45
It is not toxic unless it is in very high concentrations. It is a relatively inert gas, no
danger of fire or explosion. In freezers with carbon dioxide, freezing is very fast and
drip losses are reduced (Gokoglu 2002).
In a study in which two different freezing methods were used, forced convection
freezing and cryogenic freezing, the researchers determined that cryogenic freezing
is the best method in terms of cell and tissue structure, but they suggested forced
convection freezing method for freezing of farmed whiteleg shrimp (Litopenaeus
vannamei), because the cryogenic method is expensive (Diaz-Tenorio et al. 2007).
Innovative Freezing Methods
Temperature below −40 °C is defined as ultra-low freezing temperature. The freezing temperature greatly influences the structure and quality of a product. Ultra-lowtemperature freezing increases the freezing rate because the surface heat transfer
coefficient between the food and the freezing medium is very high and the temperature is very low (Wu et al. 2017). Tiger shrimps were frozen at different temperatures (−70, −80, −90 and −100 °C) and it was determined that the freezing time and
freezing rate increased with the temperature decline (Boonsumrej et al. 2007).
Similarly, anchovy was frozen at 3 different temperatures (−20, −40, and −80 °C)
and the highest freezing rate and shortest freezing time were determined in the product frozen at −80 °C (Aydın and Gokoglu 2014).
High pressure freezing (HPF) is a novel freezing technique, which has the potential to manage the formation and distribution of ice crystals and thus improve the
quality of frozen food (Cheng et al. 2017a). It is reported that the application of high
pressure reduces the freezing and melting points of the water to a minimum of
−22 °C at 207.5 MPa, as it opposes the volume increase in the formation of ice
crystals. In addition, during high-pressure freezing, it is possible to form small ice
crystals due to super cooling. In comparison with commercial freezing methods,
freezing with high pressure shortens the thawing time in the fish muscle and reduces
drip loss during thawing (Cheftel and Culioli 1997; Chevalier et al. 2000; Zhu et al.
2004). Slow freezing often results in larger ice crystal sizes that can cause extensive
mechanical damage. In a study, pressure assisted, and pressure shift freezing were
applied to actomyosin extracted from prawn (Metapenaeus ensis) to determine the
effect of high pressure freezing on denaturation of actomyosin. At the end of study,
it was found that pressure shift freezing at 200 MPa/20 °C/30 min conditions
reduced the denaturation of actomyosin and a pressure of 300 MPa was the critical
point to induce such a denaturation (Cheng et al. 2017b). In another study, fresh
shrimp was frozen by pressure shift freezing at 100 MPa (−8.4 °C), 150 MPa
(−14 °C) and 200 MPa (−20 °C), as well as by conventional air freezing at −20 °C
and liquid immersion freezing at −20 °C. It was found that pressure shift freezing
was the best method when investigated in terms of size, shape, and distribution of
ice crystals (Su et al. 2014).
Ultrasound is used as a non-thermal food preservation method. Ultrasound has
advantages compared to heat treatment. These are much less loss of sensory and
chemical properties of food, saving the time used and a higher rate of inactivation
2.1 Shrimps/Prawns
It is not toxic unless it is in very high concentrations. It is a relatively inert gas, no
danger of fire or explosion. In freezers with carbon dioxide, freezing is very fast and
drip losses are reduced (Gokoglu 2002).
In a study in which two different freezing methods were used, forced convection
freezing and cryogenic freezing, the researchers determined that cryogenic freezing
is the best method in terms of cell and tissue structure, but they suggested forced
convection freezing method for freezing of farmed whiteleg shrimp (Litopenaeus
vannamei), because the cryogenic method is expensive (Diaz-Tenorio et al. 2007).
Innovative Freezing Methods
Temperature below −40 °C is defined as ultra-low freezing temperature. The freezing temperature greatly influences the structure and quality of a product. Ultra-lowtemperature freezing increases the freezing rate because the surface heat transfer
coefficient between the food and the freezing medium is very high and the temperature is very low (Wu et al. 2017). Tiger shrimps were frozen at different temperatures (−70, −80, −90 and −100 °C) and it was determined that the freezing time and
freezing rate increased with the temperature decline (Boonsumrej et al. 2007).
Similarly, anchovy was frozen at 3 different temperatures (−20, −40, and −80 °C)
and the highest freezing rate and shortest freezing time were determined in the product frozen at −80 °C (Aydın and Gokoglu 2014).
High pressure freezing (HPF) is a novel freezing technique, which has the potential to manage the formation and distribution of ice crystals and thus improve the
quality of frozen food (Cheng et al. 2017a). It is reported that the application of high
pressure reduces the freezing and melting points of the water to a minimum of
−22 °C at 207.5 MPa, as it opposes the volume increase in the formation of ice
crystals. In addition, during high-pressure freezing, it is possible to form small ice
crystals due to super cooling. In comparison with commercial freezing methods,
freezing with high pressure shortens the thawing time in the fish muscle and reduces
drip loss during thawing (Cheftel and Culioli 1997; Chevalier et al. 2000; Zhu et al.
2004). Slow freezing often results in larger ice crystal sizes that can cause extensive
mechanical damage. In a study, pressure assisted, and pressure shift freezing were
applied to actomyosin extracted from prawn (Metapenaeus ensis) to determine the
effect of high pressure freezing on denaturation of actomyosin. At the end of study,
it was found that pressure shift freezing at 200 MPa/20 °C/30 min conditions
reduced the denaturation of actomyosin and a pressure of 300 MPa was the critical
point to induce such a denaturation (Cheng et al. 2017b). In another study, fresh
shrimp was frozen by pressure shift freezing at 100 MPa (−8.4 °C), 150 MPa
(−14 °C) and 200 MPa (−20 °C), as well as by conventional air freezing at −20 °C
and liquid immersion freezing at −20 °C. It was found that pressure shift freezing
was the best method when investigated in terms of size, shape, and distribution of
ice crystals (Su et al. 2014).
Ultrasound is used as a non-thermal food preservation method. Ultrasound has
advantages compared to heat treatment. These are much less loss of sensory and
chemical properties of food, saving the time used and a higher rate of inactivation
2.1 Shrimps/Prawns