Trends in valorization of citrus by-products from the net-zero perspective: Green processing innovation combined with applications in emission reduction

Background: Climate change is a serious challenge for all humans, and global net-zero targets can only be achieved with collaborative endeavors from various industries. Citrus is one of the largest fruit industries in the world, and vast quantities of citrus by-products (CBP) are produced due to large-scale planting and processing activities. However, CBP are usually left in the environment, leading to economic loss, environmental pollution, and carbon emissions. Even though a small fraction of CBP can be valorized, the processing may cause energy loss and secondary pollution. For global net-zero targets, there is an urgent need for technological innovation to develop green low-carbon processing industries and facilitate better utilization of citrus biomass resources to reduce carbon emissions. Scope and approach: This review summarizes the far-reaching impacts of CBP management on climate change, and proposes innovative technologies and solutions for CBP to facilitate sustainable development and global carbon neutrality goals. Key findings and conclusions: CBP exhibit great potential for achieving net-zero targets in terms of yield, utilization status, and composition characteristics. The carbon footprint during processing can be reduced through green equipment and solvents, as well as renewable energy sources and digital aids. Besides, the rich variety of by-product types and compositions contribute to great potential to reduce carbon footprint in food systems (soil carbon sequestration, management of livestock methane (CH4), development of low-carbon food, and reduction of food waste), develop biomass energy (biodiesel, biofuel cells and combustible gases), and sustainable materials for livelihood, pollution control and energy storage.