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FOOD SAFETY HAZARDS IN AQUACULTURE SEAFOOD HYGIENE Lecture by G za Szita

Chemical compsition of the water. Salt concentration of the sea water: 0.35 %. Chloride (Cl): 55.04 wt% Sodium (Na): 30.61 wt% Sulphate (SO4): 7.68 wt% Magnesium (Mg): 3.69 wt% Calcium (Ca): 1.16 wt.% Potassium (K): 1.10 wt.%. Freshwater. Total water 'hardness' (i

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FOOD SAFETY HAZARDS IN AQUACULTURE SEAFOOD HYGIENE Lecture by G za Szita

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    1. FOOD SAFETY HAZARDS IN AQUACULTURE SEAFOOD HYGIENE Lecture by Géza Szita

    2. Chemical compsition of the water

    3. Salt concentration of the sea water: 0.35 %

    4. Chloride (Cl): 55.04 wt% Sodium (Na): 30.61 wt% Sulphate (SO4): 7.68 wt% Magnesium (Mg): 3.69 wt% Calcium (Ca): 1.16 wt.% Potassium (K): 1.10 wt.%

    5. Freshwater

    6. Total water 'hardness' (including both Ca2+ and Mg2+ ions)

    7. Permanent hardness is hardness (mineral content) that cannot be removed by boiling. CaSO4, CaCl2 MgSO4, MgCl2

    8. Temporary hardness is hardness that can be removed by boiling Ca+HCO3- ? CaCO3 + H2O + CO2

    9. Toxic materials in the water Ammonia NH3 Hydroxil-amine OH- NH2 Nitrite NO2 Nitrate NO3 Hidrogene-sulphide H2S Sulfite ions SO3

    10. 1. TERMS, PRODUCTION ~ Seafood: alI fish and shellfish (crustaceans, molluscs) finfish: salt- and fresh-water wild fishery I aquaculture > 300 species shellfish molluscs (salt-water): mussels, snails, clams, oysters, abalone scallops, cuttlefish crustaceans (salt/fresh-water): shrimp or prawns, crayfish,lobsters, crabs etc.

    11. Molluscs include chitons, clams, mussels, snails, nudibranchs (sea-slugs), tusk shells, octopus and squid.

    12. Mollusks

    13. Mollusks

    14. Bivalves

    15. The bivalves are the second largest class of molluscs. They differ from snails in having two shells, usually mirror images of each other. Some like oysters and mussels live attached to rocks and other hard surfaces while others, like pipis, burrow in sand. Leptonoidean bivalves (in picture) are a group which usually live commensally with other animals. Most have a large foot and are active crawlers.

    16. Limatula strangei. Some bivalves, such as the scallops are able to actively move when endangered by vigorously flapping their shells and squirting out jets of water. Limatula also moves very vigorously when disturbed. The tentacles around the mantle edge are sticky, very mobile and parts can break off them when the animal is disturbed, leaving a potential predator with a sticky writhing worm-like object to deal with as the Limatula escapes (25mm).

    17. Octopus

    18. Hapalochlaena fasciata. There are a number of species of blue-ringed octopus in Australian waters. They are all dangerous to handle, as the poison they use to kill their prey (crabs, snails) is highly venomous to humans. This species is common in New South Wales. Usually a dull mottled colour, it can become yellow with bright blue markings when disturbed.

    19. Squid

    20. Tunafish

    21. Swordfish

    22. 2. FOODBORNE DISEASES FROM SEAFOOD raw shellfish or undercooked, smoked, lightly salted fishery products shellfish: sedentary animals ~ filter their food from coastal and estuar waters ~ often subject to pollution by sewage effluents and rain runoff from agricultural lands ~ bacteria, chemical contaminants are concentrated in shellfish ~ quality of shellfish .~ quality of estuarine water in which they have been harvested . finfish: prevalance of hazards higher in coastal and inland aquaculture post-harvest handling, processing

    24. Paragonimiasis endemic in Asia, South America, West Aftica snails (first) ~ crustaceans (second) ~ humans, mammals parasite infects the lungs (tuberculosis) B. Nematodiases intemediate hosts marine or ftesh-water fish definitive hosts: marine mammals, birds, pigs mode of infection: ingestion of fish infective larvae Capillariasis - gastroenteritis ~ may be fatal - migratory fish-eating birds ~ natural definitive hosts ~ spread faeces contaminated with parasite eggs in freshwater fish ponds along migratory routes - treatment: mebendazole 400 mg/day for 20-30 days Anisaldasis

    25. C Cestodiases in humans fishborne infections not common Diphyllobothriasis - D. latum: mainly in cold waters (Eastern Europe, USA) - humans and fish-eating mammals: definitive" hosts - fish: intennediate hosts (salmon) - treatment: praziquantel, niclosamide

    26. ~ Bacteria divided into two groups: naturally present in the aquatic environment (indigenous bacteria) present as a result of contamination with human or animai faeces contamination during post-harvest handling and processing Enterobacteriaceae introduced into aquaculture ponds by animaI manure or human waste ~ significant numbers in products from waste- fed systems - Salmonella: may be naturally present in some tropical aquatic environment aquatic birds spread them fishborne human infeétions rare strains isolated from humans are different from those found in products from aquaculture - E. coli : bovine manure as pond fertilizer ~ pathogenic strains into the pond water 0157:H7 ~ cattle ~ waterborne infection

