Dear Mr. Chivers,
1 Anisakis and salted anchovy
There are not too many published references on that, however, for
instance in the case of light salted and ripened herring for a 8-9 % of salt
the maximum survival time of nematodes (e.g. Anisakis) is about 5-6 weeks
(which is well below the usual ripening time for salted anchovy). You can
get the full references on this from:
"Handling and processing of herring infected with Anisakis simplex". Huss,
H.H., Roepstorff, A., Karl, H. and Bloemsna B.. In Proceedings from the 3rd
World Congress on Foodborne Infections and Intoxications. Inst. of Vet. Med.
Robert v. Ostertag-Inst. Berlin, 388-394, 1992
"Survival of Anisakis larvae in marinated herring fillets". Karl, H.;
Roepstorff, A.; Huss, H.H. and Bloemsa, B.. J. of Food Technology 29,
661-670, 1995.
There is a recent review paper that includes a discussion on the subject
that you may find useful. This is:
"Prevention and control of hazrds in seafood". Huss, H.H.; Reilly, A. and
Ben Embarek, P.K. Food Control 11, 149-156 (2000).
In any case this refers to the prevention of possible effects of live
parasites in salted fish. Prevention against possible allergic hazard due to
the ingestion of dead parasites could not be prevented through the current
fish salting and marinating techniques. In my personal opinion more resarch
is needed in this area to clarify in particular the risk and severity levels
and possible technological ways to prevent it.
2 Aw in salted anchovy
The Aw of (properly) moist salted anchovies and similar products should
be around 0.75, this means the value achieved at saturation by NaCl in
water. The correlation between Aw and salt and water content for this type
of products is:
Aw = 1.002 - 0.042 m
where m is the molality of the solute (NaCl).
The molality is a way to express concentration hardly used outside
thermodynamic books, however, in this case appart of adding beauty to the
expression it allows for the linking of the correlation to the basic
thermodynamic Aw theory (it is not just an empirical correlation). In any
case it is easy to link m to the weight of water and salt in the sample as
follows:
m = 17.111 (Ms/Mw)
where:
Ms = mass of NaCl
Mw = mass of water
(some authors prefer to express concentration as % of NaCl in the water
phase, it is basically the same concept)
You can find the theory of all this in:
"Water activity and salt content relationship in moist salted fish
products". Lupin, H.M.,
Boeri, R.L. and Moschiar S.M.; J. of Food Technology 16, pp 31-38 (1981).
In particular salted anchovies (e.g. the ones utilizzed in pizza and anchovy
paste for sandwiches, and salad dressings like the one for Cesar's salad)
are also rippened, this means that storage (for ripening) time is very long
(6-8 months at least, depending on external temperature) in order to develop
the appropriate flavour colour and texture. With such storage time at Aw
there is no possibility of survival of Anisakis spp larvae if they were
there in the first place.
In my opinion, in particular salted anchovies, as they are processed in
Mediterranean countries (e.g. France, Italy, Morocco, Spain and Turkey) and
in Latin American countries (e.g. Argentina, Uruguay, Chile and Peru) are
reasonably free of the alive nematode (Anisakis) hazard. Regarding the
possible allergic hazard (dead Anisakis) further studies are necessary,
however, risk and severity are probably very low.
Hector M. Lupin
Senior Fishery Industry Officer
Fish Utilisation and Marketing Service (FIIU)
FAO of the UN
Tel.: 39-06-570-56459 / Fax 39-06-570-55188
e.mail: hector.lupin@fao.org <mailto:hector.lupin@fao.org>
-----Original Message-----
From: Richard Chivers [mailto:richard@fishonline.co.uk]
Sent: Thursday, January 11, 2001 5:39 PM
To: seafood
Subject: Survival of worms in salted fish
Does anyone have figures for:
a) the minimum salt content of salted pressed anchovies and pilchards
sufficient to kill anisakis
b) the Aw of these products
Thanks in advance.
Richard Chivers
Fisheries Consultant
Seafood Audit International
44 (0) 1823 666666
www.fishonline.co.uk <http://www.fishonline.co.uk>
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