Express determination of antioxidant activity of confectionery products using a disposable potentiometric sensor system

The introduction of antioxidants into food systems in order to increase their functional effect, increase the shelf life creates the need for their quantitative determination. Existing methods of laboratory determination of AOA in confectionery products, using the preparation of colloidal solutions by dissolution at a controlled temperature as a stage in the preparation of solid-phase samples, solve a wide range of analytical tasks, but are characterized by high labor intensity. The article is devoted to the development of a single-use potentiometric sensor system (PSS) and its application in assessing the antioxidant activity (AOA) of solid-phase food systems on the example of confectionery products (jelly, pastille, whipped). Thick-film PSS electrodes were manufactured using screen printing; a carbon-containing electrode used as an indicator electrode was modified with multilayer carbon nanotubes (MNT), a silver-containing electrode modified with mixed sediment and stabilized with Naphion served as a reference electrode. AOA was evaluated by a potentiometric method using a mediator system of potassium hexacyanoferrates (K3[Fe(CN)6/K4[Fe(CN)6]). A schematic representation of the AOA evaluation procedure of solid-phase food samples using PSS and cyclic voltammograms recorded on a thick-film carbon-containing electrode at a speed of 50 mV/s in a sodium-phosphate buffer pH 7.4 containing 1 mmol/dm3 K3[Fe(CN)6] and 1 mmol/dm3 K4[Fe(CN)6] and the dependence of the MNT potential (1 % wt.)/C/PET in a sodium-phosphate buffer pH 7.4 containing a different ratio of K3[Fe(CN)6/K4[Fe(CN)6]. The results of the analysis of confectionery products obtained using PSS are comparable to the results obtained using commercial electrodes. The results of the analysis of sections of confectionery products obtained using PSS under load conditions (4.8 kPa) correlate with the results of the analysis of their colloidal solutions. The proposed PSS is disposable, makes it possible to analyze solid-phase samples in real time (in situ), demonstrates high analytical efficiency and can be made in the form of express tests for further use in determining the AOA of confectionery products. In combination with a portable type potentiometric analyzer, the proposed PSS can be used in non-laboratory conditions.