From Citrus Waste to Valuable Resources: A Biorefinery Approach

Abstract

Typically, citrus waste is composted on land by producers or used as livestock feed. However, the biorefinery approach offers a sustainable and economically viable solution for managing and valorizing these agricultural residues. This review examines research from the period 2014 to 2024. Citrus waste can be utilized initially by extracting the present phytochemicals and subsequently by producing value-added products using it as a raw material. The phytochemicals reported as extracted include essential oils (primarily limonene), pectin, polyphenolic components, micro- and nano-cellulose, proteins, and enzymes, among others. The components produced from the waste include bioethanol, biogas, volatile acids, biodiesel, microbial enzymes, and levulinic acid, among others. The review indicates that citrus waste has technical, economic, and environmental potential for utilization at the laboratory scale and, in some cases, at the pilot scale. However, research on refining pathways, optimization, and scalability must continue to be an active field of investigation.

Keywords

• citrus waste
• biorefinery
• phytochemicals
• biofuels
• bioactive compounds
• enzymes