An efficient DNA barcoding based method for the authentication and adulteration detection of the powdered natural spices

Natural spices are widely used as food additives, coloring and flavoring agents, preservatives, and traditional medicines. However, the authentication and adulteration detection of spices, particularly the powdered ones, is a significant challenge and public health concern in the growing spice industry. To address this issue, a DNA barcoding-based identification method was developed in this study. 16 types of representative spices and their common adulterants were successfully identified using ITS2 and psbA-trnH sequences, proving that this is an efficient and powerful method for adulteration detection. Using this method, 91 commercial spices commodities were analyzed for adulteration. Of the 91, the ITS2 and psbA-trnH sequences of respectively 78 (85.7%) and 77 (84.6%) samples were successfully obtained. Identification results using BLAST search of the ITS2 and psbA-trnH sequences indicated that only two types of natural spices (fennel and licorice) were correctly labeled, the other 14 spices had a different amounts of adulteration. Spices were commonly adulterated with congeneric species; cheaper substitutes with similar color or appearance; or crop-based products such as rice, corn, or wheat flour. These results indicate that the DNA barcoding method developed in this study is an efficient, simple, and accurate identification method, which may be a powerful tool for the quality control of powdered spices.