Selective Determination of Lysine in Dry-Cured Meats Using a Sensor Based on Lysine-α-Oxidase Immobilised on a Nylon Membrane

An enzymatic sensor employing lysine oxidase (LOx) with the immobilised enzyme system by crosslinking with glutaraldehyde using an immunodyne ABC nylon membrane, in combination with an oxygen electrode, has been optimised to determine the lysine content in dry-cured ham and dry-fermented sausage at different cured times. The amperometric signal obtained due to the oxygen depletion (consumed oxygen) during the lysine oxidation was recorded at 5 s in the immobilised enzyme sensor, and the reaction rates (slope) were related to the lysine content. A linear relationship between the consumed oxygen as a function of time (mg O2/l/s) and the lysine concentration in the range 10–250 μM (R2 = 0.9946) for the immobilised enzyme system was found. The immobilised enzyme sensor showed a high specificity and sensibility. Nevertheless, the stability of the immobilised enzyme at the assay temperature was very poor, and thus, a new membrane was required for each analysis. The analysis of lysine with the immobilised enzyme system in cured meat samples revealed very good agreement with the determination performed through standard HPLC methodology, which validated the use of this sensor as an alternative technique to evaluate cured meat quality.This study was funded by Grant Prometeo 2012/001 from Conselleria d’Educació of Generalitat Valenciana (Valencia, Spain) and the scholarship to F. A. Jadán Piedra from Secretaria de Educación Superior, Ciencia, Tecnología e Innovación (SENESCYT) of Ecuador.Peer reviewe

Endogenous and food-derived polyamines: determination by electrochemical sensing

olyamines (PAs) are involved in a variety of fundamental physio-pathologic processes. The concentration of these polycations in organs and tissues depends on their endogenous production and oxidation rates, and on their intake from foods. Besides being largely accepted as markers for the progress of several pathologies, PAs may exert themselves different effects on humans, ranging from being positive to be drastically detrimental depending on the organism conditions. Thus, if the determination of polyamines content in tissue samples is of great importance as they could be indicators of several diseases, their quantification in food is fundamental for modulating the diet to respond to a specific human health status. Thus, the determination of PA content in food is increasingly urgent. Standard analytical methods for polyamine quantification are mainly based on chromatography, where high-performance liquid chromatography and gas chromatography are the most often used, involving pre-column or post-column derivatization techniques. Driven by the growing need for rapid in situ analyses, electrochemical biosensors, comprising various combinations of different enzymes or nanomaterials for the selective bio-recognition and detection, are emerging as competitors of standard detection systems. The present review is aimed at providing an up-to-date overview on the recent progresses in the development of sensors and biosensors for the detection of polyamines in human tissues and food samples. Basic principles of different electrochemical (bio)sensor formats are reported and the applications in human tissues and in foods was evidenced