Structure of whole fresh muscle, during freezing and frozen storage changes due to shrinking of muscle fibber as a result of movement of water into extracellular spaces (Sigurgisladottir
et al., 2000).
Also, myofibrillar proteins and collagen aggregate can cause an increase of toughness of both raw and cooked muscle (Montero & Borderias, 1992),and an increase in loss of water holding capacity in fish flesh (Mackie, 1993).
The present study showed that frozen storage lead to an increase of liquid loss and fat loss in raw and smoked fillets, as reported for Atlantic salmon (Solberg et al., 2000).