A simple and reliable new microchip electrophoresis method for fast measurements of imidazole dipeptides in meat from different animal species

Abstract

Microchip electrophoresis (ME) was applied for the separation of two physiologically important imidazole dipeptides-carnosine and anserine. The capacitively coupled contactless conductivity detector (CD) was employed for quantification of both dipeptides after separation in a new home-built ME unit. The separation parameters were optimized as follows to enable quantitative, baseline separation of both dipeptides: injection time 16 s, injection voltage 900 V/cm, and separation voltage 377.1 V/cm. The CD detector responded linearly to both imidazole dipeptides in the range 0-20 mg L. The known addition methodology was applied to test the accuracy of the measurement of imidazole dipeptides in a complex sample. The recoveries for measurement of carnosine in the mixture ranged from 96.1 to 105.0%, whereas those for anserine amounted to 96.6 to 102.0%. This method was also applied to real biological samples. The results exhibited a satisfactory agreement with a standard HPLC method. The proposed ME method represents a cheap, fast, and simple alternative to the existing, more complicated and expensive HPLC methods. This method does not demand either the optical detectors nor tedious derivatization of sample, which are unavoidable in HPLC methods. The method was succesfuly applied for animal species determination in unknown meat samples using the carnosine/anserine ratio, and subsequently, it could be used in a food fraud prevention process. Graphical abstract Microchip electrophoresis portable device with a CD detector for determination of imidazole dipeptides in model samples and real meat samples from different animal species.

Nontargeted Analysis of Lipid Extracts Using 1H NMR Spectroscopy Combined with Multivariate Statistical Analysis to Discriminate between the Animal Species of Raw and Processed Meat

“…A pork sample purchased from a local butcher served as a control sample to validate the method. Processed meat products included samples produced from beef (18), pork (31), and poultry (27). In addition, five processed meat products containing poultry and pork (3), as well as beef and pork (2) were used to test the robustness of the classification model against mixtures.…”

“…The carnosine/anserine ratio has been suggested to estimate the meat species and identify the species or origin of meat used in processed meat products. For the quantification of these dipeptides, different methods were described such as high-performance liquid chromatography and microchip electrophoresis. − Similarly, it has already been possible to distinguish between different meat samples (chicken, chevon, beef, and donkey) based on the polar metabolites. The metabolic differences between the different meat samples were investigated using nuclear magnetic resonance (NMR) spectroscopy in conjunction with multivariate data analysis techniques .…”

Differentiation of meat species of raw and processed meat based on polar metabolites using 1H NMR spectroscopy combined with multivariate data analysis

“…These classes include amino acids and their derivatives, organic acids, carbohydrates, purine derivatives, imidazole dipeptides, and quaternary ammonium compounds (QAC) (26). Various extraction protocols are described in the literature to capture polar meat compounds, but these often only focus on a single class of compounds, such as amino acids or imidazole dipeptides (27)(28)(29)(30). Here, an extraction procedure was developed that allows for simultaneous extraction and detection of the majority of polar metabolites.…”

“…Buckets that were assigned to QAC (L-carnitine, choline, O-acetyl-L-carnitine), imidazole dipeptides (L-anserine, L-carnosine), and degradation products of ATP (inosine, hypoxanthine) were demonstrated to be involved in the classification of beef/lamb, beef/pork, and/or poultry/nonpoultry (Supplementary Figure 1; Supplementary Table 2). In literature, especially levels of imidazole dipeptides and their ratios were described as being species-dependent (29,(44)(45)(46)).…”

Selective detection of cytochrome C by microchip electrophoresis based on an aptamer strategy

“…Due to its high separation efficiency, easy operation, and rapid quantification, there has been great interest in using MCE for the detection of biological species, e.g. DNA, amino acids, proteins, and bacteria .…”