T. E. Sheeja

DNA Barcoding to Detect Chilli Adulteration in Traded Black Pepper Powder

Value-added forms of black pepper (Piper nigrum L.) are an important item of trade globally. Adulteration by default or design of the commodity not only leads to economic loss and public health issues but also to self-respect of a nation. DNA barcoding is assuming significance as a quality assurance technique in many agri-food commodities. Three barcoding loci viz., psbA-trnH, rbcL, rpoC1 were used in the study to detect bio adulteration of traded black pepper powder. PCR amplification of P. nigrum and traded black pepper powder was performed for all the three loci. Sequence analysis and BLAST results revealed chilli adulteration in two out of nine market samples, originating probably from exhausted black pepper powder fortified with chilli. Of the three loci, psbA-trnH proved to be the best and ideal for detection of chilli adulteration in black pepper yielding amplicons of size 600 bp and 350 bp, respectively. Cloning and sequencing of the adulterant specific band of both market samples were done to confirm the results. It was further validated using simulated samples of chilli and black pepper powders in various proportions. The method proved efficient to detect adulteration even at very low levels (0.5% adulteration). HPLC analysis also supported the chilli adulteration of black pepper powder. The method is easy, reliable and efficient, and can be used by the regulatory agencies for quality assurance of black pepper powder.

Detection of plant-based adulterants in turmeric powder using DNA barcoding

Abstract Context: In its powdered form, turmeric [Curcuma longa L. (Zingiberaceae)], a spice of medical importance, is often adulterated lowering its quality. Objective: The study sought to detect plant-based adulterants in traded turmeric powder using DNA barcoding. Materials and methods: Accessions of Curcuma longa L., Curcuma zedoaria Rosc. (Zingiberaceae), and cassava starch served as reference samples. Three barcoding loci, namely ITS, rbcL, and matK, were used for PCR amplification of the reference samples and commercial samples representing 10 different companies. PCR success rate, sequencing efficiency, occurrence of SNPs, and BLAST analysis were used to assess the potential of the barcoding loci in authenticating the traded samples of turmeric. Results: The PCR and sequencing success of the loci rbcL and ITS were found to be 100%, whereas matK showed no amplification. ITS proved to be the ideal locus because it showed greater variability than rbcL in discriminating the Curcuma species. The presence of C. zedoaria could be detected in one of the samples whereas cassava starch, wheat, barley, and rye in other two samples although the label claimed nothing other than turmeric powder in the samples. Discussion and conclusion: Unlabeled materials in turmeric powder are considered as adulterants or fillers, added to increase the bulk weight and starch content of the commodity for economic gains. These adulterants pose potential health hazards to consumers who are allergic to these plants, lowering the products medicinal value and belying the claim that the product is gluten free. The study proved DNA barcoding as an efficient tool for testing the integrity and the authenticity of commercial products of turmeric.

DNA Barcoding for Discriminating the Economically Important Cinnamomum verum from Its Adulterants

Traded forms of spice and spice powders are often subjected to admixing with inferior substances by design or default, affecting public health and national prestige. Cinnamomum verum (true cinnamon), a high-value spice, is often adulterated with its inferior species such as C. cassia and C. malabatrum. The presence and detection of the spurious species in traded barks (whole or powder) of true cinnamon is posing problems. DNA markers are now used to detect such adulteration. Here we report the application of a DNA barcoding method to detect these adulterants in traded market samples of true cinnamon using the barcoding loci rbcL, matK and psbA-trnH. The PCR success rate, sequencing efficiency, inter and intra specific divergence, and occurrence of single nucleotide polymorphisms (SNPs) were utilized to assess the potential of each barcode loci to authenticate C. verum from its related adulterants. The amplification and sequencing success was 100% for rbcL and psbA-trnH while matK failed to amplify in the market samples. The locus of rbcL showed higher interspecific divergence while psbA-trnH exhibited lower interspecific divergence. SNPs specific to C. cassia were detected in rbcL locus in seven out of the ten market samples studied thereby confirming the presence of C. cassia adulteration in commercial samples of true cinnamon. Out of the three loci, rbcL locus proved to be efficient in tracing out adulterants in traded cinnamon. The SNP sites in this locus can be exploited in designing C. cassia specific primers, enabling kit development for easy detection of adulterants at the band level itself thereby bypassing the cost of sequencing.

Advances in Adulteration and Authenticity Testing of Herbs and Spices

Abstract Natural products like herbs and spices are increasingly being used in health care products, cosmetics, and preservatives besides in flavoring foods and beverages leading to higher demands for pure commodities. Adulteration of the commodities is one of the consequences of this increasing demand resulting in erosion of the perceived biological effect of the commodity and reducing consumer trust. Adulteration detection and food authenticity testing are thus important for value assessment and to ensure consumer satisfaction. Cost-effective and high-throughput analytical methods with high-resolution power are very imperative in this context. Though conventional morphological, organoleptic markers and analytical techniques have good resolution power in detecting synthetic adulterants, they are less useful in biological adulteration detection owing to the morphological similarity of the adulterants to the original commodity and the loss of morphological characters of the samples on processing. New-generation adulteration detection methods such as DNA-based molecular techniques as compared to the traditional methods, discussed here, assume significance. Different adulteration detection methods employed in authenticating herbs and spices along with their merits and demerits are discussed.

Novel polymorphic microsatellite markers from turmeric, Curcuma longa L. (Zingiberaceae)

Abstract - Twenty one polymorphic microsatellite loci were isolated and characterized from turmeric (Curcuma longa L.). These markers were screened across thirty accessions. The number of alleles observed for each locus ranged from two to eight with an average of 4.7 alleles per locus. The discrimination power of these markers ranged from 0.25 to 0.67 (average 0.6). The simple sequence repeat (SSR) markers can complement the currently available SSR markers and would be useful for the genetic analysis of turmeric accessions.