A Comprehensive Review on the Refinery of Citrus Peel Towards the Production of Bioenergy, Biochemical and Biobased Value-Added Products: Present Insights and Futuristic Challenges.

The widespread nature of citrus cultivation, processing, and consumption on a global scale results in a substantial volume of by-products within the citrus processing industries. The indiscriminate disposal of these by-products, without a proper treatment and disposal methods, poses a significant environmental hazard. Amongst, citrus peel waste being a prolific by-product, is generated on a large scale and is increasingly gaining recognition for its industrial potential in producing fuels and chemicals. This encompasses biofuels such as ethanol and biogas, bioactive compounds like flavonoids, alkaloids, essential oils, D-limonene, and pectin, as well as various biochemical compounds including organic acid, biosurfactants, enzymes, and bioplastics through strategic valorization processes. The valorization process entails a variety of techniques, including chemical, biological, and physical treatment methods. Physical treatments, such as microwave and ultrasound-assisted extraction methods, are employed, alongside extraction using solvents and biological methods including fermentation and saccharification, which are integral components of the valorization process. Each of these methodologies contributes to the production of the aforementioned value-added compounds. Furthermore, the recently developed supercritical fluid can also be employed for extracting these valuable compounds, enhancing the versatility and efficiency of the valorization process. This review addresses a refinery strategy, emphasizing the incorporation of a suitable valorization/treatment approach to transform citrus peel waste into high-value-added products. [ABSTRACT FROM AUTHOR]