Identification of Geographic Origin of Ictalurid Catfish and Penaeid Shrimp by Elemental Profiling

Abstract

Three investigations were performed related to identification of geographic origin of aquatic products by elemental profiling and multivariate statistics. In the first study, fillets of channel catfish Ictalurus punctatus from three geographic areas, fillets of hybrid catfish (♀ I. punctatus x ♂ blue catfish I. furcatus) from one of the areas, water samples from the culture ponds, and feed samples were subjected to elemental analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES). The fillets were low in concentrations of several elements, and ICP-AES could consistently detect only 11 elements (Al, Ca, Cr, Cu, Fe, K, Mg, Na, P, S, and Zn). Catfish fillets collected from the three geographic areas were different for all the 11 elements (P<0.05) consistently detected. In addition, composition of fillets was not greatly influenced by water chemistry or feed composition. In the second study, elemental analyses (Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Na, P, S, Se, and Zn) were made on fillets of channel catfish from ponds in which fish were fed and of channel and hybrid catfish from fertilized ponds. Hybrid and channel catfish fillets from fish in fertilized ponds did not differ for most of the elements analyzed. However, Ictalurid catfish cultured in feeding ponds and fertilized ponds differed for all elements except aluminum. In the third study, 20 elements in Pacific white shrimp Litopenaeus vannamei from three geographic areas, water samples from the culture ponds, and feed samples were analyzed by ICP-AES. Three types of shrimp samples were prepared: head on shell on (HOSO), headless shell on (HLSO) and peeled undeveined (PUD). Sixteen elements were different among the three types of shrimp products (P<0.05). Nine elements in HOSO shrimp, 13 elements in HLSO shrimp and 8 elements in PUD shrimp were different among the three geographic areas (P<0.05). In addition, elemental composition of shrimp showed some relationship to elemental concentrations in water, but not to elemental concentrations in feed. Multivariate statistical methods, including principal component analysis (PCA), canonical discriminant analysis (CDA) and k-nearest-neighbor analysis, were reliable in separating Ictalurid catfish and Penaeid shrimp to their geographic origin or to the production method in all of the three investigations. Results suggested that element profiling combined with multivariate statistics has a potential for validating the geographic origin of aquatic products, but much additional research would be needed to refine the methodology.