37
The quality of the water to be used in the icing is also important. The water must
be of drinking water quality. Even if the ice is produced from clean drinking water,
some bacteria may grow depending on the storage time and temperature. Thus, the
long-standing ice is contaminated with deteriorating bacteria, and because of the
use of old and dirty ice, the product will deteriorate more quickly (Gokoglu 2002).
Giant freshwater prawn (Macrobrachium rosenbergii) and marine tiger shrimp
(Panaeus monodon) were stored in ice in two groups as head-on and headless.
According to the sensory analysis results freshwater prawn were found acceptable
up to 5 days in head-on shrimps and 6 days in headless shrimps during the storage,
while marine tiger shrimps were found acceptable up to 8 and 9 days in head-on and
headless shrimps respectively (Rahman et al. 2000). While a 10-day shelf life has
been reported for Macrobrachium rosenbergii stored at 0 °C (Leitao and Rios 2000),
it was reported as 12–16 days for the same fish species stored in ice (Lalitha and
Surendran 2006). Pacific white shrimp (Littopenaeus vannamei) had shelf life of
8 days during the storage in ice (Odilichukwu et al. 2014).
Slurry Ice/Liquid Ice
The traditional icing method may have some undesirable effects on the product. Due to
crushed ice, the product can be damaged, or some aroma losses can be seen. In addition, when large amounts catch is obtained labour and the cost increases. Liquid ice has
recently been noted as a successful method for the rapid cooling of food products.
Liquid ice provides better heat conduction due to physical properties. In addition, the
liquid ice consists of microscopic ice crystals suspended in water, also prevents physical damage. On the other hand, as the liquid ice cuts off the contact with air, the biochemical events in the presence of oxygen are delayed (Huidobro et al. 2002). The ice
slurry consists of a homogeneous mixture of small ice particles and carrier fluid. The
liquid may be pure fresh water or a double solution containing water and freezing point
lowering such as sodium chloride, ethanol, ethylene glycol and propylene glycol. Since
the slurry maintains a constant low temperature during the cooling process, it provides
a higher heat transfer coefficient than water or other single-phase liquids. Due to these
properties of the ice slurry it is useful in many applications (Kauffeld et al. 2010). In a
study in which shrimps (Pandalus borealis) were preserved using different cooling
techniques, the use of liquid ice was found to be more effective compared to the flake
ice or sea water flake ice mixture (Zeng et al. 2005).
Chilled Seawater (CSW)
Chilled sea water can be used as an alternative to ice to store raw shrimp at sea. It has
the advantage of cooling shrimp rapidly. Some shrimp vessels are equipped to hold
shrimps in sea water at 1–4 °C. CSW is very efficient in cooling because the fish are
surrounded completely by the cooling medium. In its simplest form, CSW is made by
adding fresh seawater to ice held in tubs or in subdivided waterproof compartments or
2.1 Shrimps/Prawns
The quality of the water to be used in the icing is also important. The water must
be of drinking water quality. Even if the ice is produced from clean drinking water,
some bacteria may grow depending on the storage time and temperature. Thus, the
long-standing ice is contaminated with deteriorating bacteria, and because of the
use of old and dirty ice, the product will deteriorate more quickly (Gokoglu 2002).
Giant freshwater prawn (Macrobrachium rosenbergii) and marine tiger shrimp
(Panaeus monodon) were stored in ice in two groups as head-on and headless.
According to the sensory analysis results freshwater prawn were found acceptable
up to 5 days in head-on shrimps and 6 days in headless shrimps during the storage,
while marine tiger shrimps were found acceptable up to 8 and 9 days in head-on and
headless shrimps respectively (Rahman et al. 2000). While a 10-day shelf life has
been reported for Macrobrachium rosenbergii stored at 0 °C (Leitao and Rios 2000),
it was reported as 12–16 days for the same fish species stored in ice (Lalitha and
Surendran 2006). Pacific white shrimp (Littopenaeus vannamei) had shelf life of
8 days during the storage in ice (Odilichukwu et al. 2014).
Slurry Ice/Liquid Ice
The traditional icing method may have some undesirable effects on the product. Due to
crushed ice, the product can be damaged, or some aroma losses can be seen. In addition, when large amounts catch is obtained labour and the cost increases. Liquid ice has
recently been noted as a successful method for the rapid cooling of food products.
Liquid ice provides better heat conduction due to physical properties. In addition, the
liquid ice consists of microscopic ice crystals suspended in water, also prevents physical damage. On the other hand, as the liquid ice cuts off the contact with air, the biochemical events in the presence of oxygen are delayed (Huidobro et al. 2002). The ice
slurry consists of a homogeneous mixture of small ice particles and carrier fluid. The
liquid may be pure fresh water or a double solution containing water and freezing point
lowering such as sodium chloride, ethanol, ethylene glycol and propylene glycol. Since
the slurry maintains a constant low temperature during the cooling process, it provides
a higher heat transfer coefficient than water or other single-phase liquids. Due to these
properties of the ice slurry it is useful in many applications (Kauffeld et al. 2010). In a
study in which shrimps (Pandalus borealis) were preserved using different cooling
techniques, the use of liquid ice was found to be more effective compared to the flake
ice or sea water flake ice mixture (Zeng et al. 2005).
Chilled Seawater (CSW)
Chilled sea water can be used as an alternative to ice to store raw shrimp at sea. It has
the advantage of cooling shrimp rapidly. Some shrimp vessels are equipped to hold
shrimps in sea water at 1–4 °C. CSW is very efficient in cooling because the fish are
surrounded completely by the cooling medium. In its simplest form, CSW is made by
adding fresh seawater to ice held in tubs or in subdivided waterproof compartments or
2.1 Shrimps/Prawns