A multiplex PCR assay to detect mislabelling in fish products

Area of Science:

• Food Science
• Molecular Biology
• Genetics

Background:

• Fish substitution is a significant economic issue in global fish markets.
• Accurate species authentication is crucial for consumer protection and regulatory compliance.

Purpose of the Study:

• To develop a reliable authentication protocol for Rohu (Labeo rohita), Thaila (Labeo catla), and Tilapia (Oreochromis niloticus).
• To assess the prevalence of fish mislabeling in commercial fish products.

Main Methods:

• Design of species-specific primers targeting the Cytochrome b (Cytb) gene in mitochondrial DNA.
• Development of a multiplex Polymerase Chain Reaction (PCR) assay for simultaneous detection.
• Screening of 230 commercial fish samples (fried and processed).

Main Results:

• The multiplex PCR assay successfully differentiated between L. rohita, L. catla, and O. niloticus based on unique fragment sizes (235 bp, 186 bp, 506 bp).
• High sensitivity was achieved, with DNA template detection down to 0.1 ng for L. rohita and L. catla, and 1 ng for O. niloticus.
• Significant mislabeling rates were identified: 60% in fried fish products and 30% in processed fish products.

Conclusions:

• The developed multiplex PCR protocol provides an effective tool for authenticating Rohu, Thaila, and Tilapia.
• The findings highlight widespread fish mislabeling, necessitating improved food inspection and regulatory enforcement.