Dar seafood ppp standard
Appendix 1 Hazards along the seafood production and processing supply chain
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- Bu səhifədəki naviqasiya:
- Molluscan shellfish
- Effects of processing on levels of hazards in molluscan shellfish
- Scallops
- Other bivalves
- Abalone
Appendix 1Hazards along the seafood production and processing supply chainThe public health risks posed by the consumption of seafood in Australia are affected by the production and processing practices along the entire supply chain of each commodity type. This appendix summarises, for each broad commodity sector, data indicating the potential presence of food safety hazards and the significant points along the supply chain where there is the possibility of the introduction, increase, reduction or elimination of such hazards. As well as assisting in the evaluation of public health risks due to seafood consumption, the information in this appendix may be useful for the risk manager, helping to define critical points at which risk management strategies may be applied to greatest effect. Molluscan shellfishMolluscan shellfish, specifically oysters, scallops and pipis, have been implicated in several outbreaks of food-borne illness in Australia in the period 1995 to June 2002 (outbreak data are at Appendix 2). The hazards involved have included viruses (noroviruses and hepatitis A), algal biotoxins (diarrhoeic shellfish poisons in pipis) and bacteria (Salmonella serovars). The Imported Foods Inspection Scheme, coordinated by the Australian Quarantine and Inspection Service, tests a large number of samples of seafood entering Australia each year. In the period 1998 to June 2003 (inclusive), failures were recorded for imported molluscs tested for E. coli, the Standard Plate Count (as an indicator of hygienic food preparation and handling), Salmonella, L. monocytogenes and mercury. No failures were recorded in tests for domoic acid (causes amnesic shellfish poisoning), paralytic shellfish poison, staphylococcal enterotoxin, V. parahaemolyticus, cadmium or arsenic (Table 1.1). Table 1.1: Significant imported foods testing failures for molluscs, 1998–2003*
* No failures were recorded for imported molluscs tested for V. parahaemolyticus, Staphylococcal enterotoxin, algal biotoxins, cadmium, inorganic arsenic, total arsenic, organophosphates, organochlorines or PCBs. In the period 1990–2003, FSANZ coordinated four food recalls for oysters (hepatitis A, L. monocytogenes, domoic acid and excess lead) and four for mussels (E. coli, can defects and two for L. monocytogenes). Factors affecting the presence of these and other potential hazards along the production and processing supply chain for molluscan shellfish have been considered at the point of harvest, during processing and at subsequent points in the distribution chain. The hazards are broadly summarised in Table 1.2 and discussed at greater length for the main product groups (oysters, scallops, other bivalves and abalone) below. Table 1.2: Potential food safety hazards along the molluscan shellfish supply chain
Effects of processing on levels of hazards in molluscan shellfishOystersPre-harvest: Oysters are filter feeders, extracting marine algae, bacteria and nutrients from the surrounding waters. Because of this, they are prone to contamination from the growing environment, and concentrate certain chemical hazards as well as support viability and/or growth of microbiological contaminants. In Australia, oysters are mainly grown on aquaculture leases in estuarine environments, often close to populated or tourist recreational areas. Some pathogenic bacteria are endogenous to aquatic environments and can survive or grow in oysters, presenting a risk to health if ingested. These include V. vulnificus, pathogenic strains of V. parahaemolyticus and V. cholerae, and Aeromonas hydrophila. Typically, levels of these pathogens in the environment will be low, being subject to environmental conditions such as salinity and water temperature. In Australia, A. hydrophila, V. vulnificus and pathogenic strains of V. parahaemolyticus are present in estuarine environments where oysters are grown commercially. However, only non-toxigenic strains of V. cholerae O1 have been isolated from estuarine environments and oysters [1]. Microbiological hazards may also be introduced into oyster growing waters through pollution from sewage and animal waste. These pathogens typically survive for only short periods of time in the marine environment, but maintain viability for much longer when ingested by oysters. Examples include pathogenic strains of E. coli and Salmonella, Campylobacter, Yersinia and Shigella species. These organisms can multiply quickly, particularly at higher temperatures, potentially rendering oysters unsafe for consumption. Pathogenic viruses, particularly hepatitis A and the small round structured viruses (noroviruses of the caliciviridae family) may be introduced to oyster growing waters through sewage pollution and can survive for long periods in oysters. While viruses will not replicate in shellstock, they have low infectious doses, and thus present a risk to human health. Oysters can also extract chemical contaminants from their growing waters, and bioaccumulate them to hazardous concentrations in their flesh. Industrial, agricultural and sewage pollution may introduce various hazardous chemical into waterways where oysters are grown, while natural sources of heavy metals may also be of concern. Certain species of toxin-producing marine dinoflagellate and diatomic algae present a food safety risk from oyster consumption. The algae and toxins can potentially accumulate to high concentrations in oysters, particularly during periods of algal bloom (for example, red tides) when levels of the algae suddenly increase in response to environmental triggers. The combination of factors triggering bloom events is not fully understood, and toxin concentrations do not necessarily correlate with levels of the algae in the marine environment, making it difficult to predict the degree of food safety risk from these hazards. Post-harvest: Processing of oysters before retail sale is usually minimal. When necessary, algae adhering to the shell are removed by tumbling, a process that can result in some damage to the oyster shells and potentially allow contamination of the meat. Oysters may be purified to some extent by relaying or depuration. These processes are reasonably efficient at reducing the load of enteric bacteria in oysters, but are significantly less effective at reducing the levels of viruses, endogenous marine pathogenic bacteria, chemicals and algal biotoxins. The main processing of oysters involves shucking and packing in