Application of voltammetric e-tongue for the detection of ammonia and putrescine in beef products

This work describes the sensing properties of voltammetric sensors based on modified screen-printed electrodes with bisphthalocyanine and polypyrrole, respectively. The electrochemical responses of sensors to aminic compounds, including ammonia and putrescine, were analyzed. The voltammetric signals are related to the redox properties of electroactive compounds used as modifiers, strongly influenced by amine compounds from the electrolyte solution. The possibility of detecting and quantifying the amine compounds in beef extract powder was studied. Sensors are very sensitive toward amine compounds, the lowest detection limits being 1.85 μM for ammonia and 0.34 μM for putrescine. A sensors array was developed using the two types of electrodes and was subsequently used in beef freshness monitoring. As demonstrated by means of Principal Component Analysis and Partial Least Squares-Discriminant Analysis, the multisensor system is able to discriminate and classify the samples according to their storage time.