Quantitative species determination based on real time PCR–Can the results be expressed as weight/weight equivalents?

ABSTRACT

Food adulteration is a common challenge in the meat industry. Polymerase chain reaction (PCR) has been used as a method to detect contamination from different species of meat. From a consumer perspective, a PCR method with measurements in terms of weight/weight (w/w) ratios will be more familiar. In this study, the focus was on how to convert the results of quantitative analysis from genome/genome (g/g) to w/w using real-time PCR. The mixtures with different ratios of mutton in pork were analyzed as test samples. The c values of different species, as a reflection of the key conversion factors, were established and evaluated. The effects of heat treatment on w/w conversion of PCR data were also assessed. The results indicated that the c value shows significant variability among individual samples. An average c value was found to cause a bias of more than 7% for mixtures in the range of 20–80%. For individual meat samples with pre-determined c-values, real-time PCR was useful for quantitative analysis of mutton contamination in pork within the range of 20–80%, with a bias of detection of less than 2%. However, this method was shown to have a limit of quantification of 5% with mutton in pork. Furthermore, heat treatment (121°C, 15 min) significantly reduced the accuracy of quantitative analyses. Because the c value is not available for most commercial samples, and some food products are subjected to heat treatment as a method of sterilization, accurate quantitative analysis (w/w) may not be an option for commercial samples using PCR-based technology.

KEYWORDS:

• Food adulteration
• meat
• quantitative species detection
• w/w
• real-time PCR

Acknowledgments

We thank Letpub (http://www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

Supplementary material

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This work was supported by the National Key R&D Program of China [2016YFF0203802].