The EC-JRC manuscript entitled "Interlaboratory validation of thirteen qPCR methods to quantify adulterants in culinary spices and herbs”, has recently been published (open access) in the journal of European Food Research and Technology.
The paper describes the results of a recent inter-laboratory trial using 13 qPCR assays for the detection of significant adulterants in paprika/chili, turmeric, saffron, cumin, oregano and black pepper. For paprika, adulterants tested were maize seed, tomato, and sunflower seed. For saffron, adulterants were safflower and Mexican marigold. For cumin, carroway seed. For turmeric, maize seed, rice seed, oat seed and bell pepper. For oregano, goose-foot leaf. For black pepper, rice seed.
The thirteen qPCR methods had already passed in-house validation criteria (from an original pool of 30 methods – results previously published). This study was an inter-laboratory trial involving fifteen European laboratories. For each method the participants received DNA templates of binary mixtures for five standard samples together with five test samples of unknown adulterant concentration. Interlaboratory validation parameters included repeatability, reproducibility and trueness. Measurement uncertainties, limits of detection and limits of quantification were also determined.
The authors report that, after data examination and outlier removal, relative repeatability standard deviation ranged from 4% to 25%, relative reproducibility standard deviation ranged from 6% to 25% and trueness bias ranged from − 11% to 27%.
They conclude that the thirteen qPCR methods are therefore fully validated and may be included in international standards for deployment in official control laboratories.
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