Quantitative identification of plant genera in food products using PCR and Pyrosequencing® technology

The ability to extract, amplify, identify and quantify fruit DNA from commercially available jams and yogurts was investigated. Efficient methods for extracting DNA from jams and yogurts were developed based on a modified CTAB protocol. DNA sequence alignment of plant chloroplast rbcL sequences allowed the development of a 104 bp PCR reaction capable of characterising plant genera present in fruit products using DNA amplification and direct sequencing to reveal single nucleotide polymorphisms (SNPs). The rbcL single nucleotide polymorphism approach was made quantitative by combining PCR analysis with Pyrosequencing (R) technology. This enabled the detection of rhubarb yoghurt in raspberry yogurt with a detection limit of 2% w/w based on the use of commercially available samples. The method represents a new quantitative approach for determining the identity of plant genera in products. (c) 2006 Elsevier Ltd. All rights reserved.