302
The points that can be intervened to prevent biotoxin hazard are suggested as
follows (Hegaret and Shumway 2009):
• The harvest should be stopped when potentially toxic phytoplankton species are
present
• Shellfish populations should be sampled before harvest and analysed toxicity in
the shellfish tissues
• Specific tissues containing phycotoxins should be removed after harvest
• Advisories to cook harvested shellfish should be issued thoroughly in cases
wherein phycotoxins are heat labile.
• Moreover, monitoring programs and regulations need to be established to limit
the risk of intoxication of humans by toxic shellfish. To be efficient, the monitoring programs must allow rapid detection of any toxic algae or presence of toxic
shellfish, to be able to limit the harvest and avoid contamination, as well as to
prevent unnecessary disposal of toxic shellfish already harvested. Thus, many
countries have monitoring programs screening the phytoplankton present in the
water, but also the flesh of the shellfish on a regular basis. Moreover, a good
network needs to be developed to be able to transfer the information very rapidly
and efficiently to seafood harvesters, distributors, and consumers, as well as public health and medical professionals.
5.5.2 Protection from Microbial Hazards
Conventional commercial processes employed to purge the microbial contamination of live bivalves are depuration, performed in tanks, and relaying, performed in
the natural environment. Detailed information about the depuration is given in
Chap. 3 (Molluscan shellfish). There are many factors affecting depuration process.
Some these factors are water quality, oxygenation and flow rates of water, temperature, water to bivalve ratio, salinity, removal, and deposition, of faecal material.
Some disinfection methods such as use of chlorine, UV light, ozone and iodophors
also affect depuration. In this case the most effective depuration conditions should
be constituted to provide consumer safety.
Apart from depuration and relaying, post-harvest use of various techniques such
as irradiation, pasteurization, high hydrostatic pressure (HHP) and freezing may
help reduce the risk of infection by pathogens (Soniat 2009).
One of the most widely used management approaches is the regular microbiological monitoring of shellfish harvesting areas/shellfish tissues and classifying the
areas (Rees et al. 2010). For this purpose, areas approved by various countries and
authorities have been determined. Shellfish from these areas can be used for human
consumption without further processing. The classification of a production area
determines the treatment required before living bivalve molluscs (shellfish) may be
marketed for human consumption. Shellfish production and relay areas are classified according to the levels of E. coli detected in shellfish flesh. Based on the
5 Shellfish Safety
The points that can be intervened to prevent biotoxin hazard are suggested as
follows (Hegaret and Shumway 2009):
• The harvest should be stopped when potentially toxic phytoplankton species are
present
• Shellfish populations should be sampled before harvest and analysed toxicity in
the shellfish tissues
• Specific tissues containing phycotoxins should be removed after harvest
• Advisories to cook harvested shellfish should be issued thoroughly in cases
wherein phycotoxins are heat labile.
• Moreover, monitoring programs and regulations need to be established to limit
the risk of intoxication of humans by toxic shellfish. To be efficient, the monitoring programs must allow rapid detection of any toxic algae or presence of toxic
shellfish, to be able to limit the harvest and avoid contamination, as well as to
prevent unnecessary disposal of toxic shellfish already harvested. Thus, many
countries have monitoring programs screening the phytoplankton present in the
water, but also the flesh of the shellfish on a regular basis. Moreover, a good
network needs to be developed to be able to transfer the information very rapidly
and efficiently to seafood harvesters, distributors, and consumers, as well as public health and medical professionals.
5.5.2 Protection from Microbial Hazards
Conventional commercial processes employed to purge the microbial contamination of live bivalves are depuration, performed in tanks, and relaying, performed in
the natural environment. Detailed information about the depuration is given in
Chap. 3 (Molluscan shellfish). There are many factors affecting depuration process.
Some these factors are water quality, oxygenation and flow rates of water, temperature, water to bivalve ratio, salinity, removal, and deposition, of faecal material.
Some disinfection methods such as use of chlorine, UV light, ozone and iodophors
also affect depuration. In this case the most effective depuration conditions should
be constituted to provide consumer safety.
Apart from depuration and relaying, post-harvest use of various techniques such
as irradiation, pasteurization, high hydrostatic pressure (HHP) and freezing may
help reduce the risk of infection by pathogens (Soniat 2009).
One of the most widely used management approaches is the regular microbiological monitoring of shellfish harvesting areas/shellfish tissues and classifying the
areas (Rees et al. 2010). For this purpose, areas approved by various countries and
authorities have been determined. Shellfish from these areas can be used for human
consumption without further processing. The classification of a production area
determines the treatment required before living bivalve molluscs (shellfish) may be
marketed for human consumption. Shellfish production and relay areas are classified according to the levels of E. coli detected in shellfish flesh. Based on the
5 Shellfish Safety