## 4 Electronic Nose, Electronic Tongue, and Electronic Eye in Sensory Food Sciences  
Electronic nose (E-nose) and electronic tongue (E-tongue) are gas sensors or chemical sensors that mimic the human sense of smell and taste, respectively [55]. An E-nose is a gas sensor array that generates a unique fingerprint response to specific volatile compounds. These data are processed using pattern recognition algorithms, such as artificial neural networks, to enable discrimination and classification [56]. E-nose devices typically use metal oxide semiconductor field-effect transistors, conductive polymers, quartz crystal microbalances, or, most commonly, metal oxide semiconductor sensors. These sensors detect specific gases by changing their material resistance. [PERSON] and [PERSON] [57] recently confirmed the potential of carbon nanotube-titanium dioxide hybrids for detecting volatile organic compounds in E-nose devices. The E-tongue is commonly used with chemical sensors such as electrochemical sensors, including voltammetric, amperometric, potentiometric, conductometric, impedimetric, biosensors, and optical sensors like spectroscopic sensors [58; 59; 60]. Like the gas sensors in an E-nose, the chemical sensors in an E-tongue interact with analytes, inducing reversible changes in their electrical properties. These changes generate measurable electrical signals, which are then analyzed for pattern recognition and classification [56]. A typical E-tongue system comprises a chemical sensor array, a reaction vessel, measurement devices, transducers, data acquisition units, and data processing and pattern recognition algorithms [56].  
The primary purpose of E-nose and E-tongue technologies is to enhance sensory analysis by providing objective, quantifiable data that account for human perceptions' inherent subjectivity and variability. Unlike human sensory evaluation, which depends on memory recall and individual experience, these electronic systems offer consistency,reproducibility, and the ability to detect subtle differences that may go unnoticed by the human senses [61]. While the human nose can evaluate smell, individual judgments may be biased as they cannot be used to detect toxic volatile compounds. In addition, the human nose has detection limits for different volatile compounds, making it unsuitable as a universal tool for all smell-related discrimination and classification [56]. Moreover, training and maintaining a sensory panel is time-consuming and costly. In some cases, sensory panels may introduce bias if the panelists are not well-trained. To address these limitations, researchers have increasingly employed the E-tongue as a rapid, unbiased, and cost-effective alternative to human sensory evaluation [62]. In the food and beverage industry, these devices are widely used to evaluate the sensory characteristics of products, either complementing or replacing traditional sensory analysis and serving as quality indicators.  
Initially, E-nose and E-tongue devices were expensive, required significant laboratory space, and were neither portable nor easily accessible to many companies and researchers [63]. However, recent advances have focused on developing low-cost sensors to create smaller, portable devices, significantly increasing their usability and accessibility.