Detection of adulteration in black gram-based food products using DNA barcoding

Abstract

DNA barcoding is gaining importance in food authenticity studies due to its sensitivity, reliability and accuracy in identification of adulterant species from pure food commodity. In the present study, three barcoding loci viz., rbcL, trnH-psbA and ITS were explored to test their potential in detection of adulteration of black gram flour and its products with refined wheat flour (maida) and white pea flour. All three loci exhibited 100% success rate of PCR amplification and sequencing. Amplicons of band size 600 bp, 380 bp and 680 bp were obtained for rbcL, trnH-psbA and ITS, respectively. The method was validated on simulated samples of black gram flour (variety TPU-4) adulterated with 5% each of refined wheat flour and white pea flour. Sequence analysis and BLAST searches of the model blends revealed the presence of these two potential adulterants, thereby making the method sensitive enough to detect adulteration at 5% level. Among the 3 loci studied, loci rbcL and trnH-psbA, served as ideal candidates for detection of refined wheat flour adulteration in black gram flour. Eleven market samples of black gram products such as flour, papad, instant medu vada mix and papad atta of different brands were analysed using DNA barcoding. The method could successfully detect the presence of refined wheat flour in one of the papad samples. Therefore, molecular identification of black gram flour products and its adulterants can be done using the developed DNA barcoding method based on rbcL and trnH-psbA sequences.