Orange is a fruit of great importance for the Brazilian and Spanish economy. However, the processing of this fruit to obtain juices, soft drinks, sweets, jellies and other products generates a large amount of waste. Orange peels have a large amount of cinnamic acid and its derivatives, such as ferulic, caffeic, synapic and p-coumaric acids. These compounds have antioxidant activities and several other beneficial health effects. In this sense, these peels can be reused to obtain high added-value products. The methods described in the literature for the determination of phenolic compounds are based on chromatographic, electrophoretic and spectroscopic techniques. These methods often require expensive equipment, laborious procedures, and careful sample pre-treatment. Electroanalytical methods, in turn, use cheaper and simpler equipment, apart from the fact that they do not require exhaustive sample pre-treament. On the other hand, these devices do not have adequate selectivity for individual discrimination of most existing phenolic compounds. In this sense, new strategies are necessary for the sensitive and selective determination of phenolic compounds found in orange peels. Currently, the use of molecularly imprinted polymers (MIP) as a recognition element for electronic tongues is an alternative to obtain sensitive and selective analytical platforms for several compounds. In view of this, the objective of this research project is to develop an electronic tongue using MIP-based electrochemical sensors for the sensitive and selective determination of cinnamic, ferulic, caffeic, synapic and p-coumaric acid in orange peel. This platform is based on an array of sensors capable of simultaneously discriminating different analytes in a complex matrix through mathematical methods involving pattern recognition and/or multivariate analysis. This allows the discrimination of structurally similar compounds in complex samples, such as phenolic compounds found in orange peels, through a simple analysis procedure.
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