Molecular Identification of Commercial Spicy Pollack Roe Products by PCR-RFLP Analysis

Abstract

ABSTRACT: Spicy pollack roe products are a popular seafood item made from fish eggs that should be made with salt-cured mature roes of walleye pollack Theragra chalcogramma. Because of high demand and poor catch of walleye pollack, however, spicy pollack roe products are often susceptible to substitution with roes of closely related codfish. In this study, a simple method identifying the ingredients of commercial spicy pollack roe products was developed to differentiate walleye pollack from codfish substitutes such as gray cod Gadus macrocephalus using PCR-RFLP (Restriction Fragment Length Polymorphism) analysis. PCR amplification of the mitochondrial cytochrome b gene yielded single fragments commonly from pollack and cod. Direct digestion of the PCR products with Mph11031 restriction enzyme showed an unique restriction fingerprint only in pollack. This PCR-RFLP analysis enabled the reliable identification of commercial spicy pollack roe products made by only pollack roes from products padded with cod roes. It thus can be useful to expose substitution of pollack roes with lower valued codfish roes in commercial spicy pollack roe products.