product which eventually develop into maggots and destroy the fi sh. Dry
fi sh can be stored for nearly 6 mon, but the soft or semi-dry ones have a
shelf life of up to 3 mon (Ebeling, 2002).
Hygiene of Processing
Boats, premises, fi shermen, processors, equipment, water, fi sh and
ingredients invariably have low hygienic standards at the artisanal level
of fi sh handling and processing. This may be due to lack of economic
support from the quality products' market.
Biogenic amine including tyramine, histamine, cadaverine, spermine and
spermidine are produced during fermentation of fi sh and in fermented
products (Mah et al., 2002). These biogemine amines were detected in
salted and fermented fi sh products, jeotkal s in the range of 0-75 mg/
kg (Mah et al., 2002) and in Thai fermented product, som fug (Riebroy et
Histamine poisoning has historically been referred to as scombroid
poisoning because of the frequent association of the illness with the
consumption of spoiled scombroid fi sh such as mackerels and tuna (Tsai
et al., 2004, 2005).
Histamine production in foods is by the decarboxylation of histidine
through a reaction catalyzed by the enzyme histidine decarboxylase
(Ababouch et al., 1991a) produced by microorganisms such as Clostridium,
Morganella morganii , Klebsiella pneumoniae , Proteus vulgaris, Hafnia alvei and
Lactobacillus (Tsai et al., 2006). Also, various species of fi sh are known to
have large amounts of free histidine in their muscle tissues as substrate for
histidine decarboxylase (Ababouch et al., 1991b).
Since the fermentation process involves bacterial activity, it is likely that
if conditions are not properly set to control pathogenic bacteria they may
remain in the fermented products. This is because fermentation takes
place at low temperatures. The two main factors which control the growth
of pathogens such as Clostridium botulinum are high salt concentration and
pH. All types of C. botulinum are inhibited by 10-12% salt and a pH below
4.5. C. botulinum types E, F and non-proteolytic type B are able to grow
between 8°C and 10°C but are inhibited below 4°C. From observations of
the production methods of fermented fi shery products, the low level of
incidence of C. botulinum poisoning may be mainly attributed to the high
level of salt usage (Wiriyacharee, 1992).