27
phenolic glycosides-rich Chamuang leaf extract (CLE) has been found to be
more effective in the prevention of melanosis when compared with sodium
metabisulphite (Shiekh et al. 2019). Pomegranate extract was found effective in
delaying melanosis in shrimp (Litopenaeus vannamei) (Fang et al. 2013). Lower
melanosis scores were found in Pacific white shrimp treated with lead (Leucaena
leucocephala) seed extract throughout the storage of 12 days compared with the
control and sodium metabisulphite (1.25%) treated samples (Nirmal and
Benjakul 2011a, b). The effects of Thailand native leaf extracts (Liang, Munpoo, cashew and lead) on shrimp polyphenoloxidase (PPO) activity were compared. The highest inhibitory activity was observed with cashew leaf extract. It
has been reported that immersion of the shrimp in the solution of the cashew leaf
extract (1%) is effective in preventing melanosis during refrigerated storage
(Sae-Leaw and Benjakul 2019).
Microbial Spoilage
Shrimp is a perishable product due to their protein and free amino acid content and
post-mortem changes occur faster than fish. Rapid microbial deterioration during
post-mortem storage is a serious problem in shrimp processing (Ramesh Babu et al.
2017). The muscular tissue of the shrimp deteriorates faster than the mammalian
muscles, as in the fish. The faster breakdown of the crustaceans is due to higher
water content, higher free amino acid content, and faster autolysis by existing
enzymes and less connective tissue compared to other fleshy foods (Abu Bakar et al.
2008). Free amino acid and non-nitrogenous substance contents of shrimps constitute a suitable medium for microbial growth (Zeng et al. 2005). Moreover, neutral
pH, high water activity (Aw) and high content of low molecular weight compounds
make shrimp matrix an ideal substrate for bacteria. The growth of these bacteria and
their metabolic activities cause undesired flavours, colours, and texture changes
(Gram and Huss 1996; Jaffres et al. 2011). Shrimps spoil because of improper handling, and this spoilage is irreversible, can never bring back with further processing.
Shrimps can contaminate with microorganisms in case of poor hygienic condition,
inappropriate processing, and preservation and storage conditions. Protecting the
quality of the shrimp or preventing its deterioration is one of the most important
problems facing the industry worldwide (Abu Bakar et al. 2008).
Dominant Microflora
Shrimps can have high levels of microorganism load even when caught. One of the
factors affecting the microbial quality of the shrimps is the status of microbial contamination of the waters they live in. It is likely that the microorganism load of
shrimps caught from coastal areas close to polluted regions is high. On the other
hand, fishing gears that drag the bottom of the water for shrimp catching are used.
During the application of this technique, it is possible to increase the level of contamination of shrimps by activating the sediments rich in microorganisms in the sea
2.1 Shrimps/Prawns
phenolic glycosides-rich Chamuang leaf extract (CLE) has been found to be
more effective in the prevention of melanosis when compared with sodium
metabisulphite (Shiekh et al. 2019). Pomegranate extract was found effective in
delaying melanosis in shrimp (Litopenaeus vannamei) (Fang et al. 2013). Lower
melanosis scores were found in Pacific white shrimp treated with lead (Leucaena
leucocephala) seed extract throughout the storage of 12 days compared with the
control and sodium metabisulphite (1.25%) treated samples (Nirmal and
Benjakul 2011a, b). The effects of Thailand native leaf extracts (Liang, Munpoo, cashew and lead) on shrimp polyphenoloxidase (PPO) activity were compared. The highest inhibitory activity was observed with cashew leaf extract. It
has been reported that immersion of the shrimp in the solution of the cashew leaf
extract (1%) is effective in preventing melanosis during refrigerated storage
(Sae-Leaw and Benjakul 2019).
Microbial Spoilage
Shrimp is a perishable product due to their protein and free amino acid content and
post-mortem changes occur faster than fish. Rapid microbial deterioration during
post-mortem storage is a serious problem in shrimp processing (Ramesh Babu et al.
2017). The muscular tissue of the shrimp deteriorates faster than the mammalian
muscles, as in the fish. The faster breakdown of the crustaceans is due to higher
water content, higher free amino acid content, and faster autolysis by existing
enzymes and less connective tissue compared to other fleshy foods (Abu Bakar et al.
2008). Free amino acid and non-nitrogenous substance contents of shrimps constitute a suitable medium for microbial growth (Zeng et al. 2005). Moreover, neutral
pH, high water activity (Aw) and high content of low molecular weight compounds
make shrimp matrix an ideal substrate for bacteria. The growth of these bacteria and
their metabolic activities cause undesired flavours, colours, and texture changes
(Gram and Huss 1996; Jaffres et al. 2011). Shrimps spoil because of improper handling, and this spoilage is irreversible, can never bring back with further processing.
Shrimps can contaminate with microorganisms in case of poor hygienic condition,
inappropriate processing, and preservation and storage conditions. Protecting the
quality of the shrimp or preventing its deterioration is one of the most important
problems facing the industry worldwide (Abu Bakar et al. 2008).
Dominant Microflora
Shrimps can have high levels of microorganism load even when caught. One of the
factors affecting the microbial quality of the shrimps is the status of microbial contamination of the waters they live in. It is likely that the microorganism load of
shrimps caught from coastal areas close to polluted regions is high. On the other
hand, fishing gears that drag the bottom of the water for shrimp catching are used.
During the application of this technique, it is possible to increase the level of contamination of shrimps by activating the sediments rich in microorganisms in the sea
2.1 Shrimps/Prawns