Food Protection Trends - July/August 2019 - 335

U.S., the food processor has to assess whether a foodborne
hazard due to parasites in fish is likely to occur, when "the
processor has knowledge or has reason to know that the
parasite-containing fish or fishery product will be consumed
without a process sufficient to kill the parasites, or where the
processor represents, labels, or intends for the product to be
so consumed" (16) and must establish appropriate control
measures in the form of HACCP (Fig. 1).

Figure 1. Fish fillets of red gurnard (Chelidonichthys lucerna)
infested with larvae of the nematode Pseudoterranova decipiens
(Anisakidae) (arrows). Bar: 1 cm. (Photo: Dutch reference
Laboratory for Parasites, Centre for Zoonotic Diseases and
environmental Microbiology, Bilthoven, The Netherlands.)

HACCP-based food safety systems as a means to control
fishborne parasites
Since parasites, unlike bacteria, will not multiply in post
mortem tissues, the control of parasitic stages in fishery products can make use of (a) selection of raw material with low
risk of parasitic infection (e.g., farmed Atlantic salmon with
appropriate level of biosecurity), (b) detection of parasites
and removal of infested tissues or tissues prone to infection
(e.g., the bellies in herring in the case of Anisakis sp.), or (c)
implementation of treatments that ensure inactivation of the
infective parasite stages.
For food business operators (FBO), it is essential to know
not only which parasites are relevant hazards in fish and
fishery products, but also what level of parasite inactivation
is required to render food safe for consumption. There
are several obstacles in defining such a "performance
objective" (12); for example the definition of an infective
unit, the infective dose (or a probability of infection) and
the way viability and infectivity of parasitic stages are
assessed. Consequently, EU legislation defines inactivation
temperatures and holding times, but this approach does
not take into account synergistic effects of processing

techniques, and it is not targeted against parasitic stages
of trematodes. It can be argued that it must be sufficient
for FBOs to guarantee that EU legal requirements are
fulfilled, but since, e.g., trematodes are not dealt with in the
regulations, there is a need to assess whether such hazards
are relevant and whether there is a critical control point in
the processing chain. Given the outbreaks of opisthorchiasis
in Italy (1), it is clear that trematodes are also relevant
within a European context; it should be noted that in one
outbreak, the implicated fish had been frozen at -10°C for
3 days and then marinated before consumption.
Collating data on survival and inactivation of fishborne
parasites: the "Euro-FBP" Action
In order to provide relevant information to the food
industry, the EU COST Action FA 1408, "Euro-FBP: A
European Network for Foodborne Parasites" (https://www.
euro-fbp.org/) collated and critically reviewed information
on parasite inactivation by food-processing techniques.
Unfortunately, for most parasites, data are too scarce to allow
mathematical modelling of viability and decay, especially
since (i) interspecies or intraspecies variabilities are not
always known, and (ii) standardized methods for assessment
of parasites' viability do not always exist or do not allow
quantification of reduction. For bacterial pathogens, log
reductions are a common way to describe the extent of
inactivation. However, one single parasite stage in food
may be enough to cause human infection for some species,
which calls for dose-response data dealing with exposure and
infection, and discriminating between parasite species. Also,
in case of complex food processing techniques, the relative
contributions of the single factors and the extent of synergy
are not well known, so that any deviation from the test
conditions would require re-evaluation.
Likewise, knowledge gaps exist for non-traditional fish
processing methods, such as high-pressure processing or
irradiation. The main processes have recently been reviewed
(11), and the underlying set of data has been compiled in
an excel sheet. This database will be made publicly available
and the reader may refer to the Euro-FBP FA1408 homepage
(https://eurlp.iss.it/) for further information.
Available published data suggest that heating to 60-70°C
with holding times of a few minutes will lead to a 0.5 to
1.8 log decrease in numbers of viable Anisakis larvae.
With regard to metacercariae, the few available studies
suggest a 60°C core temperature for 15 min. to inactivate
metacercariae in flesh from mullet. Likewise, metacercariae
seem to withstand deep-freezing well, and although a
temperature of -20°C for 24 h will reduce viability in some
species, it will not result in complete inactivation. The effect
of marination is quite variable, depending on salt and acid
concentrations, but several days to weeks will be required
to inactivate Anisakis larvae. Few data exist on survival of
parasites in fermented fish (11).

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