220
(Gokoglu et al. 2018), cuttlefish (Sepia aculeata) (Joseph and Perigreen 1988).
During frozen storage, protein solubility increased in pota (Todaropsis eblanae) and
white octopus (Eledone cirrhosa) after 6 and 2 months respectively, and then gradually decreased (Moral et al. 2002). However, lower protein solubility was found in
squid muscle than those of octopus and cuttlefish. The authors explained this difference by reporting that squid contains a different class of myofibrillar proteins and is
therefore less susceptible to freezing and more prone to thermal denaturation
(Gokoglu et al. 2018). Contrary to these reports, there are also researchers who
reported that there was no significant change in protein solubility during frozen storage of squid (Illex argentinus) (Mignino et al. 2008) and (Loligo vulgaris) (GomezGuillen et al. 2003). Besides the protein solubility, Gokoglu et al. (2018) also
reported changes indicating protein denaturation, such as decreases in water retention capacity and increases in loss of cooking with total free amino acid content
during frozen storage in squid, octopus and cuttlefish muscles. Increases in free
fatty acids (FFA) content were reported during frozen storage of squid (Illex argentinus). Ruiz-Capillas et al. (2002b) observed decreases in the viscosity and emulsifying capacity of protein extracts from frozen-stored squid (Illex coindetti) (Paredi
et al. 2006) (Loligo vulgaris) (Atayeter and Ercoskun 2011).
Freezing and frozen storage affect the texture of the cephalopod muscles. The
frozen mantles of Illex argentinus, Loligo edulis, Sepia pharaonis were tougher
than the unfrozen ones. Toughness increased with increasing frozen storage time.
Injury of muscle fibres associated with the formation and development of ice crystals caused protein aggregation and hence toughening (Ueng and Chow 1998).
Similarly, frozen North Atlantic squids, Loligo pealei and Illex illecebrosus, were
found tougher compared to non-frozen (Stanley and Hultin 1982). The cuttlefish
(Sepia aculeata) texture, initially defined as “firm” and “chewy”, changed to “rubbery” in frozen storage for 10 months, and 16 months later it was defined as “hard
to chew” (Joseph and Perigreen 1988). The increase in shear force values of squid
(Loligo formosana) during frozen storage of 10 months has been reported and stated
that this increase caused by protein aggregation due to injured muscle fibres
(Benjakul et al. 2012).
Sensory changes are also observed in cephalopod meats in frozen storage. Squid
(Sepioteuthıs lessonıan), which was kept on ice using flake ice for 20 h and then
frozen with a horizontal contact plate freezer and stored at −20 °C, was reported to
be sensorially fair and acceptable until the end of the sixth month (Sukumar et al.
2014). Cuttlefish (Sepia aculeata) fillet inside colour turned pale yellow in 7 months
storage and its density increased with storage. The surface colour began to fade after
10 months of storage (Joseph and Perigreen 1988).
Thermal Processing of Cephalopods
The use of cephalopod molluscs as canned raw materials is low. One of the reasons
for this is the low yield in the final products due to the high losses of the nutrients
during processing, making them unprofitable as a canned food under current
3 Molluscan Shellfish
(Gokoglu et al. 2018), cuttlefish (Sepia aculeata) (Joseph and Perigreen 1988).
During frozen storage, protein solubility increased in pota (Todaropsis eblanae) and
white octopus (Eledone cirrhosa) after 6 and 2 months respectively, and then gradually decreased (Moral et al. 2002). However, lower protein solubility was found in
squid muscle than those of octopus and cuttlefish. The authors explained this difference by reporting that squid contains a different class of myofibrillar proteins and is
therefore less susceptible to freezing and more prone to thermal denaturation
(Gokoglu et al. 2018). Contrary to these reports, there are also researchers who
reported that there was no significant change in protein solubility during frozen storage of squid (Illex argentinus) (Mignino et al. 2008) and (Loligo vulgaris) (GomezGuillen et al. 2003). Besides the protein solubility, Gokoglu et al. (2018) also
reported changes indicating protein denaturation, such as decreases in water retention capacity and increases in loss of cooking with total free amino acid content
during frozen storage in squid, octopus and cuttlefish muscles. Increases in free
fatty acids (FFA) content were reported during frozen storage of squid (Illex argentinus). Ruiz-Capillas et al. (2002b) observed decreases in the viscosity and emulsifying capacity of protein extracts from frozen-stored squid (Illex coindetti) (Paredi
et al. 2006) (Loligo vulgaris) (Atayeter and Ercoskun 2011).
Freezing and frozen storage affect the texture of the cephalopod muscles. The
frozen mantles of Illex argentinus, Loligo edulis, Sepia pharaonis were tougher
than the unfrozen ones. Toughness increased with increasing frozen storage time.
Injury of muscle fibres associated with the formation and development of ice crystals caused protein aggregation and hence toughening (Ueng and Chow 1998).
Similarly, frozen North Atlantic squids, Loligo pealei and Illex illecebrosus, were
found tougher compared to non-frozen (Stanley and Hultin 1982). The cuttlefish
(Sepia aculeata) texture, initially defined as “firm” and “chewy”, changed to “rubbery” in frozen storage for 10 months, and 16 months later it was defined as “hard
to chew” (Joseph and Perigreen 1988). The increase in shear force values of squid
(Loligo formosana) during frozen storage of 10 months has been reported and stated
that this increase caused by protein aggregation due to injured muscle fibres
(Benjakul et al. 2012).
Sensory changes are also observed in cephalopod meats in frozen storage. Squid
(Sepioteuthıs lessonıan), which was kept on ice using flake ice for 20 h and then
frozen with a horizontal contact plate freezer and stored at −20 °C, was reported to
be sensorially fair and acceptable until the end of the sixth month (Sukumar et al.
2014). Cuttlefish (Sepia aculeata) fillet inside colour turned pale yellow in 7 months
storage and its density increased with storage. The surface colour began to fade after
10 months of storage (Joseph and Perigreen 1988).
Thermal Processing of Cephalopods
The use of cephalopod molluscs as canned raw materials is low. One of the reasons
for this is the low yield in the final products due to the high losses of the nutrients
during processing, making them unprofitable as a canned food under current
3 Molluscan Shellfish