Determination of honey adulterated with corn syrup by quantitative amplification of maize residual DNA using ultra-rapid real-time PCR

BACKGROUND Honey is a naturally sweet syrup made by honeybees from floral nectar. However, high-fructose corn syrup has been prevalently used for the adulteration of honey. A novel molecular method was developed for the characterization of corn syrup-adulterated honey by specific amplification and quantification of maize residual DNA in honey. An ultra-rapid real-time polymerase chain reaction (UR-qPCR) system for rapid amplification and protocol for direct purification of residual DNA from honey were described. RESULTS Rapidity of maize DNA amplification was acquired within 20 min for a limit of detection of around three copies of targeted DNAs. The amplification of maize residual DNA in honeys adulterated with corn syrup from 5% to 80% (v/v) showed that a minimum rate of 10% adulteration can be identified, and Maize genomic DNA in 5 mL of adulterated honeys was from 13 +/- 9 copies to 2478 +/- 827 copies, respectively. However, the residual DNA of maize was also detected in natural honey produced in the region where pollen and nectar of maize were collected, and the quantity of maize genomic DNA in these natural honeys was in the range of 10% adulteration with corn syrup. Therefore, detection of both pollen and residual DNA of maize in honey is important in identifying the source of maize residual DNA present in honey. CONCLUSION A rapid PCR assay was first developed for the accurate detection and quantification of maize residual DNA in honey. It is a useful tool for specific identification of the corn syrup used for honey adulteration. Further studies on residual DNA in various types of corn syrup and specificity of primer are recommended. (c) 2021 Society of Chemical Industry