A Duplex PCR–RFLP–CE for Simultaneous Detection of Mandarin and Grapefruit in Orange Juice

Orange juice is a kind of fruit juice with huge market share. The most common adulteration is the addition of mandarin juice and grapefruit juice. Therefore, it is necessary to develop a method that can simultaneously detect mandarin and grapefruit components in orange juice. In this study, the specific site of the trnL-trnF gene of mandarin and the specific site of the accD-psaI gene of grapefruit were used for digestion and capillary electrophoresis separation to establish a duplex PCR–RFLP–CE method of simultaneous detection of mandarin and grapefruit components. By this method, the detection limits of mandarin and grapefruit components were 5% and 2.5%, respectively. About the specificity, only the 83–177 bp amplified bands of mandarin and grapefruit were specifically digested, while none of them were cut in the 8 kinds of fruits such as pear, apple, peach, papaya, pineapple, hawthorn, grape and banana. Duplex PCR–RFLP–CE tests were performed on the 8 commercially available fruit juices. As a result, grapefruit components were found in orange juice (C5) and other ingredients to be identified in grapefruit juice (C8). The established duplex PCR–RFLP–CE method can provide an effective detection method for orange juice adulteration in the future.