Barcode high-resolution melting (Bar-HRM) analysis to authenticate true cinnamon (Cinnamomum verum) from its adulterants and contaminants

Abstract

Sri Lankan cinnamon, widely known as true cinnamon (Cinnamomum verum), is a world-renowned commodity. With the high market demand, many incidents have reported adulteration of true cinnamon with other cinnamon species such as Cinnamomum aromaticum, Cinnamomum burmanni, and Cinnamomum loureiroi. Moreover, the contamination of cinnamon products with fungi (Aspergillus flavus) has also significantly negatively impacted the cinnamon export market. Morphological and chemical detection of adulterations has limitations, benchmarking the necessity for precise and effective new detection methods. The current study reports gene-specific novel molecular markers that can be used in Barcode High-Resolution Melting (Bar-HRM) analysis to distinguish C. verum from other substitutes. Six barcode regions (rbcL, trnH-psbA, matK, ITS2, trnL, trnL-trnF) were analyzed. The results demonstrate that trnH-psbA can effectively discriminate all selected cinnamon species from one another. Novel markers were designed to target the diagnostic nucleotide variations found within the designated barcode regions. Commercial cinnamon products and authentic samples of C. verum were used to validate the assay, and the DNA extraction protocol was optimized to ensure the acquisition of high-quality DNA. Bar-HRM was performed with the novel markers, and the four major cinnamon species in the international market were successfully distinguished. The spiked-in A. flavus DNA was also detected in a cinnamon admixture. Hence, these Bar-HRM conditions with the novel gene-specific markers can serve as an economical, efficient, and promising assay to detect the authenticity and purity of cinnamon samples.