Molecular Marker-Based TaqMan PCR Approach for Determination of Origin and Content in Commercial Ginger Powder

Ginger is a spice with a distinctive flavor and is sold in processed forms such as powder. However, the origin and content of most processed ginger products are difficult to identify because of alterations in the raw materials. Moreover, the processing of raw materials can facilitate food fraud, deceiving consumers and posing a threat to food safety; therefore, technologies for verification are necessary. The purpose of this study is to genotype the origins of commercial ginger powders using cleaved amplified polymorphic sequence (CAPS) molecular markers and to determine their actual content using TaqMan PCR. CAPS markers based on the restriction enzymes DraI, ClaI, and BglII were successfully used to identify the origins of nine commercial ginger powders. The ClaI-based CAPS marker, in conjunction with the TaqMan PCR system, efficiently distinguished Chinese imported ginger (Cg) and Korean indigenous ginger (Bg) in commercial ginger powder, which was applied to measure their actual content. Among the nine commercial ginger powder samples, eight products were confirmed to be of Cg origin, while one product was found to be a mixture of Cg and Bg. Among them, seven had insufficient ginger content. Moreover, the degree of DNA degradation did not affect the PCR results, while long-term drying, autoclaving, and freeze-drying of ginger powder negatively affected PCR results. In this study, we report a molecular marker-based approach for genotyping the origin and measuring the actual content of commercial ginger powder. Our findings would help establish a system that would promote transparency and ethics in the food industry, in addition to providing consumers with information for better product choices.