Articoli in Scholar Use of screen-printed sensors for quality loss determination in vegetables rich in vitamin C or with high ascorbate oxidative metabolism: a fresh-cut parsley and iceberg lettuce case study

Introduction: The use of screen-printed sensors for ascorbic acid (AA) electrochemical determination in fresh-cut fruit and vegetables is the core of the Real Time Check IV Gamma project since when AA has been recognized as rapid and reliable quality indicator in minimally processed produce. Methods: A carbon screen-printed electrode, coupled with an innovative telemetry device based on IoT (Internet of Things) technology, was used for a real time assessing of quality loss of fresh-cut parsley and iceberg lettuce, by recording the AA content, at harvest, during the processing and transport, and all along 5 days of shelf life, both when the cold chain was strictly respected and interrupted. The sensors work at an applied potential of + 120 mV, are specific for AA, and have been proven to be free of interferences. The sensitivity is 0.3001 ± 0.029 nA*µM-1 and the LOD 0.72 ± 0.117 µM. Results: AA content in parsley is high and was recorded by the sensors as a baselinesubtracted currents, expressed in nanoamperes, and transformed in mg*kg-1 of fresh weight. Differently, a direct amperometric real time detection of AA content in iceberg lettuce was not possible since a strong enzymatic activity, consistent with ascorbate peroxidase and ascorbate oxidase activity, prevailed. This enzymatic activity was recorded by the sensor system as an AA decreasing current and the half-life of exponential decay of the current curves was used as an indicator of the speed of quality loss. All the results were confirmed by traditional methods, AA with the titrimetric one and enzymatic activity by specific assays. Discussion: the proposed device is built with simple and inexpensive disposable components. It works as a portable workstation and was designed to be used by non-specialized personnel, at a farm level, in all the companies involved in the productive chain.