46
of enzymes and microorganisms. Ultrasonic is a technology that can meet the needs
such as determining the physical and chemical properties of foods, modifying,
observing during the process and helping them to control the quality. The ultrasound applied material particles vibrate under the influence of ultrasonic waves and
the total number of vibrations per minute is called frequency (Knorr et al. 2004). In
addition, high-energy ultrasound application has been proven to accelerate crystal
formation in the crystallization process. It has been determined that ultrasonic freezing processes shorten the time required for the product to freeze and improve the
quality of the frozen product. It has been found that high-energy ultrasonic application affects the crystallisation process in many ways, such as supporting the formation of crystal nuclei, ensuring the formation of small and regular crystals and
preventing the uneven surface structure (Kiani et al. 2013; Saclier et al. 2010). There
is no study on use of ultrasound assisted freezing of shrimp. This is one of the issues
to be studied in the future.
Changes in Frozen Storage
Freezing is more effective in long-term preservation, physical, chemical, and biochemical events continue during storage. The low temperature in freezing, although
slowing down the formation of enzymatic and chemical changes, cannot completely
prevent it (Fennema et al. 1973). The most important changes during frozen storage
occur in proteins and lipids. These changes affect sensory properties such as odour,
colour, and texture. Frozen storage causes changes in the proteins of fish meat
known as freezing denaturation. These changes occur in the form of opening of
protein molecules, secondary reactions between the different reactive groups of proteins and other components of the fish muscle. Proteins lose some of their solubility
and have lower enzyme activity. As a result of these changes, significant changes in
the functional properties of fish meat are observed. These occur in the form of water
retention capacity; gel forming capability and decreases in emulsion capacity and
negative changes in texture (Sikorski and Kolakowski 1990). The freezing process
promotes changes in muscle tissue with the formation and accretion of ice crystals,
dehydration and increase of solute (Shenouda 1980).
Protein denaturation and textural defects may occur depending on many factors
such as species, freezing and thawing rates, storage temperatures, storage conditions between harvesting and freezing (Diaz-Tenorio et al. 2007). It has been
reported that sea animals’ muscles are more sensitive to protein denaturation caused
by freezing than that of mammalian muscle (Matsumoto 1979).
During frozen storage, drying or dehydration may develop on the surface of frozen seafood. Excessive drying causes “freezer burn”. To avoid this, the seafood is
covered with ice glass called “glazing”. Glazing means that the use a protective ice
coating on frozen seafood. The glazing process, which is to wrap the product with a
thin layer of ice, increases the shelf life of the product by protecting it from oxygen
and dehydration. Glazing is usually accomplished by dipping or spraying frozen
seafood in potable water (Solval et al. 2014).
2 Crustacean Shellfish
of enzymes and microorganisms. Ultrasonic is a technology that can meet the needs
such as determining the physical and chemical properties of foods, modifying,
observing during the process and helping them to control the quality. The ultrasound applied material particles vibrate under the influence of ultrasonic waves and
the total number of vibrations per minute is called frequency (Knorr et al. 2004). In
addition, high-energy ultrasound application has been proven to accelerate crystal
formation in the crystallization process. It has been determined that ultrasonic freezing processes shorten the time required for the product to freeze and improve the
quality of the frozen product. It has been found that high-energy ultrasonic application affects the crystallisation process in many ways, such as supporting the formation of crystal nuclei, ensuring the formation of small and regular crystals and
preventing the uneven surface structure (Kiani et al. 2013; Saclier et al. 2010). There
is no study on use of ultrasound assisted freezing of shrimp. This is one of the issues
to be studied in the future.
Changes in Frozen Storage
Freezing is more effective in long-term preservation, physical, chemical, and biochemical events continue during storage. The low temperature in freezing, although
slowing down the formation of enzymatic and chemical changes, cannot completely
prevent it (Fennema et al. 1973). The most important changes during frozen storage
occur in proteins and lipids. These changes affect sensory properties such as odour,
colour, and texture. Frozen storage causes changes in the proteins of fish meat
known as freezing denaturation. These changes occur in the form of opening of
protein molecules, secondary reactions between the different reactive groups of proteins and other components of the fish muscle. Proteins lose some of their solubility
and have lower enzyme activity. As a result of these changes, significant changes in
the functional properties of fish meat are observed. These occur in the form of water
retention capacity; gel forming capability and decreases in emulsion capacity and
negative changes in texture (Sikorski and Kolakowski 1990). The freezing process
promotes changes in muscle tissue with the formation and accretion of ice crystals,
dehydration and increase of solute (Shenouda 1980).
Protein denaturation and textural defects may occur depending on many factors
such as species, freezing and thawing rates, storage temperatures, storage conditions between harvesting and freezing (Diaz-Tenorio et al. 2007). It has been
reported that sea animals’ muscles are more sensitive to protein denaturation caused
by freezing than that of mammalian muscle (Matsumoto 1979).
During frozen storage, drying or dehydration may develop on the surface of frozen seafood. Excessive drying causes “freezer burn”. To avoid this, the seafood is
covered with ice glass called “glazing”. Glazing means that the use a protective ice
coating on frozen seafood. The glazing process, which is to wrap the product with a
thin layer of ice, increases the shelf life of the product by protecting it from oxygen
and dehydration. Glazing is usually accomplished by dipping or spraying frozen
seafood in potable water (Solval et al. 2014).
2 Crustacean Shellfish