502 Chapter 29
articles have been published regarding the
detection of GMOs in meat products. For
example, Taski - Ajdukovic et al. (2008) ana-
lyzed 50 processed meat products containing
soybean and found 12 positive within a 35S
promoter. In order to fulfi l regulations and to
ensure consumers ’ rights to information, as
well as to introduce new insights for per-
forming traceability and coexistent GMO
studies (Aarts et al. 2002 ), several analytical
approaches have been developed, mostly
based on molecular methodologies that rely
on the detection of either protein or DNA.
Protein - based methods employ western
blots, enzyme - linked immunosorbent assays
(ELISA), or lateral fl ow strips, while DNA -
based methods use traditional, hybridization
techniques such as southern blotting, qualita-
tive - and quantitative - PCR, or new hybrid-
ization techniques such as microarrays.
This chapter summarizes the current
available DNA - based methodologies for the
detection, identifi cation, and quantifi cation
of GMOs, as well as their uses, limitations,
and key issues in implementation.DNA - Based Methodologies for
GMO Analysis
The current methodologies for GMO analysis
are based on the detection of nucleic acids
(DNA by PCR, or RNA by RT - PCR or
NASBA). DNA is a ubiquitous molecule in
living organisms with chemical properties
that confer resistance to the harsh treatments
performed by food industries, and therefore,
the analytical methods based on its detection
are nowadays the methodologies of choice in
GMO analysis. Consequently, the analytical
strategy is based on the detection and identi-
fi cation of the introduced DNA (the analyti-
cal result is the presence/absence of a given
GMO), and/or its quantifi cation (the analyti-
cal result is the exact GMO percentage).
However, prior to handling and processing
any sample in the laboratory, a critical aspect
that must be carefully addressed in any meth-compulsory labeling requirements. This
policy has been introduced to carry out com-
mercial regulations for the use of GMOs in
the food chain and guarantee consumers ’
rights to information for making an informed
choice.
The European Union (EU) made labeling
mandatory since 1997 in food and feed prod-
ucts containing, consisting of, or produced
from GMOs in a proportion higher than 0.9%
of authorized GMO, 0.5% for nonauthorized
GMOs, and compulsory at any level if the
GMO presence could not be demonstrated to
be adventitious or technically unavoidable
(European Commission 2003a, b ). In addi-
tion, all GM additives and GM fl avorings
have to be labeled according to Regulation
(EC) 50/2000 (European Commission 2000 ).
Prepackaged products containing GMO
delivered to the fi nal consumer or to mass
caterers are required to state on the label
“ This product contains genetically modifi ed
organisms, ” and in non - prepackaged prod-
ucts, the words must appear in the display of
the product (European Commission 2003a,
b ). Norway and Switzerland, which are
not members of the European Union, also
demand the labeling of GMOs in their food.
Competent authorities of different countries
(Australia, New Zealand, Brazil, Chile,
China, Croatia, Ecuador, El Salvador,
Indonesia, Japan, Mauritius, Mexico, Russia,
Saudi Arabia, South Africa, South Korea, Sri
Lanka, Taiwan, Ukraine, Thailand, and
Vietnam) have also established a labeling
policy for products containing detectable
ingredients produced from GMOs, and in
other countries, such as the United States or
Canada, voluntary labeling of bioengineered
foods is recommended (Marmiroli et al.
2008 ).
Model studies to detect GMOs in animal
products have been carried out, showing that
analysis of milk, muscle, or blood cannot
serve as an indicator of the use of GMOs for
feeding animals (Poms et al. 2003 ; Nemeth
et al. 2004 ; Bertheau et al. 2009 ), and a few