Overview of Analytical Tools for the Identification of Adulterants in Commonly Traded Herbs and Spices

Background: Spices and aromatic herbs have long been used by people to impart sensory appetizing elements, including aroma, flavor, and color, to foods and beverages in an effort to enhance their palatability. Herbs and spices exhibit a plethora of medicinal properties including antimicrobial and antioxidant properties. Spices serve as natural preservatives to delay food spoilage and extend shelf life. As spice trading has exponentially increased globally, herbs and spices have become prone to adulteration, which can be deliberate or unintentional. Deliberate adulteration is usually economically motivated, aimed at maximizing profit margins, whereas unintentional adulteration is often attributed to improper harvesting or processing of the plant material or collecting/substituting closely related species. Adulteration of herbs or spices with toxic ingredients such as Sudan dyes or metal salts (e.g., lead chromate) may result in serious public health consequences. Objective: To provide a concise account of ongoing adulteration issues with spices and herbs in order to enhance general awareness of the short- and longer-term implications of such fraud. Method: Last twenty-years of literature on various aspects of spice adulteration including text books and online resources were gathered and compiled. In addition, a number of original reports have been published prior to year 2000 that are directly associated with adulteration of commonly traded herbs and spices were also included. Results: The current review covers the role of spices and herbs in human life, adulteration of the commonly consumed spices and herbs, identification of their adulterants, as well as the most popular analytical techniques and methods used in their detection, including spectroscopic, chromatographic, electronic sensing, and deoxyribonucleic acid-based methodologies. Conclusions: Spices and herbs, being high-priced commodities, have been often subjected to adulteration in many ways which reduces their quality and potentially has harmful health implications. Adulteration is attributed primarily to increased demand or supply shortage of the spices and aromatic herbs. The motivation for spice fraud is largely attributed to economical interest to gain greater profit margins and such adulteration of spices can have serious implications for public health. To combat the adulteration of spices and herbs effectively, a range of analytical techniques across many different technologies have been developed. These techniques are expected to aid in the detection of adulterants and establish quantifiable concentrations for the compounds in question in various matrices, including spices and aromatic herbs.