    27. Shigella: occasionally, very little risk Campylobacter: little information on the occurrence in aquaculture use of poultry manure for fertilizing ponds ~ potential risk Vibrio spp. Salt-tolerant organisms ~ occour naturally in marine environments in both tropical and temperate regions V. cholerae also occours in fresh water frequently isolated from sediments, plankton, molluscs, finfish, crustaceans positive correlation with admixture of contaminated human waste 12 species associated with seefood some human pathogenic Vibrio spp. may also be fish pathogens

    28. V. Parahaemolyticus ~ particularly associated with consumption of raw marine crustaceans and fish Aeromonas part of the normal aquatic flora A. hydrophila ~ fishbome disease' ~ risk is low

    29. Clostridium botulinum anaerobic, neurotoxin-producing organisms seven types ~ type E is naturally found in aquatic ~environments ~ often isolated from fish prevention of toxin production Listeria monocytogenes frequently isolated from aquaculture products in temperate regions risk: raw or without heat treatment

    30. Viruses Viruses causing disease in fish are not pathogenic to humans transmission of enteric virus diseases through waste-water reuse systems is far not so important as bacterial or helminthic diseases

    31. Other biological hazards large number of toxic compounds produced by aquatic organisms can cause human diseases produced by aquatic microorganisms: algae, bacteria that serve as food for the larvae of commercially important crustaceans and finfish possible sources of infection in farmed finfish and crustaceans: ingestion of toxic microorganisms or toxic products in feed marine zootoxins are among the most highly toxic substances known:

    32. Toxin LD50 (micro g/kg) in mice (IP) Ciguatoxin 0.5 Saxitoxin 3.0 Tetrodotoxin 8.0 Botulinum A 0.0001 TCDD 2.0

    33. A. Ciguatera poisoning produced by dinoflagellate algae small fish feed algae ~ eaten by larger predatory fish annually 10,000-50,000 cases (USA ~ Florida, Hawaii) mostly due to group er, red snapper, Sphyraena barracuda ciguatoxin accumulates in the liver, intestines, reproductive organs and muscles of the fish Cats are particularly sensitive ~ indicator Prevention difficult: ciguatoxin fish do not appear or taste spoiled

    34. B. Saxitoxin poisoning (paralytic shellfish poisoning, PSP) Saxitoxin: produced by toxic dinoflagellates ~ food base for millions of marine organisms toxin accumulates in the tissues of bivalve molluscs (mussels, clams, oysters, etc.) ingestion of a single clam, if heavily contaminated ~ can kilI a person Prevention: coastal shellfish monitoring programs ~ prohibit harvest during periods when toxin levels are high ("bIoom")

    35. C Tetrodotoxin poisoning (Puffer fish poisoning) Many species of puffer fish ~ tetrodotoxin Major cause offatal food poisoning in Japan (fugu) (Captain Cook nearly died of tetrodotoxin poisoning in New Caledonia in 1774) Tetrodotoxin: potent vasopressor and neurotoxin concentrates in the liver, skin ~ flesh becomes contaminated while the fish is cleaned Dogs, cats and birds are also susceptible

    36. D. Histamine Due to ingestion of spoiled fish -) mostly Scombroidae (eg, tuna, machereI) develops post-mortem due to improper handling and inadequate refrigeration tissues of scromboid fish contains high level of histidine -). histamine (Vibrio, Klebsiella, etc.) Histamine degraded orally - cadaverine and putrescine (cocontaminants) inhibit histaminases in human intestine Levels > 50mg histamine / 100 g of flesh ~ hazardous

    37. 4. CHEMICAL HAZARDS Through exposure to compounds used in the aquaculture systems or by pollution of waterways or sources of water

    38. A. Agrochemicals Fertilizers (urea, ammon ion, salts, trace element mixes) ~ usually no risk to food safety when used according to good agricultural practice Water treatment compounds (lime, oxidizing agents, flocculants)~ non-hazardous Pesticides (algicides, herbicides) no major risk disinfectants ~ widely used ~ no risk to consumer chemotherapeutica (antimicrobials, parasiticides) . drugs approved . drug residues

    39. - Metals (Pb, Cd, Cu, Zn, Fe ) present as a result of geochemical processes result of pollution pH of the water pollutants Mercury Chlorinated compounds (DDT, PCBs, dioxins)

    40. 5. CONTROL OF FOODBORNE DISEASE FROM SEEFOOD Fish · must be washed and chilled in ice or in cold water immediatley after catching · all of the ship equipment use for fish chilling must be c1eaned and disinfected after each debarkation · fish must be eviscerated as quickly as possible · chilling is also required during transportation to port and during distribution for further pocessing · thorough washing is very important ~ removes up to 95% of putrefactive microorganisms present on the fish skin · during transportation for long distances, the water must be aired; optimum temperature 4-80 oC

    41. Shellfish environmental monitoring of water quality US Public Health Service: shellfish growing areas are surveyed for safety ~ only those waters not subject to sewage contamination and havingcoliform counts <: 70 organisms/100 ml are approved for harvesting shellfish transferred from marginally polluted areas to unpolluted waters and left min. 14-28 days ~ will purify themselves (depuration) public education about the risks associated with eating raw shell fish

    42. pH of fish meat = 6.8 - 7.0 H2S (lead acetate) at 50 oC free ammonia trimethil-amine histamine - below 100 ppm

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