Equivalence testing of histamine methods - Final Report

Histamine fish poisoning is an allergy-like form of food poisoning that continues to be a major problem in seafood safety. The FAO/WHO Codex Alimentarius as well as EU legislation have therefore set maximum limits for histamine in fish and fish products. The analytical methods requested by Codex and by EU are different and concern has been raised that this could lead to disputes in the international trade of seafood. This report describes the outcome of a study, commissioned by DG Health and Consumers and carried out by DG Joint Research Centre, that compared the performance of the method for determining histamine in fish as mandated by Regulation (EC) No 2073/2005 to the method mandated in Codex Alimentarius Standard 165-1989. The EU mandated method is based on HPLC separation of histamine and subsequent detection by a UV detector. It was published in the Journal of AOAC International, but has not been validated by a collaborative study. The Codex method is AOAC 977.13, which is a based on the formation of a fluorescent derivative of histamine and subsequent measurement in a fluorimeter; it has been validated by collaborative trial. The correct implementation of both methods by JRC was assessed by carrying out performance verification studies using various canned and fresh scromboid fish samples (tuna, macrel, and herring) taken from the Belgian market. Repeatability (RSDr) and intermediate precision (RSDip) as well as recovery data were generated. Both methods conformed to specifications. Various approaches were followed to test the equivalency of both methods, which were based on statistical hypothesis testing (t-test), regression analysis and benchmarking against established reference values. All approaches indicated that the two methods are not fully equivalent. The EU mandated method has a tendency to overestimate, while the Codex method has a tendency to underestimate the histamine content in fish. It was recognised that the EU mandated method was very accurate when applied to fresh tuna. A distinct matrix influence was noticed for all other fish species tested, leading to an overestimation of the histamine content. It is therefore recommended to optimise the EU method so that matrix effects can be eliminated, or at least taken into account in an appropriate manner, In addition, a collaborative trial for the HPLC method to establish reproducibility data for the method should be organised. In line with current practice the collaborative study should also require to correct the reported data for recovery. Furthermore, as an ad-hoc measure the replacement of the HPLC method mentioned in Regulation (EC) No 2073/2005 by a ring-tested HPLC method, which are already available, could be considered.JRC.D.5-Standards for Food Bioscienc