Abstract:
Authentication of canned tuna fish product is mandatory due to the growing occurrence of
fraud in the processed fish industry. Different values and quality of tuna species can lead to
the replacement or mixing of expensive fish by less expensive ones. Detection of species
adulteration in canned tuna is much more difficult because of the DNA degradation and
fragmentation results by high temperature and high pressure throughout the canning
process. In this study Yellow-fin Tuna, Big eye Tuna and Skipjack Tuna species were
selected for the adulteration detection and thirteen canned tuna samples were taken and two
sardine samples and one mackerel sample were taken as negative samples from local and
foreign markets which were dipped in different solutions. Isolation of DNA was performed
by 200mg small fragment protocol of DNeasy Mericon food kit, QIAGEN. Extracted DNA
was confirmed using spectrophotometer and fluorometer. Confirmed DNA were subjected
to the conventional one-way triplex polymerase Chain Reaction (PCR) targeting 284 bp
Yellow fin Tuna, 140 bp Big eye Tuna and 251 bp Skipjack Tuna regions from cytochrome
b gene. Six samples out of thirteen were identified as adulterated against the label indicated
in the cans in three replicated triplex PCR trials. LT1, LT2, LT6 labeled as Skipjack Tuna,
but PCR products correspond to big eye for LT1, Yellow fin and Skipjack for LT2 and
Yellow fin and big eye for LT3. LT7, LT8, MT13 labeled as yellow fin, but all resulted
positive for big eye tuna. 2% agarose gel which has a higher resolution allowed the precise
band separation. In this study conventional triplex PCR methodology proved to be an
inexpensive, reliable and sensitive tool for detecting canned tuna DNA fragments (longer
than 100 bp) present in canned tuna products.
