Fast determination of histamine in cheese by nuclear magnetic resonance (NMR).

A rapid and quantitative (1)H nuclear magnetic resonance (NMR) method was developed to analyze histamine in cheeses. The procedure is simple because the acid extract is analyzed directly, without any need for further filtration, derivatization, or other manipulation. This NMR method was demonstrated to be specific by 2D total correlation spectroscopy (TOCSY) and heteronuclear multiple-quantum coherence (HMQC) experiments and reliable in terms of linearity, accuracy, recovery, repeatability, and limits of detection (LOD). Good precision, with relative standard deviation (RSD) <4%, recovery of 100%, and a range of 0.6-1 mg/kg for the LOD were obtained. The NMR method was successfully applied to different types of cheese, ranging from soft to hard. No interference from free amino acids, proteins, and other natural components was detected. The NMR method could be transferred to other kinds of food.