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- Author or Editor: G. Ujhelyi x
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The aim of the study was to assay by PCR screening method whether the processing and the thermal stress have any influence on the feasibility of the detection of genetically modified DNA in different kinds of processed meat products such as sausages, liver cans, ready-to-eat hamburgers. The model meat products have been prepared with soybean meal spiked with RR (Roundup Ready) soybean meal in 0.5%, 1%, 1.5% and 2%. The samples were prepared under industrial circumstances. The assay was based on the detection of the specific part of the 35S promoter and the NOS terminator sequences. The modified PCR method was shown to be suitable for screening of GMOs in raw and also in moderately and highly processed meat samples when extreme heat treatment and pressure were used for the preparation of meat products. Half a percent RR soy contamination could be detected even if the food products underwent high temperature treatment.
It is well established that the ingestion of cereal prolamins, such as gluten, causes the characteristic symptoms of celiac disease (CD) in people predisposed to it. DNA-based PCR method provides new ways to detect gluten in processed foodstuffs, such as bread. The aim of this work was to adapt a new primer pair combination and to initiate a carefully elaborated PCR methodology to experiment with DNA-based analysis. At first, the purity of cleaned DNA was verified using B49317 and A49855 chloroplast DNA primer pair. Then TR01/2 wheat specific PCR primer pair was used for checking the origin of the DNA, and P1/2 microsatellite (SSR) adapted primer pair for detecting allergen (gluten) specific residues. Method optimisation was achieved with cereal flour samples, then bread and dry pasta products from wheat were used, which were analysed as heat-treated samples with three primer pairs. The gluten specific primer pair was tested on cross-reactive cereals such as rye, barley, triticale and on some questionable cereals, such as oat, and pseudo-cereals, e.g. buck wheat and amaranth.
The main goal of our work was to develop a rapid, simple, and economical DNA extraction method for food (especially for meat products) analysis. This extraction and purification procedure was based on the three-phase partitioning (TPP) method. The developed new DNA-TPP method and Wizard DNA Clean-Up System (Promega, USA) have been compared concerning extraction efficiency, purity and DNA suitability for amplification. The quality and quantity of the purified DNA solutions were controlled by spectrophotometer and the amplification efficiency by simple qualitative PCR. All of prepared DNA solutions were pure enough for the PCR and contained appropriate quantity of DNA. Thus, 118 bp length amplicons could have been obtained by the specific lectin-gene PCR in all cases. This method proved to be an alternative one to isolate DNA from meat samples simply and economically.
