from Carmen Diaz-Amigo and Bert Popping writing in Real-Time PCR in Food Science: Current Technology and Applications:
Food allergens, responsible for IgE-mediated allergic responses and listed in European, North American and Japanese regulations, are exclusively proteins and are ideally detected by analytical methods targeting either peptides or proteins. However, in some cases where no suitable methods for proteins exist or as an alternative method to substantiate results from protein-based methods, DNA-targeting methods can be used as indicators of the presence of potentially allergenic proteins. The advantage of DNA-targeting methods like PCR, real-time PCR is presently the lower cost and availability of free literature on several detection systems, including a certain degree of multiplexing. Clear disadvantages include the poor sensitivity for egg, milk and samples containing inhibitors (like polyphenols in chocolate) as well as its limited applicability in some industrial protein concentrates. In addition, if quantitative results need to be obtained, the DNA-based system needs to be calibrated for each matrix tested as protein-to-DNA composition is typically matrix specific. However, PCR based methods are well established in many laboratories and still regularly used. This review discusses suitable systems for detection of DNA of ingredients and foods containing allergenic proteins, potential pitfalls and multiplex capabilities of such systems.
Further reading: Real-Time PCR in Food Science: Current Technology and Applications