samples with 3% salt and cryoprotectants.