Sensitive Detection of Chicken Meat in Commercial Processed Food Products Based on One-Step Colourimetric Loop-Mediated Isothermal Amplification

Abstract

Meat adulteration has been a great concern in the food industry worldwide. Due to its lower cost, chicken is generally used as an adulterant in several meat products. The main objective of this research was to develop a novel detection platform based on colourimetric loop-mediated isothermal amplification (LAMP) for authenticating chicken content in raw and processed meat products. Conditions for the colourimetric LAMP were thus optimised. Neutral red, a pH-sensitive indicator, was introduced into the LAMP reactions to help distinguish the positive/negative outcomes. LAMP reaction containing amplified LAMP amplicons changed its colour from yellow to pink/magenta, while the reaction without amplified DNA products remained in its original yellow colour. This single-step colourimetric LAMP was also validated for its high specificity towards chicken DNA without any cross-reactivity with the DNA from other types of meat. The limits of detection (LOD) for chicken DNA and chicken in binary meat admixtures were 1 pg and 0.01% (w/w), respectively. From 33 different commercial processed food samples, the assay confirmed chicken content in 14 declared chicken-containing products and in 8 products without the declaration of chicken content, while the remaining 11 meat samples without the declaration of chicken content showed no detectable chicken DNA. Furthermore, without the requirement of DNA purification, the direct colourimetric LAMP assay is capable of accurate authentication of chicken content in raw meat matrices and commercial processed food samples, making it a valuable analytical tool to facilitate on-site food authentication, as well as in low-resource laboratory settings.