boxes for sale on the half shell or bottling in fresh water, depending on the grade. The shucking process does not kill pathogenic micro-organisms or remove chemical contaminants, but introduces the potential for further contamination by enteric pathogens. In addition, the potential exists during shucking and transportation for temperature abuse, allowing multiplication of bacterial pathogens to levels that might pose a public health risk. Further handling in the distribution chain also carries with it the potential for contamination and temperature abuse. ScallopsPre-harvest: Wild-catch southern scallops are harvested by dredging or diving in coastal waters up to 120 metres deep. Saucer scallops are capable of swimming out of the way of dredges, and are primarily caught by trawling (often as by-catch of demersal otter prawn trawling) in shallower waters, up to 75 metres deep. Scallops filter-feed on plankton and organic detritus from water and sediments in which they settle. As filter feeders, they are subject to the same potential for bioaccumulation of chemical and biological food safety hazards as oysters (see above). However, the growing environments of wild-caught scallops are less likely to be subjected to significant levels of contamination by human sewage pollution or agricultural run-off. Levels of enteric pathogens and agricultural chemical residues are likely to be low at point of harvest. Endogenous marine pathogens may still present a risk, particularly the Vibrio species and also C. botulinum, which is found in marine sediments. Until recently, aquaculture of southern scallops in Australia was limited to rearing wild or hatchery spat to the stage at which they detach from their initial sessile state. Intermediate culture in midwater cages was usually followed by reseeding of the sea floor for grow out to commercial size. More recently, the use of lantern nets or more rigid nets suspended from longlines throughout the ~18 month grow out cycle has been successfully employed. Food safety risks arising from water quality issues in the aquaculture of scallops are obviously related to the choice of site. Shallower coastal sites are preferred, which are closer to land and subject to greater potential for contamination by sewage and agricultural run-offs. The potential for contamination by algal biotoxins would be similar for farmed and wild scallops. Post-harvest: After catching, scallops are sorted and washed on board, and stored live in steel crates or hessian sacks at ambient temperature. The processing of scallops involves removing the gut and shell and retaining the adductor muscle (scallop meat) and the roe (where applicable). After landing, the crates or sacks are opened and the scallops are emptied into hoppers. A knife is inserted to open the shell and the meat and roe are cut out and placed into containers. The freshly shucked scallops are washed and drained before being chilled or frozen. The potential for contamination and temperature abuse during shucking, transport and downstream food handling is similar to that encountered with oysters. Consumption of saucer scallops is usually restricted to the adductor muscle tissue, which tends to accumulate lower levels of food safety hazards than the roe. Other bivalvesMussels are grown by longline open water aquaculture in Australia. They obtain all their nutrients from the growing environment, filter feeding on plankton and other organic matter, and do not need additional dietary supplementation. All of Australia’s mussel production is consumed locally, along with a similar amount of imported mussels (mostly from New Zealand). After reaching marketable size (65–85 mm) the mussels are removed from the long lines and the shells cleaned of external fouling, usually in a washer–tumbler machine in which the mussels are rotated and rub against each other to dislodge small mussels, barnacles and other fouling organisms. The mussels are then cleaned, graded and bagged for sale, live, without further processing. Aside from the potential for shell damage, and consequent contamination of the flesh, the major source of food safety risk is in the quality of the growing waters. The choice of site determines the potential for contamination by sewage and industrial and agricultural run-off, while the risk from hazardous algal blooms is similar in scope (and unpredictability) to that encountered for scallops. Mussels are usually shipped and sold live. Dead mussels tend to gape, providing a convenient indicator of quality. Good quality mussels have closed shells, minimising the risk of contamination by food handlers. Small quantities of pipis (also known as Goolwa cockles) are commercially harvested in Australia, mainly in New South Wales and South Australia, with smaller commercial catches in Queensland and Victoria. They are harvested along the waterline, and are usually sold live in the shells, with no processing. The main hazards likely to be present are endogenous marine pathogens and algal biotoxins, with the potential for temperature abuse after harvest and during transport. AbaloneAbalone are gastropod molluscs that feed on drift algae and seagrass leaves. They are found primarily on rocky reefs in waters up to 40 metres deep around the southern coasts of Australia. Although there is increasing interest and investment in aquaculture of abalone, the vast majority (>99%) of Australia’s abalone production is wild-caught, usually by diving. The abalone are usually landed live and processed onshore except in South Australia, where a large proportion of the catch is shucked at sea. After shucking, the meat (adductor muscle) is cleaned and graded, before being bulk frozen, parboiled then frozen, or cooked in brine then canned. A small amount is frozen whole on the shell. As only the adductor muscle is eaten, the potential for accumulation of microbiological hazards and chemical contaminants from the growing environment is similar to that encountered with saucer scallops, as many of these hazards are preferentially concentrated in the viscera, which is discarded. During post-harvest handling, shucking and transport, contamination with microbiological (for example, S. aureus) and chemical hazards and temperature abuse are possible. The microbiological hazards will be controlled to some extent by chilling/freezing and canning processes. In aquaculture of abalone, the potential for contamination by agricultural run-off is greater than for wild-caught abalone, and antibiotic and anaesthetic residues are also a potential hazard, while the hazards potentially introduced during handling are similar to those for wild-caught abalone. Yüklə 2,7 Mb. Dostları ilə paylaş:
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