Enzyme-Enhanced Selective Physicochemical Transformation of Lignocellulosic Fibers for Green Textiles: A Case Study with Dual-Purpose Pineapple Plant toward Sustainable Agro-Industries

Using leaf fibers from pineapple (PALFs) as a model dual-purpose plant, we deliberately explore the effect of bio- and semibiobased treatment using xylanase, cellulase, and a mixture of pectinase and amylase. We assess these treatments for their potential to selectively and precisely remove lignocellulosic components. Additionally, we examine how they modify the relative content of cellulose, hemicellulose, and lignin, as these are key factors affecting the physical appearance, dimensional structures, and mechanical integrity. Pretreatment and post-treatment with alkaline further affect how efficiently the enzymes function toward hemicellulose and lignin elimination. As the degradation yield can be as high as 99 wt %, i.e., overdigestion, for alkaline pretreatment followed by xylanase or cellulase, the chemical analysis by Fourier transform infrared spectroscopy (ATR-FTIR) finds that each treatment selectively removes different lignocellulose compounds (up to over 50% for hemicellulose and lignin) when compared to the normalized amount of cellulose. In addition, disintegration of the microfiber bundles (10–50 μm) in the PALFs upon removal of hemicellulose and lignin into individual fibers of size around 5–8 μm is also detected under scanning electron microscopy (SEM). Even though the mechanical properties and load-bearing capacity of the treated fibers are reduced upon the treatment, optimally treated fibers by diluted xylanase and diluted xylanase + alkaline, with light appearance, soft touch, and a well-defined and debundling structure, are successfully fabricated into yarns under an industrial ring spinning process with as high as 80 wt % PALF content. Despite a change in surface chemistry, the treated PALFs can be naturally dyed by both hot and cold processes with excellent color fastness to washing, perspiration, and light under AATCC TM 61:2013 METHOD 1A. The PALFs after enzyme and alkaline treatment with a thickness of 10–50 mm have high sound absorption capability in the frequency range of 800–6300 Hz. The PALF yarns are successfully woven into plain and patterned fabrics using an industrial loom, illustrating the scalability and practicality of our nature-based solution to valuation of the dual-purpose plant's wastes.