64
JUL 2017
FOOD FOCUSTHAILAND
SAFETY
ALERT
HeavyMetalsToxicityFound in
Tunaand itsEffectsonExports
Thailand is theworld’s leadingproducer andexporter of canned tuna (INFOFISH) brought yearlyover several billion
Baht into the country.Whereas the demands for fresh tuna and canned tuna in international markets is on the rise
year after year, the importing countries aremore cautious about food safety.
ToxinsFound inTuna
Nontoxic residue is often considered safety in tuna
products. Themost important toxin commonly found
in tuna is Scombrotoxin. It is a histamine-producing
toxin that occurs naturally from the degradation of
free histidine contained in fish tissues, bywhich the
enzyme inbacteriacatalyzesHistidinedecarboxylase
to formhistamine.Anumberof histamineoccurred in
thedeadfishdependson thestorage temperatureof
the fish. The optimal temperature for the growth of
thehistamine-producingbacteriaare in the rangeof
20-30 °C.
Attributesof Scombrotoxinareheat resistant, no
odor or strange taste. The symptoms typically
developed in the patients after ingestion of food
containing toxic histamine levels include skin rash,
nausea, vomiting, diarrhea. In severe cases, the
patientsmayexperiencehypotension,blurredvision,
and tongue burning. At one time intake of fish
contained 70-1,000 mg of histamine can cause
Scombrotoxinpoisoning. Ifanallergic reactionoccurs,
the patient can be fatal. Therefore, many countries
have been established an acceptable standard of
histamine levels to prevent potential harm.
Histamine is classified as an amine that
accumulates in thebody'smast cell,which is formed
and released when an allergic reaction occurs.
Histamine is a food-borne chemical hazard that
causes toxicity to the body after ingestion.
Scombrotoxin isalsoknownashistaminepoisoning.
Bacteria isanother factor influencing theamount
of histamine in fish. Mesophilic bacteria are the
bacteria that grow best in moderate temperatures
typically between 20-40 ° C. This resulted in the
presenceof Scombrotoxinwhen fishwere storedat
high temperature. However, fish stored at low
temperature (0-5 ° C) usually contain less than 10
parts per million (ppm) of histamine. Nevertheless,
thehistamine levelwill be increased to30ppmwhen
fish turn bad and escalated to more than 50 ppm
when fish starting to rot.
