The DNA fingerprint in food forensics: the Basmati rice case
Due to its exceptional aroma and cooking characteristics Basmati rice is one of the most popular rice specialities in the EU and the Middle East and is attracting a premium price. In the EU the strict authenticity definitions by the UK Code of Practice on Basmati Rice (CoP) of 2005 contributed significantly to improve the quality of this product and thereby its success on the market. Fifteen varieties were defined as authentic and a DNA fingerprinting method was determined for authenticity testing. Twenty-six new varieties had been released since then by India and Pakistan as Basmati and had to be included in the revised CoP of 2017. This study reports the analysis of the DNA fingerprints of these cultivars from reference materials from official sources to enable the application of the CoP. Results not only allow the enforcement of the revised CoP, but provide further insights into the genetic relationships between the varieties and their descent from common ancestors. The Basmati cultivars of major economic importance can be grouped in four types due to their close relationship: Basmati 370, Kernel/Taraori, Super Basmati and Pusa Basmati 1. The genotype fgr is supposedly the major cause of the Basmati aroma and is missing in 6 of the new varieties. Because it is not the only functional polymorphism associated with fragrance of rice the content of aroma in these new varieties should be studied and further requirements should be defined including the organoleptic characteristics of Basmati.
Due to recent food scandals like melamine in dairy products and horse meat in beef products the topic food fraud is receiving increasing attention. Innovations in laboratory analysis provide tools to detect adulterations and particularly DNA analysis is gaining increasing importance. Two principal methods in DNA analysis for food control can be distinguished (1, 2): (a) DNA barcoding to identify species of plants, animals and microorganisms like horse meat in beef products and (b) DNA fingerprinting to differentiate animal breeds and plant varieties, like for the detection of cheap long grain rice mixed into high value Basmati (3). DNA fingerprinting is based on allele differences in hypervariable sequences. These are for example microsatellites (also called simple sequence repeats, SSRs, or short tandem repeats, STRs) and single nucleotide polymorphisms, SNPs, in fingerprinting of the second and third generation, respectively. It was first used for the identification of human individuals and has revolutionized forensics and the combat against crime. Basmati authenticity testing is a prominent example for i ...