Over the last years, there has been an increasing demand for fast, highly sensitive and selective methods of analysis to meet new challenges in environmental monitoring, food safety and public health. In response to this demand, biosensors have arisen as a promising tool, which offers accurate chemical data in a timely and cost-effective manner. However, the difficulty to obtain sensors with appropriate selectivity and sensitivity for a given analyte, and to solve analytical problems which do not require the quantification of a certain analyte, but an overall effect on a biological system (e.g. toxicity, quality indices, provenance, freshness, etc.), led to the concept of electronic tongues as a new strategy to tackle these problems.In this direction, to improve the performance of electronic tongues, and thus to spawn new application fields, biosensors have recently been incorporated to electronic tongue arrays, leading to what is known as bioelectronic tongues. Bioelectronic tongues provide superior performance by combining the capabilities of electronic tongues to derive meaning from complex or imprecise data, and the high selectivity and specificity of biosensors. The result is postulated as a tool that exploits chemometrics to solve biosensors’ interference problems, and biosensors to solve electronic tongues’ selectivity problems.The review presented herein aims to illustrate the capabilities of bioelectronic tongues as analytical tools, especially suited for screening analysis, with particular emphasis in water analysis and the characterization of food and beverages. After briefly reviewing the key concepts related to the design and principles of electronic tongues, we provide an overview of significant contributions to the field of bioelectronic tongues and their future perspectives.

Colorimetric sensors based on polydiacetylene (PDA) materials have been developed for detecting acid-base. Since PDAs often change color upon exposure to organic solvents, most of previous studies used water as a medium. This presents a problem for detecting organic acids and bases with limited solubility in water. In this contribution, we explore the applications of PDA/Zn²⁺/ZnO nanocomposites as colorimetric sensors for detecting organic acid-base in various organic solvents and food products. Owning to its high color stability, this class of PDA materials can be dispersed in tetrahydrofuran, dimethyl sulfoxide, and ethanol while the blue phase remains. We have found that the sensitivity of PDA/Zn²⁺/ZnO nanocomposites to acid-base varies with the solvent properties. The sensors prepared by dispersing in different solvents can detect acid-base at different concentrations. Raman spectroscopy carried out directly in the liquid suspensions reveals the mechanisms of color transition in each system. Fine-tuning of the sensitivity can also be achieved by varying the ZnO ratios within nanocomposites. The ability to control the sensitivity allows the utilization of PDA/Zn²⁺/ZnO nanocomposites for semi-quantitative analysis of acid-base in food products. Solid-state sensors fabricated by embedding in nylon filters can determine the concentration of sorbic acid in fruit juices. The freshness of milk can be indicated via naked-eye detection as well. Our study expands the applications of PDA materials as colorimetric sensors for food industries.