Pectin production involves extracting soluble pectin from citrus peels and apple pomace, leaving behind significant quantities of residual material. After extraction and primary separation, a wet, fibrous biomass remains, alongside smaller quantities of fine residues generated during clarification steps. These side streams, typically called spent peels or used citrus peels, can contain structural polysaccharides, residual pectin, sugars, organic acids, and minerals. 

Currently, these materials are typically managed through low-value routes such as neutralization and disposal or energy recovery, which can incur costs and underutilize their potential. Their high moisture content, variable composition, and exposure to process conditions can limit reuse options, while regulatory constraints may restrict applications in areas such as food. However this should not limit the use and application of the spent peels. Where necessary, the regulatory aspect needs to be looked at. 

New approaches that enable the extraction, fractionation, or transformation of these side streams into functional materials or industrial inputs could unlock the value embedded in them and enable their integration into higher-value applications. This would reduce reliance on disposal routes and support more sustainable and circular production practices.