Evaluating PCR and ELISA for porcine detection in collagen-based products for halal authentication

Abstract

Collagen is a widely used protein in various highly processed products across the food, cosmetic, pharmaceutical, and biomedical industries due to its versatility and unique properties. Its primary sources include pigs, cows, and marine animals, with industrial extraction typically performed from hides, bones, tendons, and skin. Given the importance of halal authentication, especially in Muslim-majority markets, a key challenge lies in reliably detecting porcine-derived collagen in highly processed products due to DNA degradation, protein denaturation, and matrix interference. These issues often result in detection failures and false negatives, underscoring the need for a comparative evaluation of available analytical methods. This study compares two analytical approaches for porcine detection: the DNA-based Polymerase Chain Reaction (PCR) and the protein-based Enzyme-Linked Immunosorbent Assay (ELISA). A total of nine collagen-based samples were analysed. PCR successfully detected porcine DNA in three samples, while ELISA detected porcine antigen in two samples, including one not detected by PCR. However, two porcine-labelled samples were missed, leading to a false negative rate of 66.7%. Four samples, specifically samples 5, 6, 8, and 9, resulted in an Overall Agreement Rate (OAR) of 44.4%. The combination of real-time PCR and ELISA offers complementary advantages. Real-time PCR is particularly effective for detecting low-level porcine DNA in undenatured type II collagen. At the same time, ELISA helps mitigate false negatives that may arise from DNA degradation or PCR inhibition caused by the presence of the collagen matrix. These findings suggest that integrating real-time PCR for detecting trace DNA in less processed matrices with ELISA for identifying degraded proteins in hydrolysed products enhances the overall reliability of porcine detection and strengthens halal authentication protocols across diverse product types.