The citrus industry produces substantial peel waste, often regarded as an environmental challenge but rich in bioactive compounds, particularly polyphenols, such as phenolic acids, flavonoids, and limonoids. These components hold potential applications in food, pharmaceuticals, and biofuel industries. This chapter explores the application of an electronic nose (E-nose) coupled with chemometric methods, such as principal component analysis (PCA), hierarchical cluster analysis (HCA), and discriminant analysis (DA), in the discrimination of citrus peel waste from varying geographical regions. The procedures for conducting chemometric methods are also discussed in detail. This protocol may provide valuable insight into the chemical complexities of citrus peels, facilitating their classification and thereby emphasizing the importance of chemometric methods in advancing food quality and authenticity assurance and environmental sustainability.