Stepwise degumming of pineapple leaf fibers with tunable fineness and excellent antibacterial property

Pineapple leaf fibers (PALFs) are often disposed of as agricultural waste or byproducts. These fibers have great potential for textile and functional applications due to their high cellulose content, good tensile strength, and excellent antibacterial properties. Degumming is a critical process to remove non-cellulose components, enabling the transformation of PALFs into value-added products. However, traditional one-step alkaline degumming cannot precisely remove target specific gum residues, complicating the control of fiber fineness and promising antibacterial properties. To address these challenges, this study proposed an innovative step-by-step degumming strategy for PALF, termed SSD-PALF in short, which enabled the selective and sequential removal of components such as lignin and hemicellulose. This approach allowed separation of tightly packed fiber bundles into individual ribbon-like fibrils. The ultimate fineness and chemical components of four widely cultivated varieties across the globe were investigated. Furthermore, the proposed SSD-PALF enabled a remarkable reduction in hemicellulose content of Queen PALF from 23.49% to 4.89 %, while preserving over 10 % lignin. Correspondingly, the fiber width decreased significantly, from 45 to 75 μm to 16.7 μm, reflecting a 72.2 % improvement in fineness. It is evident that the fiber fineness can be well regulated through the precise control of hemicellulose ratio within PALF. It is flexible to reduce the fiber fineness by 42 %, 31 % and up to 28 % of its original value according to our stepwise degumming method. Notably, the refined PALF maintained robust antibacterial properties against three bacteria (S. aureus, E. coli and C. albicans), with > 90 % bacteriostatic rate. These findings point to ways of tuning PALF fineness and retaining its functional properties, potentially extending its applications in both textile and non-textile industries.